Class Parser

see

MANY

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

see

MANY_SEP

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);
    });
  })

• See more details on the unique suffixes requirement.

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

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.

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.

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.

deprecated

• will be removed in the future