From 65396e6d7c4813051fabf8f6aff1353907280581 Mon Sep 17 00:00:00 2001
From: parrt <parrt@antlr.org>
Date: Sat, 16 Jul 2011 11:49:14 -0800
Subject: [PATCH] don't reduce SETs if elements ref'd in -> rewrite

[git-p4: depot-paths = "//depot/code/antlr4/main/": change = 8864]
---
 tool/playground/T.g                           |  1 +
 .../org/antlr/v4/parse/BlockSetTransformer.g  | 33 ++++++++++---------
 2 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/tool/playground/T.g b/tool/playground/T.g
index 716d09e3f..9bf5d38f8 100644
--- a/tool/playground/T.g
+++ b/tool/playground/T.g
@@ -2,6 +2,7 @@ grammar T;
 options {output=AST;}
 tokens {DUH;}
 a : (A|B) ;
+b : (A|B) -> A ;
 /*
 type returns [int i] : ID;
 ID : 'a'..'z'+ ;
diff --git a/tool/src/org/antlr/v4/parse/BlockSetTransformer.g b/tool/src/org/antlr/v4/parse/BlockSetTransformer.g
index a8cb38e7b..36833b36e 100644
--- a/tool/src/org/antlr/v4/parse/BlockSetTransformer.g
+++ b/tool/src/org/antlr/v4/parse/BlockSetTransformer.g
@@ -12,6 +12,8 @@ package org.antlr.v4.parse;
 import org.antlr.v4.misc.Utils;
 import org.antlr.v4.tool.*;
 import java.util.List;
+import java.util.Set;
+import java.util.HashSet;
 import java.util.ArrayList;
 import org.antlr.v4.runtime.misc.IntervalSet;
 }
@@ -19,6 +21,7 @@ import org.antlr.v4.runtime.misc.IntervalSet;
 @members {
 public String currentRuleName;
 public GrammarAST currentAlt;
+public Set<String> rewriteElems = new HashSet<String>();
 }
 
 topdown
@@ -30,10 +33,19 @@ topdown
 
 setAlt
 	:	{inContext("RULE BLOCK")}?
-		( ALT {currentAlt = (AltAST)$start;}
-		| ALT_REWRITE {currentAlt = (AltAST)$start.getChild(0);}
+		(	ALT {currentAlt = $start; rewriteElems.clear();}
+		|	ALT_REWRITE {currentAlt = $start;}
+			{
+			IntervalSet s = new IntervalSet();
+			s.add(RULE_REF);
+			s.add(STRING_LITERAL);
+			s.add(TOKEN_REF);
+			List<GrammarAST> nodes = ((GrammarAST)(currentAlt.getChild(1))).getNodesWithType(s);
+			for (GrammarAST n : nodes) {rewriteElems.add(n.getText());}
+			System.out.println("stuff in rewrite: "+rewriteElems);
+			}
 		)
-		
+				
 	;
 
 // (BLOCK (ALT (+ (BLOCK (ALT INT) (ALT ID)))))
@@ -50,22 +62,13 @@ ebnfSuffix
 	
 blockSet
 @init {
-	if ( currentAlt!=null && currentAlt.getType()==ANTLRParser.ALT_REWRITE ) {
-		IntervalSet s = new IntervalSet();
-		s.add(RULE_REF);
-		s.add(STRING_LITERAL);
-		s.add(TOKEN_REF);
-		List<GrammarAST> elems = currentAlt.getNodesWithType(s);
-		System.out.println("stuff in rewrite: "+elems);
-	}
 }
 	:	{Character.isLowerCase(currentRuleName.charAt(0)) &&
-		!inContext("ALT_REWRITE ...") && !inContext("RULE")}?
+		 !inContext("RULE")}? // if non-lexer rule and not rule block
 		^(BLOCK ( ^(ALT setElement) )+) -> ^(SET[$BLOCK.token, "SET"] setElement+)
 	;
 	
 setElement
-@after {$tree = new TerminalAST($start);}
-	:	STRING_LITERAL
-	|	TOKEN_REF
+@after {$tree = new TerminalAST($start);} // elem can't be to right of ->
+	:	{!rewriteElems.contains($start.getText())}? (STRING_LITERAL|TOKEN_REF)
 	;
\ No newline at end of file