diff --git a/runtime/Java/src/org/antlr/v4/runtime/tree/BaseTree.java b/runtime/Java/src/org/antlr/v4/runtime/tree/BaseTree.java
index 5e99a19fc..7b0aaba23 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/tree/BaseTree.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/tree/BaseTree.java
@@ -252,6 +252,20 @@ public abstract class BaseTree implements Tree {
 		}
 	}
 
+	public void freshenParentAndChildIndexesDeeply() {
+		freshenParentAndChildIndexesDeeply(0);
+	}
+
+	public void freshenParentAndChildIndexesDeeply(int offset) {
+		int n = getChildCount();
+		for (int c = offset; c < n; c++) {
+			BaseTree child = (BaseTree)getChild(c);
+			child.setChildIndex(c);
+			child.setParent(this);
+			child.freshenParentAndChildIndexesDeeply();
+		}
+	}
+
 	public void sanityCheckParentAndChildIndexes() {
 		sanityCheckParentAndChildIndexes(null, -1);
 	}
diff --git a/tool/playground/T.g b/tool/playground/T.g
index 69584e464..1f4f21a7b 100644
--- a/tool/playground/T.g
+++ b/tool/playground/T.g
@@ -1,7 +1,7 @@
 grammar T;
 options {output=AST;}
 
-a : 'var' (ID ':' type ';')+ -> ^('var' ^(':' ID type)*) ;
+a : 'var' (ID ':' type ';')+ -> ^('var' ^(':' ID<Foo> type)*) ;
 type returns [int i] : ID;
 ID : 'a'..'z'+ ;
 INT : '0'..'9'+;
diff --git a/tool/src/org/antlr/v4/Tool.java b/tool/src/org/antlr/v4/Tool.java
index d3f626d12..179ae0e0f 100644
--- a/tool/src/org/antlr/v4/Tool.java
+++ b/tool/src/org/antlr/v4/Tool.java
@@ -432,6 +432,8 @@ public class Tool {
 			lexerRulesRoot.getChildren().add(0, litRule); // add first
 		}
 
+		lexerRulesRoot.freshenParentAndChildIndexesDeeply();
+
 		System.out.println("after ="+combinedAST.toStringTree());
 		System.out.println("lexer ="+lexerAST.toStringTree());
 		return lexerAST;
diff --git a/tool/src/org/antlr/v4/parse/ANTLRParser.g b/tool/src/org/antlr/v4/parse/ANTLRParser.g
index 2fe215747..01d56bf84 100644
--- a/tool/src/org/antlr/v4/parse/ANTLRParser.g
+++ b/tool/src/org/antlr/v4/parse/ANTLRParser.g
@@ -786,9 +786,8 @@ range
     ;
 
 terminal
-    :   // Args are only valid for lexer rules
-		TOKEN_REF ARG_ACTION? elementOptions? -> ^(TOKEN_REF<TerminalAST> ARG_ACTION<ActionAST>? elementOptions?)
-	|   STRING_LITERAL elementOptions?		  -> ^(STRING_LITERAL<TerminalAST> elementOptions?)
+    :   TOKEN_REF elementOptions?		-> ^(TOKEN_REF<TerminalAST> elementOptions?)
+	|   STRING_LITERAL elementOptions?	-> ^(STRING_LITERAL<TerminalAST> elementOptions?)
 	;
 
 // Terminals may be adorned with certain options when
diff --git a/tool/src/org/antlr/v4/parse/ASTVerifier.g b/tool/src/org/antlr/v4/parse/ASTVerifier.g
index 95779220f..728823960 100644
--- a/tool/src/org/antlr/v4/parse/ASTVerifier.g
+++ b/tool/src/org/antlr/v4/parse/ASTVerifier.g
@@ -334,8 +334,6 @@ range
 terminal
     :  ^(STRING_LITERAL elementOptions)
     |	STRING_LITERAL
-    |	^(TOKEN_REF ARG_ACTION elementOptions)
-    |	^(TOKEN_REF ARG_ACTION)
     |	^(TOKEN_REF elementOptions)
     |	TOKEN_REF
     ;
diff --git a/tool/src/org/antlr/v4/parse/GrammarTreeVisitor.g b/tool/src/org/antlr/v4/parse/GrammarTreeVisitor.g
index 3fdc82cee..c307bcbf3 100644
--- a/tool/src/org/antlr/v4/parse/GrammarTreeVisitor.g
+++ b/tool/src/org/antlr/v4/parse/GrammarTreeVisitor.g
@@ -70,6 +70,7 @@ options {
 package org.antlr.v4.parse;
 import org.antlr.v4.tool.*;
 import org.antlr.v4.runtime.tree.CommonTree; // use updated v4 one not v3
+import java.lang.reflect.Method;
 }
 
