From b79272d9a24256bee2755a21d6ee666e6eb6b9cb Mon Sep 17 00:00:00 2001
From: Ken Thompson <ken@golang.org>
Date: Sat, 6 Dec 2008 13:40:30 -0800
Subject: [PATCH] allowed syntax for range

a range m (implies :=)
a,b range m (implies :=)
a:b range m (implies :=)

a := range m
a,b := range m
a:b := range m

a = range m
a,b = range m
a:b = range m

R=r
OCL=20676
CL=20676
---
 src/cmd/gc/go.h   |  4 ++--
 src/cmd/gc/go.y   | 58 +++++++++++++++++++++++++++++++++++------------
 src/cmd/gc/subr.c |  1 +
 src/cmd/gc/walk.c | 36 +++++++++++++++++++++++------
 4 files changed, 76 insertions(+), 23 deletions(-)

diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index b8429c3bd0..68898c9988 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -300,7 +300,7 @@ enum
 	ONAME, ONONAME,
 	ODOT, ODOTPTR, ODOTMETH, ODOTINTER,
 	ODCLFUNC, ODCLFIELD, ODCLARG,
-	OLIST, OCMP, OPTR, OARRAY,
+	OLIST, OCMP, OPTR, OARRAY, ORANGE,
 	ORETURN, OFOR, OIF, OSWITCH,
 	OAS, OASOP, OCASE, OXCASE, OFALL, OXFALL,
 	OGOTO, OPROC, ONEW, OEMPTY, OSELECT,
@@ -806,7 +806,7 @@ int	isandss(Type*, Node*);
 Node*	convas(Node*);
 void	arrayconv(Type*, Node*);
 Node*	colas(Node*, Node*);
-Node*	dorange(Node*, Node*, Node*, int);
+Node*	dorange(Node*);
 Node*	reorder1(Node*);
 Node*	reorder2(Node*);
 Node*	reorder3(Node*);
diff --git a/src/cmd/gc/go.y b/src/cmd/gc/go.y
index 2944d55101..bcee5ec5b3 100644
--- a/src/cmd/gc/go.y
+++ b/src/cmd/gc/go.y
@@ -52,7 +52,7 @@
 %type	<node>		Astmt Bstmt
 %type	<node>		for_stmt for_body for_header
 %type	<node>		if_stmt if_body if_header select_stmt
-%type	<node>		simple_stmt osimple_stmt semi_stmt
+%type	<node>		simple_stmt osimple_stmt orange_stmt semi_stmt
 %type	<node>		expr uexpr pexpr expr_list oexpr oexpr_list expr_list_r
 %type	<node>		exprsym3_list_r exprsym3
 %type	<node>		name onew_name new_name new_name_list_r new_field
@@ -416,7 +416,6 @@ simple_stmt:
 	{
 		if(addtop != N)
 			fatal("exprsym3_list_r LCOLAS expr_list");
-
 		$$ = rev($1);
 		$$ = colas($$, $3);
 		$$ = nod(OAS, $$, $3);
@@ -555,31 +554,62 @@ compound_stmt:
 		popdcl();
 	}
 
