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/**
 * Copyright (c) 2008, http://www.snakeyaml.org
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.yaml.snakeyaml.parser;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.yaml.snakeyaml.DumperOptions;
import org.yaml.snakeyaml.DumperOptions.Version;
import org.yaml.snakeyaml.error.Mark;
import org.yaml.snakeyaml.error.YAMLException;
import org.yaml.snakeyaml.events.AliasEvent;
import org.yaml.snakeyaml.events.DocumentEndEvent;
import org.yaml.snakeyaml.events.DocumentStartEvent;
import org.yaml.snakeyaml.events.Event;
import org.yaml.snakeyaml.events.ImplicitTuple;
import org.yaml.snakeyaml.events.MappingEndEvent;
import org.yaml.snakeyaml.events.MappingStartEvent;
import org.yaml.snakeyaml.events.ScalarEvent;
import org.yaml.snakeyaml.events.SequenceEndEvent;
import org.yaml.snakeyaml.events.SequenceStartEvent;
import org.yaml.snakeyaml.events.StreamEndEvent;
import org.yaml.snakeyaml.events.StreamStartEvent;
import org.yaml.snakeyaml.nodes.Tag;
import org.yaml.snakeyaml.reader.StreamReader;
import org.yaml.snakeyaml.scanner.Scanner;
import org.yaml.snakeyaml.scanner.ScannerImpl;
import org.yaml.snakeyaml.tokens.AliasToken;
import org.yaml.snakeyaml.tokens.AnchorToken;
import org.yaml.snakeyaml.tokens.BlockEntryToken;
import org.yaml.snakeyaml.tokens.DirectiveToken;
import org.yaml.snakeyaml.tokens.ScalarToken;
import org.yaml.snakeyaml.tokens.StreamEndToken;
import org.yaml.snakeyaml.tokens.StreamStartToken;
import org.yaml.snakeyaml.tokens.TagToken;
import org.yaml.snakeyaml.tokens.TagTuple;
import org.yaml.snakeyaml.tokens.Token;
import org.yaml.snakeyaml.util.ArrayStack;

/**
 * 
 * # The following YAML grammar is LL(1) and is parsed by a recursive descent
 * parser.
 * stream            ::= STREAM-START implicit_document? explicit_document* STREAM-END
 * implicit_document ::= block_node DOCUMENT-END*
 * explicit_document ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
 * block_node_or_indentless_sequence ::=
 *                       ALIAS
 *                       | properties (block_content | indentless_block_sequence)?
 *                       | block_content
 *                       | indentless_block_sequence
 * block_node        ::= ALIAS
 *                       | properties block_content?
 *                       | block_content
 * flow_node         ::= ALIAS
 *                       | properties flow_content?
 *                       | flow_content
 * properties        ::= TAG ANCHOR? | ANCHOR TAG?
 * block_content     ::= block_collection | flow_collection | SCALAR
 * flow_content      ::= flow_collection | SCALAR
 * block_collection  ::= block_sequence | block_mapping
 * flow_collection   ::= flow_sequence | flow_mapping
 * block_sequence    ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
 * indentless_sequence   ::= (BLOCK-ENTRY block_node?)+
 * block_mapping     ::= BLOCK-MAPPING_START
 *                       ((KEY block_node_or_indentless_sequence?)?
 *                       (VALUE block_node_or_indentless_sequence?)?)*
 *                       BLOCK-END
 * flow_sequence     ::= FLOW-SEQUENCE-START
 *                       (flow_sequence_entry FLOW-ENTRY)*
 *                       flow_sequence_entry?
 *                       FLOW-SEQUENCE-END
 * flow_sequence_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
 * flow_mapping      ::= FLOW-MAPPING-START
 *                       (flow_mapping_entry FLOW-ENTRY)*
 *                       flow_mapping_entry?
 *                       FLOW-MAPPING-END
 * flow_mapping_entry    ::= flow_node | KEY flow_node? (VALUE flow_node?)?