 @members {
@@ -83,29 +84,66 @@ public int rewriteEBNFLevel = 0;
 public boolean inRewrite;
 public boolean currentOuterAltHasRewrite;
 
-public void visitGrammar(ErrorManager errMgr) {
-	try { grammarSpec(); }
-	catch (org.antlr.runtime.RecognitionException re) {
-		errMgr.grammarError(ErrorType.INTERNAL_ERROR,
-								   null, re.token, re);
+public GrammarTreeVisitor() { this(null); }
+
+public ErrorManager getErrorManager() { return null; }
+
+public void visitGrammar(GrammarAST t) { visit(t, "grammarSpec"); }
+public void visitRewrite(GrammarAST t) { visit(t, "rewrite"); }
+public void visitRewriteEBNF(GrammarAST t) { visit(t, "rewriteTreeEbnf"); }
+public void visit(GrammarAST t, String ruleName) {
+	CommonTreeNodeStream nodes = new CommonTreeNodeStream(t);
+	setTreeNodeStream(nodes);
+	try {
+		Method m = getClass().getMethod(ruleName);
+		m.invoke(this);
 	}
-}
-public void visitRewrite(ErrorManager errMgr) {
-	try { rewrite(); }
-	catch (org.antlr.runtime.RecognitionException re) {
-		errMgr.grammarError(ErrorType.INTERNAL_ERROR,
-								   null, re.token, re);
-	}
-}
-public void visitRewriteEBNF(ErrorManager errMgr) {
-	try { rewriteTreeEbnf(); }
-	catch (org.antlr.runtime.RecognitionException re) {
-		errMgr.grammarError(ErrorType.INTERNAL_ERROR,
-								   null, re.token, re);
+	catch (Exception e) {
+		ErrorManager errMgr = getErrorManager();
+		if ( errMgr==null ) System.err.println("can't find rule "+ruleName+
+											   " or tree structure error: "+t.toStringTree()
+											  );
+		else errMgr.toolError(ErrorType.INTERNAL_ERROR, e);
 	}
 }
 
+public void discoverGrammar(GrammarRootAST root, GrammarAST ID) { }
+public void finishPrequels(GrammarAST firstPrequel) { }
+public void finishGrammar(GrammarRootAST root, GrammarAST ID) { }
+
+public void grammarOption(GrammarAST ID, String value) { }
+public void ruleOption(GrammarAST ID, String value) { }
+public void blockOption(GrammarAST ID, String value) { }
+public void tokenAlias(GrammarAST ID, GrammarAST literal) { }
+
+public void importGrammar(GrammarAST label, GrammarAST ID) { }
+
+public void modeDef(GrammarAST m, GrammarAST ID) { }
+
+public void discoverRules(GrammarAST rules) { }
+public void finishRules(GrammarAST rule) { }
+public void discoverRule(GrammarAST rule, GrammarAST ID) { }
+public void finishRule(GrammarAST rule, GrammarAST ID) { }
+public void discoverAlt(GrammarAST alt) { }
+public void finishAlt(GrammarAST alt) { }
+public void discoverAltWithRewrite(GrammarAST alt) { }
+public void finishAltWithRewrite(GrammarAST alt) { }
+public void discoverSTRewrite(GrammarAST rew) { }
+public void discoverTreeRewrite(GrammarAST rew) { }
+
+public void ruleRef(GrammarAST ref, GrammarAST arg) { }
+public void tokenRef(GrammarAST ref, GrammarAST options) { }
+public void terminalOption(TerminalAST t, GrammarAST ID, GrammarAST value) { }
+public void stringRef(GrammarAST ref, GrammarAST options) { }
+public void wildcardRef(GrammarAST ref, GrammarAST options) { }
+
+public void rootOp(GrammarAST op, GrammarAST opnd) { }
+public void bangOp(GrammarAST op, GrammarAST opnd) { }
+
+public void discoverRewrites(GrammarAST result) { }
+public void finishRewrites(GrammarAST result) { }
 public void rewriteTokenRef(GrammarAST ast, GrammarAST options, GrammarAST arg) { }
+public void rewriteTerminalOption(TerminalAST t, GrammarAST ID, GrammarAST value) { }
 public void rewriteStringRef(GrammarAST ast, GrammarAST options) { }
 public void rewriteRuleRef(GrammarAST ast) { }
 public void rewriteLabelRef(GrammarAST ast) { }
@@ -113,9 +151,19 @@ public void rewriteAction(GrammarAST ast) { }
 }
 
 grammarSpec
-    :   ^(GRAMMAR ID {grammarName=$ID.text;} DOC_COMMENT? prequelConstruct* rules mode*)
+    :   ^(	GRAMMAR ID {grammarName=$ID.text;} DOC_COMMENT?
+    		{discoverGrammar((GrammarRootAST)$GRAMMAR, $ID);}
+ 		   	prequelConstructs
+    		{finishPrequels($prequelConstructs.start);}
+ 		   	rules mode*
+    		{finishGrammar((GrammarRootAST)$GRAMMAR, $ID);}
+ 		 )
 	;
 
