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The ANTLR 4 grammar compiler.
/*
* [The "BSD license"]
* Copyright (c) 2012 Terence Parr
* Copyright (c) 2012 Sam Harwell
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.antlr.v4.automata;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.Token;
import org.antlr.runtime.tree.CommonTreeNodeStream;
import org.antlr.runtime.tree.Tree;
import org.antlr.v4.analysis.LeftRecursiveRuleTransformer;
import org.antlr.v4.misc.CharSupport;
import org.antlr.v4.parse.ANTLRParser;
import org.antlr.v4.parse.ATNBuilder;
import org.antlr.v4.parse.GrammarASTAdaptor;
import org.antlr.v4.runtime.atn.ATN;
import org.antlr.v4.runtime.atn.ATNState;
import org.antlr.v4.runtime.atn.AbstractPredicateTransition;
import org.antlr.v4.runtime.atn.ActionTransition;
import org.antlr.v4.runtime.atn.AtomTransition;
import org.antlr.v4.runtime.atn.BasicBlockStartState;
import org.antlr.v4.runtime.atn.BasicState;
import org.antlr.v4.runtime.atn.BlockEndState;
import org.antlr.v4.runtime.atn.BlockStartState;
import org.antlr.v4.runtime.atn.DecisionState;
import org.antlr.v4.runtime.atn.EpsilonTransition;
import org.antlr.v4.runtime.atn.LL1Analyzer;
import org.antlr.v4.runtime.atn.LoopEndState;
import org.antlr.v4.runtime.atn.NotSetTransition;
import org.antlr.v4.runtime.atn.PlusBlockStartState;
import org.antlr.v4.runtime.atn.PlusLoopbackState;
import org.antlr.v4.runtime.atn.PrecedencePredicateTransition;
import org.antlr.v4.runtime.atn.PredicateTransition;
import org.antlr.v4.runtime.atn.PredictionContext;
import org.antlr.v4.runtime.atn.RuleStartState;
import org.antlr.v4.runtime.atn.RuleStopState;
import org.antlr.v4.runtime.atn.RuleTransition;
import org.antlr.v4.runtime.atn.SetTransition;
import org.antlr.v4.runtime.atn.StarBlockStartState;
import org.antlr.v4.runtime.atn.StarLoopEntryState;
import org.antlr.v4.runtime.atn.StarLoopbackState;
import org.antlr.v4.runtime.atn.Transition;
import org.antlr.v4.runtime.atn.WildcardTransition;
import org.antlr.v4.runtime.misc.IntervalSet;
import org.antlr.v4.runtime.misc.NotNull;
import org.antlr.v4.runtime.misc.Nullable;
import org.antlr.v4.runtime.misc.Tuple;
import org.antlr.v4.runtime.misc.Tuple2;
import org.antlr.v4.semantics.UseDefAnalyzer;
import org.antlr.v4.tool.ErrorManager;
import org.antlr.v4.tool.ErrorType;
import org.antlr.v4.tool.Grammar;
import org.antlr.v4.tool.LeftRecursiveRule;
import org.antlr.v4.tool.Rule;
import org.antlr.v4.tool.ast.ActionAST;
import org.antlr.v4.tool.ast.AltAST;
import org.antlr.v4.tool.ast.BlockAST;
import org.antlr.v4.tool.ast.GrammarAST;
import org.antlr.v4.tool.ast.GrammarASTWithOptions;
import org.antlr.v4.tool.ast.PredAST;
import org.antlr.v4.tool.ast.QuantifierAST;
import org.antlr.v4.tool.ast.TerminalAST;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
/** ATN construction routines triggered by ATNBuilder.g.
*
* No side-effects. It builds an ATN object and returns it.