 * FIRST sets:
 * stream: { STREAM-START }
 * explicit_document: { DIRECTIVE DOCUMENT-START }
 * implicit_document: FIRST(block_node)
 * block_node: { ALIAS TAG ANCHOR SCALAR BLOCK-SEQUENCE-START BLOCK-MAPPING-START FLOW-SEQUENCE-START FLOW-MAPPING-START }
 * flow_node: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START FLOW-MAPPING-START }
 * block_content: { BLOCK-SEQUENCE-START BLOCK-MAPPING-START FLOW-SEQUENCE-START FLOW-MAPPING-START SCALAR }
 * flow_content: { FLOW-SEQUENCE-START FLOW-MAPPING-START SCALAR }
 * block_collection: { BLOCK-SEQUENCE-START BLOCK-MAPPING-START }
 * flow_collection: { FLOW-SEQUENCE-START FLOW-MAPPING-START }
 * block_sequence: { BLOCK-SEQUENCE-START }
 * block_mapping: { BLOCK-MAPPING-START }
 * block_node_or_indentless_sequence: { ALIAS ANCHOR TAG SCALAR BLOCK-SEQUENCE-START BLOCK-MAPPING-START FLOW-SEQUENCE-START FLOW-MAPPING-START BLOCK-ENTRY }
 * indentless_sequence: { ENTRY }
 * flow_collection: { FLOW-SEQUENCE-START FLOW-MAPPING-START }
 * flow_sequence: { FLOW-SEQUENCE-START }
 * flow_mapping: { FLOW-MAPPING-START }
 * flow_sequence_entry: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START FLOW-MAPPING-START KEY }
 * flow_mapping_entry: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START FLOW-MAPPING-START KEY }
 * 
* * Since writing a recursive-descendant parser is a straightforward task, we do * not give many comments here. */ public class ParserImpl implements Parser { private static final Map DEFAULT_TAGS = new HashMap(); static { DEFAULT_TAGS.put("!", "!"); DEFAULT_TAGS.put("!!", Tag.PREFIX); } protected final Scanner scanner; private Event currentEvent; private final ArrayStack states; private final ArrayStack marks; private Production state; private VersionTagsTuple directives; public ParserImpl(StreamReader reader) { this(new ScannerImpl(reader)); } public ParserImpl(Scanner scanner) { this.scanner = scanner; currentEvent = null; directives = new VersionTagsTuple(null, new HashMap(DEFAULT_TAGS)); states = new ArrayStack(100); marks = new ArrayStack(10); state = new ParseStreamStart(); } /** * Check the type of the next event. */ public boolean checkEvent(Event.ID choice) { peekEvent(); return currentEvent != null && currentEvent.is(choice); } /** * Get the next event. */ public Event peekEvent() { if (currentEvent == null) { if (state != null) { currentEvent = state.produce(); } } return currentEvent; } /** * Get the next event and proceed further. */ public Event getEvent() { peekEvent(); Event value = currentEvent; currentEvent = null; return value; } /** *
     * stream    ::= STREAM-START implicit_document? explicit_document* STREAM-END
     * implicit_document ::= block_node DOCUMENT-END*
     * explicit_document ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
     * 
*/ private class ParseStreamStart implements Production { public Event produce() { // Parse the stream start. StreamStartToken token = (StreamStartToken) scanner.getToken(); Event event = new StreamStartEvent(token.getStartMark(), token.getEndMark()); // Prepare the next state. state = new ParseImplicitDocumentStart(); return event; } } private class ParseImplicitDocumentStart implements Production { public Event produce() { // Parse an implicit document. if (!scanner.checkToken(Token.ID.Directive, Token.ID.DocumentStart, Token.ID.StreamEnd)) { directives = new VersionTagsTuple(null, DEFAULT_TAGS); Token token = scanner.peekToken(); Mark startMark = token.getStartMark(); Mark endMark = startMark; Event event = new DocumentStartEvent(startMark, endMark, false, null, null); // Prepare the next state. states.push(new ParseDocumentEnd()); state = new ParseBlockNode(); return event; } else { Production p = new ParseDocumentStart(); return