+prequelConstructs
+	:	prequelConstruct*
+	;
+	
 prequelConstruct
 	:   optionsSpec
     |   delegateGrammars
@@ -130,9 +178,15 @@ optionsSpec
 
 option
     :   ^(ASSIGN ID optionValue)
+    	{
+    	if ( inContext("RULE") ) ruleOption($ID, $optionValue.v);
+    	else if ( inContext("BLOCK") ) blockOption($ID, $optionValue.v);
+    	else grammarOption($ID, $optionValue.v);
+    	}
     ;
 
-optionValue
+optionValue returns [String v]
+@init {$v = $start.token.getText();}
     :   ID
     |   STRING_LITERAL
     |   INT
@@ -144,8 +198,8 @@ delegateGrammars
 	;
 
 delegateGrammar
-    :   ^(ASSIGN ID ID)
-    |   ID
+    :   ^(ASSIGN label=ID id=ID)	{importGrammar($label, $id);}
+    |   id=ID						{importGrammar(null, $id);}
     ;
 
 tokensSpec
@@ -153,7 +207,7 @@ tokensSpec
 	;
 
 tokenSpec
-	:	^(ASSIGN ID STRING_LITERAL)
+	:	^(ASSIGN ID STRING_LITERAL)	{tokenAlias($ID, $STRING_LITERAL);}
 	|	ID
 	;
 
@@ -166,14 +220,15 @@ action
 	;
 
 rules
-    : ^(RULES rule*)
+    : ^(RULES {discoverRules($RULES);} rule* {finishRules($RULES);})
     ;
 
-mode:	^( MODE ID rule+ ) ;
+mode:	^( MODE ID {modeDef($MODE, $ID);} rule+ ) ;
 
-rule:   ^(	RULE ID {currentRuleName=$ID.text; currentRule=$RULE;}
+rule:   ^(	RULE ID {currentRuleName=$ID.text; currentRule=$RULE; discoverRule($RULE, $ID);}
 			DOC_COMMENT? ruleModifiers? ARG_ACTION?
       		ruleReturns? rulePrequel* ruleBlock exceptionGroup
+      		{finishRule($RULE, $ID);}
       	 )
     ;
 
@@ -246,7 +301,15 @@ ruleBlock
     ;
 
 alternative
-    :	^(ALT_REWRITE {inRewrite=true;} alternative rewrite)
+@init {
+	if ( $start.getType()==ALT_REWRITE ) discoverAltWithRewrite($start);
+	else discoverAlt($start);
+}
+@after {
+	if ( $start.getType()==ALT_REWRITE ) finishAltWithRewrite($start);
+	else finishAlt($start);
+}
+    :	^(ALT_REWRITE alternative {inRewrite=true;} rewrite)
     |	^(ALT EPSILON)
     |   ^(ALT element+)
     ;
@@ -260,8 +323,8 @@ element
 	|   SEMPRED
 	|	GATED_SEMPRED
 	|	treeSpec
-	|	^(ROOT astOperand)
-	|	^(BANG astOperand)
+	|	^(ROOT astOperand)	{rootOp($ROOT, $astOperand.start);}
+	|	^(BANG astOperand)	{bangOp($BANG, $astOperand.start);}
 	|	^(NOT blockSet)
 	|	^(NOT block)
 	;
@@ -301,8 +364,8 @@ ebnfSuffix
 atom:	range
 	|	^(DOT ID terminal)
 	|	^(DOT ID ruleref)
-    |	^(WILDCARD elementOptions)
-    |	WILDCARD
+    |	^(WILDCARD elementOptions)	{wildcardRef($WILDCARD, $elementOptions.start);}
+    |	WILDCARD					{wildcardRef($WILDCARD, null);}
     |   terminal
     |	blockSet
     |   ruleref
@@ -322,7 +385,7 @@ block
     ;
 
 ruleref
-    :	^(RULE_REF ARG_ACTION?)
+    :	^(RULE_REF ARG_ACTION?) {ruleRef($RULE_REF, $ARG_ACTION);}
     ;
 
 range
@@ -331,30 +394,29 @@ range
 
 terminal
     :  ^(STRING_LITERAL elementOptions)
-    |	STRING_LITERAL
-    |	^(TOKEN_REF ARG_ACTION elementOptions)
-    |	^(TOKEN_REF ARG_ACTION)
-    |	^(TOKEN_REF elementOptions)
-    |	TOKEN_REF
+    								{stringRef($STRING_LITERAL, $elementOptions.start);}
+    |	STRING_LITERAL				{stringRef($STRING_LITERAL, null);}
+    |	^(TOKEN_REF elementOptions)	{tokenRef($TOKEN_REF, $elementOptions.start);}
+    |	TOKEN_REF	    			{tokenRef($TOKEN_REF, null);}
     ;
 
 elementOptions
-    :	^(ELEMENT_OPTIONS elementOption+)
+    :	^(ELEMENT_OPTIONS elementOption[(TerminalAST)$start.getParent()]+)
     ;
 
