move settings and datastructure projects from content to here

benchmark/build.gradle

@@ -1,9 +1,9 @@
 plugins {
-    id "io.morethan.jmhreport" version "0.9.0"
-    id "org.cyclonedx.bom" version "1.7.2"
-    id "com.github.spotbugs" version "5.0.13"
     id "checkstyle"
     id "pmd"
+    id "io.morethan.jmhreport" version "0.9.0"
+    id "org.cyclonedx.bom" version "1.7.4"
+    id "com.github.spotbugs" version "6.0.0-beta.3"
 }
 
 apply from: rootProject.file('gradle/test/jmh.gradle')

build.gradle

@@ -31,7 +31,7 @@ ext {
 }
 
 subprojects {
-    apply from: rootProject.file('gradle/ide/idea.gradle')
+    //apply from: rootProject.file('gradle/ide/idea.gradle')
     apply from: rootProject.file('gradle/repositories/maven.gradle')
     apply from: rootProject.file('gradle/compile/java.gradle')
     apply from: rootProject.file('gradle/test/junit5.gradle')

config/build.gradle

@@ -0,0 +1,5 @@
+dependencies {
+    api project(':settings-datastructures')
+    testImplementation project(':settings-datastructures-json')
+    testImplementation project(':settings-datastructures-yaml')
+}

config/gradle.properties

@@ -0,0 +1 @@
+version = 5.0.5

config/src/main/java/module-info.java

@@ -0,0 +1,13 @@
+import org.xbib.config.ConfigLogger;
+import org.xbib.config.NullConfigLogger;
+import org.xbib.config.SystemConfigLogger;
+import org.xbib.settings.SettingsLoader;
+
+module org.xbib.config {
+    exports org.xbib.config;
+    uses ConfigLogger;
+    uses SettingsLoader;
+    provides ConfigLogger with NullConfigLogger, SystemConfigLogger;
+    requires org.xbib.settings.api;
+    requires transitive org.xbib.settings.datastructures;
+}

config/src/main/java/org/xbib/config/ConfigException.java

@@ -0,0 +1,17 @@
+package org.xbib.config;
+
+@SuppressWarnings("serial")
+public class ConfigException extends RuntimeException {
+
+    public ConfigException(Exception e) {
+        super(e);
+    }
+
+    public ConfigException(String message) {
+        super(message);
+    }
+
+    public ConfigException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

config/src/main/java/org/xbib/config/ConfigFinder.java

@@ -0,0 +1,168 @@
+package org.xbib.config;
+
+import java.io.IOException;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.FileVisitOption;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.PathMatcher;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.nio.file.attribute.FileTime;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class ConfigFinder {
+
+    private final FileSystem fileSystem;
+
+    private final EnumSet<FileVisitOption> opts;
+
+    private final List<Path> result;
+
+    private Comparator<Path> comparator;
+
+    public ConfigFinder() {
+        this(FileSystems.getDefault(), EnumSet.of(FileVisitOption.FOLLOW_LINKS));
+    }
+
+    public ConfigFinder(FileSystem fileSystem, EnumSet<FileVisitOption> opts) {
+        this.fileSystem = fileSystem;
+        this.opts = opts;
+        this.result = new ArrayList<>();
+    }
+
+    public ConfigFinder find(String path, String pathPattern) throws IOException {
+        return find(null, null, fileSystem.getPath(path), pathPattern);
+    }
+
+    public ConfigFinder find(String base, String basePattern, String path, String pathPattern) throws IOException {
+        return find(base == null || base.isEmpty() ? null : fileSystem.getPath(base), basePattern,
+                path == null || path.isEmpty() ? null : fileSystem.getPath(path), pathPattern);
+    }
+
+    public ConfigFinder find(Path base, String basePattern, Path path, String pathPattern) throws IOException {
+        return find(base, basePattern, path, pathPattern, null);
+    }
+
+    /**
+     * Find the most recent version of a file.
+     *
+     * @param base        the path of the base directory
+     * @param basePattern a pattern to match directory entries in the base directory or null to match '*'
+     * @param path        the path of the file if no recent path can be found in the base directory or null
+     * @param pathPattern     the file name pattern to match
+     * @param modifiedSince time stamp for file or null
+     * @return this Finder
+     * @throws IOException if find fails
+     */
+    public ConfigFinder find(Path base,
+                             String basePattern,
+                             Path path,
+                             String pathPattern,
+                             FileTime modifiedSince) throws IOException {
+        if (base != null && path == null) {
+            // find input in base
+            final PathMatcher baseMatcher = base.getFileSystem()
+                    .getPathMatcher("glob:" + (basePattern != null ? basePattern : "*"));
+            final PathMatcher pathMatcher = base.getFileSystem()
+                    .getPathMatcher("glob:" + (pathPattern != null ? pathPattern : "*"));
+            List<Path> directories = new ArrayList<>();
+            List<Path> list = Files.find(base, 1,
+                    (p, a) -> {
+                        if (Files.isDirectory(p) && baseMatcher.matches(p.getFileName())) {
+                            directories.add(p);
+                            return false;
+                        }
+                        return Files.isRegularFile(p) && pathMatcher.matches(p.getFileName());
+                    }, FileVisitOption.FOLLOW_LINKS)
+                    .collect(Collectors.toList());
+            if (directories.isEmpty()) {
+                return this;
+            }
+            list.sort(LAST_MODIFIED_COMPARATOR.reversed());
+            result.addAll(list);
+            path = list.iterator().next();
+        }
+        if (path == null) {
+            return this;
+        }
+        final PathMatcher pathMatcher = path.getFileSystem()
+                .getPathMatcher("glob:" + (pathPattern != null ? pathPattern : "*"));
+        Files.walkFileTree(path, opts, Integer.MAX_VALUE, new SimpleFileVisitor<>() {
+            @Override
+            public FileVisitResult visitFile(Path p, BasicFileAttributes a) {
+                if ((Files.isRegularFile(p) && pathMatcher.matches(p.getFileName())) &&
+                        (modifiedSince == null || a.lastModifiedTime().toMillis() > modifiedSince.toMillis())) {
+                    result.add(p);
+                }
+                return FileVisitResult.CONTINUE;
+            }
+        });
+        return this;
+    }
+
+    public ConfigFinder sortBy(String mode) {
+        if ("lastmodified".equals(mode)) {
+            this.comparator = LAST_MODIFIED_COMPARATOR;
+        } else if ("name".equals(mode)) {
+            this.comparator = PATH_NAME_COMPARATOR;
+        }
+        return this;
+    }
+
+    public ConfigFinder order(String mode) {
+        if ("desc".equals(mode)) {
+            this.comparator = Collections.reverseOrder(comparator);
+        }
+        return this;
+    }
+
+    public Stream<Path> getPathFiles() {
+        return getPathFiles(-1);
+    }
+
+    public Stream<Path> getPathFiles(long max) {
+        if (comparator != null) {
+            result.sort(comparator);
+        }
+        return result.stream().limit(max < 0 ? result.size() : max);
+    }
+
+    public Stream<Path> skipPathFiles(long skip) {
+        if (comparator != null) {
+            result.sort(comparator);
+        }
+        return result.stream().skip(skip < 0 ? 0 : skip);
+    }
+
+    public Stream<String> getPaths() {
+        return getPaths(-1);
+    }
+
+    public Stream<String> getPaths(long max) {
+        if (comparator != null) {
+            result.sort(comparator);
+        }
+        return result.stream()
+                .map(p -> p.toAbsolutePath().toString())
+                .limit(max < 0 ? result.size() : max);
+    }
+
+   private static final Comparator<Path> LAST_MODIFIED_COMPARATOR = Comparator.comparing(p -> {
+        try {
+            return Files.getLastModifiedTime(p);
+        } catch (IOException e) {
+            return null;
+        }
+   });
+
+    private static final Comparator<Path> PATH_NAME_COMPARATOR = Comparator.comparing(Path::toString);
+}