p.produce(); } } } private class ParseDocumentStart implements Production { public Event produce() { // Parse any extra document end indicators. while (scanner.checkToken(Token.ID.DocumentEnd)) { scanner.getToken(); } // Parse an explicit document. Event event; if (!scanner.checkToken(Token.ID.StreamEnd)) { Token token = scanner.peekToken(); Mark startMark = token.getStartMark(); VersionTagsTuple tuple = processDirectives(); if (!scanner.checkToken(Token.ID.DocumentStart)) { throw new ParserException(null, null, "expected '', but found '" + scanner.peekToken().getTokenId() + "'", scanner.peekToken().getStartMark()); } token = scanner.getToken(); Mark endMark = token.getEndMark(); event = new DocumentStartEvent(startMark, endMark, true, tuple.getVersion(), tuple.getTags()); states.push(new ParseDocumentEnd()); state = new ParseDocumentContent(); } else { // Parse the end of the stream. StreamEndToken token = (StreamEndToken) scanner.getToken(); event = new StreamEndEvent(token.getStartMark(), token.getEndMark()); if (!states.isEmpty()) { throw new YAMLException("Unexpected end of stream. States left: " + states); } if (!marks.isEmpty()) { throw new YAMLException("Unexpected end of stream. Marks left: " + marks); } state = null; } return event; } } private class ParseDocumentEnd implements Production { public Event produce() { // Parse the document end. Token token = scanner.peekToken(); Mark startMark = token.getStartMark(); Mark endMark = startMark; boolean explicit = false; if (scanner.checkToken(Token.ID.DocumentEnd)) { token = scanner.getToken(); endMark = token.getEndMark(); explicit = true; } Event event = new DocumentEndEvent(startMark, endMark, explicit); // Prepare the next state. state = new ParseDocumentStart(); return event; } } private class ParseDocumentContent implements Production { public Event produce() { Event event; if (scanner.checkToken(Token.ID.Directive, Token.ID.DocumentStart, Token.ID.DocumentEnd, Token.ID.StreamEnd)) { event = processEmptyScalar(scanner.peekToken().getStartMark()); state = states.pop(); return event; } else { Production p = new ParseBlockNode(); return p.produce(); } } } @SuppressWarnings("unchecked") private VersionTagsTuple processDirectives() { Version yamlVersion = null; HashMap tagHandles = new HashMap(); while (scanner.checkToken(Token.ID.Directive)) { @SuppressWarnings("rawtypes") DirectiveToken token = (DirectiveToken) scanner.getToken(); if (token.getName().equals("YAML")) { if (yamlVersion != null) { throw new ParserException(null, null, "found duplicate YAML directive", token.getStartMark()); } List value = (List) token.getValue(); Integer major = value.get(0); if (major != 1) { throw new ParserException(null, null, "found incompatible YAML document (version 1.* is required)", token.getStartMark()); } Integer minor = value.get(1); switch (minor) { case 0: yamlVersion = Version.V1_0; break; default: yamlVersion = Version.V1_1; break; } } else if (token.getName().equals("TAG")) { List value = (List) token.getValue(); String handle = value.get(0); String prefix = value.get(1); if (tagHandles.containsKey(handle)) { throw new ParserException(null, null, "duplicate tag handle " + handle, token.getStartMark()); } tagHandles.put(handle, prefix); } } if (yamlVersion != null || !tagHandles.isEmpty()) { // directives in the document found - drop the previous for (String key : DEFAULT_TAGS.keySet()) { // do not overwrite re-defined tags if (!tagHandles.containsKey(key)) { tagHandles.put(key, DEFAULT_TAGS.get(key)); } } directives = new VersionTagsTuple(yamlVersion, tagHandles); } return directives; } /** *
     *  block_node_or_indentless_sequence ::= ALIAS
     *                | properties (block_content | indentless_block_sequence)?