-elementOption
-    :	ID
-    |   ^(ASSIGN ID ID)
-    |   ^(ASSIGN ID STRING_LITERAL)
+elementOption[TerminalAST t]
+    :	ID								{terminalOption(t, $ID, null);}
+    |   ^(ASSIGN id=ID v=ID)			{terminalOption(t, $id, $v);}
+    |   ^(ASSIGN ID v=STRING_LITERAL)	{terminalOption(t, $ID, $v);}
     ;
 
 rewrite
-	:	predicatedRewrite* nakedRewrite
+	:	{discoverRewrites($start);} predicatedRewrite* nakedRewrite {finishRewrites($start);} 
 	;
 
 predicatedRewrite
-	:	^(ST_RESULT SEMPRED rewriteAlt)
-	|	^(RESULT SEMPRED rewriteAlt)
+	:	^(ST_RESULT SEMPRED {discoverSTRewrite($start);} rewriteAlt)
+	|	^(RESULT SEMPRED {discoverTreeRewrite($start);} rewriteAlt)
 	;
 
 nakedRewrite
@@ -381,17 +443,29 @@ rewriteTreeElement
 	;
 
 rewriteTreeAtom
-    :   ^(TOKEN_REF elementOptions ARG_ACTION)	{rewriteTokenRef($start,$elementOptions.start,$ARG_ACTION);}
-    |   ^(TOKEN_REF elementOptions)				{rewriteTokenRef($start,$elementOptions.start,null);}
-    |   ^(TOKEN_REF ARG_ACTION)					{rewriteTokenRef($start,null,$ARG_ACTION);}
-	|   TOKEN_REF								{rewriteTokenRef($start,null,null);}
-    |   RULE_REF								{rewriteRuleRef($start);}
-	|   ^(STRING_LITERAL elementOptions)		{rewriteStringRef($start,$elementOptions.start);}
-	|   STRING_LITERAL							{rewriteStringRef($start,null);}
-	|   LABEL									{rewriteLabelRef($start);}
-	|	ACTION									{rewriteAction($start);}
+    :   ^(TOKEN_REF rewriteElementOptions ARG_ACTION)
+    										{rewriteTokenRef($start,$rewriteElementOptions.start,$ARG_ACTION);}
+    |   ^(TOKEN_REF rewriteElementOptions)	{rewriteTokenRef($start,$rewriteElementOptions.start,null);}
+    |   ^(TOKEN_REF ARG_ACTION)				{rewriteTokenRef($start,null,$ARG_ACTION);}
+	|   TOKEN_REF							{rewriteTokenRef($start,null,null);}
+    |   RULE_REF							{rewriteRuleRef($start);}
+	|   ^(STRING_LITERAL rewriteElementOptions)
+											{rewriteStringRef($start,$rewriteElementOptions.start);}
+	|   STRING_LITERAL						{rewriteStringRef($start,null);}
+	|   LABEL								{rewriteLabelRef($start);}
+	|	ACTION								{rewriteAction($start);}
 	;
 
+rewriteElementOptions
+    :	^(ELEMENT_OPTIONS rewriteElementOption[(TerminalAST)$start.getParent()]+)
+    ;
+   
+rewriteElementOption[TerminalAST t]
+    :	ID								{rewriteTerminalOption(t, $ID, null);}
+    |   ^(ASSIGN id=ID v=ID)			{rewriteTerminalOption(t, $id, $v);}
+    |   ^(ASSIGN ID v=STRING_LITERAL)	{rewriteTerminalOption(t, $ID, $v);}
+    ;
+
 rewriteTreeEbnf
 	:	^(ebnfSuffix ^(REWRITE_BLOCK {rewriteEBNFLevel++;} rewriteTreeAlt {rewriteEBNFLevel--;}))
 	;
diff --git a/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java b/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java
index d03d9274d..17db606be 100644
--- a/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java
+++ b/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java
@@ -31,14 +31,17 @@ package org.antlr.v4.semantics;
 
 import org.antlr.runtime.Token;
 import org.antlr.v4.misc.Utils;
-import org.antlr.v4.parse.ANTLRParser;
+import org.antlr.v4.parse.*;
 import org.antlr.v4.tool.*;
 import org.stringtemplate.v4.misc.MultiMap;
 
 import java.io.File;
 import java.util.*;
 