*/
public class ParserATNFactory implements ATNFactory {
@NotNull
public final Grammar g;
@NotNull
public final ATN atn;
public Rule currentRule;
public int currentOuterAlt;
protected final List> preventEpsilonDecisions =
new ArrayList>();
public ParserATNFactory(@NotNull Grammar g) {
if (g == null) {
throw new NullPointerException("g");
}
this.g = g;
this.atn = new ATN();
}
@Override
public ATN createATN() {
_createATN(g.rules.values());
atn.maxTokenType = g.getMaxTokenType();
addRuleFollowLinks();
addEOFTransitionToStartRules();
ATNOptimizer.optimize(g, atn);
for (Tuple2 pair : preventEpsilonDecisions) {
LL1Analyzer analyzer = new LL1Analyzer(atn);
if (analyzer.LOOK(pair.getItem2(), PredictionContext.EMPTY_LOCAL).contains(org.antlr.v4.runtime.Token.EPSILON)) {
g.tool.errMgr.grammarError(ErrorType.EPSILON_LR_FOLLOW, g.fileName, ((GrammarAST)pair.getItem1().ast.getChild(0)).getToken(), pair.getItem1().name);
}
}
return atn;
}
protected void _createATN(Collection rules) {
createRuleStartAndStopATNStates();
GrammarASTAdaptor adaptor = new GrammarASTAdaptor();
for (Rule r : rules) {
// find rule's block
GrammarAST blk = (GrammarAST)r.ast.getFirstChildWithType(ANTLRParser.BLOCK);
CommonTreeNodeStream nodes = new CommonTreeNodeStream(adaptor,blk);
ATNBuilder b = new ATNBuilder(nodes,this);
try {
setCurrentRuleName(r.name);
Handle h = b.ruleBlock(null);
rule(r.ast, r.name, h);
}
catch (RecognitionException re) {
ErrorManager.fatalInternalError("bad grammar AST structure", re);
}
}
}
@Override
public void setCurrentRuleName(String name) {
this.currentRule = g.getRule(name);
}
@Override
public void setCurrentOuterAlt(int alt) {
currentOuterAlt = alt;
}
/* start->ruleblock->end */
@Override
public Handle rule(GrammarAST ruleAST, String name, Handle blk) {
Rule r = g.getRule(name);
RuleStartState start = atn.ruleToStartState[r.index];
epsilon(start, blk.left);
RuleStopState stop = atn.ruleToStopState[r.index];
epsilon(blk.right, stop);
Handle h = new Handle(start, stop);
// ATNPrinter ser = new ATNPrinter(g, h.left);
// System.out.println(ruleAST.toStringTree()+":\n"+ser.asString());
ruleAST.atnState = start;
return h;
}
/** From label {@code A} build graph {@code o-A->o}. */
@Override
public Handle tokenRef(TerminalAST node) {
ATNState left = newState(node);
ATNState right = newState(node);
int ttype = g.getTokenType(node.getText());
left.addTransition(new AtomTransition(right, ttype));
node.atnState = left;
return new Handle(left, right);
}
/** From set build single edge graph {@code o->o-set->o}. To conform to
* what an alt block looks like, must have extra state on left.
* This also handles {@code ~A}, converted to {@code ~{A}} set.
*/
@Override
public Handle set(GrammarAST associatedAST, List terminals, boolean invert) {
ATNState left = newState(associatedAST);
ATNState right = newState(associatedAST);
IntervalSet set = new IntervalSet();
for (GrammarAST t : terminals) {
int ttype = g.getTokenType(t.getText());
set.add(ttype);
}
if ( invert ) {
left.addTransition(new NotSetTransition(right, set));
}
else {
left.addTransition(new SetTransition(right, set));
}
associatedAST.atnState = left;
return new Handle(left, right);
}
/** Not valid for non-lexers. */
@Override
public Handle range(GrammarAST a, GrammarAST b) {
throw new UnsupportedOperationException();
}
protected int getTokenType(GrammarAST atom) {
int ttype;
if ( g.isLexer() ) {
ttype = CharSupport.getCharValueFromGrammarCharLiteral(atom.getText());
}
else {
ttype = g.getTokenType(atom.getText());
}
return ttype;
}
/** For a non-lexer, just build a simple token reference atom. */
@Override
public Handle stringLiteral(TerminalAST stringLiteralAST) {
return tokenRef(stringLiteralAST);
}
/** {@code [Aa]} char sets not allowed in parser */
@Override
public Handle charSetLiteral(GrammarAST charSetAST) {
return null;
}
/**
* For reference to rule {@code r}, build
*
*
* o->(r) o
*
*
* where {@code (r)} is the start of rule {@code r} and the trailing
* {@code o} is not linked to from rule ref state directly (uses
* {@link RuleTransition#followState}).
*/
@Override
public Handle ruleRef(GrammarAST node) {
Handle h = _ruleRef(node);
return h;
}
public Handle _ruleRef(GrammarAST node) {
Rule r = g.getRule(node.getText());
if ( r==null ) {
g.tool.errMgr.toolError(ErrorType.INTERNAL_ERROR, "Rule "+node.getText()+" undefined");
return null;
}
RuleStartState start = atn.ruleToStartState[r.index];
ATNState left = newState(node);
ATNState right = newState(node);
int precedence = 0;
if (((GrammarASTWithOptions)node).getOptionString(LeftRecursiveRuleTransformer.PRECEDENCE_OPTION_NAME) != null) {
precedence = Integer.parseInt(((GrammarASTWithOptions)node).getOptionString(LeftRecursiveRuleTransformer.PRECEDENCE_OPTION_NAME));
}
RuleTransition call = new RuleTransition(start, r.index, precedence, right);
left.addTransition(call);
node.atnState = left;
return new Handle(left, right);
}
public void addFollowLink(int ruleIndex, ATNState right) {
// add follow edge from end of invoked rule
RuleStopState stop = atn.ruleToStopState[ruleIndex];
// System.out.println("add follow link from "+ruleIndex+" to "+right);
epsilon(stop, right);
}
/** From an empty alternative build {@code o-e->o}. */
@Override
public Handle epsilon(GrammarAST node) {
ATNState left = newState(node);
ATNState right = newState(node);
epsilon(left, right);
node.atnState = left;
return new Handle(left, right);
}
/** Build what amounts to an epsilon transition with a semantic
* predicate action. The {@code pred} is a pointer into the AST of
* the {@link ANTLRParser#SEMPRED} token.
*/
@Override
public Handle sempred(PredAST pred) {
//System.out.println("sempred: "+ pred);
ATNState left = newState(pred);
ATNState right = newState(pred);
AbstractPredicateTransition p;
if (pred.getOptionString(LeftRecursiveRuleTransformer.PRECEDENCE_OPTION_NAME) != null) {
int precedence = Integer.parseInt(pred.getOptionString(LeftRecursiveRuleTransformer.PRECEDENCE_OPTION_NAME));
p = new PrecedencePredicateTransition(right, precedence);
}
else {
boolean isCtxDependent = UseDefAnalyzer.actionIsContextDependent(pred);
p = new PredicateTransition(right, currentRule.index, g.sempreds.get(pred), isCtxDependent);
}
left.addTransition(p);
pred.atnState = left;
return new Handle(left, right);
}
/** Build what amounts to an epsilon transition with an action.
* The action goes into ATN though it is ignored during prediction
* if {@link ActionTransition#actionIndex actionIndex}{@code <0}.
*/
@Override
public Handle action(ActionAST action) {
//System.out.println("action: "+action);
ATNState left = newState(action);
ATNState right = newState(action);
ActionTransition a = new ActionTransition(right, currentRule.index);
left.addTransition(a);
action.atnState = left;
return new Handle(left, right);
}
@Override
public Handle action(String action) {
return null;
}
/**
* From {@code A|B|..|Z} alternative block build
*
*
* o->o-A->o->o (last ATNState is BlockEndState pointed to by all alts)
* | ^
* |->o-B->o--|
* | |
* ... |
* | |
* |->o-Z->o--|
*
*
* So start node points at every alternative with epsilon transition and
* every alt right side points at a block 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 edged o-set->o graph.
*
* TODO: Set alt number (1..n) in the states?
*/
@Override
public Handle block(BlockAST blkAST, GrammarAST ebnfRoot, List alts) {
if ( ebnfRoot==null ) {
if ( alts.size()==1 ) {
Handle h = alts.get(0);
blkAST.atnState = h.left;
return h;
}
BlockStartState start = newState(BasicBlockStartState.class, blkAST);
if ( alts.size()>1 ) atn.defineDecisionState(start);
return makeBlock(start, blkAST, alts);
}
switch ( ebnfRoot.getType() ) {
case ANTLRParser.OPTIONAL :
BlockStartState start = newState(BasicBlockStartState.class, blkAST);
atn.defineDecisionState(start);
Handle h = makeBlock(start, blkAST, alts);
return optional(ebnfRoot, h);
case ANTLRParser.CLOSURE :
BlockStartState star = newState(StarBlockStartState.class, ebnfRoot);
if ( alts.size()>1 ) atn.defineDecisionState(star);
h = makeBlock(star, blkAST, alts);
return star(ebnfRoot, h);
case ANTLRParser.POSITIVE_CLOSURE :
PlusBlockStartState plus = newState(PlusBlockStartState.class, ebnfRoot);
if ( alts.size()>1 ) atn.defineDecisionState(plus);
h = makeBlock(plus, blkAST, alts);
return plus(ebnfRoot, h);
}
return null;
}
protected Handle makeBlock(BlockStartState start, BlockAST blkAST, List alts) {
start.sll = isSLLDecision(blkAST);
BlockEndState end = newState(BlockEndState.class, blkAST);
start.endState = end;
for (Handle alt : alts) {
// hook alts up to decision block
epsilon(start, alt.left);
epsilon(alt.right, end);
// no back link in ATN so must walk entire alt to see if we can
// strip out the epsilon to 'end' state
TailEpsilonRemover opt = new TailEpsilonRemover(atn);
opt.visit(alt.left);
}
Handle h = new Handle(start, end);
// FASerializer ser = new FASerializer(g, h.left);
// System.out.println(blkAST.toStringTree()+":\n"+ser);
blkAST.atnState = start;
if (Boolean.valueOf(blkAST.getOptionString("preventepsilon"))) {
preventEpsilonDecisions.add(Tuple.create(currentRule, start));
}
return h;
}
@NotNull
@Override
public Handle alt(@NotNull List els) {
return elemList(els);
}
@NotNull
public Handle elemList(@NotNull List els) {
int n = els.size();
for (int i = 0; i < n - 1; i++) { // hook up elements (visit all but last)
Handle el = els.get(i);
// if el is of form o-x->o for x in {rule, action, pred, token, ...}
// and not last in alt
Transition tr = null;
if ( el.left.getNumberOfTransitions()==1 ) tr = el.left.transition(0);
boolean isRuleTrans = tr instanceof RuleTransition;
if ( el.left.getStateType() == ATNState.BASIC &&
el.right.getStateType()== ATNState.BASIC &&
tr!=null && (isRuleTrans || tr.target == el.right) )
{
// we can avoid epsilon edge to next el
if ( isRuleTrans ) ((RuleTransition)tr).followState = els.get(i+1).left;
else tr.target = els.get(i+1).left;
atn.removeState(el.right); // we skipped over this state
}
else { // need epsilon if previous block's right end node is complicated
epsilon(el.right, els.get(i+1).left);
}
}
Handle first = els.get(0);
Handle last = els.get(n -1);
if ( first==null || last==null ) {
g.tool.errMgr.toolError(ErrorType.INTERNAL_ERROR, "element list has first|last == null");
}
return new Handle(first.left, last.right);
}
/**
* From {@code (A)?} build either:
*
*
* o--A->o
* | ^
* o---->|
*
*
* or, if {@code A} is a block, just add an empty alt to the end of the
* block
*/
@NotNull
@Override
public Handle optional(@NotNull GrammarAST optAST, @NotNull Handle blk) {
BlockStartState blkStart = (BlockStartState)blk.left;
blkStart.nonGreedy = !((QuantifierAST)optAST).isGreedy();
blkStart.sll = false; // no way to express SLL restriction
if (((QuantifierAST)optAST).isGreedy()) {
epsilon(blkStart, blk.right);
} else {
Transition existing = blkStart.removeTransition(0);
epsilon(blkStart, blk.right);
blkStart.addTransition(existing);
}
optAST.atnState = blk.left;
return blk;
}
/**
* From {@code (blk)+} build
*
*
* |---------|
* v |
* [o-blk-o]->o->o
*
*
* We add a decision for loop back node to the existing one at {@code blk}
* start.
*/
@NotNull
@Override
public Handle plus(@NotNull GrammarAST plusAST, @NotNull Handle blk) {
PlusBlockStartState blkStart = (PlusBlockStartState)blk.left;
BlockEndState blkEnd = (BlockEndState)blk.right;
PlusLoopbackState loop = newState(PlusLoopbackState.class, plusAST);
loop.nonGreedy = !((QuantifierAST)plusAST).isGreedy();
loop.sll = false; // no way to express SLL restriction
atn.defineDecisionState(loop);
LoopEndState end = newState(LoopEndState.class, plusAST);
blkStart.loopBackState = loop;
end.loopBackState = loop;
plusAST.atnState = blkStart;
epsilon(blkEnd, loop); // blk can see loop back
BlockAST blkAST = (BlockAST)plusAST.getChild(0);
if ( ((QuantifierAST)plusAST).isGreedy() ) {
if (expectNonGreedy(blkAST)) {
g.tool.errMgr.grammarError(ErrorType.EXPECTED_NON_GREEDY_WILDCARD_BLOCK, g.fileName, plusAST.getToken(), plusAST.getToken().getText());
}
epsilon(loop, blkStart); // loop back to start
epsilon(loop, end); // or exit
}
else {
// if not greedy, priority to exit branch; make it first
epsilon(loop, end); // exit
epsilon(loop, blkStart); // loop back to start
}
return new Handle(blkStart, end);
}
/**
* From {@code (blk)*} build {@code ( blk+ )?} with *two* decisions, one for
* entry and one for choosing alts of {@code blk}.
*
*
* |-------------|
* v |
* o--[o-blk-o]->o o
* | ^
* -----------------|
*
*
* Note that the optional bypass must jump outside the loop as
* {@code (A|B)*} is not the same thing as {@code (A|B|)+}.
*/
@NotNull
@Override
public Handle star(@NotNull GrammarAST starAST, @NotNull Handle elem) {
StarBlockStartState blkStart = (StarBlockStartState)elem.left;
BlockEndState blkEnd = (BlockEndState)elem.right;
StarLoopEntryState entry = newState(StarLoopEntryState.class, starAST);
entry.nonGreedy = !((QuantifierAST)starAST).isGreedy();
entry.sll = false; // no way to express SLL restriction
atn.defineDecisionState(entry);
LoopEndState end = newState(LoopEndState.class, starAST);
StarLoopbackState loop = newState(StarLoopbackState.class, starAST);
entry.loopBackState = loop;
end.loopBackState = loop;
BlockAST blkAST = (BlockAST)starAST.getChild(0);
if ( ((QuantifierAST)starAST).isGreedy() ) {
if (expectNonGreedy(blkAST)) {
g.tool.errMgr.grammarError(ErrorType.EXPECTED_NON_GREEDY_WILDCARD_BLOCK, g.fileName, starAST.getToken(), starAST.getToken().getText());
}
epsilon(entry, blkStart); // loop enter edge (alt 1)
epsilon(entry, end); // bypass loop edge (alt 2)
}
else {
// if not greedy, priority to exit branch; make it first
epsilon(entry, end); // bypass loop edge (alt 1)
epsilon(entry, blkStart); // loop enter edge (alt 2)
}
epsilon(blkEnd, loop); // block end hits loop back
epsilon(loop, entry); // loop back to entry/exit decision
starAST.atnState = entry; // decision is to enter/exit; blk is its own decision
return new Handle(entry, end);
}
/** Build an atom with all possible values in its label. */
@NotNull
@Override
public Handle wildcard(GrammarAST node) {
ATNState left = newState(node);
ATNState right = newState(node);
left.addTransition(new WildcardTransition(right));
node.atnState = left;
return new Handle(left, right);
}
void epsilon(ATNState a, @NotNull ATNState b) {
if ( a!=null ) a.addTransition(new EpsilonTransition(b));
}
/** Define all the rule begin/end ATNStates to solve forward reference
* issues.