     *                | block_content
     *                | indentless_block_sequence
     *  block_node    ::= ALIAS
     *                    | properties block_content?
     *                    | block_content
     *  flow_node     ::= ALIAS
     *                    | properties flow_content?
     *                    | flow_content
     *  properties    ::= TAG ANCHOR? | ANCHOR TAG?
     *  block_content     ::= block_collection | flow_collection | SCALAR
     *  flow_content      ::= flow_collection | SCALAR
     *  block_collection  ::= block_sequence | block_mapping
     *  flow_collection   ::= flow_sequence | flow_mapping
     * 
*/ private class ParseBlockNode implements Production { public Event produce() { return parseNode(true, false); } } private Event parseFlowNode() { return parseNode(false, false); } private Event parseBlockNodeOrIndentlessSequence() { return parseNode(true, true); } private Event parseNode(boolean block, boolean indentlessSequence) { Event event; Mark startMark = null; Mark endMark = null; Mark tagMark = null; if (scanner.checkToken(Token.ID.Alias)) { AliasToken token = (AliasToken) scanner.getToken(); event = new AliasEvent(token.getValue(), token.getStartMark(), token.getEndMark()); state = states.pop(); } else { String anchor = null; TagTuple tagTokenTag = null; if (scanner.checkToken(Token.ID.Anchor)) { AnchorToken token = (AnchorToken) scanner.getToken(); startMark = token.getStartMark(); endMark = token.getEndMark(); anchor = token.getValue(); if (scanner.checkToken(Token.ID.Tag)) { TagToken tagToken = (TagToken) scanner.getToken(); tagMark = tagToken.getStartMark(); endMark = tagToken.getEndMark(); tagTokenTag = tagToken.getValue(); } } else if (scanner.checkToken(Token.ID.Tag)) { TagToken tagToken = (TagToken) scanner.getToken(); startMark = tagToken.getStartMark(); tagMark = startMark; endMark = tagToken.getEndMark(); tagTokenTag = tagToken.getValue(); if (scanner.checkToken(Token.ID.Anchor)) { AnchorToken token = (AnchorToken) scanner.getToken(); endMark = token.getEndMark(); anchor = token.getValue(); } } String tag = null; if (tagTokenTag != null) { String handle = tagTokenTag.getHandle(); String suffix = tagTokenTag.getSuffix(); if (handle != null) { if (!directives.getTags().containsKey(handle)) { throw new ParserException("while parsing a node", startMark, "found undefined tag handle " + handle, tagMark); } tag = directives.getTags().get(handle) + suffix; } else { tag = suffix; } } if (startMark == null) { startMark = scanner.peekToken().getStartMark(); endMark = startMark; } event = null; boolean implicit = tag == null || tag.equals("!"); if (indentlessSequence && scanner.checkToken(Token.ID.BlockEntry)) { endMark = scanner.peekToken().getEndMark(); event = new SequenceStartEvent(anchor, tag, implicit, startMark, endMark, DumperOptions.FlowStyle.BLOCK); state = new ParseIndentlessSequenceEntry(); } else { if (scanner.checkToken(Token.ID.Scalar)) { ScalarToken token = (ScalarToken) scanner.getToken(); endMark = token.getEndMark(); ImplicitTuple implicitValues; if ((token.getPlain() && tag == null) || "!".equals(tag)) { implicitValues = new ImplicitTuple(true, false); } else if (tag == null) { implicitValues = new ImplicitTuple(false, true); } else { implicitValues = new ImplicitTuple(false, false); } event = new ScalarEvent(anchor, tag, implicitValues, token.getValue(), startMark, endMark, token.getStyle()); state = states.pop(); } else if (scanner.checkToken(Token.ID.FlowSequenceStart)) { endMark = scanner.peekToken().getEndMark(); event = new SequenceStartEvent(anchor, tag, implicit, startMark, endMark, DumperOptions.FlowStyle.FLOW); state = new ParseFlowSequenceFirstEntry(); } else if (scanner.checkToken(Token.ID.FlowMappingStart)) { endMark = scanner.peekToken().getEndMark(); event = new MappingStartEvent(anchor, tag, implicit, startMark, endMark, DumperOptions.FlowStyle.FLOW); state = new ParseFlowMappingFirstKey(); } else if (block && scanner.checkToken(Token.ID.BlockSequenceStart)) { endMark = scanner.peekToken().getStartMark(); event = new SequenceStartEvent(anchor, tag, implicit, startMark, endMark, DumperOptions.FlowStyle.BLOCK); state = new ParseBlockSequenceFirstEntry(); } else if (block && scanner.checkToken(Token.ID.BlockMappingStart)) { endMark = scanner.peekToken().getStartMark(); event = new MappingStartEvent(anchor, tag, implicit, startMark, endMark, DumperOptions.FlowStyle.BLOCK); state = new ParseBlockMappingFirstKey(); } else if (anchor != null || tag != null) { // Empty scalars are allowed even if a tag or an anchor is // specified. event = new ScalarEvent(anchor, tag, new ImplicitTuple(implicit, false), "", startMark, endMark, DumperOptions.ScalarStyle.PLAIN); state = states.pop(); } else { String node; if (block) { node = "block"; } else { node = "flow"; } Token token = scanner.peekToken(); throw new ParserException("while parsing a " + node + " node", startMark, "expected the node content, but found '" + token.getTokenId() + "'", token.getStartMark()); } } } return event; } // block_sequence ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* // BLOCK-END private class ParseBlockSequenceFirstEntry implements Production { public Event produce() { Token token = scanner.getToken(); marks.push(token.getStartMark()); return new ParseBlockSequenceEntry().produce(); } } private class ParseBlockSequenceEntry implements Production { public Event produce() { if (scanner.checkToken(Token.ID.BlockEntry)) { BlockEntryToken token = (BlockEntryToken) scanner.getToken(); if (!scanner.checkToken(Token.ID.BlockEntry, Token.ID.BlockEnd)) { states.push(new ParseBlockSequenceEntry()); return new ParseBlockNode().produce(); } else { state = new ParseBlockSequenceEntry(); return processEmptyScalar(token.getEndMark()); } } if (!scanner.checkToken(Token.ID.BlockEnd)) { Token token = scanner.peekToken(); throw new ParserException("while parsing a block collection", marks.pop(), "expected , but found '" + token.getTokenId() + "'", token.getStartMark()); } Token token = scanner.getToken(); Event event = new SequenceEndEvent(token.getStartMark(), token.getEndMark()); state = states.pop(); marks.pop(); return event; } } // indentless_sequence ::= (BLOCK-ENTRY block_node?)+ private class ParseIndentlessSequenceEntry implements Production { public Event produce() { if (scanner.checkToken(Token.ID.BlockEntry)) { Token token = scanner.getToken(); if (!scanner.checkToken(Token.ID.BlockEntry, Token.ID.Key, Token.ID.Value, Token.ID.BlockEnd)) { states.push(new ParseIndentlessSequenceEntry()); return new ParseBlockNode().produce(); } else { state = new ParseIndentlessSequenceEntry(); return processEmptyScalar(token.getEndMark()); } } Token token = scanner.peekToken(); Event event = new SequenceEndEvent(token.getStartMark(), token.getEndMark()); state = states.pop(); return event; } } private class ParseBlockMappingFirstKey implements Production { public Event produce() { Token token = scanner.getToken(); marks.push(token.getStartMark()); return new ParseBlockMappingKey().produce(); } } private class ParseBlockMappingKey implements Production { public Event produce() { if (scanner.checkToken(Token.ID.Key)) { Token token = scanner.getToken(); if (!scanner.checkToken(Token.ID.Key, Token.ID.Value, Token.ID.BlockEnd)) { states.push(new ParseBlockMappingValue()); return parseBlockNodeOrIndentlessSequence(); } else { state = new ParseBlockMappingValue(); return processEmptyScalar(token.getEndMark()); } } if (!scanner.checkToken(Token.ID.BlockEnd)) { Token token = scanner.peekToken(); throw new ParserException("while parsing a block mapping", marks.pop(), "expected , but found '" + token.getTokenId() + "'", token.getStartMark()); } Token token = scanner.getToken(); Event event = new