config/src/main/java/org/xbib/config/ConfigLoader.java

@@ -0,0 +1,311 @@
+package org.xbib.config;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.io.StringReader;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Optional;
+import java.util.ServiceLoader;
+import java.util.stream.Collectors;
+import org.xbib.settings.Settings;
+import org.xbib.settings.SettingsBuilder;
+import org.xbib.settings.SettingsLoader;
+import org.xbib.settings.SettingsLoaderService;
+
+/**
+ * A configuration loader for configuration files.
+ */
+public class ConfigLoader {
+
+    private static final Map<ConfigParams, Settings> map = new HashMap<>();
+
+    private ConfigLogger logger;
+
+    private ConfigLoader() {
+    }
+
+    private static class Holder {
+        private static ConfigLogger createConfigLogger() {
+            ServiceLoader<ConfigLogger> serviceLoader = ServiceLoader.load(ConfigLogger.class);
+            Optional<ConfigLogger> optionalConfigLogger = serviceLoader.findFirst();
+            return optionalConfigLogger.orElse(new NullConfigLogger());
+        }
+
+        private static final ConfigLoader configLoader = new ConfigLoader().withLogger(createConfigLogger());
+    }
+
+    public static ConfigLoader getInstance() {
+        return Holder.configLoader;
+    }
+
+    public ConfigLoader withLogger(ConfigLogger logger) {
+        this.logger = logger;
+        return this;
+    }
+
+    public synchronized Settings load(ConfigParams configParams) throws ConfigException {
+        map.computeIfAbsent(configParams, p -> internalLoad(p)
+                .replacePropertyPlaceholders()
+                .build());
+        return map.get(configParams);
+    }
+
+    private SettingsBuilder internalLoad(ConfigParams params) throws ConfigException {
+        SettingsBuilder settings = Settings.settingsBuilder();
+        if (params.withSystemEnvironment) {
+            settings.loadFromSystemEnvironment();
+        }
+        if (params.withSystemProperties) {
+            settings.loadFromSystemProperties();
+        }
+        if (!params.settings.isEmpty()) {
+            for (Settings s : params.settings) {
+                settings.put(s);
+            }
+        }
+        if (!params.reader.isEmpty()) {
+            for (ConfigParams.SuffixedReader reader : params.reader) {
+                SettingsBuilder readerSettings = createSettingsFromReader(reader.reader, reader.suffix);
+                if (readerSettings != null) {
+                    settings.put(readerSettings.build());
+                    if (!params.includeAll) {
+                        return overrideFromProperties(params, settings);
+                    }
+                }
+            }
+        }
+        if (params.args != null) {
+            SettingsBuilder argsSettings = createSettingsFromArgs(params);
+            if (argsSettings != null) {
+                settings.put(argsSettings.build());
+                if (!params.includeAll) {
+                    return overrideFromProperties(params, settings);
+                }
+            }
+        }
+        if (params.withStdin) {
+            SettingsBuilder stdinSettings = createSettingsFromStdin();
+            if (stdinSettings != null) {
+                settings.put(stdinSettings.build());
+                if (!params.includeAll) {
+                    return overrideFromProperties(params, settings);
+                }
+            }
+        }
+        if (!params.fileLocations.isEmpty()) {
+            SettingsBuilder fileSettings = createSettingsFromFile(params.fileLocations);
+            if (fileSettings != null) {
+                settings.put(fileSettings.build());
+                if (!params.includeAll) {
+                    return overrideFromProperties(params, settings);
+                }
+            }
+        }
+        if (!params.fileNamesWithoutSuffix.isEmpty()) {
+            for (String fileNameWithoutSuffix : params.fileNamesWithoutSuffix) {
+                SettingsBuilder fileSettings = createSettingsFromFile(createListOfLocations(params, fileNameWithoutSuffix));
+                if (fileSettings != null) {
+                    settings.put(fileSettings.build());
+                    if (!params.includeAll) {
+                        return overrideFromProperties(params, settings);
+                    }
+                }
+            }
+            for (String fileNameWithoutSuffix : params.fileNamesWithoutSuffix) {
+                if (params.classLoaders != null) {
+                    for (ClassLoader cl : params.classLoaders) {
+                        if (cl != null) {
+                            SettingsBuilder classpathSettings = createClasspathSettings(params, cl, fileNameWithoutSuffix);
+                            if (classpathSettings != null) {
+                                settings.put(classpathSettings.build());
+                                if (!params.includeAll) {
+                                    return overrideFromProperties(params, settings);
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        if (!params.jdbcLookups.isEmpty()) {
+            for (ConfigParams.JdbcLookup jdbcLookup : params.jdbcLookups) {
+                try {
+                    settings.fromJdbc(jdbcLookup.connection, jdbcLookup.statement, jdbcLookup.params);
+                } catch (SQLException sqlException) {
+                    throw new ConfigException(sqlException);
+                }
+            }
+        }
+        if (params.includeAll) {
+            return overrideFromProperties(params, settings);
+        }
+        if (params.failIfEmpty) {
+            throw new ConfigException("no config found");
+        }
+        return settings;
+    }
+
+    private SettingsBuilder createSettingsFromArgs(ConfigParams params) throws ConfigException {
+        if (!params.fileNamesWithoutSuffix.isEmpty() && params.args != null) {
+            for (String fileNameWithoutSuffix : params.fileNamesWithoutSuffix) {
+                for (String suffix : SettingsLoaderService.getInstance().getSuffixes()) {
+                    for (int i = 0; i < params.args.size() - 1; i++) {
+                        String arg = params.args.get(i);
+                        String s = params.directoryName != null ?
+                                "--" + params.directoryName + "-" + fileNameWithoutSuffix + "." + suffix :
+                                "--" + fileNameWithoutSuffix + "." + suffix;
+                        if (arg.equals(s)) {
+                            return createSettingsFromReader(new StringReader(params.args.get(i + 1)), suffix);
+                        }
+                    }
+                }
+            }
+        }
+        return null;
+    }
+
+    private SettingsBuilder createSettingsFromStdin() throws ConfigException {
+        if (System.in != null) {
+            try {
+                int numBytesWaiting = System.in.available();
+                if (numBytesWaiting > 0) {
+                    String suffix = System.getProperty("config.format", "yaml");
+                    return createSettingsFromStream(System.in, "." + suffix);
+                }
+            } catch (IOException e) {
+                throw new ConfigException(e);
+            }
+        }
+        return null;
+    }
+
+    private SettingsBuilder createSettingsFromFile(List<String> settingsFileNames) throws ConfigException {
+        SettingsBuilder settings = Settings.settingsBuilder();
+        for (String settingsFileName: settingsFileNames) {
+            int pos = settingsFileName.lastIndexOf('.');
+            String suffix = (pos > 0 ? settingsFileName.substring(pos + 1) : "").toLowerCase(Locale.ROOT);
+            Path path = Paths.get(settingsFileName);
+            if (logger != null) {
+                logger.info("trying " + path);
+            }
+            if (Files.exists(path)) {
+                if (logger != null) {
+                    logger.info("found path: " + path);
+                }
+                System.setProperty("config.path", path.getParent().toString());
+                try {
+                    InputStream inputStream = Files.newInputStream(path);
+                    SettingsBuilder fileSettings = createSettingsFromStream(inputStream, suffix);
+                    if (fileSettings != null) {
+                        settings.put(fileSettings.build());
+                    }
+                } catch (Exception e) {
+                    throw new ConfigException(e);
+                }
+            }
+        }
+        return settings.isEmpty() ? null : settings;
+    }
+
+    private SettingsBuilder createClasspathSettings(ConfigParams params,
+                                                    ClassLoader classLoader,
+                                                    String fileNameWithoutSuffix) throws ConfigException {
+        SettingsBuilder settings = Settings.settingsBuilder();
+        for (String suffix : SettingsLoaderService.getInstance().getSuffixes()) {
+            String path = params.directoryName != null ?
+                    params.directoryName + '-' + fileNameWithoutSuffix + suffix :  fileNameWithoutSuffix + suffix;
+            InputStream inputStream = classLoader.getResourceAsStream(path);
+            if (inputStream != null) {
+                if (logger != null) {
+                    logger.info("found resource: " + path);
+                }
+                SettingsBuilder streamSettings = createSettingsFromStream(inputStream, suffix);
+                if (streamSettings != null) {
+                    settings.put(streamSettings.build());
+                }
+            }
+        }
+        return settings.isEmpty() ? null : settings;
+    }
+
+    private SettingsBuilder createSettingsFromStream(InputStream inputStream,
+                                                     String suffix) throws ConfigException {
+        if (inputStream == null) {
+            if (logger != null) {
+                logger.error("unable to open input stream");
+            }
+            return null;
+        }
+        return createSettingsFromReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8), suffix);
+    }
+
+    private SettingsBuilder createSettingsFromReader(Reader reader,
+                                                     String suffix) throws ConfigException {
+        if (reader == null) {
+            if (logger != null) {
+                logger.error("unable to open reader");
+            }
+            return null;
+        }
+        SettingsLoader settingsLoader = SettingsLoaderService.getInstance().loaderFromResource(suffix);
+        if (settingsLoader != null) {
+            SettingsBuilder settings;
+            try (BufferedReader bufferedReader = new BufferedReader(reader)) {
+                String content = bufferedReader.lines().collect(Collectors.joining("\n"));
+                settings = Settings.settingsBuilder().put(settingsLoader.load(content));
+            } catch (IOException e) {
+                throw new ConfigException(e);
+            }
+            return settings;
+        } else {
+            if (logger != null) {
+                logger.error("suffix is invalid: " + suffix);
+            }
+        }
+        return null;
+    }
+
+    private SettingsBuilder overrideFromProperties(ConfigParams params, SettingsBuilder settingsBuilder) {
+        if (params.withSystemPropertiesOverride) {
+            settingsBuilder.map(e -> {
+                String key = e.getKey();
+                String value = System.getProperty(params.directoryName != null ? params.directoryName + '.' + key : key);
+                return value != null ? Map.entry(key, value) : Map.entry(key, e.getValue());
+            });
+        }
+        return settingsBuilder;
+    }
+
+    private List<String> createListOfLocations(ConfigParams params,
+                                               String fileNameWithoutSuffix) {
+        List<String> list = new ArrayList<>();
+        for (String suffix : SettingsLoaderService.getInstance().getSuffixes()) {
+            String xdgConfigHome = System.getenv("XDG_CONFIG_HOME");
+            if (xdgConfigHome == null) {
+                xdgConfigHome = System.getProperty("user.home") + "/.config";
+            }
+            if (params.directoryName != null) {
+                list.add(params.directoryName + '-' + fileNameWithoutSuffix + "." + suffix);
+                list.add(xdgConfigHome + '/' + params.directoryName + '/' + fileNameWithoutSuffix + "." + suffix);
+                list.add("/etc/" + params.directoryName + '/' + fileNameWithoutSuffix + "." + suffix);
+            } else {
+                list.add(fileNameWithoutSuffix + "." + suffix);
+                list.add(xdgConfigHome + '/' + fileNameWithoutSuffix + "." + suffix);
+                list.add("/etc/" + fileNameWithoutSuffix + "." + suffix);
+            }
+        }
+        return list;
+    }
+}

config/src/main/java/org/xbib/config/ConfigLogger.java

@@ -0,0 +1,10 @@
+package org.xbib.config;
+
+public interface ConfigLogger {
+
+    void info(String string);
+
+    void warn(String string);
+
+    void error(String message);
+}

