removes the individual stacks to track rule invocations. $a::x now looks up the context stack for rule index RULE_a. they're not done very often and so it's better to say all of the overhead pushing and popping the contexts.

[git-p4: depot-paths = "//depot/code/antlr4/main/": change = 9066]

runtime/Java/src/org/antlr/v4/runtime/BaseRecognizer.java

@@ -586,6 +586,20 @@ public abstract class BaseRecognizer extends Recognizer<ParserATNSimulator> {
 		}
 	}
 
+	public ParserRuleContext getInvokingContext(int ruleIndex) {
+		ParserRuleContext p = _ctx;
+		while ( p!=null ) {
+			if ( p.getRuleIndex() == ruleIndex ) return p;
+			p = (ParserRuleContext)p.parent;
+		}
+		return null;
+	}
+
+	public boolean inContext(String context) {
+		// TODO: useful in parser?
+		return false;
+	}
+
 	/** Return List<String> of the rules in your parser instance
 	 *  leading up to a call to this method.  You could override if
 	 *  you want more details such as the file/line info of where
@@ -595,6 +609,7 @@ public abstract class BaseRecognizer extends Recognizer<ParserATNSimulator> {
 	 *  error recovery.
 	 */
 	public List getRuleInvocationStack() {
+		// TODO: walk ctx chain now; this is legacy
 		String parserClassName = getClass().getName();
 		return getRuleInvocationStack(new Throwable(), parserClassName);
 	}
@@ -609,6 +624,7 @@ public abstract class BaseRecognizer extends Recognizer<ParserATNSimulator> {
 	public static List getRuleInvocationStack(Throwable e,
 											  String recognizerClassName)
 	{
+		// TODO: walk ctx chain now; this is legacy
 		List rules = new ArrayList();
 		StackTraceElement[] stack = e.getStackTrace();
 		int i = 0;

tool/playground/T.g

@@ -1,7 +1,7 @@
 grammar T;
 s : i=ifstat  {System.out.println(_input.toString(0,_input.index()-1));} ;
 
-ifstat : 'if' '(' INT ')' ID '=' ID ';' # DoIf;
+ifstat : 'if' {$s::start = null;} '(' INT ')' ID '=' ID ';' # DoIf;
 
 r[int x] returns [int y]
 locals [int z]

tool/resources/org/antlr/v4/tool/templates/codegen/Java/Java.stg

@@ -159,11 +159,8 @@ RuleFunction(currentRule,code,locals,ruleCtx,altLabelCtxs,namedActions,finallyAc
 <ruleCtx>
 <altLabelCtxs; separator="\n">
 
-public QStack\<<currentRule.ctxType>\> <currentRule.name>_stk = new QStack\<<currentRule.ctxType>\>();
-
 <if(currentRule.modifiers)><currentRule.modifiers:{f | <f> }><else>public final <endif><currentRule.ctxType> <currentRule.name>(<currentRule.args; separator=",">) throws RecognitionException {
     <currentRule.ctxType> _localctx = new <currentRule.ctxType>(_ctx, <currentRule.startState><currentRule.args:{a | , <a.name>}>);
-    <currentRule.name>_stk.push(_localctx);
     enterRule(_localctx, <currentRule.index>);
     //System.out.println("enter "+ruleNames[<currentRule.index>]+", LT(1)="+_input.LT(1).getText());
     <namedActions.init>
@@ -179,7 +176,6 @@ public QStack\<<currentRule.ctxType>\> <currentRule.name>_stk = new QStack\<<cur
 		recover();
 	}
 	finally {
-        <currentRule.name>_stk.pop();
         <finallyAction>
         exitRule(<currentRule.index>);
     	// System.out.println("exit "+ruleNames[<currentRule.index>]);
@@ -419,10 +415,9 @@ ThisRulePropertyRef_tree(r)  ::= "_localctx.tree"
 ThisRulePropertyRef_text(r)  ::= "((TokenStream)_input).toString(_localctx.start, _input.LT(-1))"
 ThisRulePropertyRef_st(r)    ::= "_localctx.st"
 
-//NonLocalContextRef(s)           ::= "<s.scope>"
-NonLocalAttrRef(s)       ::= "<s.scope>.peek().<s.attr>"
-SetNonLocalAttr(s, rhsChunks)            ::=
-    "<s.scope>.peek().<s.attr> =<rhsChunks>;"
+NonLocalAttrRef(s)       ::= "((<s.ruleName>Context)getInvokingContext(<s.ruleIndex>)).<s.name>"
+SetNonLocalAttr(s, rhsChunks)     ::=
+	"((<s.ruleName>Context)getInvokingContext(<s.ruleIndex>)).<s.name> = <rhsChunks>;"
 
 AddToLabelList(a) ::= "_localctx.<a.listName>.add(<labelref(a.label)>);"
 

tool/src/org/antlr/v4/codegen/ActionTranslator.java

@@ -207,14 +207,16 @@ public class ActionTranslator implements ActionSplitterListener {
 	}
 
 	public void nonLocalAttr(String expr, Token x, Token y) {
-		System.out.println("nonLocalAttr "+x+"."+y);
-		chunks.add(new NonLocalAttrRef(x.getText(), y.getText()));
+		System.out.println("nonLocalAttr "+x+"::"+y);
+		Rule r = factory.getGrammar().getRule(x.getText());
+		chunks.add(new NonLocalAttrRef(x.getText(), y.getText(), r.index));
 	}
 
 	public void setNonLocalAttr(String expr, Token x, Token y, Token rhs) {
 		System.out.println("setNonLocalAttr "+x+"::"+y+"="+rhs);
+		Rule r = factory.getGrammar().getRule(x.getText());
 		List<ActionChunk> rhsChunks = translateActionChunk(factory,rf,rhs.getText(),node);
-		SetNonLocalAttr s = new SetNonLocalAttr(x.getText(), y.getText(), rhsChunks);
+		SetNonLocalAttr s = new SetNonLocalAttr(x.getText(), y.getText(), r.index, rhsChunks);
 		chunks.add(s);
 	}
 

tool/src/org/antlr/v4/codegen/model/actions/NonLocalAttrRef.java

@@ -30,11 +30,14 @@
 package org.antlr.v4.codegen.model.actions;
 
 public class NonLocalAttrRef extends ActionChunk {
-	public String context;
+	public String ruleName;
 	public String name;
-	public NonLocalAttrRef(String context, String name) {
-		this.context = context;
+	public int ruleIndex;
+
+	public NonLocalAttrRef(String ruleName, String name, int ruleIndex) {
 		this.name = name;
+		this.ruleName = ruleName;
+		this.ruleIndex = ruleIndex;
 	}
 
 }

tool/src/org/antlr/v4/codegen/model/actions/SetNonLocalAttr.java

@@ -32,9 +32,14 @@ package org.antlr.v4.codegen.model.actions;
 import java.util.List;
 
 public class SetNonLocalAttr extends SetAttr {
-	public String context;
-	public SetNonLocalAttr(String context, String name, List<ActionChunk> rhsChunks) {
+	public String ruleName;
+	public int ruleIndex;
+
+	public SetNonLocalAttr(String ruleName, String name, int ruleIndex,
+						   List<ActionChunk> rhsChunks)
+	{
 		super(name, rhsChunks);
-		this.context = context;
+		this.ruleName = ruleName;
+		this.ruleIndex = ruleIndex;
 	}
 }