begin of MARC parsing in JSON

gradle.properties

@@ -1,5 +1,5 @@
 group = org.xbib
 name = marc
-version = 2.9.20
+version = 2.9.21
 
 org.gradle.warning.mode = ALL

src/main/java/org/xbib/marc/MarcRecord.java

@@ -15,6 +15,7 @@
  */
 package org.xbib.marc;
 
+import java.util.Objects;
 import org.xbib.marc.label.RecordLabel;
 
 import java.io.InputStream;
@@ -44,7 +45,7 @@ import static org.xbib.marc.json.MarcJsonWriter.LEADER_TAG;
 import static org.xbib.marc.json.MarcJsonWriter.TYPE_TAG;
 
 /**
- * A MARC record. This is an extended MARC record augmented with MarcXchange information.
+ * A MARC record.
  */
 public class MarcRecord implements Map<String, Object> {
 
@@ -91,9 +92,7 @@ public class MarcRecord implements Map<String, Object> {
         this.format = format;
         this.type = type;
         this.recordLabel = recordLabel;
-        if (recordLabel == null) {
+        Objects.requireNonNull(recordLabel, "record label must not be null");
-            throw new NullPointerException("record label must not be null");
-        }
         this.marcFields = marcFields;
         this.delegate = lightweight ? Map.of() : createMapFromMarcFields(comparator);
     }
@@ -179,6 +178,15 @@ public class MarcRecord implements Map<String, Object> {
         return recordLabel;
     }
 
+    /**
+     * Return the MARC fields of this record.
+     *
+     * @return the MARC field list
+     */
+    public List<MarcField> getFields() {
+        return marcFields;
+    }
+
     public LocalDate getCreationDate(LocalDate defaultDate) {
         if (marcFields != null) {
             MarcField marcField = getFirst("008");
@@ -255,15 +263,6 @@ public class MarcRecord implements Map<String, Object> {
         }
     }
 
-    /**
-     * Return the MARC fields of this record.
-     *
-     * @return the MARC field list
-     */
-    public List<MarcField> getFields() {
-        return marcFields;
-    }
-
     /**
      * Filter all MARC fields of this record with a given tag.
      *

src/main/java/org/xbib/marc/json/JsonException.java

@@ -0,0 +1,13 @@
+package org.xbib.marc.json;
+
+@SuppressWarnings("serial")
+public class JsonException extends RuntimeException {
+
+    public JsonException(String message) {
+        super(message);
+    }
+
+    public JsonException(Exception exception) {
+        super(exception);
+    }
+}

src/main/java/org/xbib/marc/json/JsonListener.java

@@ -0,0 +1,30 @@
+package org.xbib.marc.json;
+
+public interface JsonListener {
+
+    void begin();
+
+    void end();
+
+    void onNull();
+
+    void onTrue();
+
+    void onFalse();
+
+    void onKey(CharSequence key);
+
+    void onValue(CharSequence value);
+
+    void onLong(Long value);
+
+    void onDouble(Double value);
+
+    void beginCollection();
+
+    void endCollection();
+
+    void beginMap();
+
+    void endMap();
+}