config/src/main/java/org/xbib/config/ConfigParams.java

@@ -0,0 +1,192 @@
+package org.xbib.config;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.sql.Connection;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Objects;
+import org.xbib.settings.Settings;
+import org.xbib.settings.datastructures.DatastructureSettings;
+
+public class ConfigParams implements Comparable<ConfigParams> {
+
+    private static final Comparator<ConfigParams> COMPARATOR =
+            Comparator.comparing(ConfigParams::toString);
+
+    boolean withSystemEnvironment = false;
+
+    boolean withSystemProperties = false;
+
+    boolean failIfEmpty = false;
+
+    boolean includeAll = false;
+
+    boolean withStdin = false;
+
+    boolean withSystemPropertiesOverride = false;
+
+    List<ClassLoader> classLoaders = null;
+
+    final List<SuffixedReader> reader = new ArrayList<>();
+
+    final List<JdbcLookup> jdbcLookups = new ArrayList<>();
+
+    final List<DatastructureSettings> settings = new ArrayList<>();
+
+    List<String> args = null;
+
+    String directoryName = null;
+
+    final List<String> fileNamesWithoutSuffix = new ArrayList<>();
+
+    final List<String> fileLocations = new ArrayList<>();
+
+    public ConfigParams() {
+    }
+
+    public ConfigParams withSystemEnvironment() {
+        this.withSystemEnvironment = true;
+        return this;
+    }
+
+    public ConfigParams withSystemProperties() {
+        this.withSystemProperties = true;
+        return this;
+    }
+
+    public ConfigParams withSystemPropertiesOverride() {
+        this.withSystemPropertiesOverride = true;
+        return this;
+    }
+
+    public ConfigParams includeAll() {
+        this.includeAll = true;
+        return this;
+    }
+
+    public ConfigParams failIfEmpty() {
+        this.failIfEmpty = true;
+        return this;
+    }
+
+    public ConfigParams withStdin(boolean withStdin) {
+        this.withStdin = withStdin;
+        return this;
+    }
+
+    public ConfigParams withArgs(String[] args) {
+        this.args = Arrays.asList(args);
+        return this;
+    }
+
+    public ConfigParams withClassLoaders(ClassLoader... classLoaders) {
+        this.classLoaders = Arrays.asList(classLoaders);
+        return this;
+    }
+
+    public ConfigParams withReader(Reader reader, String suffix) {
+        SuffixedReader suffixedReader = new SuffixedReader();
+        suffixedReader.reader = reader;
+        suffixedReader.suffix = suffix;
+        this.reader.add(suffixedReader);
+        return this;
+    }
+
+    public ConfigParams withSettings(Settings settings) {
+        this.settings.add(DatastructureSettings.builder().put(settings.getAsMap()).build());
+        return this;
+    }
+
+    public ConfigParams withDirectoryName(String directoryName) {
+        this.directoryName = directoryName;
+        return this;
+    }
+
+    public ConfigParams withFileNamesWithoutSuffix(String... fileNamesWithoutSuffix) {
+        this.fileNamesWithoutSuffix.addAll(Arrays.asList(fileNamesWithoutSuffix));
+        return this;
+    }
+
+    public ConfigParams withLocation(String location) {
+        this.fileLocations.add(location);
+        return this;
+    }
+
+    public ConfigParams withPath(String basePath, String basePattern, String path, String pathPattern) throws IOException {
+        ConfigFinder configFinder = new ConfigFinder();
+        configFinder.find(basePath, basePattern, path, pathPattern).getPaths().forEach(this::withLocation);
+        return this;
+    }
+
+    public ConfigParams withJdbc(Connection connection, String statement, String[] params) {
+        JdbcLookup jdbcLookup = new JdbcLookup();
+        jdbcLookup.connection = connection;
+        jdbcLookup.statement = statement;
+        jdbcLookup.params = params;
+        jdbcLookups.add(jdbcLookup);
+        return this;
+    }
+
+    @Override
+    public int hashCode() {
+        return toString().hashCode();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        ConfigParams that = (ConfigParams) o;
+        return withSystemEnvironment == that.withSystemEnvironment &&
+                withSystemProperties == that.withSystemProperties &&
+                failIfEmpty == that.failIfEmpty &&
+                includeAll == that.includeAll &&
+                withStdin == that.withStdin &&
+                withSystemPropertiesOverride == that.withSystemPropertiesOverride &&
+                Objects.equals(classLoaders, that.classLoaders) &&
+                Objects.equals(reader, that.reader) &&
+                Objects.equals(jdbcLookups, that.jdbcLookups) &&
+                Objects.equals(settings, that.settings) &&
+                Objects.equals(args, that.args) &&
+                Objects.equals(directoryName, that.directoryName) &&
+                Objects.equals(fileNamesWithoutSuffix, that.fileNamesWithoutSuffix) &&
+                Objects.equals(fileLocations, that.fileLocations);
+    }
+
+    @Override
+    public int compareTo(ConfigParams o) {
+        return COMPARATOR.compare(this, o);
+    }
+
+    @Override
+    public String toString() {
+        return "" +
+                withSystemEnvironment +
+                withSystemProperties +
+                withStdin +
+                classLoaders +
+                reader +
+                args +
+                directoryName +
+                fileNamesWithoutSuffix +
+                fileLocations;
+    }
+
+    static class SuffixedReader {
+        Reader reader;
+        String suffix;
+    }
+
+    static class JdbcLookup {
+        Connection connection;
+        String statement;
+        String[] params;
+    }
+}

config/src/main/java/org/xbib/config/NullConfigLogger.java

@@ -0,0 +1,19 @@
+package org.xbib.config;
+
+public class NullConfigLogger implements ConfigLogger {
+
+    public NullConfigLogger() {
+    }
+
+    @Override
+    public void info(String string) {
+    }
+
+    @Override
+    public void warn(String message) {
+    }
+
+    @Override
+    public void error(String message) {
+    }
+}

config/src/main/java/org/xbib/config/SystemConfigLogger.java

@@ -0,0 +1,22 @@
+package org.xbib.config;
+
+public class SystemConfigLogger implements ConfigLogger {
+
+    public SystemConfigLogger() {
+    }
+
+    @Override
+    public void info(String string) {
+        System.err.println("info: " + string);
+    }
+
+    @Override
+    public void warn(String message) {
+        System.err.println("warning: " + message);
+    }
+
+    @Override
+    public void error(String message) {
+        System.err.println("error: " + message);
+    }
+}

config/src/main/java/org/xbib/config/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Classes for configuration setup.
+ */
+package org.xbib.config;

config/src/test/java/org/xbib/config/test/ConfigLoaderTest.java

@@ -0,0 +1,76 @@
+package org.xbib.config.test;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.io.StringReader;
+import org.junit.jupiter.api.Test;
+import org.xbib.config.ConfigLoader;
+import org.xbib.config.ConfigParams;
+import org.xbib.settings.Settings;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class ConfigLoaderTest {
+
+    @Test
+    public void configEmptyTest() {
+        Settings settings = ConfigLoader.getInstance()
+                .load(new ConfigParams());
+        assertTrue(settings.isEmpty());
+    }
+
+    @Test
+    public void configSettingsTest() {
+        Settings configSettings = Settings.settingsBuilder()
+                .put("hello", "world")
+                .build();
+        Settings settings = ConfigLoader.getInstance()
+                .load(new ConfigParams().withSettings(configSettings));
+        assertEquals("world", settings.get("hello"));
+    }
+
+    @Test
+    public void configArgsTest() {
+        String[] args = new String[] {
+                "--config.yaml",
+                "hello: world"
+        };
+        Settings settings = ConfigLoader.getInstance()
+                .load(new ConfigParams()
+                        .withArgs(args)
+                        .withFileNamesWithoutSuffix("config"));
+        assertEquals("world", settings.get("hello"));
+    }
+
+    @Test
+    public void configPropertiesTest() {
+        Reader reader = new StringReader("a=b");
+        Settings settings = ConfigLoader.getInstance()
+                .load(new ConfigParams()
+                        .withReader(reader, "properties"));
+        assertEquals("b", settings.get("a"));
+    }
+
+    @Test
+    public void configFileTest() throws IOException {
+        Settings settings = ConfigLoader.getInstance()
+                .load(new ConfigParams()
+                        .withPath(null, null, "src/test/resources", "config.*"));
+        assertEquals("world", settings.get("hello"));
+        assertEquals("world2", settings.get("hello2"));
+    }
+
+    @Test
+    public void testSystemPropertiesOverride() throws IOException {
+        System.setProperty("hello", "override");
+        Settings settings = ConfigLoader.getInstance()
+                .load(new ConfigParams()
+                        .withPath(null, null, "src/test/resources", "config.*"));
+        assertEquals("world", settings.get("hello"));
+        settings = ConfigLoader.getInstance()
+                .load(new ConfigParams()
+                        .withSystemPropertiesOverride()
+                        .withPath(null, null, "src/test/resources", "config.*"));
+        assertEquals("override", settings.get("hello"));
+    }
+}

config/src/test/java/org/xbib/config/test/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Test classes for config.
+ */
+package org.xbib.config.test;

config/src/test/resources/META-INF/services/org.xbib.config.ConfigLogger

@@ -0,0 +1,2 @@
+org.xbib.config.NullConfigLogger
+org.xbib.config.SystemConfigLogger

config/src/test/resources/META-INF/services/org.xbib.settings.SettingsLoader

@@ -0,0 +1,3 @@
+org.xbib.settings.datastructures.PropertiesSettingsLoader
+org.xbib.settings.datastructures.json.JsonSettingsLoader
+org.xbib.settings.datastructures.yaml.YamlSettingsLoader

config/src/test/resources/config.json

@@ -0,0 +1,3 @@
+{
+  "hello2": "world2"
+}

config/src/test/resources/config.yaml

@@ -0,0 +1 @@
+hello: world

gradle/test/jmh.gradle

@@ -7,8 +7,8 @@ sourceSets {
 }
 
 dependencies {
-    jmhImplementation 'org.openjdk.jmh:jmh-core:1.32'
+    jmhImplementation 'org.openjdk.jmh:jmh-core:1.37'
-    jmhAnnotationProcessor 'org.openjdk.jmh:jmh-generator-annprocess:1.32'
+    jmhAnnotationProcessor 'org.openjdk.jmh:jmh-generator-annprocess:1.37'
 }
 
 task jmh(type: JavaExec, group: 'jmh', dependsOn: jmhClasses) {

settings-api/build.gradle

@@ -0,0 +1,3 @@
+dependencies {
+    api project(':datastructures-api')
+}

settings-api/gradle.properties

@@ -0,0 +1 @@
+version = 5.0.5

settings-api/src/main/java/module-info.java

@@ -0,0 +1,10 @@
+import org.xbib.settings.SettingsBuilder;
+import org.xbib.settings.SettingsLoader;
+
+module org.xbib.settings.api {
+    exports org.xbib.settings;
+    uses SettingsBuilder;
+    uses SettingsLoader;
+    requires transitive org.xbib.datastructures.api;
+    requires transitive java.sql;
+}

settings-api/src/main/java/org/xbib/settings/PlaceholderResolver.java

@@ -0,0 +1,16 @@
+package org.xbib.settings;
+
+/**
+ * Strategy interface used to resolve replacement values for placeholders contained in Strings.
+ */
+@FunctionalInterface
+public interface PlaceholderResolver {
+
+    /**
+     * Resolves the supplied placeholder name into the replacement value.
+     *
+     * @param placeholderName the name of the placeholder to resolve.
+     * @return the replacement value or <code>null</code> if no replacement is to be made.
+     */
+    String resolvePlaceholder(String placeholderName);
+}

