Package org.yaml.snakeyaml.parser
Class ParserImpl
- java.lang.Object
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- org.yaml.snakeyaml.parser.ParserImpl
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- All Implemented Interfaces:
Parser
public class ParserImpl extends java.lang.Object implements Parser
# 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.
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Nested Class Summary
Nested Classes Modifier and Type Class Description private class
ParserImpl.ParseBlockMappingFirstKey
private class
ParserImpl.ParseBlockMappingKey
private class
ParserImpl.ParseBlockMappingValue
private class
ParserImpl.ParseBlockNode
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_mappingprivate class
ParserImpl.ParseBlockSequenceEntry
private class
ParserImpl.ParseBlockSequenceFirstEntry
private class
ParserImpl.ParseDocumentContent
private class
ParserImpl.ParseDocumentEnd
private class
ParserImpl.ParseDocumentStart
private class
ParserImpl.ParseFlowMappingEmptyValue
private class
ParserImpl.ParseFlowMappingFirstKey
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
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? 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.private class
ParserImpl.ParseImplicitDocumentStart
private class
ParserImpl.ParseIndentlessSequenceEntry
private class
ParserImpl.ParseStreamStart
stream ::= STREAM-START implicit_document? explicit_document* STREAM-END implicit_document ::= block_node DOCUMENT-END* explicit_document ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
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Field Summary
Fields Modifier and Type Field Description private Event
currentEvent
private static java.util.Map<java.lang.String,java.lang.String>
DEFAULT_TAGS
private VersionTagsTuple
directives
private ArrayStack<Mark>
marks
protected Scanner
scanner
private Production
state
private ArrayStack<Production>
states
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Constructor Summary
Constructors Constructor Description ParserImpl(StreamReader reader)
ParserImpl(Scanner scanner)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
checkEvent(Event.ID choice)
Check the type of the next event.Event
getEvent()
Get the next event and proceed further.private Event
parseBlockNodeOrIndentlessSequence()
private Event
parseFlowNode()
private Event
parseNode(boolean block, boolean indentlessSequence)
Event
peekEvent()
Get the next event.private VersionTagsTuple
processDirectives()
private Event
processEmptyScalar(Mark mark)
block_mapping ::= BLOCK-MAPPING_START ((KEY block_node_or_indentless_sequence?)? (VALUE block_node_or_indentless_sequence?)?)* BLOCK-END
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Field Detail
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DEFAULT_TAGS
private static final java.util.Map<java.lang.String,java.lang.String> DEFAULT_TAGS
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scanner
protected final Scanner scanner
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currentEvent
private Event currentEvent
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states
private final ArrayStack<Production> states
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marks
private final ArrayStack<Mark> marks
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state
private Production state
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directives
private VersionTagsTuple directives
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Constructor Detail
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ParserImpl
public ParserImpl(StreamReader reader)
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ParserImpl
public ParserImpl(Scanner scanner)
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Method Detail
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checkEvent
public boolean checkEvent(Event.ID choice)
Check the type of the next event.- Specified by:
checkEvent
in interfaceParser
- Parameters:
choice
- Event ID.- Returns:
true
if the next event can be assigned to a variable of the given type. Returnsfalse
if no more events are available.
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peekEvent
public Event peekEvent()
Get the next event.- Specified by:
peekEvent
in interfaceParser
- Returns:
- The event that will be returned on the next call to
Parser.getEvent()
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getEvent
public Event getEvent()
Get the next event and proceed further.
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processDirectives
private VersionTagsTuple processDirectives()
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parseFlowNode
private Event parseFlowNode()
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parseBlockNodeOrIndentlessSequence
private Event parseBlockNodeOrIndentlessSequence()
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parseNode
private Event parseNode(boolean block, boolean indentlessSequence)
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