x[y:] for strings

R=ken2
http://codereview.appspot.com/157114

6 files changed, 32 insertions, 6 deletions

diff --git a/src/cmd/gc/builtin.c.boot b/src/cmd/gc/builtin.c.boot
index 58d6f9e82..d2ff0ff90 100644
--- a/src/cmd/gc/builtin.c.boot
+++ b/src/cmd/gc/builtin.c.boot
@@ -19,6 +19,7 @@ char *runtimeimport =
 	"func runtime.catstring (? string, ? string) (? string)\n"
 	"func runtime.cmpstring (? string, ? string) (? int)\n"
 	"func runtime.slicestring (? string, ? int, ? int) (? string)\n"
+	"func runtime.slicestring1 (? string, ? int) (? string)\n"
 	"func runtime.indexstring (? string, ? int) (? uint8)\n"
 	"func runtime.intstring (? int64) (? string)\n"
 	"func runtime.slicebytetostring (? []uint8) (? string)\n"
diff --git a/src/cmd/gc/const.c b/src/cmd/gc/const.c
index cca13b952..4575ff6da 100644
--- a/src/cmd/gc/const.c
+++ b/src/cmd/gc/const.c
@@ -55,7 +55,7 @@ truncfltlit(Mpflt *oldv, Type *t)
 void
 convlit(Node **np, Type *t)
 {
-	return convlit1(np, t, 0);
+	convlit1(np, t, 0);
 }
 
 /*
diff --git a/src/cmd/gc/runtime.go b/src/cmd/gc/runtime.go
index ea4084012..6413db5e2 100644
--- a/src/cmd/gc/runtime.go
+++ b/src/cmd/gc/runtime.go
@@ -27,6 +27,7 @@ func printsp()
 func catstring(string, string) string
 func cmpstring(string, string) int
 func slicestring(string, int, int) string
+func slicestring1(string, int) string
 func indexstring(string, int) byte
 func intstring(int64) string
 func slicebytetostring([]byte) string
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index bf35b3891..3c3a00cfd 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -918,10 +918,16 @@ walkexpr(Node **np, NodeList **init)
 
 	case OSLICESTR:
 		// sys_slicestring(s, lb, hb)
-		n = mkcall("slicestring", n->type, init,
-			conv(n->left, types[TSTRING]),
-			conv(n->right->left, types[TINT]),
-			conv(n->right->right, types[TINT]));
+		if(n->right->right) {
+			n = mkcall("slicestring", n->type, init,
+				conv(n->left, types[TSTRING]),
+				conv(n->right->left, types[TINT]),
+				conv(n->right->right, types[TINT]));
+		} else {
+			n = mkcall("slicestring1", n->type, init,
+				conv(n->left, types[TSTRING]),
+				conv(n->right->left, types[TINT]));
+		}
 		goto ret;
 
 	case OINDEXSTR:
diff --git a/src/pkg/runtime/string.cgo b/src/pkg/runtime/string.cgo
index bafa6791b..6e380a107 100644
--- a/src/pkg/runtime/string.cgo
+++ b/src/pkg/runtime/string.cgo
@@ -142,6 +142,24 @@ func slicestring(si String, lindex int32, hindex int32) (so String) {
 //	mcpy(so.str, si.str+lindex, l);
 }
 
+func slicestring1(si String, lindex int32) (so String) {
+	int32 l;
+
+	if(lindex < 0 || lindex > si.len) {
+		runtime·printpc(&si);
+		prints(" ");
+		prbounds("slice", lindex, si.len, si.len);
+	}
+
+	l = si.len-lindex;
+	so.str = si.str + lindex;
+	so.len = l;
+
+//	alternate to create a new string
+//	so = gostringsize(l);
+//	mcpy(so.str, si.str+lindex, l);
+}
+
 func indexstring(s String, i int32) (b byte) {
 	if(i < 0 || i >= s.len) {
 		runtime·printpc(&s);
diff --git a/test/ken/string.go b/test/ken/string.go
index f7c02822f..03e81a05d 100644
--- a/test/ken/string.go
+++ b/test/ken/string.go
@@ -64,7 +64,7 @@ main()
 	}
 
 	/* slice strings */
-	print(c[0:3], c[3:6]);
+	print(c[0:3], c[3:]);
 
 	print("\n");