settings-api/src/main/java/org/xbib/settings/PropertyPlaceholder.java

@@ -0,0 +1,120 @@
+package org.xbib.settings;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ *
+ */
+public class PropertyPlaceholder {
+
+    private final String placeholderPrefix;
+
+    private final String placeholderSuffix;
+
+    private final boolean ignoreUnresolvablePlaceholders;
+
+    /**
+     * Creates a new <code>PropertyPlaceholderHelper</code> that uses the supplied prefix and suffix.
+     *
+     * @param placeholderPrefix              the prefix that denotes the start of a placeholder.
+     * @param placeholderSuffix              the suffix that denotes the end of a placeholder.
+     * @param ignoreUnresolvablePlaceholders indicates whether unresolvable placeholders should be ignored
+     *                                       (<code>true</code>) or cause an exception (<code>false</code>).
+     */
+    public PropertyPlaceholder(String placeholderPrefix,
+                               String placeholderSuffix,
+                               boolean ignoreUnresolvablePlaceholders) {
+        this.placeholderPrefix = placeholderPrefix;
+        this.placeholderSuffix = placeholderSuffix;
+        this.ignoreUnresolvablePlaceholders = ignoreUnresolvablePlaceholders;
+    }
+
+    /**
+     * Replaces all placeholders of format <code>${name}</code> with the value returned from the supplied {@link
+     * PlaceholderResolver}.
+     *
+     * @param value               the value containing the placeholders to be replaced.
+     * @param placeholderResolver the <code>PlaceholderResolver</code> to use for replacement.
+     * @return the supplied value with placeholders replaced inline.
+     */
+    public String replacePlaceholders(String value,
+                                      PlaceholderResolver placeholderResolver) {
+        return parseStringValue(value, placeholderResolver, new HashSet<>());
+    }
+
+    protected String parseStringValue(String value,
+                                      PlaceholderResolver placeholderResolver,
+                                      Set<String> visitedPlaceholders) {
+        if (value == null) {
+            return null;
+        }
+        StringBuilder sb = new StringBuilder(value);
+        int startIndex = value.indexOf(this.placeholderPrefix);
+        while (startIndex != -1) {
+            int endIndex = findPlaceholderEndIndex(sb, startIndex);
+            if (endIndex != -1) {
+                String placeholder = sb.substring(startIndex + this.placeholderPrefix.length(), endIndex);
+                if (!visitedPlaceholders.add(placeholder)) {
+                    throw new IllegalArgumentException("Circular placeholder reference '" + placeholder + "' in property definitions");
+                }
+                placeholder = parseStringValue(placeholder, placeholderResolver, visitedPlaceholders);
+                int defaultValueIdx = placeholder.indexOf(':');
+                String defaultValue = null;
+                if (defaultValueIdx != -1) {
+                    defaultValue = placeholder.substring(defaultValueIdx + 1);
+                    placeholder = placeholder.substring(0, defaultValueIdx);
+                }
+                String propVal = placeholderResolver.resolvePlaceholder(placeholder);
+                if (propVal == null) {
+                    propVal = defaultValue;
+                }
+                if (propVal != null) {
+                    propVal = parseStringValue(propVal, placeholderResolver, visitedPlaceholders);
+                    sb.replace(startIndex, endIndex + this.placeholderSuffix.length(), propVal);
+                    startIndex = sb.indexOf(this.placeholderPrefix, startIndex + propVal.length());
+                } else if (this.ignoreUnresolvablePlaceholders) {
+                    // Proceed with unprocessed value.
+                    startIndex = sb.indexOf(this.placeholderPrefix, endIndex + this.placeholderSuffix.length());
+                } else {
+                    throw new IllegalArgumentException("could not resolve placeholder '" + placeholder + "'");
+                }
+                visitedPlaceholders.remove(placeholder);
+            } else {
+                startIndex = -1;
+            }
+        }
+        return sb.toString();
+    }
+
+    private int findPlaceholderEndIndex(CharSequence charSequence, int startIndex) {
+        int index = startIndex + this.placeholderPrefix.length();
+        int withinNestedPlaceholder = 0;
+        while (index < charSequence.length()) {
+            if (substringMatch(charSequence, index, this.placeholderSuffix)) {
+                if (withinNestedPlaceholder > 0) {
+                    withinNestedPlaceholder--;
+                    index = index + this.placeholderPrefix.length() - 1;
+                } else {
+                    return index;
+                }
+            } else if (substringMatch(charSequence, index, this.placeholderPrefix)) {
+                withinNestedPlaceholder++;
+                index = index + this.placeholderPrefix.length();
+            } else {
+                index++;
+            }
+        }
+        return -1;
+    }
+
+    private boolean substringMatch(CharSequence charSequence, int index, CharSequence substring) {
+        for (int j = 0; j < substring.length(); j++) {
+            int i = index + j;
+            if (i >= charSequence.length() || charSequence.charAt(i) != substring.charAt(j)) {
+                return false;
+            }
+        }
+        return true;
+    }
+}

settings-api/src/main/java/org/xbib/settings/Settings.java

@@ -0,0 +1,71 @@
+package org.xbib.settings;
+
+import org.xbib.datastructures.api.ByteSizeValue;
+import org.xbib.datastructures.api.TimeValue;
+import java.io.IOException;
+import java.util.Map;
+import java.util.Optional;
+import java.util.ServiceLoader;
+
+public interface Settings extends AutoCloseable {
+
+    class Holder {
+
+        private Holder() {
+        }
+
+        private static SettingsBuilder createBuilder() {
+            ServiceLoader<SettingsBuilder> serviceLoader = ServiceLoader.load(SettingsBuilder.class);
+            Optional<SettingsBuilder> optionalSettingsBuilder = serviceLoader.findFirst();
+            return optionalSettingsBuilder.orElse(null);
+        }
+
+        private static final Settings emptySettings = createBuilder().build();
+    }
+
+    static SettingsBuilder settingsBuilder() {
+        return Holder.createBuilder();
+    }
+
+    static Settings emptySettings() {
+        return Holder.emptySettings;
+    }
+
+    boolean isEmpty();
+
+    String get(String setting);
+
+    String get(String setting, String defaultValue);
+
+    float getAsFloat(String setting, float defaultValue);
+
+    double getAsDouble(String setting, double defaultValue);
+
+    int getAsInt(String setting, int defaultValue);
+
+    long getAsLong(String setting, long defaultValue);
+
+    boolean getAsBoolean(String setting, boolean defaultValue);
+
+    TimeValue getAsTime(String setting, TimeValue defaultValue);
+
+    ByteSizeValue getAsBytesSize(String setting, ByteSizeValue defaultValue);
+
+    String[] getAsArray(String settingPrefix);
+
+    String[] getAsArray(String settingPrefix, String[] defaultArray);
+
+    Map<String, String> getAsMap();
+
+    Map<String, Object> getAsStructuredMap();
+
+    Map<String, Settings> getGroups(String prefix);
+
+    Settings getAsSettings(String setting);
+
+    Settings getByPrefix(String prefix);
+
+    boolean containsSetting(String setting);
+
+    void close() throws IOException;
+}

settings-api/src/main/java/org/xbib/settings/SettingsBuilder.java

@@ -0,0 +1,105 @@
+package org.xbib.settings;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Path;
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Function;
+
+public interface SettingsBuilder {
+
+    SettingsBuilder put(String setting, String value);
+
+    SettingsBuilder put(String setting, boolean value);
+
+    SettingsBuilder put(String setting, int value);
+
+    SettingsBuilder put(String setting, long value);
+
+    SettingsBuilder put(String setting, float value);
+
+    SettingsBuilder put(String setting, double value);
+
+    SettingsBuilder putArray(String setting, String... values);
+
+    SettingsBuilder putArray(String setting, List<String> values);
+
+    SettingsBuilder put(String settingPrefix, String groupName, String[] settings, String[] values)
+            throws SettingsException;
+
+    SettingsBuilder put(Settings settings);
+
+    SettingsBuilder put(Map<String, String> settings);
+
+    SettingsBuilder loadFromString(String resourceName, String content);
+
+    SettingsBuilder loadFromResource(String resourceName, InputStream inputStream);
+
+    default SettingsBuilder fromJdbc(Connection connection, String statement, String[] params) throws SQLException {
+        try (PreparedStatement preparedStatement = connection.prepareStatement(statement, params);
+             ResultSet resultSet = preparedStatement.executeQuery()) {
+            while (resultSet.next()) {
+                String key = resultSet.getString("key");
+                String value = resultSet.getString("value");
+                put(key, value);
+            }
+        }
+        return this;
+    }
+
+    SettingsBuilder loadFromSystemProperties();
+
+    SettingsBuilder loadFromSystemEnvironment();
+
+    /**
+     * Runs across all the settings set on this builder and replaces {@code ${...}} elements in the
+     * each setting value according to the following logic:
+     * First, tries to resolve it against a System property ({@link System#getProperty(String)}), next,
+     * tries and resolve it against an environment variable ({@link System#getenv(String)}), next,
+     * tries and resolve it against a date pattern to resolve the current date,
+     * and last, tries and replace it with another setting already set on this builder.
+     * @param propertyPlaceholder the property place holder
+     * @param placeholderResolver  the place holder resolver
+     * @return this builder
+     */
+    SettingsBuilder replacePropertyPlaceholders(PropertyPlaceholder propertyPlaceholder,
+                                                PlaceholderResolver placeholderResolver);
+
+    /**
+     * A default method to replace property placeholders.
+     * @return this builder
+     */
+    SettingsBuilder replacePropertyPlaceholders();
+
+    /**
+     * Optional settings refresh mechanism, using reloading from a path after a give time period.
+     * May not be implemented at all.
+     */
+    SettingsBuilder setRefresh(Path path, long initialDelay, long period, TimeUnit timeUnit);
+
+    /**
+     * Map all settings keys and values to other keys and values.
+     * Example usage is to override settings from another priority source.
+     * @return this builder
+     */
+    SettingsBuilder map(Function<Map.Entry<String, String>, Map.Entry<String, String>> function);
+
+    /**
+     * Return the Settings from this SettingsBuilder.
+     * @return the settings
+     */
+    Settings build();
+
+    /**
+     * Returns true if the settings builder is empty.
+     * @return true if empty
+     */
+    boolean isEmpty();
+
+}

settings-api/src/main/java/org/xbib/settings/SettingsException.java

@@ -0,0 +1,16 @@
+package org.xbib.settings;
+
+/**
+ * A generic failure to handle settings.
+ */
+@SuppressWarnings("serial")
+public class SettingsException extends RuntimeException {
+
+    public SettingsException(String message) {
+        super(message);
+    }
+
+    public SettingsException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

settings-api/src/main/java/org/xbib/settings/SettingsLoader.java

@@ -0,0 +1,33 @@
+package org.xbib.settings;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Provides the ability to load settings from
+ * the actual source content that represents them.
+ */
+public interface SettingsLoader {
+
+    /**
+     * Suffices for file names to load from.
+     * @return a set of suffices
+     */
+    Set<String> suffixes();
+
+    /**
+     * Loads the settings from a source string.
+     * @param source the source
+     * @return a Map
+     */
+    Map<String, String> load(String source) throws IOException;
+
+    /**
+     * Loads the settings from a map.
+     * @param source the map with the source
+     * @return a Map
+     */
+    Map<String, String> load(Map<String, Object> source) throws IOException;
+
+}