MappingEndEvent(token.getStartMark(), token.getEndMark()); state = states.pop(); marks.pop(); return event; } } private class ParseBlockMappingValue implements Production { public Event produce() { if (scanner.checkToken(Token.ID.Value)) { Token token = scanner.getToken(); if (!scanner.checkToken(Token.ID.Key, Token.ID.Value, Token.ID.BlockEnd)) { states.push(new ParseBlockMappingKey()); return parseBlockNodeOrIndentlessSequence(); } else { state = new ParseBlockMappingKey(); return processEmptyScalar(token.getEndMark()); } } state = new ParseBlockMappingKey(); Token token = scanner.peekToken(); return processEmptyScalar(token.getStartMark()); } } /** *
     * flow_sequence     ::= FLOW-SEQUENCE-START
     *                       (flow_sequence_entry FLOW-ENTRY)*
     *                       flow_sequence_entry?
     *                       FLOW-SEQUENCE-END
     * flow_sequence_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
     * Note that while production rules for both flow_sequence_entry and
     * flow_mapping_entry are equal, their interpretations are different.
     * For `flow_sequence_entry`, the part `KEY flow_node? (VALUE flow_node?)?`
     * generate an inline mapping (set syntax).
     * 
*/ private class ParseFlowSequenceFirstEntry implements Production { public Event produce() { Token token = scanner.getToken(); marks.push(token.getStartMark()); return new ParseFlowSequenceEntry(true).produce(); } } private class ParseFlowSequenceEntry implements Production { private boolean first = false; public ParseFlowSequenceEntry(boolean first) { this.first = first; } public Event produce() { if (!scanner.checkToken(Token.ID.FlowSequenceEnd)) { if (!first) { if (scanner.checkToken(Token.ID.FlowEntry)) { scanner.getToken(); } else { Token token = scanner.peekToken(); throw new ParserException("while parsing a flow sequence", marks.pop(), "expected ',' or ']', but got " + token.getTokenId(), token.getStartMark()); } } if (scanner.checkToken(Token.ID.Key)) { Token token = scanner.peekToken(); Event event = new MappingStartEvent(null, null, true, token.getStartMark(), token.getEndMark(), DumperOptions.FlowStyle.FLOW); state = new ParseFlowSequenceEntryMappingKey(); return event; } else if (!scanner.checkToken(Token.ID.FlowSequenceEnd)) { states.push(new ParseFlowSequenceEntry(false)); return parseFlowNode(); } } Token token = scanner.getToken(); Event event = new SequenceEndEvent(token.getStartMark(), token.getEndMark()); state = states.pop(); marks.pop(); return event; } } private class ParseFlowSequenceEntryMappingKey implements Production { public Event produce() { Token token = scanner.getToken(); if (!scanner.checkToken(Token.ID.Value, Token.ID.FlowEntry, Token.ID.FlowSequenceEnd)) { states.push(new ParseFlowSequenceEntryMappingValue()); return parseFlowNode(); } else { state = new ParseFlowSequenceEntryMappingValue(); return processEmptyScalar(token.getEndMark()); } } } private class ParseFlowSequenceEntryMappingValue implements Production { public Event produce() { if (scanner.checkToken(Token.ID.Value)) { Token token = scanner.getToken(); if (!scanner.checkToken(Token.ID.FlowEntry, Token.ID.FlowSequenceEnd)) { states.push(new ParseFlowSequenceEntryMappingEnd()); return parseFlowNode(); } else { state = new ParseFlowSequenceEntryMappingEnd(); return processEmptyScalar(token.getEndMark()); } } else { state = new ParseFlowSequenceEntryMappingEnd(); Token token = scanner.peekToken(); return processEmptyScalar(token.getStartMark()); } } } private class ParseFlowSequenceEntryMappingEnd implements Production { public Event produce() { state = new ParseFlowSequenceEntry(false); Token token = scanner.peekToken(); return new MappingEndEvent(token.getStartMark(), token.getEndMark()); } } /** *
     *   flow_mapping  ::= FLOW-MAPPING-START
     *          (flow_mapping_entry FLOW-ENTRY)*
     *          flow_mapping_entry?