-/** No side-effects; BasicSemanticTriggers.g invokes check rules for these:
+/** No side-effects except for setting options into the appropriate node.
+ *  TODO:  make the side effects into a separate pass this
+ *
+ * Invokes check rules for these:
  *
  * FILE_AND_GRAMMAR_NAME_DIFFER
  * LEXER_RULES_NOT_ALLOWED
@@ -62,7 +65,7 @@ import java.util.*;
  *
  * TODO: 1 action per lex rule
  */
-public class BasicSemanticChecks {
+public class BasicSemanticChecks extends GrammarTreeVisitor {
 	public static final Set legalLexerOptions =
 		new HashSet() {
 			{
@@ -151,6 +154,110 @@ public class BasicSemanticChecks {
 		this.errMgr = g.tool.errMgr;
 	}
 
+	public void process() {	visitGrammar(g.ast); }
+
+	// Routines to route visitor traffic to the checking routines
+
+	@Override
+	public void discoverGrammar(GrammarRootAST root, GrammarAST ID) {
+		checkGrammarName(ID.token);
+	}
+
+	@Override
+	public void finishGrammar(GrammarRootAST root, GrammarAST ID) {
+		checkTreeFilterOptions(root, g.ast.getOptions());
+	}
+
+	@Override
+	public void finishPrequels(GrammarAST firstPrequel) {
+		List<GrammarAST> options = firstPrequel.getNodesWithType(OPTIONS);
+		List<GrammarAST> imports = firstPrequel.getNodesWithType(IMPORT);
+		List<GrammarAST> tokens = firstPrequel.getNodesWithType(TOKENS);
+		checkNumPrequels(options, imports, tokens);
+	}
+
+	@Override
+	public void importGrammar(GrammarAST label, GrammarAST ID) {
+		checkImport(ID.token);
+	}
+
+	@Override
+	public void discoverRules(GrammarAST rules) {
+		checkNumRules(rules);
+	}
+
+	@Override
+	public void modeDef(GrammarAST m, GrammarAST ID) {
+		checkMode(ID.token);
+	}
+
+	@Override
+	public void grammarOption(GrammarAST ID, String value) {
+		boolean ok = checkOptions(g.ast, ID.token, value);
+		if ( ok ) g.ast.setOption(ID.getText(), value);
+	}
+
+	@Override
+	public void discoverRule(GrammarAST rule, GrammarAST ID) {
+		checkInvalidRuleDef(ID.token);
+	}
+
+	@Override
+	public void ruleRef(GrammarAST ref, GrammarAST arg) {
+		checkInvalidRuleRef(ref.token);
+	}
+
+	@Override
+	public void terminalOption(TerminalAST t, GrammarAST ID, GrammarAST value) {
+		String v = null;
+		if ( value!=null ) v = value.getText();
+		boolean ok = checkTokenOptions(ID, v);
+		if ( ok ) {
+			if ( v!=null ) {
+				t.setOption(ID.getText(), v);
+			}
+			else {
+				t.setOption(TerminalAST.defaultTokenOption, v);
+			}
+		}
+	}
+
+	@Override
+	public void discoverAltWithRewrite(GrammarAST alt) {
+		GrammarAST firstNode = (GrammarAST)alt.getChild(0);
+		checkRewriteForMultiRootAltInTreeGrammar(g.ast.getOptions(),
+												 firstNode.token,
+												 currentOuterAltNumber);
+	}
+
+	@Override
+	public void rootOp(GrammarAST op, GrammarAST opnd) {
+		checkASTOps(g.ast.getOptions(), op, opnd);
+	}
+
+	@Override
+	public void bangOp(GrammarAST op, GrammarAST opnd) {
+		checkASTOps(g.ast.getOptions(), op, opnd);
+	}
+
+	@Override
+	public void discoverTreeRewrite(GrammarAST rew) {
+		checkRewriteOk(g.ast.getOptions(), rew);
+	}
+
+	@Override
+	public void discoverSTRewrite(GrammarAST rew) {
+		checkRewriteOk(g.ast.getOptions(), rew);
+	}
+
+	@Override
+	public void wildcardRef(GrammarAST ref, GrammarAST options) {
+		checkWildcardRoot(ref.token);
+	}
+
+	// Routines to do the actual work of checking issues with a grammar.
+	// They are triggered by the visitor methods above.
+
 	void checkGrammarName(Token nameToken) {
 		if ( g.implicitLexer==null ) return;
 		String fullyQualifiedName = nameToken.getInputStream().getSourceName();
@@ -241,18 +348,6 @@ public class BasicSemanticChecks {
 		}
 	}
 