settings-api/src/main/java/org/xbib/settings/SettingsLoaderService.java

@@ -0,0 +1,54 @@
+package org.xbib.settings;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.ServiceLoader;
+import java.util.Set;
+
+/**
+ * A settings loader service for loading {@link SettingsLoader} implementations.
+ */
+public final class SettingsLoaderService {
+
+    private static final SettingsLoaderService INSTANCE = new SettingsLoaderService();
+
+    private final Map<Set<String>, SettingsLoader> settingsLoaderMap;
+
+    private SettingsLoaderService() {
+        this.settingsLoaderMap = new HashMap<>();
+        ServiceLoader<SettingsLoader> serviceLoader = ServiceLoader.load(SettingsLoader.class);
+        for (SettingsLoader settingsLoader : serviceLoader) {
+            settingsLoaderMap.put(settingsLoader.suffixes(), settingsLoader);
+        }
+    }
+
+    public static SettingsLoaderService getInstance() {
+        return INSTANCE;
+    }
+
+    /**
+     * Returns a {@link SettingsLoader} based on the resource name.
+     * @param resourceName the resource
+     * @return the settings loader
+     */
+    public SettingsLoader loaderFromResource(String resourceName) {
+        for (Map.Entry<Set<String>, SettingsLoader> entry : settingsLoaderMap.entrySet()) {
+            Set<String> suffixes = entry.getKey();
+            for (String suffix : suffixes) {
+                if (resourceName.endsWith(suffix)) {
+                    return entry.getValue();
+                }
+            }
+        }
+        throw new IllegalArgumentException("no settings loader for " + resourceName + " in " + settingsLoaderMap.keySet());
+    }
+
+    public Set<String> getSuffixes() {
+        Set<String> suffixes = new HashSet<>();
+        for (Set<String> set : settingsLoaderMap.keySet()) {
+            suffixes.addAll(set);
+        }
+        return suffixes;
+    }
+}

settings-api/src/main/java/org/xbib/settings/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Settings API.
+ */
+package org.xbib.settings;

settings-datastructures-json/build.gradle

@@ -0,0 +1,4 @@
+dependencies {
+    api project(':settings-datastructures')
+    api project(':datastructures-json-tiny')
+}

settings-datastructures-json/gradle.properties

@@ -0,0 +1 @@
+version = 5.0.5

settings-datastructures-json/src/main/java/module-info.java

@@ -0,0 +1,10 @@
+import org.xbib.settings.SettingsLoader;
+import org.xbib.settings.datastructures.json.JsonSettingsLoader;
+
+module org.xbib.settings.datastructures.json {
+    exports org.xbib.settings.datastructures.json;
+    requires transitive org.xbib.settings.datastructures;
+    requires org.xbib.datastructures.json.tiny;
+    uses SettingsLoader;
+    provides SettingsLoader with JsonSettingsLoader;
+}

settings-datastructures-json/src/main/java/org/xbib/settings/datastructures/json/JsonSettingsLoader.java

@@ -0,0 +1,22 @@
+package org.xbib.settings.datastructures.json;
+
+import org.xbib.settings.datastructures.AbstractSettingsLoader;
+import org.xbib.datastructures.api.DataStructure;
+import org.xbib.datastructures.json.tiny.Json;
+import java.util.Set;
+
+public class JsonSettingsLoader extends AbstractSettingsLoader {
+
+    public JsonSettingsLoader() {
+    }
+
+    @Override
+    public DataStructure dataStructure() {
+        return new Json();
+    }
+
+    @Override
+    public Set<String> suffixes() {
+        return Set.of("json");
+    }
+}

settings-datastructures-json/src/main/java/org/xbib/settings/datastructures/json/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * JSON settings with the datastructures package.
+ */
+package org.xbib.settings.datastructures.json;

settings-datastructures-json/src/main/resources/META-INF.services/org.xbib.settings.SettingsLoader

@@ -0,0 +1 @@
+org.xbib.settings.datastructures.json.JsonSettingsLoader

settings-datastructures-json/src/test/java/org/xbib/settings/datastructures/json/test/JsonSettingsTest.java

@@ -0,0 +1,82 @@
+package org.xbib.settings.datastructures.json.test;
+
+import org.junit.jupiter.api.Test;
+import org.xbib.settings.Settings;
+import org.xbib.settings.SettingsLoader;
+import org.xbib.settings.datastructures.json.JsonSettingsLoader;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class JsonSettingsTest {
+
+    @Test
+    public void testMapForSettings() throws IOException {
+        Map<String, String> map = new HashMap<>();
+        map.put("hello", "world");
+        Map<String, Object> settingsMap = new HashMap<>();
+        settingsMap.put("map", map);
+        SettingsLoader settingsLoader = new JsonSettingsLoader();
+        Settings settings = Settings.settingsBuilder()
+                .put(settingsLoader.load(settingsMap))
+                .build();
+        assertEquals("{map.hello=world}", settings.getAsMap().toString());
+    }
+
+    @Test
+    public void testMapSettingsFromReader() throws IOException {
+        Map<String, Object> map =  Map.of("map", Map.of("hello", "world"));
+        SettingsLoader settingsLoader = new JsonSettingsLoader();
+        Settings settings = Settings.settingsBuilder()
+                .put(settingsLoader.load(map))
+                .build();
+        assertEquals("{map.hello=world}", settings.getAsMap().toString());
+    }
+
+    @Test
+    public void testLoadFromString() throws IOException {
+        String json = "{\"Hello\":\"World\"}";
+        SettingsLoader loader = new JsonSettingsLoader();
+        Map<String, String> result = loader.load(json);
+        assertEquals("{Hello=World}", result.toString());
+    }
+
+    @Test
+    public void testLoadSettingsFromString() {
+        String json = "{\"Hello\":\"World\"}";
+        Settings settings = Settings.settingsBuilder().loadFromString("json", json).build();
+        assertEquals("{Hello=World}", settings.getAsMap().toString());
+    }
+
+    @Test
+    public void testFlatLoader() throws IOException {
+        String s = "{\"a\":{\"b\":\"c\"}}";
+        SettingsLoader loader = new JsonSettingsLoader();
+        Map<String, String> flatMap = loader.load(s);
+        assertEquals("{a.b=c}", flatMap.toString());
+    }
+
+    @Test
+    public void testLoadFromMap() throws IOException {
+        Map<String, Object> map = new LinkedHashMap<>();
+        Map<String, Object> code = new LinkedHashMap<>();
+        code.put("a", "b");
+        code.put("b", "c");
+        Map<String, Object> name = new LinkedHashMap<>();
+        name.put("a", "b");
+        name.put("b", "c");
+        List<String> list = Arrays.asList("a", "b");
+        map.put("code", code);
+        map.put("name", name);
+        map.put("list", list);
+        map.put("null", null);
+        SettingsLoader loader = new JsonSettingsLoader();
+        Map<String, String> result = loader.load(map);
+        assertEquals("{code.a=b, code.b=c, name.a=b, name.b=c, list.0=a, list.1=b, null=null}", result.toString());
+    }
+}

settings-datastructures-json/src/test/java/org/xbib/settings/datastructures/json/test/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Testing JSON settings with the datastructures package.
+ */
+package org.xbib.settings.datastructures.json.test;

settings-datastructures-json/src/test/resources/META-INF/services/org.xbib.settings.SettingsLoader

@@ -0,0 +1 @@
+org.xbib.settings.datastructures.json.JsonSettingsLoader

settings-datastructures-json/src/test/resources/org/xbib/settings/datastructures/json/test/test-settings.json

@@ -0,0 +1,3 @@
+{
+  "a": "b"
+}

settings-datastructures-yaml/build.gradle

@@ -0,0 +1,4 @@
+dependencies {
+    api project(':settings-datastructures')
+    api project(':datastructures-yaml-tiny')
+}

settings-datastructures-yaml/gradle.properties

@@ -0,0 +1 @@
+version = 5.0.5

settings-datastructures-yaml/src/main/java/module-info.java

@@ -0,0 +1,10 @@
+import org.xbib.settings.SettingsLoader;
+import org.xbib.settings.datastructures.yaml.YamlSettingsLoader;
+
+module org.xbib.settings.datastructures.yaml {
+    exports org.xbib.settings.datastructures.yaml;
+    requires transitive org.xbib.settings.datastructures;
+    requires org.xbib.datastructures.yaml.tiny;
+    uses SettingsLoader;
+    provides SettingsLoader with YamlSettingsLoader;
+}

settings-datastructures-yaml/src/main/java/org/xbib/settings/datastructures/yaml/YamlSettingsLoader.java

@@ -0,0 +1,31 @@
+package org.xbib.settings.datastructures.yaml;
+
+import org.xbib.settings.datastructures.AbstractSettingsLoader;
+import org.xbib.datastructures.api.DataStructure;
+import org.xbib.datastructures.yaml.tiny.Yaml;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Set;
+
+public class YamlSettingsLoader extends AbstractSettingsLoader {
+
+    public YamlSettingsLoader() {
+    }
+
+    @Override
+    public DataStructure dataStructure() {
+        return new Yaml();
+    }
+
+    @Override
+    public Set<String> suffixes() {
+        return Set.of("yml", "yaml");
+    }
+
+    @Override
+    public Map<String, String> load(String source) throws IOException {
+        // replace tabs with whitespace (yaml does not accept tabs, but many users might use it still...)
+        return super.load(source.replace("\t", "  "));
+    }
+}

settings-datastructures-yaml/src/main/java/org/xbib/settings/datastructures/yaml/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * YAML settings with the datastructures package.
+ */
+package org.xbib.settings.datastructures.yaml;

settings-datastructures-yaml/src/main/resources/META-INF/services/org.xbib.content.settings.datastructures.SettingsLoader

@@ -0,0 +1 @@
+org.xbib.settings.datastructures.yaml.YamlSettingsLoader

settings-datastructures-yaml/src/test/java/org/xbib/settings/datastructures/yaml/test/YamlSettingsTest.java

@@ -0,0 +1,67 @@
+package org.xbib.settings.datastructures.yaml.test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+import org.xbib.settings.Settings;
+import org.xbib.settings.SettingsLoader;
+import org.xbib.settings.datastructures.yaml.YamlSettingsLoader;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+public class YamlSettingsTest {
+
+    @Test
+    public void testMapForSettings() throws IOException {
+        Map<String, String> map = new HashMap<>();
+        map.put("hello", "world");
+        Map<String, Object> settingsMap = new HashMap<>();
+        settingsMap.put("map", map);
+        SettingsLoader settingsLoader = new YamlSettingsLoader();
+        Settings settings = Settings.settingsBuilder()
+                .put(settingsLoader.load(settingsMap))
+                .build();
+        assertEquals("{map.hello=world}", settings.getAsMap().toString());
+    }
+
+    @Test
+    public void testMapSettingsFromReader() throws IOException {
+        Map<String, Object> map =  Map.of("map", Map.of("hello", "world"));
+        SettingsLoader settingsLoader = new YamlSettingsLoader();
+        Settings settings = Settings.settingsBuilder()
+                .put(settingsLoader.load(map))
+                .build();
+        assertEquals("{map.hello=world}", settings.getAsMap().toString());
+    }
+
+    @Test
+    public void testFlatLoader() throws IOException {
+        String s = "a:\n  b: c\n";
+        SettingsLoader loader = new YamlSettingsLoader();
+        Map<String, String> flatMap = loader.load(s);
+        assertEquals("{a.b=c}", flatMap.toString());
+    }
+
+    @Test
+    public void testLoadFromMap() throws IOException {
+        Map<String, Object> map = new LinkedHashMap<>();
+        Map<String, Object> code = new LinkedHashMap<>();
+        code.put("a", "b");
+        code.put("b", "c");
+        Map<String, Object> name = new LinkedHashMap<>();
+        name.put("a", "b");
+        name.put("b", "c");
+        List<String> list = Arrays.asList("a", "b");
+        map.put("code", code);
+        map.put("name", name);
+        map.put("list", list);
+        map.put("null", null);
+        SettingsLoader loader = new YamlSettingsLoader();
+        Map<String, String> result = loader.load(map);
+        assertEquals("{code.a=b, code.b=c, name.a=b, name.b=c, list.0=a, list.1=b, null=null}", result.toString());
+    }
+}