src/main/java/org/xbib/marc/json/JsonParser.java

@@ -0,0 +1,291 @@
+package org.xbib.marc.json;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.util.Objects;
+
+public class JsonParser implements Parser {
+
+    private final JsonResultListener listener;
+
+    private Reader reader;
+
+    private int ch;
+
+    public JsonParser() {
+        this(new MarcJsonListener());
+    }
+
+    public JsonParser(JsonResultListener listener) {
+        this.listener = listener;
+    }
+
+    @Override
+    public Node<?> parse(Reader reader) throws IOException {
+        Objects.requireNonNull(reader);
+        Objects.requireNonNull(listener);
+        this.reader = reader;
+        listener.begin();
+        ch = reader.read();
+        skipWhitespace();
+        parseValue();
+        skipWhitespace();
+        if (ch != -1) {
+            throw new JsonException("malformed json: " + ch);
+        }
+        listener.end();
+        return listener.getResult();
+    }
+
+    private void parseValue() throws IOException, JsonException {
+        switch (ch) {
+            case '"' -> parseString(false);
+            case '{' -> parseMap();
+            case '[' -> parseList();
+            case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-' -> parseNumber();
+            case 't' -> parseTrue();
+            case 'f' -> parseFalse();
+            case 'n' -> parseNull();
+            default -> throw new JsonException("illegal character: " + ch);
+        }
+    }
+
+    private void parseNumber() throws IOException, JsonException {
+        boolean minus = false;
+        boolean dot = false;
+        boolean exponent = false;
+        StringBuilder sb = new StringBuilder();
+        while (true) {
+            if (ch == '-') {
+                if (sb.length() > 1) {
+                    throw new JsonException("minus inside number");
+                }
+                sb.append((char) ch);
+                ch = reader.read();
+                minus = true;
+            } else if (ch == 'e' || ch == 'E') {
+                sb.append((char) ch);
+                ch = reader.read();
+                if (exponent) {
+                    throw new JsonException("double exponents");
+                }
+                exponent = true;
+                ch = reader.read();
+                if (ch == '-' || ch == '+') {
+                    ch = reader.read();
+                    if (ch < '0' || ch > '9') {
+                        throw new JsonException("invalid exponent");
+                    }
+                } else if (ch < '0' || ch > '9') {
+                    throw new JsonException("invalid exponent");
+                }
+            } else if (ch == '.') {
+                sb.append((char) ch);
+                ch = reader.read();
+                if (dot) {
+                    throw new JsonException("multiple dots");
+                }
+                if (sb.length() == 1) {
+                    throw new JsonException("no digit before dot");
+                }
+                dot = true;
+            } else if (ch >= '0' && ch <= '9') {
+                sb.append((char) ch);
+                ch = reader.read();
+            } else {
+                break;
+            }
+        }
+        if (minus && sb.length() == 1) {
+            throw new JsonException("isolated minus");
+        }
+        if (dot || exponent) {
+            listener.onDouble(Double.parseDouble(sb.toString()));
+        } else {
+            listener.onLong(Long.parseLong(sb.toString()));
+        }
+    }
+
+    private void parseString(boolean isKey) throws IOException, JsonException {
+        reader.mark(1024);
+        ch = reader.read();
+        boolean escaped = false;
+        int count = 1;
+        while (true) {
+            if (ch == '"') {
+                char[] buffer = new char[count - 1];
+                reader.reset();
+                reader.read(buffer, 0, count - 1);
+                reader.read();
+                CharSequence s = new String(buffer);
+                if (escaped) {
+                    s = unescape(s);
+                    if (isKey) {
+                        listener.onKey(s);
+                    } else {
+                        listener.onValue(s);
+                    }
+                } else {
+                    if (isKey) {
+                        listener.onKey(s);
+                    } else {
+                        listener.onValue(s);
+                    }
+                }
+                ch = reader.read();
+                return;
+            } else if (ch == '\\') {
+                escaped = true;
+                ch = reader.read();
+                if (ch == '"' || ch == '/' || ch == '\\' || ch == 'b' || ch == 'f' || ch == 'n' || ch == 'r' || ch == 't') {
+                    ch = reader.read();
+                    count += 2;
+                } else if (ch == 'u') {
+                    expectHex();
+                    expectHex();
+                    expectHex();
+                    expectHex();
+                    count += 5;
+                } else {
+                    throw new JsonException("illegal escape char: " + ch);
+                }
+            } else if (ch < 32) {
+                throw new JsonException("illegal control char: " + ch);
+            } else {
+                count++;
+                ch = reader.read();
+            }
+        }
+    }
+
+    private void parseList() throws IOException {
+        int count = 0;
+        listener.beginCollection();
+        ch = reader.read();
+        while (true) {
+            skipWhitespace();
+            if (ch == ']') {
+                listener.endCollection();
+                ch = reader.read();
+                return;
+            }
+            if (count > 0) {
+                expectChar(',');
+                ch = reader.read();
+                skipWhitespace();
+            }
+            parseValue();
+            count++;
+        }
+    }
+
+    private void parseMap() throws IOException, JsonException {
+        int count = 0;
+        listener.beginMap();
+        ch = reader.read();
+        while (true) {
+            skipWhitespace();
+            if (ch == '}') {
+                listener.endMap();
+                ch = reader.read();
+                return;
+            }
+            if (count > 0) {
+                expectChar(',');
+                ch = reader.read();
+                skipWhitespace();
+            }
+            expectChar('"');
+            parseString(true);
+            skipWhitespace();
+            expectChar(':');
+            ch = reader.read();
+            skipWhitespace();
+            parseValue();
+            count++;
+        }
+    }
+
+    private void parseNull() throws IOException, JsonException {
+        ch = reader.read();
+        expectChar('u');
+        ch = reader.read();
+        expectChar('l');
+        ch = reader.read();
+        expectChar('l');
+        listener.onNull();
+        ch = reader.read();
+    }
+
+    private void parseTrue() throws IOException, JsonException {
+        ch = reader.read();
+        expectChar('r');
+        ch = reader.read();
+        expectChar('u');
+        ch = reader.read();
+        expectChar('e');
+        listener.onTrue();
+        ch = reader.read();
+    }
+
+    private void parseFalse() throws IOException, JsonException {
+        ch = reader.read();
+        expectChar('a');
+        ch = reader.read();
+        expectChar('l');
+        ch = reader.read();
+        expectChar('s');
+        ch = reader.read();
+        expectChar('e');
+        listener.onFalse();
+        ch = reader.read();
+    }
+
+    private void expectChar(char expected) throws JsonException {
+        if (ch != expected) {
+            throw new JsonException("expected char " + expected + " but got " + (char)ch);
+        }
+    }
+
+    private void expectHex() throws IOException, JsonException {
+        ch = reader.read();
+        if ((ch >= '0' && ch <= '9') || (ch >= 'a' && ch <= 'f') || (ch >= 'A' && ch <= 'F')) {
+            return;
+        }
+        throw new JsonException("invalid hex char " + ch);
+    }
+
+    private void skipWhitespace() throws IOException {
+        while (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r') {
+            ch = reader.read();
+        }
+    }
+
+    private static CharSequence unescape(CharSequence input) {
+        StringBuilder result = new StringBuilder(input.length());
+        int i = 0;
+        while (i < input.length()) {
+            if (input.charAt(i) == '\\') {
+                i++;
+                switch (input.charAt(i)) {
+                    case '\\' -> result.append('\\');
+                    case '/' -> result.append('/');
+                    case '"' -> result.append('"');
+                    case 'b' -> result.append('\b');
+                    case 'f' -> result.append('\f');
+                    case 'n' -> result.append('\n');
+                    case 'r' -> result.append('\r');
+                    case 't' -> result.append('\t');
+                    case 'u' -> {
+                        result.append(Character.toChars(Integer.parseInt(input.toString().substring(i + 1, i + 5), 16)));
+                        i += 4;
+                    }
+                }
+            } else {
+                result.append(input.charAt(i));
+            }
+            i++;
+        }
+        return result;
+    }
+}