-	/** At this point, we can only rule out obvious problems like ID[3]
-	 *  in parser.  Might be illegal too in later stage when we see ID
-	 *  isn't a fragment.
-	 */
-	void checkTokenArgs(Token tokenID) {
-		String fileName = tokenID.getInputStream().getSourceName();
-		if ( !g.isLexer() ) {
-			g.tool.errMgr.grammarError(ErrorType.ARGS_ON_TOKEN_REF,
-									   fileName, tokenID, tokenID.getText());
-		}
-	}
-
 	/** Check option is appropriate for grammar, rule, subrule */
 	boolean checkOptions(GrammarAST parent,
 						 Token optionID, String value)
@@ -299,9 +394,8 @@ public class BasicSemanticChecks {
 	}
 
 	/** Check option is appropriate for token; parent is ELEMENT_OPTIONS */
-	boolean checkTokenOptions(GrammarAST parent,
-							  Token optionID, String value)
-	{
+	boolean checkTokenOptions(GrammarAST ID, String value)	{
+		Token optionID = ID.token;
 		String fileName = optionID.getInputStream().getSourceName();
 		// don't care about ID<ASTNodeName> options
 		if ( value!=null && !legalTokenOptions.contains(optionID.getText()) ) {
@@ -312,18 +406,12 @@ public class BasicSemanticChecks {
 			return false;
 		}
 		// example (ALT_REWRITE (ALT (ID (ELEMENT_OPTIONS Foo))) (-> (ALT ID))
-		if ( parent.hasAncestor(ANTLRParser.ALT_REWRITE) ) {
+		if ( inRewrite ) {
 			g.tool.errMgr.grammarError(ErrorType.HETERO_ILLEGAL_IN_REWRITE_ALT,
 									   fileName,
 									   optionID);
-
 		}
 		// TODO: extra checks depending on terminal kind?
-		switch ( parent.getType() ) {
-			case ANTLRParser.TOKEN_REF :
-			case ANTLRParser.STRING_LITERAL :
-			case ANTLRParser.WILDCARD :
-		}
 		return true;
 	}
 
@@ -395,8 +483,7 @@ public class BasicSemanticChecks {
 	}
 
 	void checkRewriteOk(Map<String, String> options, GrammarAST elementRoot) {
-		RuleAST rule = (RuleAST)elementRoot.getAncestor(ANTLRParser.RULE);
-		String ruleName = rule.getChild(0).getText();
+		String ruleName = currentRule.getChild(0).getText();
 		String fileName = elementRoot.token.getInputStream().getSourceName();
 		if ( options!=null && options.get("output")==null ) {
 			g.tool.errMgr.grammarWarning(ErrorType.REWRITE_OR_OP_WITH_NO_OUTPUT_OPTION,
diff --git a/tool/src/org/antlr/v4/semantics/BasicSemanticTriggers.g b/tool/src/org/antlr/v4/semantics/BasicSemanticTriggers.g
deleted file mode 100644
index f36d1eb69..000000000
--- a/tool/src/org/antlr/v4/semantics/BasicSemanticTriggers.g
+++ /dev/null
@@ -1,240 +0,0 @@
-/*
- [The "BSD license"]
- Copyright (c) 2010 Terence Parr
- 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.
-*/
-
-/** Triggers for the basic semantics of the input.  Side-effects:
- *  Set token, block, rule options in the tree.  Load field option
- *  with grammar options. Only legal options are set.
- */
-tree grammar BasicSemanticTriggers;
-options {
-	language      = Java;
-	tokenVocab    = ANTLRParser;
-	ASTLabelType  = GrammarAST;
-	filter        = true;
-	//superClass	  = 'org.antlr.v4.runtime.tree.TreeFilter';
-}
-
-// Include the copyright in this source and also the generated source
-@header {
-/*
- [The "BSD license"]
- Copyright (c) 2010 Terence Parr
- 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.semantics;
-import org.antlr.v4.tool.*;
-}
-
-@members {
-// TODO: SHOULD we fix up grammar AST to remove errors?  Like kill refs to bad rules?
-// that is, rewrite tree?  maybe all passes are filters until code gen, which needs
-// tree grammar. 'course we won't try codegen if errors.
-public String name;
-GrammarASTWithOptions root;
-Grammar g; // which grammar are we checking
-BasicSemanticChecks checker;
-public BasicSemanticTriggers(TreeNodeStream input, Grammar g) {
-	this(input);
-	this.g = g;
-	checker = new BasicSemanticChecks(g);
-}
-}
-
-topdown  // do these on way down so options and such are set first
-	:	grammarSpec
-	|	rules
-	|	mode
-	|	option
-	|	rule
-	|	tokenAlias
-	|	rewrite
-	;
-
-bottomup // do these "inside to outside" of expressions.
-	:	multiElementAltInTreeGrammar
-	|	astOps
-	|	ruleref
-	|	tokenRefWithArgs
-	|	elementOption
-	|	checkGrammarOptions // do after we see everything
-	|	wildcardRoot
-	;
-
-grammarSpec
-    :   ^(	GRAMMAR ID DOC_COMMENT?
-	    	{
-	    	name = $ID.text;
-	    	checker.checkGrammarName($ID.token);
-	    	root = (GrammarRootAST)$start;
-	    	}
-    		prequelConstructs ^(RULES .*)
-    	)
-	;
-
-checkGrammarOptions // when we get back to root
-	:	GRAMMAR
-		{checker.checkTreeFilterOptions((GrammarRootAST)$GRAMMAR,
-										root.getOptions());}
-	;
-
-/*
-grammarType
-@init {gtype = $start.getType(); root = (GrammarASTWithOptions)$start;}
-    :   LEXER_GRAMMAR | PARSER_GRAMMAR | TREE_GRAMMAR | COMBINED_GRAMMAR
-    ;
-    */
-
-prequelConstructs
-	:	(	^(o+=OPTIONS .+)
-		|	^(i+=IMPORT delegateGrammar+)
-		|	^(t+=TOKENS .+)
-		)*
-		{checker.checkNumPrequels($o, $i, $t);}
-	;
-
-delegateGrammar
-    :   (	^(ASSIGN ID id=ID)
-	    |   id=ID
-	    )
-	    {checker.checkImport($id.token);}
-    ;
-
-rules : RULES {checker.checkNumRules($RULES);} ;
-
-mode : ^(MODE ID .*) {checker.checkMode($ID.token);} ;
-
-option // TODO: put in grammar, or rule, or block
-    :   {inContext("OPTIONS")}? ^(ASSIGN o=ID optionValue)
-    	{
-   	    GrammarAST parent = (GrammarAST)$start.getParent();   // OPTION
-   		GrammarAST parentWithOptionKind = (GrammarAST)parent.getParent();
-    	boolean ok = checker.checkOptions(parentWithOptionKind,
-    									  $ID.token, $optionValue.v);
-		//  store options into XXX_GRAMMAR, RULE, BLOCK nodes
-    	if ( ok ) {
-    		((GrammarASTWithOptions)parentWithOptionKind).setOption($o.text, $optionValue.v);
-    	}
-    	}
-    ;
-
-optionValue returns [String v]
-@init {$v = $start.token.getText();}
-    :   ID
-    |   STRING_LITERAL
-    |   INT
-    |   STAR
-    ;
-
-rule:   ^( RULE r=ID .*) {checker.checkInvalidRuleDef($r.token);}
-    ;
-
-ruleref
-    :	RULE_REF {checker.checkInvalidRuleRef($RULE_REF.token);}
-    ;
-
-tokenAlias
-	:	{inContext("TOKENS")}? ^(ASSIGN ID STRING_LITERAL)
-		{checker.checkTokenAlias($ID.token);}
-	;
-
-tokenRefWithArgs
-	:	{!inContext("RESULT ...")}? // if not on right side of ->
-    	^(TOKEN_REF ARG_ACTION)
-		{checker.checkTokenArgs($TOKEN_REF.token);}
-	;
-
-elementOption
-    :	{!inContext("RESULT ...")}? // not on right side of ->
-    	^(	ELEMENT_OPTIONS
-	    	(	^(ASSIGN o=ID value=ID)
-		   	|   ^(ASSIGN o=ID value=STRING_LITERAL)
- 		   	|	o=ID
-		   	)
-		)
-	   	{
-    	boolean ok = checker.checkTokenOptions((GrammarAST)$o.getParent(),
-    										   $o.token, $value.text);
-    	if ( ok ) {
-			if ( value!=null ) {
-	    		TerminalAST terminal = (TerminalAST)$start.getParent();
-	    		terminal.setOption($o.text, $value.text);
-    		}
-    		else {
-	    		TerminalAST terminal = (TerminalAST)$start.getParent();
-	    		terminal.setOption(TerminalAST.defaultTokenOption, $o.text);
-    		}
-    	}
-    	}
-    ;
-
-// (ALT_REWRITE (ALT A B)   ^( ALT ^( A B ) ) or ( ALT A )
-multiElementAltInTreeGrammar
-	:	{inContext("ALT_REWRITE")}?
-		^( ALT ~(SEMPRED|ACTION) ~(SEMPRED|ACTION)+ ) // > 1 element at outer level
-		{
-		int altNum = $start.getParent().getChildIndex() + 1; // alts are 1..n
-		GrammarAST firstNode = (GrammarAST)$start.getChild(0);
-		checker.checkRewriteForMultiRootAltInTreeGrammar(root.getOptions(),
-														 firstNode.token,
-														 altNum);
-		}
-	;
-
-// Check stuff like (^ A) (! r)
-astOps
-	:	^(ROOT el=.) {checker.checkASTOps(root.getOptions(), $start, $el);}
-	|	^(BANG el=.) {checker.checkASTOps(root.getOptions(), $start, $el);}
-	;
-
-rewrite
-	:	(RESULT|ST_RESULT)
-		{checker.checkRewriteOk(root.getOptions(),$start);}
-	;
-
-wildcardRoot
-    :	^(TREE_BEGIN WILDCARD .*)
-    	{checker.checkWildcardRoot($WILDCARD.token);}
-    ;
diff --git a/tool/src/org/antlr/v4/semantics/RewriteRefs.java b/tool/src/org/antlr/v4/semantics/RewriteRefs.java
index 60c7762ef..f97efbab0 100644
--- a/tool/src/org/antlr/v4/semantics/RewriteRefs.java
+++ b/tool/src/org/antlr/v4/semantics/RewriteRefs.java
@@ -29,20 +29,20 @@
 