settings-datastructures-yaml/src/test/java/org/xbib/settings/datastructures/yaml/test/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Testing YAML settings with the datastructures package.
+ */
+package org.xbib.settings.datastructures.yaml.test;

settings-datastructures/build.gradle

@@ -0,0 +1,4 @@
+dependencies {
+    api project(':settings-api')
+    api project(':datastructures-tiny')
+}

settings-datastructures/gradle.properties

@@ -0,0 +1 @@
+version = 5.0.5

settings-datastructures/src/main/java/module-info.java

@@ -0,0 +1,15 @@
+import org.xbib.settings.SettingsBuilder;
+import org.xbib.settings.SettingsLoader;
+import org.xbib.settings.datastructures.DatastructureSettingsBuilder;
+import org.xbib.settings.datastructures.PropertiesSettingsLoader;
+
+module org.xbib.settings.datastructures {
+    uses SettingsLoader;
+    provides SettingsLoader with PropertiesSettingsLoader;
+    uses SettingsBuilder;
+    provides SettingsBuilder with DatastructureSettingsBuilder;
+    exports org.xbib.settings.datastructures;
+    requires transitive org.xbib.settings.api;
+    requires org.xbib.datastructures.tiny;
+    requires transitive org.xbib.datastructures.api;
+}

settings-datastructures/src/main/java/org/xbib/settings/datastructures/AbstractSettingsLoader.java

@@ -0,0 +1,80 @@
+package org.xbib.settings.datastructures;
+
+import org.xbib.settings.SettingsLoader;
+import org.xbib.datastructures.api.Builder;
+import org.xbib.datastructures.api.DataStructure;
+import org.xbib.datastructures.api.ListNode;
+import org.xbib.datastructures.api.MapNode;
+import org.xbib.datastructures.api.Node;
+import org.xbib.datastructures.api.Parser;
+import org.xbib.datastructures.api.ValueNode;
+import org.xbib.datastructures.tiny.TinyMap;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.io.StringReader;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+public abstract class AbstractSettingsLoader implements SettingsLoader {
+
+    public AbstractSettingsLoader() {
+    }
+
+    public abstract DataStructure dataStructure();
+
+    @Override
+    public Map<String, String> load(Map<String, Object> map) throws IOException {
+        Builder builder = dataStructure().createBuilder();
+        builder.buildMap(map);
+        return load(builder.build());
+    }
+
+    @Override
+    public Map<String, String> load(String source) throws IOException {
+        Parser parser = dataStructure().createParser();
+        return load(parser, new StringReader(source));
+    }
+
+    private Map<String, String> load(Parser parser, Reader reader) throws IOException {
+        List<CharSequence> path = new ArrayList<>();
+        TinyMap.Builder<String, String> map = TinyMap.builder();
+        Node<?> node = parser.parse(reader);
+        parseObject(node, map, path, null);
+        return map.build();
+    }
+
+    private void parseObject(Node<?> node,
+                             TinyMap.Builder<String, String> map,
+                             List<CharSequence> path,
+                             CharSequence name) {
+        if (node instanceof ValueNode) {
+            ValueNode valueNode = (ValueNode) node;
+            StringBuilder sb = new StringBuilder();
+            for (CharSequence s : path) {
+                sb.append(s).append('.');
+            }
+            sb.append(name);
+            Object object = valueNode.get();
+            map.put(sb.toString(), object != null ? object.toString() : null);
+        } else if (node instanceof ListNode) {
+            ListNode listNode = (ListNode) node;
+            int counter = 0;
+            for (Node<?> nn : listNode.get()) {
+                parseObject(nn, map, path, name + "." + (counter++));
+            }
+        } else if (node instanceof MapNode) {
+            if (name != null) {
+                path.add(name);
+            }
+            MapNode mapNode = (MapNode) node;
+            for (Map.Entry<CharSequence, Node<?>> me : mapNode.get().entrySet()) {
+                parseObject(me.getValue(), map, path, me.getKey());
+            }
+            if (name != null) {
+                path.remove(path.size() - 1);
+            }
+        }
+    }
+}

settings-datastructures/src/main/java/org/xbib/settings/datastructures/DatastructureSettings.java

@@ -0,0 +1,367 @@
+package org.xbib.settings.datastructures;
+
+import org.xbib.settings.Settings;
+import org.xbib.settings.SettingsException;
+import org.xbib.datastructures.api.ByteSizeValue;
+import org.xbib.datastructures.api.TimeValue;
+import org.xbib.datastructures.tiny.TinyMap;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+public class DatastructureSettings implements Settings {
+
+    private static final String[] EMPTY_ARRAY = new String[0];
+
+    private final TinyMap<String, String> map;
+
+    DatastructureSettings(TinyMap<String, String> map) {
+        this.map = map;
+    }
+
+    public static DatastructureSettingsBuilder builder() {
+        return new DatastructureSettingsBuilder();
+    }
+
+    public static DatastructureSettings fromMap(Map<String, Object> map) {
+        DatastructureSettingsBuilder builder = new DatastructureSettingsBuilder();
+        for (Map.Entry<String, Object> entry : map.entrySet()) {
+            builder.put(entry.getKey(), entry.getValue() != null ? entry.getValue().toString() : null);
+        }
+        return builder.build();
+    }
+
+    public static void toMap(DatastructureSettings settings, Map<String, Object> map) {
+        for (String key : settings.getAsMap().keySet()) {
+            map.put(key, settings.get(key));
+        }
+    }
+
+    public static String[] splitStringByCommaToArray(String s) {
+        return splitStringToArray(s, ',');
+    }
+
+    public static String[] splitStringToArray(String s, char c) {
+        if (s.length() == 0) {
+            return EMPTY_ARRAY;
+        }
+        final char[] chars = s.toCharArray();
+        int count = 1;
+        for (final char x : chars) {
+            if (x == c) {
+                count++;
+            }
+        }
+        final String[] result = new String[count];
+        final int len = chars.length;
+        int start = 0;
+        int pos = 0;
+        int i = 0;
+        for (; pos < len; pos++) {
+            if (chars[pos] == c) {
+                int size = pos - start;
+                if (size > 0) {
+                    result[i++] = new String(chars, start, size);
+                }
+                start = pos + 1;
+            }
+        }
+        int size = pos - start;
+        if (size > 0) {
+            result[i++] = new String(chars, start, size);
+        }
+        if (i != count) {
+            String[] result1 = new String[i];
+            System.arraycopy(result, 0, result1, 0, i);
+            return result1;
+        }
+        return result;
+    }
+
+    @Override
+    public Map<String, String> getAsMap() {
+        return this.map;
+    }
+
+    @Override
+    public Map<String, Object> getAsStructuredMap() {
+        TinyMap.Builder<String, Object> stringObjectMap = TinyMap.builder();
+        for (Map.Entry<String, String> entry : map.entrySet()) {
+            String key = entry.getKey();
+            String value = entry.getValue();
+            processSetting(stringObjectMap, "", key, value);
+        }
+        for (Map.Entry<String, Object> entry : stringObjectMap.entrySet()) {
+            String key = entry.getKey();
+            Object object = entry.getValue();
+            if (object instanceof Map) {
+                @SuppressWarnings("unchecked")
+                Map<String, Object> valMap = (Map<String, Object>) object;
+                stringObjectMap.put(key, convertMapsToArrays(valMap));
+            }
+        }
+        return stringObjectMap.build();
+    }
+
+    @Override
+    public Settings getByPrefix(String prefix) {
+        DatastructureSettingsBuilder builder = new DatastructureSettingsBuilder();
+        for (Map.Entry<String, String> entry : map.entrySet()) {
+            String key = entry.getKey();
+            String value = entry.getValue();
+            if (key.startsWith(prefix)) {
+                if (key.length() < prefix.length()) {
+                    continue;
+                }
+                builder.put(key.substring(prefix.length()), value);
+            }
+        }
+        return builder.build();
+    }
+
+    @Override
+    public Settings getAsSettings(String setting) {
+        return getByPrefix(setting + ".");
+    }
+
+    @Override
+    public boolean containsSetting(String setting) {
+        if (map.containsKey(setting)) {
+            return true;
+        }
+        for (String key : map.keySet()) {
+            if (key.startsWith(setting)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    @Override
+    public String get(String setting) {
+        return map.get(setting);
+    }
+
+    @Override
+    public String get(String setting, String defaultValue) {
+        String s = map.get(setting);
+        return s == null ? defaultValue : s;
+    }
+
+    @Override
+    public float getAsFloat(String setting, float defaultValue) {
+        String s = get(setting);
+        try {
+            return s == null ? defaultValue : Float.parseFloat(s);
+        } catch (NumberFormatException e) {
+            throw new SettingsException("Failed to parse float setting [" + setting + "] with value [" + s + "]", e);
+        }
+    }
+
+    @Override
+    public double getAsDouble(String setting, double defaultValue) {
+        String s = get(setting);
+        try {
+            return s == null ? defaultValue : Double.parseDouble(s);
+        } catch (NumberFormatException e) {
+            throw new SettingsException("Failed to parse double setting [" + setting + "] with value [" + s + "]", e);
+        }
+    }
+
+    @Override
+    public int getAsInt(String setting, int defaultValue) {
+        String s = get(setting);
+        try {
+            return s == null ? defaultValue : Integer.parseInt(s);
+        } catch (NumberFormatException e) {
+            throw new SettingsException("Failed to parse int setting [" + setting + "] with value [" + s + "]", e);
+        }
+    }
+
+    @Override
+    public long getAsLong(String setting, long defaultValue) {
+        String s = get(setting);
+        try {
+            return s == null ? defaultValue : Long.parseLong(s);
+        } catch (NumberFormatException e) {
+            throw new SettingsException("Failed to parse long setting [" + setting + "] with value [" + s + "]", e);
+        }
+    }
+
+    @Override
+    public boolean getAsBoolean(String setting, boolean defaultValue) {
+        String value = get(setting);
+        if (value == null) {
+            return defaultValue;
+        }
+        return !("false".equals(value) || "0".equals(value) || "off".equals(value) || "no".equals(value));
+    }
+
+    @Override
+    public TimeValue getAsTime(String setting, TimeValue defaultValue) {
+        return TimeValue.parseTimeValue(get(setting), defaultValue);
+    }
+
+    @Override
+    public ByteSizeValue getAsBytesSize(String setting, ByteSizeValue defaultValue) {
+        return ByteSizeValue.parseBytesSizeValue(get(setting), defaultValue);
+    }
+
+    @Override
+    public String[] getAsArray(String settingPrefix) {
+        return getAsArray(settingPrefix, EMPTY_ARRAY);
+    }
+
+    @Override
+    public String[] getAsArray(String settingPrefix, String[] defaultArray) {
+        List<String> result = new ArrayList<>();
+        if (get(settingPrefix) != null) {
+            String[] strings = splitStringByCommaToArray(get(settingPrefix));
+            if (strings.length > 0) {
+                for (String string : strings) {
+                    result.add(string.trim());
+                }
+            }
+        }
+        int counter = 0;
+        while (true) {
+            String value = get(settingPrefix + '.' + (counter++));
+            if (value == null) {
+                break;
+            }
+            result.add(value.trim());
+        }
+        if (result.isEmpty()) {
+            return defaultArray;
+        }
+        return result.toArray(new String[0]);
+    }
+
+    @Override
+    public Map<String, Settings> getGroups(String prefix) {
+        String settingPrefix = prefix;
+        if (settingPrefix.charAt(settingPrefix.length() - 1) != '.') {
+            settingPrefix = settingPrefix + ".";
+        }
+        // we don't really care that it might happen twice
+        TinyMap.Builder<String, TinyMap.Builder<String, String>> hashMap = TinyMap.builder();
+        for (String o : this.map.keySet()) {
+            if (o.startsWith(settingPrefix)) {
+                String nameValue = o.substring(settingPrefix.length());
+                int dotIndex = nameValue.indexOf('.');
+                if (dotIndex == -1) {
+                    throw new SettingsException("failed to get setting group for ["
+                            + settingPrefix
+                            + "] setting prefix and setting [" + o + "] because of a missing '.'");
+                }
+                String name = nameValue.substring(0, dotIndex);
+                String value = nameValue.substring(dotIndex + 1);
+                Map<String, String> groupSettings = hashMap.computeIfAbsent(name, k -> TinyMap.builder());
+                groupSettings.put(value, get(o));
+            }
+        }
+        TinyMap.Builder<String, Settings> retVal = TinyMap.builder();
+        for (Map.Entry<String, TinyMap.Builder<String, String>> entry : hashMap.entrySet()) {
+            String key = entry.getKey();
+            TinyMap.Builder<String, String> value = entry.getValue();
+            retVal.put(key, new DatastructureSettings(value.build()));
+        }
+        return retVal.build();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        return this == o || !(o == null || getClass() != o.getClass()) && map.equals(((DatastructureSettings) o).map);
+    }
+
+    @Override
+    public int hashCode() {
+        return map.hashCode();
+    }
+
+    private void processSetting(Map<String, Object> map, String prefix, String setting, String value) {
+        int prefixLength = setting.indexOf('.');
+        if (prefixLength == -1) {
+            @SuppressWarnings("unchecked")
+            Map<String, Object> innerMap = (Map<String, Object>) map.get(prefix + setting);
+            if (innerMap != null) {
+                for (Map.Entry<String, Object> e : innerMap.entrySet()) {
+                    String k = e.getKey();
+                    Object v = e.getValue();
+                    map.put(prefix + setting + "." + k, v);
+                }
+            }
+            map.put(prefix + setting, value);
+        } else {
+            String key = setting.substring(0, prefixLength);
+            String rest = setting.substring(prefixLength + 1);
+            Object existingValue = map.get(prefix + key);
+            if (existingValue == null) {
+                Map<String, Object> newMap = TinyMap.builder();
+                processSetting(newMap, "", rest, value);
+                map.put(key, newMap);
+            } else {
+                if (existingValue instanceof Map) {
+                    @SuppressWarnings("unchecked")
+                    Map<String, Object> innerMap = (Map<String, Object>) existingValue;
+                    processSetting(innerMap, "", rest, value);
+                    map.put(key, innerMap);
+                } else {
+                    processSetting(map, prefix + key + ".", rest, value);
+                }
+            }
+        }
+    }
+
+    private Object convertMapsToArrays(Map<String, Object> map) {
+        if (map.isEmpty()) {
+            return map;
+        }
+        boolean isArray = true;
+        int maxIndex = -1;
+        for (Map.Entry<String, Object> entry : map.entrySet()) {
+            String key = entry.getKey();
+            Object value = entry.getValue();
+            if (isArray) {
+                try {
+                    int index = Integer.parseInt(key);
+                    if (index >= 0) {
+                        maxIndex = Math.max(maxIndex, index);
+                    } else {
+                        isArray = false;
+                    }
+                } catch (NumberFormatException ex) {
+                    isArray = false;
+                }
+            }
+            if (value instanceof Map) {
+                @SuppressWarnings("unchecked")
+                Map<String, Object> valMap = (Map<String, Object>) value;
+                map.put(key, convertMapsToArrays(valMap));
+            }
+        }
+        if (isArray && (maxIndex + 1) == map.size()) {
+            ArrayList<Object> newValue = new ArrayList<>(maxIndex + 1);
+            for (int i = 0; i <= maxIndex; i++) {
+                Object obj = map.get(Integer.toString(i));
+                if (obj == null) {
+                    return map;
+                }
+                newValue.add(obj);
+            }
+            return newValue;
+        }
+        return map;
+    }
+
+    public boolean isEmpty() {
+        return map.isEmpty();
+    }
+
+    @Override
+    public void close() throws IOException {
+        // do nothing
+    }
+}

