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Class BaseParser

This class does not actually exists nor is exposed at runtime. This is just a helper to avoid duplications in the Type Definitions Of CstParser and EmbeddedActionsParser

Hierarchy

Index

Constructors

constructor

Properties

RECORDING_PHASE

RECORDING_PHASE: boolean

Flag indicating the Parser is at the recording phase. Can be used to implement methods similar to BaseParser.ACTION Or any other logic to requires knowledge of the recording phase. See:

errors

input

input: IToken[]

Methods

ACTION

  • ACTION<T>(impl: function): T

AT_LEAST_ONE

  • Convenience method, same as MANY but the repetition is of one or more. failing to match at least one repetition will result in a parsing error and cause a parsing error.

    see

    MANY

    Parameters

    • actionORMethodDef: GrammarAction<any> | DSLMethodOptsWithErr<any>

      The grammar action to optionally invoke multiple times or an "OPTIONS" object describing the grammar action and optional properties.

    Returns void

AT_LEAST_ONE_SEP

  • Convenience method, same as MANY_SEP but the repetition is of one or more. failing to match at least one repetition will result in a parsing error and cause the parser to attempt error recovery.

    Note that an additional optional property ERR_MSG can be used to provide custom error messages.

    see

    MANY_SEP

    Parameters

    • options: AtLeastOneSepMethodOpts<any>

      An object defining the grammar of each iteration and the separator between iterations

    Returns void

BACKTRACK

  • BACKTRACK<T>(grammarRule: function, args?: any[]): function
  • Type parameters

    • T

    Parameters

    • grammarRule: function

      The rule to try and parse in backtracking mode.

        • (...args: any[]): T
        • Parameters

          • Rest ...args: any[]

          Returns T

    • Optional args: any[]

      argumens to be passed to the grammar rule execution

    Returns function

    a lookahead function that will try to parse the given grammarRule and will return true if succeed.

      • (): boolean
      • Returns boolean

CONSUME

  • A Parsing DSL method use to consume a single Token. In EBNF terms this is equivalent to a Terminal.

    A Token will be consumed, IFF the next token in the token vector matches . otherwise the parser may attempt to perform error recovery (if enabled).

    The index in the method name indicates the unique occurrence of a terminal consumption inside a the top level rule. What this means is that if a terminal appears more than once in a single rule, each appearance must have a different index.

    For example:

      this.RULE("qualifiedName", () => {
      this.CONSUME1(Identifier);
        this.MANY(() => {
          this.CONSUME1(Dot);
          // here we use CONSUME2 because the terminal
          // 'Identifier' has already appeared previously in the
          // the rule 'parseQualifiedName'
          this.CONSUME2(Identifier);
        });
      })

    Parameters

    • tokType: TokenType

      The Type of the token to be consumed.

    • Optional options: ConsumeMethodOpts

      optional properties to modify the behavior of CONSUME.

    Returns IToken

LA

  • Look-Ahead for the Token Vector LA(1) is the next Token ahead. LA(n) is the nth Token ahead. LA(0) is the previously consumed Token.

    Looking beyond the end of the Token Vector or before its begining will return in an IToken of type EOF EOF. This behavior can be used to avoid infinite loops.

    This is often used to implement custom lookahead logic for GATES. https://sap.github.io/chevrotain/docs/features/gates.html

    Parameters

    • howMuch: number

    Returns IToken

MANY

  • Parsing DSL method, that indicates a repetition of zero or more. This is equivalent to EBNF repetition {...}.

    Note that there are two syntax forms:

    • Passing the grammar action directly:

        this.MANY(() => {
          this.CONSUME(Comma)
          this.CONSUME(Digit)
         })
    • using an "options" object:

        this.MANY({
          GATE: predicateFunc,
          DEF: () => {
                 this.CONSUME(Comma)
                 this.CONSUME(Digit)
               }
        });

    The optional 'GATE' property in "options" object form can be used to add constraints to invoking the grammar action.

    As in CONSUME the index in the method name indicates the occurrence of the repetition production in it's top rule.

    Parameters

    • actionORMethodDef: GrammarAction<any> | DSLMethodOpts<any>

      The grammar action to optionally invoke multiple times or an "OPTIONS" object describing the grammar action and optional properties.

    Returns void

MANY_SEP

  • Parsing DSL method, that indicates a repetition of zero or more with a separator Token between the repetitions.

    Example:

        this.MANY_SEP({
            SEP:Comma,
            DEF: () => {
                this.CONSUME(Number};
                // ...
            })

    Note that because this DSL method always requires more than one argument the options object is always required and it is not possible to use a shorter form like in the MANY DSL method.