     *          FLOW-MAPPING-END
     *   flow_mapping_entry    ::= flow_node | KEY flow_node? (VALUE flow_node?)?
     * 
*/ private class ParseFlowMappingFirstKey implements Production { public Event produce() { Token token = scanner.getToken(); marks.push(token.getStartMark()); return new ParseFlowMappingKey(true).produce(); } } private class ParseFlowMappingKey implements Production { private boolean first = false; public ParseFlowMappingKey(boolean first) { this.first = first; } public Event produce() { if (!scanner.checkToken(Token.ID.FlowMappingEnd)) { if (!first) { if (scanner.checkToken(Token.ID.FlowEntry)) { scanner.getToken(); } else { Token token = scanner.peekToken(); throw new ParserException("while parsing a flow mapping", marks.pop(), "expected ',' or '}', but got " + token.getTokenId(), token.getStartMark()); } } if (scanner.checkToken(Token.ID.Key)) { Token token = scanner.getToken(); if (!scanner.checkToken(Token.ID.Value, Token.ID.FlowEntry, Token.ID.FlowMappingEnd)) { states.push(new ParseFlowMappingValue()); return parseFlowNode(); } else { state = new ParseFlowMappingValue(); return processEmptyScalar(token.getEndMark()); } } else if (!scanner.checkToken(Token.ID.FlowMappingEnd)) { states.push(new ParseFlowMappingEmptyValue()); return parseFlowNode(); } } Token token = scanner.getToken(); Event event = new MappingEndEvent(token.getStartMark(), token.getEndMark()); state = states.pop(); marks.pop(); return event; } } private class ParseFlowMappingValue implements Production { public Event produce() { if (scanner.checkToken(Token.ID.Value)) { Token token = scanner.getToken(); if (!scanner.checkToken(Token.ID.FlowEntry, Token.ID.FlowMappingEnd)) { states.push(new ParseFlowMappingKey(false)); return parseFlowNode(); } else { state = new ParseFlowMappingKey(false); return processEmptyScalar(token.getEndMark()); } } else { state = new ParseFlowMappingKey(false); Token token = scanner.peekToken(); return processEmptyScalar(token.getStartMark()); } } } private class ParseFlowMappingEmptyValue implements Production { public Event produce() { state = new ParseFlowMappingKey(false); return processEmptyScalar(scanner.peekToken().getStartMark()); } } /** *
     * block_mapping     ::= BLOCK-MAPPING_START
     *           ((KEY block_node_or_indentless_sequence?)?
     *           (VALUE block_node_or_indentless_sequence?)?)*
     *           BLOCK-END
     * 
*/ private Event processEmptyScalar(Mark mark) { return new ScalarEvent(null, null, new ImplicitTuple(true, false), "", mark, mark, DumperOptions.ScalarStyle.PLAIN); } }




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