settings-datastructures/src/main/java/org/xbib/settings/datastructures/DatastructureSettingsBuilder.java

@@ -0,0 +1,332 @@
+package org.xbib.settings.datastructures;
+
+import org.xbib.settings.PlaceholderResolver;
+import org.xbib.settings.PropertyPlaceholder;
+import org.xbib.settings.Settings;
+import org.xbib.settings.SettingsBuilder;
+import org.xbib.settings.SettingsException;
+import org.xbib.settings.SettingsLoader;
+import org.xbib.settings.SettingsLoaderService;
+import org.xbib.datastructures.tiny.TinyMap;
+
+import java.io.BufferedReader;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Path;
+import java.time.DateTimeException;
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+/**
+ *
+ */
+public class DatastructureSettingsBuilder implements SettingsBuilder {
+
+    private final SettingsLoaderService settingsLoaderService;
+
+    private final TinyMap.Builder<String, String> map;
+
+    public DatastructureSettingsBuilder() {
+        this.settingsLoaderService = SettingsLoaderService.getInstance();
+        this.map = TinyMap.builder();
+    }
+
+    public String remove(String key) {
+        return map.remove(key);
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return map.isEmpty();
+    }
+
+    /**
+     * Sets a setting with the provided setting key and value.
+     *
+     * @param key   The setting key
+     * @param value The setting value
+     * @return The builder
+     */
+    @Override
+    public DatastructureSettingsBuilder put(String key, String value) {
+        map.put(key, value);
+        return this;
+    }
+
+    /**
+     * Sets the setting with the provided setting key and the boolean value.
+     *
+     * @param setting The setting key
+     * @param value   The boolean value
+     * @return The builder
+     */
+    @Override
+    public DatastructureSettingsBuilder put(String setting, boolean value) {
+        put(setting, String.valueOf(value));
+        return this;
+    }
+
+    /**
+     * Sets the setting with the provided setting key and the int value.
+     *
+     * @param setting The setting key
+     * @param value   The int value
+     * @return The builder
+     */
+    @Override
+    public DatastructureSettingsBuilder put(String setting, int value) {
+        put(setting, String.valueOf(value));
+        return this;
+    }
+
+    /**
+     * Sets the setting with the provided setting key and the long value.
+     *
+     * @param setting The setting key
+     * @param value   The long value
+     * @return The builder
+     */
+    @Override
+    public DatastructureSettingsBuilder put(String setting, long value) {
+        put(setting, String.valueOf(value));
+        return this;
+    }
+
+    /**
+     * Sets the setting with the provided setting key and the float value.
+     *
+     * @param setting The setting key
+     * @param value   The float value
+     * @return The builder
+     */
+    @Override
+    public DatastructureSettingsBuilder put(String setting, float value) {
+        put(setting, String.valueOf(value));
+        return this;
+    }
+
+    /**
+     * Sets the setting with the provided setting key and the double value.
+     *
+     * @param setting The setting key
+     * @param value   The double value
+     * @return The builder
+     */
+    @Override
+    public DatastructureSettingsBuilder put(String setting, double value) {
+        put(setting, String.valueOf(value));
+        return this;
+    }
+
+    /**
+     * Sets the setting with the provided setting key and an array of values.
+     *
+     * @param setting The setting key
+     * @param values  The values
+     * @return The builder
+     */
+    @Override
+    public DatastructureSettingsBuilder putArray(String setting, String... values) {
+        remove(setting);
+        int counter = 0;
+        while (true) {
+            String value = map.remove(setting + '.' + (counter++));
+            if (value == null) {
+                break;
+            }
+        }
+        for (int i = 0; i < values.length; i++) {
+            put(setting + '.' + i, values[i]);
+        }
+        return this;
+    }
+
+    /**
+     * Sets the setting with the provided setting key and an array of values.
+     *
+     * @param setting The setting key
+     * @param values  The values
+     * @return The builder
+     */
+    @Override
+    public DatastructureSettingsBuilder putArray(String setting, List<String> values) {
+        remove(setting);
+        int counter = 0;
+        while (true) {
+            String value = map.remove(setting + '.' + (counter++));
+            if (value == null) {
+                break;
+            }
+        }
+        for (int i = 0; i < values.size(); i++) {
+            put(setting + '.' + i, values.get(i));
+        }
+        return this;
+    }
+
+    /**
+     * Sets the setting group.
+     *
+     * @param settingPrefix setting prefix
+     * @param groupName     group name
+     * @param settings      settings
+     * @param values        values
+     * @return a builder
+     * @throws SettingsException if setting fails
+     */
+    @Override
+    public DatastructureSettingsBuilder put(String settingPrefix, String groupName, String[] settings, String[] values)
+            throws SettingsException {
+        if (settings.length != values.length) {
+            throw new SettingsException("the settings length must match the value length");
+        }
+        for (int i = 0; i < settings.length; i++) {
+            if (values[i] == null) {
+                continue;
+            }
+            put(settingPrefix + "" + groupName + "." + settings[i], values[i]);
+        }
+        return this;
+    }
+
+    /**
+     * Sets all the provided settings.
+     *
+     * @param settings settings
+     * @return builder
+     */
+    @Override
+    public DatastructureSettingsBuilder put(Settings settings) {
+        map.putAll(settings.getAsMap());
+        return this;
+    }
+
+    /**
+     * Sets all the provided settings.
+     *
+     * @param settings settings
+     * @return a builder
+     */
+    @Override
+    public DatastructureSettingsBuilder put(Map<String, String> settings) {
+        map.putAll(settings);
+        return this;
+    }
+
+    /**
+     * Loads settings from a resource.
+     *
+     * @param resourceName resource name
+     * @param inputStream  input stream
+     * @return builder
+     */
+    @Override
+    public DatastructureSettingsBuilder loadFromResource(String resourceName, InputStream inputStream) {
+        SettingsLoader settingsLoader = settingsLoaderService.loaderFromResource(resourceName);
+        try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8))) {
+            Map<String, String> loadedSettings = settingsLoader.load(bufferedReader.lines().collect(Collectors.joining()));
+            put(loadedSettings);
+        } catch (Exception e) {
+            throw new SettingsException("failed to load settings from [" + resourceName + "]", e);
+        }
+        return this;
+    }
+
+    /**
+     * Loads settings from the actual string content that represents them using the
+     * {@link SettingsLoaderService#loaderFromResource(String)} (String)}.
+     *
+     * @param resourceName the resource name
+     * @param  source the source
+     * @return builder
+     */
+    @Override
+    public DatastructureSettingsBuilder loadFromString(String resourceName, String source) {
+        SettingsLoader settingsLoader = settingsLoaderService.loaderFromResource(resourceName);
+        try {
+            put(settingsLoader.load(source));
+        } catch (Exception e) {
+            throw new SettingsException("failed to load settings from [" + source + "]", e);
+        }
+        return this;
+    }
+
+    /**
+     * Load system properties to this settings.
+     *
+     * @return builder
+     */
+    @Override
+    public DatastructureSettingsBuilder loadFromSystemProperties() {
+        for (Map.Entry<Object, Object> entry : System.getProperties().entrySet()) {
+            put((String) entry.getKey(), (String) entry.getValue());
+        }
+        return this;
+    }
+
+    /**
+     * Load system environment to this settings.
+     *
+     * @return builder
+     */
+    @Override
+    public DatastructureSettingsBuilder loadFromSystemEnvironment() {
+        for (Map.Entry<String, String> entry : System.getenv().entrySet()) {
+            put(entry.getKey(), entry.getValue());
+        }
+        return this;
+    }
+
+    @Override
+    public DatastructureSettingsBuilder replacePropertyPlaceholders(PropertyPlaceholder propertyPlaceholder,
+                                                                    PlaceholderResolver placeholderResolver) {
+        map.replaceAll((k, v) -> propertyPlaceholder.replacePlaceholders(v, placeholderResolver));
+        return this;
+    }
+
+    @Override
+    public DatastructureSettingsBuilder replacePropertyPlaceholders() {
+        return replacePropertyPlaceholders(new PropertyPlaceholder("${", "}", false),
+                placeholderName -> {
+                    // system property
+                    String value = System.getProperty(placeholderName);
+                    if (value != null) {
+                        return value;
+                    }
+                    // environment
+                    value = System.getenv(placeholderName);
+                    if (value != null) {
+                        return value;
+                    }
+                    // current date
+                    try {
+                        return DateTimeFormatter.ofPattern(placeholderName).format(LocalDate.now());
+                    } catch (IllegalArgumentException | DateTimeException e) {
+                        return map.get(placeholderName);
+                    }
+                }
+        );
+    }
+
+    @Override
+    public DatastructureSettingsBuilder setRefresh(Path path, long initialDelay, long period, TimeUnit timeUnit) {
+        return this;
+    }
+
+    @Override
+    public SettingsBuilder map(Function<Map.Entry<String, String>, Map.Entry<String, String>> function) {
+        map.entrySet().stream().map(function).forEach(e -> put(e.getKey(), e.getValue()));
+        return this;
+    }
+
+    @Override
+    public DatastructureSettings build() {
+        return new DatastructureSettings(map.build());
+    }
+}

