Package org.antlr.tool

Class GrammarSanity

  • public class GrammarSanity
extends java.lang.Object
    Factor out routines that check sanity of rules, alts, grammars, etc..

    • Field Detail

      • visitedDuringRecursionCheck

        protected java.util.Set<Rule> visitedDuringRecursionCheck
        The checkForLeftRecursion method needs to track what rules it has visited to track infinite recursion.

      • grammar

        protected Grammar grammar

    • Constructor Detail

      • GrammarSanity

        public GrammarSanity​(Grammar grammar)

    • Method Detail

      • checkAllRulesForLeftRecursion

        public java.util.List<java.util.Set<Rule>> checkAllRulesForLeftRecursion()
        Check all rules for infinite left recursion before analysis. Return list of troublesome rule cycles. This method has two side-effects: it notifies the error manager that we have problems and it sets the list of recursive rules that we should ignore during analysis.

      • traceStatesLookingForLeftRecursion

        protected boolean traceStatesLookingForLeftRecursion​(NFAState s,
                                                     java.util.Set<NFAState> visitedStates,
                                                     java.util.List<java.util.Set<Rule>> listOfRecursiveCycles)
        From state s, look for any transition to a rule that is currently being traced. When tracing r, visitedDuringRecursionCheck has r initially. If you reach an accept state, return but notify the invoking rule that it is nullable, which implies that invoking rule must look at follow transition for that invoking state. The visitedStates tracks visited states within a single rule so we can avoid epsilon-loop-induced infinite recursion here. Keep filling the cycles in listOfRecursiveCycles and also, as a side-effect, set leftRecursiveRules.

      • addRulesToCycle

        protected void addRulesToCycle​(Rule targetRule,
                               Rule enclosingRule,
                               java.util.List<java.util.Set<Rule>> listOfRecursiveCycles)
        enclosingRuleName calls targetRuleName, find the cycle containing the target and add the caller. Find the cycle containing the caller and add the target. If no cycles contain either, then create a new cycle. listOfRecursiveCycles is List<Set<String>> that holds a list of cycles (sets of rule names).

      • checkRuleReference

        public void checkRuleReference​(GrammarAST scopeAST,
                               GrammarAST refAST,
                               GrammarAST argsAST,
                               java.lang.String currentRuleName)

      • ensureAltIsSimpleNodeOrTree

        public void ensureAltIsSimpleNodeOrTree​(GrammarAST altAST,
                                        GrammarAST elementAST,
                                        int outerAltNum)
        Rules in tree grammar that use -> rewrites and are spitting out templates via output=template and then use rewrite=true must only use -> on alts that are simple nodes or trees or single rule refs that match either nodes or trees. The altAST is the ALT node for an ALT. Verify that its first child is simple. Must be either ( ALT ^( A B ) <end-of-alt> ) or ( ALT A <end-of-alt> ) or other element. Ignore predicates in front and labels.

      • isValidSimpleElementNode

        protected boolean isValidSimpleElementNode​(org.antlr.runtime.tree.Tree t)

      • isNextNonActionElementEOA

        protected boolean isNextNonActionElementEOA​(GrammarAST t)