    Note that for the purposes of deciding on whether or not another iteration exists Only a single Token is examined (The separator). Therefore if the grammar being implemented is so "crazy" to require multiple tokens to identify an item separator please use the more basic DSL methods to implement it.

    As in CONSUME the index in the method name indicates the occurrence of the repetition production in it's top rule.

    Parameters

    • options: ManySepMethodOpts<any>

      An object defining the grammar of each iteration and the separator between iterations

    Returns void

OPTION

  • Parsing DSL Method that Indicates an Optional production. in EBNF notation this is equivalent to: "[...]".

    Note that there are two syntax forms:

    • Passing the grammar action directly:

        this.OPTION(() => {
          this.CONSUME(Digit)}
        );
    • using an "options" object:

        this.OPTION({
          GATE:predicateFunc,
          DEF: () => {
            this.CONSUME(Digit)
        }});

    The optional 'GATE' property in "options" object form can be used to add constraints to invoking the grammar action.

    As in CONSUME the index in the method name indicates the occurrence of the optional production in it's top rule.

    Type parameters

    • OUT

    Parameters

    • actionORMethodDef: GrammarAction<OUT> | DSLMethodOpts<OUT>

      The grammar action to optionally invoke once or an "OPTIONS" object describing the grammar action and optional properties.

    Returns OUT

OR

  • Parsing DSL method that indicates a choice between a set of alternatives must be made. This is equivalent to an EBNF alternation (A | B | C | D ...), except that the alternatives are ordered like in a PEG grammar. This means that the first matching alternative is always chosen.

    There are several forms for the inner alternatives array:

    • Passing alternatives array directly:

        this.OR([
          { ALT:() => { this.CONSUME(One) }},
          { ALT:() => { this.CONSUME(Two) }},
          { ALT:() => { this.CONSUME(Three) }}
        ])
    • Passing alternative array directly with predicates (GATE):

        this.OR([
          { GATE: predicateFunc1, ALT:() => { this.CONSUME(One) }},
          { GATE: predicateFuncX, ALT:() => { this.CONSUME(Two) }},
          { GATE: predicateFuncX, ALT:() => { this.CONSUME(Three) }}
        ])
    • These syntax forms can also be mixed:

        this.OR([
          {
            GATE: predicateFunc1,
            ALT:() => { this.CONSUME(One) }
          },
          { ALT:() => { this.CONSUME(Two) }},
          { ALT:() => { this.CONSUME(Three) }}
        ])
    • Additionally an "options" object may be used:

        this.OR({
          DEF:[
            { ALT:() => { this.CONSUME(One) }},
            { ALT:() => { this.CONSUME(Two) }},
            { ALT:() => { this.CONSUME(Three) }}
          ],
          // OPTIONAL property
          ERR_MSG: "A Number"
        })

    The 'predicateFuncX' in the long form can be used to add constraints to choosing the alternative.

    As in CONSUME the index in the method name indicates the occurrence of the alternation production in it's top rule.

    Parameters

    • altsOrOpts: IOrAlt[] | OrMethodOpts

      A set of alternatives or an "OPTIONS" object describing the alternatives and optional properties.

    Returns any

    The result of invoking the chosen alternative.

SKIP_TOKEN

canTokenTypeBeInsertedInRecovery

  • canTokenTypeBeInsertedInRecovery(tokType: TokenType): boolean
  • By default all tokens type may be inserted. This behavior may be overridden in inheriting Recognizers for example: One may decide that only punctuation tokens may be inserted automatically as they have no additional semantic value. (A mandatory semicolon has no additional semantic meaning, but an Integer may have additional meaning depending on its int value and context (Inserting an integer 0 in cardinality: "[1..]" will cause semantic issues as the max of the cardinality will be greater than the min value (and this is a false error!).

    Parameters

    Returns boolean

computeContentAssist

getBaseCstVisitorConstructor

  • getBaseCstVisitorConstructor(): object

getBaseCstVisitorConstructorWithDefaults

  • getBaseCstVisitorConstructorWithDefaults(): object

getGAstProductions

  • getGAstProductions(): Record<string, Rule>

getNextPossibleTokenTypes

getSerializedGastProductions

getTokenToInsert

  • Returns an "imaginary" Token to insert when Single Token Insertion is done Override this if you require special behavior in your grammar. For example if an IntegerToken is required provide one with the image '0' so it would be valid syntactically.

    Parameters

    Returns IToken

performSelfAnalysis

  • performSelfAnalysis(): void

reset

  • reset(): void
  • Resets the parser state, should be overridden for custom parsers which "carry" additional state. When overriding, remember to also invoke the super implementation!

    Returns void

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