src/main/java/org/xbib/marc/json/JsonResultListener.java

@@ -0,0 +1,6 @@
+package org.xbib.marc.json;
+
+public interface JsonResultListener extends JsonListener {
+
+    Node<?> getResult();
+}

src/main/java/org/xbib/marc/json/KeyNode.java

@@ -0,0 +1,24 @@
+package org.xbib.marc.json;
+
+public class KeyNode implements Node<CharSequence> {
+
+    private CharSequence value;
+
+    public KeyNode(CharSequence value) {
+        this.value = value;
+    }
+
+    public void setValue(String value) {
+        this.value = value;
+    }
+
+    @Override
+    public CharSequence get() {
+        return value;
+    }
+
+    @Override
+    public String toString() {
+        return value != null ? value.toString() : null;
+    }
+}

src/main/java/org/xbib/marc/json/ListNode.java

@@ -0,0 +1,6 @@
+package org.xbib.marc.json;
+
+import java.util.List;
+
+public interface ListNode extends Node<List<Node<?>>> {
+}

src/main/java/org/xbib/marc/json/MapNode.java

@@ -0,0 +1,6 @@
+package org.xbib.marc.json;
+
+import java.util.Map;
+
+public interface MapNode extends Node<Map<CharSequence, Node<?>>> {
+}

