SnakeYAML 2.2 · org.yaml.snakeyaml.parser.ParserImpl

# 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.

Modifier and Type	Class and Description
private class	ParserImpl.ParseBlockMappingFirstKey
private class	ParserImpl.ParseBlockMappingKey
private class	ParserImpl.ParseBlockMappingValue
private class	ParserImpl.ParseBlockMappingValueComment
private class	ParserImpl.ParseBlockMappingValueCommentList
private class	ParserImpl.ParseBlockNode block_node_or_indentless_sequence ::= ALIAS \| properties (block_content \| indentless_block_sequence)?
private class	ParserImpl.ParseBlockSequenceEntryKey
private class	ParserImpl.ParseBlockSequenceEntryValue
private class	ParserImpl.ParseBlockSequenceFirstEntry
private class	ParserImpl.ParseDocumentContent
private class	ParserImpl.ParseDocumentEnd
private class	ParserImpl.ParseDocumentStart
private class	ParserImpl.ParseFlowEndComment
private class	ParserImpl.ParseFlowMappingEmptyValue
private class	ParserImpl.ParseFlowMappingFirstKey flow_mapping ::= FLOW-MAPPING-START (flow_mapping_entry FLOW-ENTRY)* flow_mapping_entry?
private class	ParserImpl.ParseFlowMappingKey
private class	ParserImpl.ParseFlowMappingValue
private class	ParserImpl.ParseFlowSequenceEntry
private class	ParserImpl.ParseFlowSequenceEntryMappingEnd
private class	ParserImpl.ParseFlowSequenceEntryMappingKey
private class	ParserImpl.ParseFlowSequenceEntryMappingValue
private class	ParserImpl.ParseFlowSequenceFirstEntry flow_sequence ::= FLOW-SEQUENCE-START (flow_sequence_entry FLOW-ENTRY)* flow_sequence_entry?
private class	ParserImpl.ParseImplicitDocumentStart
private class	ParserImpl.ParseIndentlessSequenceEntryKey
private class	ParserImpl.ParseIndentlessSequenceEntryValue
private class	ParserImpl.ParseStreamStart stream ::= STREAM-START implicit_document?

Field Summary

Modifier and Type	Field and Description
private Event	currentEvent
private static final Map<String, String>	DEFAULT_TAGS
private VersionTagsTuple	directives
private final ArrayStack<Mark>	marks
protected final Scanner	scanner
private Production	state
private final ArrayStack<Production>	states

Access	Constructor and Description
public	ParserImpl(StreamReader reader, LoaderOptions options)
public	ParserImpl(Scanner scanner)

Method Summary

Modifier and Type	Method and Description
public boolean	checkEvent(Event.ID Event ID. choice) Implements org.yaml.snakeyaml.parser.Parser.checkEvent. Check the type of the next event.
public Event	getEvent() Implements org.yaml.snakeyaml.parser.Parser.getEvent. Get the next event and proceed further.
private Event	parseBlockNodeOrIndentlessSequence()
private Event	parseFlowNode()
private Event	parseNode(boolean block, boolean indentlessSequence)
public Event	peekEvent() Implements org.yaml.snakeyaml.parser.Parser.peekEvent. Peek the next event (keeping it in the stream)
private VersionTagsTuple	Returns: directives to be applied for the current document processDirectives() https://yaml.org/spec/1.1/#id898785 says "If the document specifies no directives, it is parsed using the same settings as the previous document.
private Event	processEmptyScalar(Mark mark) block_mapping ::= BLOCK-MAPPING_START ((KEY block_node_or_indentless_sequence?)?
private CommentEvent	produceCommentEvent(CommentToken token)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

public Class ParserImpl

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary