handles nongreedy + and * loops. rewinds properly to last good accept if we kept going and failed.

[git-p4: depot-paths = "//depot/code/antlr4/main/": change = 6828]

runtime/Java/src/org/antlr/v4/runtime/nfa/NFA.java

@@ -193,6 +193,8 @@ workLoop:
 		List<Integer> reach = new ArrayList<Integer>();
 		int prevAcceptAddr = Integer.MAX_VALUE;
 		int prevAcceptLastCharIndex = -1;
+		int prevAcceptInputMarker = -1;
+		int firstAcceptInputMarker = -1;
 		addToClosure(closure, ip);
 		do { // while more work
 			c = input.LA(1);
@@ -238,12 +240,15 @@ processOneChar:
 							// choose longest match so far regardless of rule priority
 							System.out.println("replacing old best match @ "+prevAcceptAddr);
 							prevAcceptAddr = ip-1;
+							prevAcceptInputMarker = input.mark();
+							firstAcceptInputMarker = prevAcceptInputMarker;
 						}
 						else if ( tokenLastCharIndex == prevAcceptLastCharIndex ) {
 							// choose first rule matched if match is of same length
 							if ( ip-1 < prevAcceptAddr ) { // it will see both accepts for ambig rules
 								System.out.println("replacing old best match @ "+prevAcceptAddr);
 								prevAcceptAddr = ip-1;
+								prevAcceptInputMarker = input.mark();
 							}
 						}
 						// if we reach accept state, toss out any addresses in rest
@@ -285,6 +290,11 @@ processOneChar:
 
 		if ( prevAcceptAddr >= code.length ) return Token.INVALID_TOKEN_TYPE;
 		int ttype = getShort(code, prevAcceptAddr+1);
+		System.out.println("done at index "+input.index());
+		System.out.println("accept marker="+prevAcceptInputMarker);
+		input.rewind(prevAcceptInputMarker); // does nothing if we accept'd at input.index() but might need to rewind
+		input.release(firstAcceptInputMarker); // kill any other markers in stream we made
+		System.out.println("leaving with index "+input.index());
 		return ttype;
 	}
 

tool/src/org/antlr/v4/codegen/NFABytecodeTriggers.g

@@ -9,6 +9,10 @@ options {
 @header {
 package org.antlr.v4.codegen;
 import org.antlr.v4.tool.GrammarAST;
+import org.antlr.v4.tool.GrammarASTWithOptions;
+import java.util.Collections;
+import java.util.Map;
+import java.util.HashMap;
 }
 
 /*
@@ -83,6 +87,10 @@ treeSpec
     ;
 
 ebnf
+@init {
+	GrammarASTWithOptions blk = (GrammarASTWithOptions)$start.getChild(0);
+	String greedyOption = blk.getOption("greedy");
+}
 	:	^(astBlockSuffix block)		
 	|	{
 	   	SplitInstr S = new SplitInstr(2);
@@ -97,15 +105,16 @@ ebnf
 		int start=ip;
 	   	SplitInstr S = new SplitInstr(2);
 		emit(S);
-		int blk = ip;
+		int blkStart = ip;
 		}
 		^(CLOSURE block)			
 		{
 	    JumpInstr J = new JumpInstr();
 	    emit(J);
 	    J.target = start;
-   		S.addrs.add(blk);
-	    S.addrs.add(ip); // reverse for nongreedy
+   		S.addrs.add(blkStart);
+	    S.addrs.add(ip);
+	    if ( greedyOption!=null && greedyOption.equals("false") ) Collections.reverse(S.addrs);
 		}
 	|	{int start=ip;} ^(POSITIVE_CLOSURE block)
 		{
@@ -114,6 +123,7 @@ ebnf
 		int stop = ip;
    		S.addrs.add(start);
    		S.addrs.add(stop);
+	    if ( greedyOption!=null && greedyOption.equals("false") ) Collections.reverse(S.addrs);
 		}
 	| 	block						
     ;