src/main/java/org/xbib/marc/json/MarcJsonListener.java

@@ -0,0 +1,113 @@
+package org.xbib.marc.json;
+
+import java.util.Deque;
+import java.util.LinkedList;
+
+public class MarcJsonListener implements JsonResultListener {
+
+    private Node<?> node;
+
+    private final Deque<Node<?>> stack = new LinkedList<>();
+
+    private final ValueNode NULL_NODE = new ValueNode(null);
+
+    private final ValueNode TRUE_NODE = new ValueNode(Boolean.TRUE);
+
+    private final ValueNode FALSE_NODE = new ValueNode(Boolean.FALSE);
+
+    public MarcJsonListener() {
+    }
+
+    @Override
+    public Node<?> getResult() {
+        return node;
+    }
+
+    @Override
+    public void begin() {
+        stack.clear();
+    }
+
+    @Override
+    public void end() {
+    }
+
+    @Override
+    public void onNull() {
+        valueNode(NULL_NODE);
+    }
+
+    @Override
+    public void onTrue() {
+        valueNode(TRUE_NODE);
+    }
+
+    @Override
+    public void onFalse() {
+        valueNode(FALSE_NODE);
+    }
+
+    @Override
+    public void onKey(CharSequence key) {
+        stack.push(new KeyNode(key));
+    }
+
+    @Override
+    public void onValue(CharSequence value) {
+        valueNode(new ValueNode(value));
+    }
+
+    @Override
+    public void onLong(Long value) {
+        valueNode(new ValueNode(value));
+    }
+
+    @Override
+    public void onDouble(Double value) {
+        valueNode(new ValueNode(value));
+    }
+
+    @Override
+    public void beginCollection() {
+        stack.push(new MarcListNode());
+    }
+
+    @Override
+    public void endCollection() {
+        node = stack.pop();
+        tryAppend(node);
+    }
+
+    @Override
+    public void beginMap() {
+        stack.push(new MarcMapNode());
+    }
+
+    @Override
+    public void endMap() {
+        node = stack.pop();
+        tryAppend(node);
+    }
+
+    private void valueNode(ValueNode valueNode) {
+        if (!tryAppend(valueNode)) {
+            stack.push(valueNode);
+            node = valueNode;
+        }
+    }
+
+    private boolean tryAppend(Node<?> node) {
+        if (!stack.isEmpty()) {
+            if (stack.peek() instanceof MarcListNode listNode) {
+                listNode.add(node);
+                return true;
+            } else if (stack.peek() instanceof KeyNode) {
+                KeyNode keyNode = (KeyNode) stack.pop();
+                MarcMapNode mapNode = (MarcMapNode) stack.peek();
+                mapNode.put(keyNode.get(), node);
+                return true;
+            }
+        }
+        return false;
+    }
+}

src/main/java/org/xbib/marc/json/MarcListNode.java

@@ -0,0 +1,15 @@
+package org.xbib.marc.json;
+
+import java.util.LinkedList;
+import java.util.List;
+
+public class MarcListNode extends LinkedList<Node<?>> implements ListNode {
+
+    public MarcListNode() {
+    }
+
+    @Override
+    public List<Node<?>> get() {
+        return this;
+    }
+}

src/main/java/org/xbib/marc/json/MarcMapNode.java

@@ -0,0 +1,15 @@
+package org.xbib.marc.json;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+public class MarcMapNode extends LinkedHashMap<CharSequence, Node<?>> implements MapNode {
+
+    public MarcMapNode() {
+    }
+
+    @Override
+    public Map<CharSequence, Node<?>> get() {
+        return this;
+    }
+}

src/main/java/org/xbib/marc/json/Node.java

@@ -0,0 +1,6 @@
+package org.xbib.marc.json;
+
+public interface Node<T> {
+
+    T get();
+}

src/main/java/org/xbib/marc/json/Parser.java

@@ -0,0 +1,9 @@
+package org.xbib.marc.json;
+
+import java.io.IOException;
+import java.io.Reader;
+
+public interface Parser {
+
+    Node<?> parse(Reader reader) throws IOException;
+}

src/main/java/org/xbib/marc/json/ValueNode.java

@@ -0,0 +1,29 @@
+package org.xbib.marc.json;
+
+public class ValueNode implements Node<Object> {
+
+    private Object value;
+
+    public ValueNode(Object value) {
+        this.value = value;
+    }
+
+    @Override
+    public int getDepth() {
+        return 0;
+    }
+
+    public void set(Object value) {
+        this.value = value;
+    }
+
+    @Override
+    public Object get() {
+        return value;
+    }
+
+    @Override
+    public String toString() {
+        return value != null ? value.toString() : null;
+    }
+}