-for_header:
-	osimple_stmt ';' osimple_stmt ';' osimple_stmt
+ocolas:
+|	LCOLAS
+
+orange_stmt:
+	osimple_stmt
+|	exprsym3_list_r '=' LRANGE expr
 	{
+		$$ = nod(ORANGE, $1, $4);
+		$$->etype = 0;	// := flag
+	}
+|	exprsym3 ':' exprsym3 '=' LRANGE expr
+	{
+		$$ = nod(OLIST, $1, $3);
+		$$ = nod(ORANGE, $$, $6);
+		$$->etype = 0;
+	}
+|	exprsym3_list_r ocolas LRANGE expr
+	{
+		$$ = nod(ORANGE, $1, $4);
+		$$->etype = 1;
+	}
+|	exprsym3 ':' exprsym3 ocolas LRANGE expr
+	{
+		$$ = nod(OLIST, $1, $3);
+		$$ = nod(ORANGE, $$, $6);
+		$$->etype = 1;
+	}
+
+for_header:
+	osimple_stmt ';' orange_stmt ';' osimple_stmt
+	{
+		if($3 != N && $3->op == ORANGE) {
+			$$ = dorange($3);
+			$$->ninit = list($$->ninit, $1);
+			$$->nincr = list($$->nincr, $5);
+			break;
+		}
 		// init ; test ; incr
 		$$ = nod(OFOR, N, N);
 		$$->ninit = $1;
 		$$->ntest = $3;
 		$$->nincr = $5;
 	}
-|	osimple_stmt
+|	orange_stmt
 	{
-		// test
+		// range
+		if($1 != N && $1->op == ORANGE) {
+			$$ = dorange($1);
+			break;
+		}
+		// normal test
 		$$ = nod(OFOR, N, N);
 		$$->ninit = N;
 		$$->ntest = $1;
 		$$->nincr = N;
 	}
-|	new_name ':' new_name LRANGE expr
-	{
-		$$ = dorange($1, $3, $5, 1);
-	}
-|	new_name LRANGE expr
-	{
-		$$ = dorange($1, N, $3, 1);
-	}
 
 for_body:
 	for_header compound_stmt
diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index 851f17404f..cd2fc4d2d5 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -687,6 +687,7 @@ opnames[] =
 	[OREGISTER]	= "REGISTER",
 	[OINDREG]	= "INDREG",
 	[OSEND]		= "SEND",
+	[ORANGE]	= "RANGE",
 	[ORECV]		= "RECV",
 	[OPTR]		= "PTR",
 	[ORETURN]	= "RETURN",
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 68cf9123de..067aed49d4 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -3033,14 +3033,32 @@ badt:
 	return nl;
 }
 
+/*
+ * rewrite a range statement
+ * k and v are names/new_names
+ * m is an array or map
+ * local is =/0 or :=/1
+ */
 Node*
-dorange(Node *k, Node *v, Node *m, int local)
+dorange(Node *nn)
 {
+	Node *k, *v, *m;
 	Node *n, *hk, *on, *r, *a;
 	Type *t, *th;
+	int local;
 
-	if(!local)
-		fatal("only local varables now");
+	if(nn->op != ORANGE)
+		fatal("dorange not ORANGE");
+
+	k = nn->left;
+	m = nn->right;
+	local = nn->etype;
+
+	v = N;
+	if(k->op == OLIST) {
+		v = k->right;
+		k = k->left;
+	}
 
 	n = nod(OFOR, N, N);
 
@@ -3073,11 +3091,13 @@ ary:
 	n->nincr = nod(OASOP, hk, literal(1));
 	n->nincr->etype = OADD;
 
-	k = old2new(k, hk->type);
+	if(local)
+		k = old2new(k, hk->type);
 	n->nbody = nod(OAS, k, hk);
 
 	if(v != N) {
-		v = old2new(v, t->type);
+		if(local)
+			v = old2new(v, t->type);
 		n->nbody = list(n->nbody,
 			nod(OAS, v, nod(OINDEX, m, hk)) );
 	}
@@ -3112,7 +3132,8 @@ map:
 	r = nod(OCALL, on, r);
 	n->nincr = r;
 
-	k = old2new(k, t->down);
+	if(local)
+		k = old2new(k, t->down);
 	if(v == N) {
 		on = syslook("mapiter1", 1);
 		argtype(on, th);
@@ -3122,7 +3143,8 @@ map:
 		n->nbody = nod(OAS, k, r);
 		goto out;
 	}
-	v = old2new(v, t->type);
+	if(local)
+		v = old2new(v, t->type);
 	on = syslook("mapiter2", 1);
 	argtype(on, th);
 	argtype(on, t->down);