Interface ATNFactory

    • Method Detail

      • createATN

        ATN createATN()
      • setCurrentRuleName

        void setCurrentRuleName​(String name)
      • setCurrentOuterAlt

        void setCurrentOuterAlt​(int alt)
      • stringLiteral

        ATNFactory.Handle stringLiteral​(TerminalAST stringLiteralAST)
        For a non-lexer, just build a simple token reference atom. For a lexer, a string is a sequence of char to match. That is, "fog" is treated as 'f' 'o' 'g' not as a single transition in the DFA. Machine== o-'f'->o-'o'->o-'g'->o and has n+1 states for n characters.
      • ruleRef

        ATNFactory.Handle ruleRef​(GrammarAST node)
        For reference to rule r, build o-e->(r) o where (r) is the start of rule r and the trailing o is not linked to from rule ref state directly (it's done thru the transition(0) RuleClosureTransition. If the rule r is just a list of tokens, it's block will be just a set on an edge o->o->o-set->o->o->o, could inline it rather than doing the rule reference, but i'm not doing this yet as I'm not sure it would help much in the ATN->DFA construction. TODO add to codegen: collapse alt blks that are sets into single matchSet
        node -
      • sempred

        ATNFactory.Handle sempred​(PredAST pred)
        Build what amounts to an epsilon transition with a semantic predicate action. The pred is a pointer into the AST of the SEMPRED token.
      • action

        ATNFactory.Handle action​(ActionAST action)
        Build what amounts to an epsilon transition with an action. The action goes into ATN though it is ignored during analysis.
      • block

        ATNFactory.Handle block​(BlockAST blockAST,
                                GrammarAST ebnfRoot,
                                List<ATNFactory.Handle> alternativeGrips)
        From A|B|..|Z alternative block build o->o-A->o->o (last ATNState is blockEndATNState pointed to by all alts) | ^ o->o-B->o--| | | ... | | | o->o-Z->o--| So every alternative gets begin ATNState connected by epsilon and every alt right side points at a block end ATNState. There is a new ATNState in the ATNState in the Grip for each alt plus one for the end ATNState. Special case: only one alternative: don't make a block with alt begin/end. Special case: if just a list of tokens/chars/sets, then collapse to a single edge'd o-set->o graph. Set alt number (1..n) in the left-Transition ATNState.
      • plus

        ATNFactory.Handle plus​(GrammarAST plusAST,
                               ATNFactory.Handle blk)
        From (A)+ build |---| (Transition 2 from A.right points at alt 1) v | (follow of loop is Transition 1) o->o-A-o->o Meaning that the last ATNState in A points back to A's left Transition ATNState and we add a new begin/end ATNState. A can be single alternative or multiple. During analysis we'll call the follow link (transition 1) alt n+1 for an n-alt A block.
      • star

        ATNFactory.Handle star​(GrammarAST starAST,
                               ATNFactory.Handle blk)
        From (A)* build |---| v | o->o-A-o--o (Transition 2 from block end points at alt 1; follow is Transition 1) | ^ o---------| (optional branch is 2nd alt of optional block containing A+) Meaning that the last (end) ATNState in A points back to A's left side ATNState and we add 3 new ATNStates (the optional branch is built just like an optional subrule). See the Aplus() method for more on the loop back Transition. The new node on right edge is set to RIGHT_EDGE_OF_CLOSURE so we can detect nested (A*)* loops and insert an extra node. Previously, two blocks shared same EOB node. There are 2 or 3 decision points in a A*. If A is not a block (i.e., it only has one alt), then there are two decisions: the optional bypass and then loopback. If A is a block of alts, then there are three decisions: bypass, loopback, and A's decision point. Note that the optional bypass must be outside the loop as (A|B)* is not the same thing as (A|B|)+. This is an accurate ATN representation of the meaning of (A)*, but for generating code, I don't need a DFA for the optional branch by virtue of how I generate code. The exit-loopback-branch decision is sufficient to let me make an appropriate enter, exit, loop determination. See codegen.g