 package org.antlr.v4.semantics;
 
-import org.antlr.runtime.tree.TreeNodeStream;
 import org.antlr.v4.parse.GrammarTreeVisitor;
-import org.antlr.v4.tool.GrammarAST;
+import org.antlr.v4.tool.*;
 
 import java.util.*;
 
 public class RewriteRefs extends GrammarTreeVisitor {
 	List<GrammarAST> shallow = new ArrayList<GrammarAST>();
 	List<GrammarAST> deep = new ArrayList<GrammarAST>();
-	public int desiredShallowLevel;
+	int desiredShallowLevel;
+	Grammar g;
 
-	public RewriteRefs(TreeNodeStream input, int desiredShallowLevel) {
-		super(input);
+	public RewriteRefs(Grammar g, int desiredShallowLevel) {
 		this.desiredShallowLevel = desiredShallowLevel;
+		this.g = g;
 	}
 
 	public void track(GrammarAST t) {
@@ -50,6 +50,9 @@ public class RewriteRefs extends GrammarTreeVisitor {
 		if ( rewriteEBNFLevel==desiredShallowLevel ) shallow.add(t);
 	}
 
+	@Override
+	public ErrorManager getErrorManager() { return g.tool.errMgr; }
+
 	@Override
 	public void rewriteTokenRef(GrammarAST ast, GrammarAST options, GrammarAST arg) {
 		track(ast);
diff --git a/tool/src/org/antlr/v4/semantics/SemanticPipeline.java b/tool/src/org/antlr/v4/semantics/SemanticPipeline.java
index 00ed2078c..042156509 100644
--- a/tool/src/org/antlr/v4/semantics/SemanticPipeline.java
+++ b/tool/src/org/antlr/v4/semantics/SemanticPipeline.java
@@ -77,9 +77,11 @@ public class SemanticPipeline {
 		}
 
 		// DO BASIC / EASY SEMANTIC CHECKS
-		nodes.reset();
-		BasicSemanticTriggers basics = new BasicSemanticTriggers(nodes,g);
-		basics.downup(g.ast);
+//		nodes.reset();
+//		BasicSemanticTriggers basics = new BasicSemanticTriggers(nodes,g);
+//		basics.downup(g.ast);
+		BasicSemanticChecks basics = new BasicSemanticChecks(g);
+		basics.process();
 
 		// don't continue if we get errors in this basic check
 		if ( false ) return;
diff --git a/tool/src/org/antlr/v4/semantics/UseDefAnalyzer.java b/tool/src/org/antlr/v4/semantics/UseDefAnalyzer.java
index f8a14d093..96cefef4f 100644
--- a/tool/src/org/antlr/v4/semantics/UseDefAnalyzer.java
+++ b/tool/src/org/antlr/v4/semantics/UseDefAnalyzer.java
@@ -29,7 +29,6 @@
 
 package org.antlr.v4.semantics;
 
-import org.antlr.runtime.tree.CommonTreeNodeStream;
 import org.antlr.v4.parse.ANTLRParser;
 import org.antlr.v4.runtime.Token;
 import org.antlr.v4.tool.*;
@@ -117,10 +116,9 @@ public class UseDefAnalyzer {
 														 int desiredShallowLevel,
 														 boolean deep)
 	{
-		CommonTreeNodeStream nodes = new CommonTreeNodeStream(root);
-		RewriteRefs collector = new RewriteRefs(nodes, desiredShallowLevel);
-		if ( root.getType()==ANTLRParser.RESULT ) collector.visitRewrite(g.tool.errMgr);
-		else collector.visitRewriteEBNF(g.tool.errMgr);
+		RewriteRefs collector = new RewriteRefs(g, desiredShallowLevel);
+		if ( root.getType()==ANTLRParser.RESULT ) collector.visitRewrite(root);
+		else collector.visitRewriteEBNF(root);
 		System.out.println("from "+root.toStringTree());
 		System.out.println("shallow: "+collector.shallow);
 		System.out.println("deep: "+collector.deep);