settings-datastructures/src/main/java/org/xbib/settings/datastructures/PropertiesSettingsLoader.java

@@ -0,0 +1,47 @@
+package org.xbib.settings.datastructures;
+
+import org.xbib.settings.SettingsLoader;
+import org.xbib.datastructures.tiny.TinyMap;
+import java.io.IOException;
+import java.io.StringReader;
+import java.util.Map;
+import java.util.Properties;
+import java.util.Set;
+
+/**
+ * Settings loader that loads (parses) the settings in a properties format.
+ */
+public class PropertiesSettingsLoader implements SettingsLoader {
+
+    public PropertiesSettingsLoader() {
+    }
+
+    @Override
+    public Set<String> suffixes() {
+        return Set.of("properties");
+    }
+
+    @Override
+    public Map<String, String> load(String source) throws IOException {
+        Properties props = new Properties();
+        try (StringReader reader = new StringReader(source)) {
+            props.load(reader);
+            TinyMap.Builder<String, String> result = TinyMap.builder();
+            for (Map.Entry<Object, Object> entry : props.entrySet()) {
+                result.put((String) entry.getKey(), (String) entry.getValue());
+            }
+            return result.build();
+        }
+    }
+
+    @Override
+    public Map<String, String> load(Map<String, Object> source) {
+        Properties props = new Properties();
+        props.putAll(source);
+        TinyMap.Builder<String, String> result = TinyMap.builder();
+        for (Map.Entry<Object, Object> entry : props.entrySet()) {
+            result.put((String) entry.getKey(), (String) entry.getValue());
+        }
+        return result.build();
+    }
+}

settings-datastructures/src/main/java/org/xbib/settings/datastructures/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Classes for settings using the datastructures API.
+ */
+package org.xbib.settings.datastructures;

settings-datastructures/src/main/resources/META-INF/services/org.xbib.settings.SettingsBuilder

@@ -0,0 +1 @@
+org.xbib.settings.datastructures.DatastructureSettingsBuilder

settings-datastructures/src/test/java/org/xbib/settings/datastructures/test/SettingsTest.java

@@ -0,0 +1,134 @@
+package org.xbib.settings.datastructures.test;
+
+import org.junit.jupiter.api.Test;
+import org.xbib.settings.Settings;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class SettingsTest {
+
+    @Test
+    public void testEmpty() {
+        Settings settings = Settings.emptySettings();
+        assertTrue(settings.isEmpty());
+    }
+
+    @Test
+    public void testSimpleSettings() {
+        Settings settings = Settings.settingsBuilder()
+                .put("a", "b")
+                .build();
+        assertEquals("{a=b}", settings.getAsMap().toString());
+        assertEquals("{a=b}", settings.getAsStructuredMap().toString());
+    }
+
+    @Test
+    public void testArray() {
+        Settings settings = Settings.settingsBuilder()
+                .putArray("input", Arrays.asList("a", "b", "c")).build();
+        assertEquals("a", settings.getAsArray("input")[0]);
+        assertEquals("b", settings.getAsArray("input")[1]);
+        assertEquals("c", settings.getAsArray("input")[2]);
+    }
+
+    @SuppressWarnings("unchecked")
+    @Test
+    public void testArrayOfMaps() {
+        Settings settings = Settings.settingsBuilder()
+                .put("location.0.code", "Code 0")
+                .put("location.0.name", "Name 0")
+                .put("location.1.code", "Code 1")
+                .put("location.1.name", "Name 1")
+                .build();
+
+        // turn map with index keys 0,1,... into a list of maps
+        Map<String, Object> map = settings.getAsSettings("location").getAsStructuredMap();
+        List<Map<String, Object>> list = new ArrayList<>();
+        for (Map.Entry<String, Object> entry : map.entrySet()) {
+            list.add((Map<String, Object>) entry.getValue());
+        }
+        assertEquals("[{code=Code 0, name=Name 0}, {code=Code 1, name=Name 1}]", list.toString());
+    }
+
+    @Test
+    public void testGroups() {
+        Settings settings = Settings.settingsBuilder()
+                .put("prefix.group1.k1", "v1")
+                .put("prefix.group1.k2", "v2")
+                .put("prefix.group1.k3", "v3")
+                .put("prefix.group2.k1", "v1")
+                .put("prefix.group2.k2", "v2")
+                .put("prefix.group2.k3", "v3")
+                .build();
+        Map<String, Settings> groups = settings.getGroups("prefix");
+        assertEquals("[group1, group2]", groups.keySet().toString());
+        assertTrue(groups.get("group1").getAsMap().containsKey("k1"));
+        assertTrue(groups.get("group1").getAsMap().containsKey("k2"));
+        assertTrue(groups.get("group1").getAsMap().containsKey("k3"));
+        assertTrue(groups.get("group2").getAsMap().containsKey("k1"));
+        assertTrue(groups.get("group2").getAsMap().containsKey("k2"));
+        assertTrue(groups.get("group2").getAsMap().containsKey("k3"));
+    }
+
+    @Test
+    public void testCurrentYearInSettings() {
+        Settings settings = Settings.settingsBuilder()
+                .put("date", "${yyyy}")
+                .replacePropertyPlaceholders()
+                .build();
+        assertEquals(LocalDate.now().getYear(), Integer.parseInt(settings.get("date")));
+    }
+
+    @Test
+    public void testPropertyReplaceNull() {
+        Settings settings = Settings.settingsBuilder()
+                .put("null", null)
+                .replacePropertyPlaceholders()
+                .build();
+        assertNull(settings.get("null"));
+    }
+
+    @Test
+    public void testSystemEnvironment() {
+        Settings settings = Settings.settingsBuilder()
+                .loadFromSystemEnvironment()
+                .build();
+        assertFalse(settings.getAsMap().isEmpty());
+    }
+
+    @Test
+    public void testSystemProperties() {
+        Settings settings = Settings.settingsBuilder()
+                .loadFromSystemProperties()
+                .build();
+        assertFalse(settings.getAsMap().isEmpty());
+    }
+
+    @Test
+    public void testPropertiesLoaderFromResource() {
+        Settings settings = Settings.settingsBuilder()
+                .loadFromResource("properties", new ByteArrayInputStream("a.b=c".getBytes(StandardCharsets.UTF_8)))
+                .build();
+        assertEquals("{a.b=c}", settings.getAsMap().toString());
+    }
+
+    @Test
+    public void testPropertiesLoaderFromString() {
+        Settings settings = Settings.settingsBuilder()
+                .loadFromString("properties", "#\na.b=c")
+                .build();
+        assertEquals("{a.b=c}", settings.getAsMap().toString());
+    }
+}

settings-datastructures/src/test/resources/META-INF/services/org.xbib.settings.SettingsLoader

@@ -0,0 +1 @@
+org.xbib.settings.datastructures.PropertiesSettingsLoader

settings.gradle

@@ -65,3 +65,8 @@ include 'datastructures-yaml-tiny'
 include 'datastructures-validation'
 include 'datastructures-trie'
 include 'datastructures-raml'
+include 'settings-api'
+include 'settings-datastructures'
+include 'settings-datastructures-json'
+include 'settings-datastructures-yaml'
+include 'config'