*/
void createRuleStartAndStopATNStates() {
atn.ruleToStartState = new RuleStartState[g.rules.size()];
atn.ruleToStopState = new RuleStopState[g.rules.size()];
for (Rule r : g.rules.values()) {
RuleStartState start = newState(RuleStartState.class, r.ast);
RuleStopState stop = newState(RuleStopState.class, r.ast);
start.stopState = stop;
start.isPrecedenceRule = r instanceof LeftRecursiveRule;
start.setRuleIndex(r.index);
stop.setRuleIndex(r.index);
atn.ruleToStartState[r.index] = start;
atn.ruleToStopState[r.index] = stop;
}
}
public void addRuleFollowLinks() {
for (ATNState p : atn.states) {
if ( p!=null &&
p.getStateType() == ATNState.BASIC && p.getNumberOfTransitions()==1 &&
p.transition(0) instanceof RuleTransition )
{
RuleTransition rt = (RuleTransition) p.transition(0);
addFollowLink(rt.ruleIndex, rt.followState);
}
}
}
/** Add an EOF transition to any rule end ATNState that points to nothing
* (i.e., for all those rules not invoked by another rule). These
* are start symbols then.
*
* Return the number of grammar entry points; i.e., how many rules are
* not invoked by another rule (they can only be invoked from outside).
* These are the start rules.
*/
public int addEOFTransitionToStartRules() {
int n = 0;
ATNState eofTarget = newState(null); // one unique EOF target for all rules
for (Rule r : g.rules.values()) {
ATNState stop = atn.ruleToStopState[r.index];
if ( stop.getNumberOfTransitions()>0 ) continue;
n++;
Transition t = new AtomTransition(eofTarget, Token.EOF);
stop.addTransition(t);
}
return n;
}
@Override
public Handle label(Handle t) {
return t;
}
@Override
public Handle listLabel(Handle t) {
return t;
}
@NotNull
public T newState(@NotNull Class nodeType, GrammarAST node) {
Exception cause;
try {
Constructor ctor = nodeType.getConstructor();
T s = ctor.newInstance();
if ( currentRule==null ) s.setRuleIndex(-1);
else s.setRuleIndex(currentRule.index);
atn.addState(s);
return s;
} catch (InstantiationException ex) {
cause = ex;
} catch (IllegalAccessException ex) {
cause = ex;
} catch (IllegalArgumentException ex) {
cause = ex;
} catch (InvocationTargetException ex) {
cause = ex;
} catch (NoSuchMethodException ex) {
cause = ex;
} catch (SecurityException ex) {
cause = ex;
}
String message = String.format("Could not create %s of type %s.", ATNState.class.getName(), nodeType.getName());
throw new UnsupportedOperationException(message, cause);
}
@NotNull
public ATNState newState(@Nullable GrammarAST node) {
ATNState n = new BasicState();
n.setRuleIndex(currentRule.index);
atn.addState(n);
return n;
}
@NotNull
@Override
public ATNState newState() { return newState(null); }
public boolean expectNonGreedy(@NotNull BlockAST blkAST) {
if ( blockHasWildcardAlt(blkAST) ) {
return true;
}
return false;
}
public boolean isSLLDecision(@NotNull BlockAST blkAST) {
return Boolean.toString(true).equalsIgnoreCase(blkAST.getOptionString("sll"));
}
/**
* {@code (BLOCK (ALT .))} or {@code (BLOCK (ALT 'a') (ALT .))}.
*/
public static boolean blockHasWildcardAlt(@NotNull GrammarAST block) {
for (Object alt : block.getChildren()) {
if ( !(alt instanceof AltAST) ) continue;
AltAST altAST = (AltAST)alt;
if ( altAST.getChildCount()==1 ) {
Tree e = altAST.getChild(0);
if ( e.getType()==ANTLRParser.WILDCARD ) {
return true;
}
}
}
return false;
}
@Override
public Handle lexerAltCommands(Handle alt, Handle cmds) {
return null;
}
@Override
public String lexerCallCommand(GrammarAST ID, GrammarAST arg) {
return null;
}
@Override
public String lexerCommand(GrammarAST ID) {
return null;
}
}