Package org.snakeyaml.engine.v2.parser

Class ParserImpl

  • All Implemented Interfaces:
    java.util.Iterator<Event>, 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.

    • Field Detail

      • DEFAULT_TAGS

        private static final java.util.Map<java.lang.String,​java.lang.String> DEFAULT_TAGS

      • scanner

        protected final Scanner scanner
        tokeniser

      • marksStack

        private final ArrayStack<java.util.Optional<Mark>> marksStack

      • currentEvent

        private java.util.Optional<Event> currentEvent

      • state

        private java.util.Optional<Production> state

      • directiveTags

        private java.util.Map<java.lang.String,​java.lang.String> directiveTags

    • Constructor Detail

      • ParserImpl

        @Deprecated
public ParserImpl​(StreamReader reader,
                  LoadSettings settings)
        Deprecated.
        use the other constructor with LoadSettings first
        Parameters:
        reader - - the input
        settings - - the configuration options

      • ParserImpl

        public ParserImpl​(LoadSettings settings,
                  StreamReader reader)
        Create
        Parameters:
        settings - - configuration options
        reader - - the input

      • ParserImpl

        @Deprecated
public ParserImpl​(Scanner scanner,
                  LoadSettings settings)
        Deprecated.
        use the other constructor with LoadSettings first
        Parameters:
        scanner - - input
        settings - - configuration options

      • ParserImpl

        public ParserImpl​(LoadSettings settings,
                  Scanner scanner)
        Create
        Parameters:
        settings - - configuration options
        scanner - - input

    • Method Detail

      • checkEvent

        public boolean checkEvent​(Event.ID id)
        Check the ID of the next event.
        Specified by:
        checkEvent in interface Parser
        Parameters:
        id - Event ID to match
        Returns:
        true if the next event has the given ID. Returns false if no more events are available.

      • peekEvent

        public Event peekEvent()
        Get the next event (and keep it). Produce the event if not yet present.
        Specified by:
        peekEvent in interface Parser
        Returns:
        The event that will be returned on the next call to Parser.next()

      • next

        public Event next()
        Consume the event (get the next event and removed it).
        Specified by:
        next in interface java.util.Iterator<Event>
        Specified by:
        next in interface Parser
        Returns:
        the next parsed event

      • hasNext

        public boolean hasNext()
        Produce the event if not yet present.
        Specified by:
        hasNext in interface java.util.Iterator<Event>
        Returns:
        true if there is another event

      • produce

        private void produce()

      • parseFlowNode

        private Event parseFlowNode()

      • parseBlockNodeOrIndentlessSequence

        private Event parseBlockNodeOrIndentlessSequence()

      • parseNode

        private Event parseNode​(boolean block,
                        boolean indentlessSequence)

      • processEmptyScalar

        private Event processEmptyScalar​(java.util.Optional<Mark> mark)
         block_mapping     ::= BLOCK-MAPPING_START
           ((KEY block_node_or_indentless_sequence?)?
           (VALUE block_node_or_indentless_sequence?)?)*
           BLOCK-END

      • markPop

        private java.util.Optional<Mark> markPop()

      • markPush

        private void markPush​(java.util.Optional<Mark> mark)