Revert the [string reverse] rewrite in a branch for more review.

2 files changed, 80 insertions, 84 deletions

diff --git a/ChangeLog b/ChangeLog
index bc323fa..b927a2e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,10 +2,6 @@
 
 	* generic/tclIORChan.c:	[Bug 3396948] Leak of ReflectedChannelMap.
 
-2011-08-23  Jan Nijtmans  <nijtmans@users.sf.net>
-
-	* generic/tclStringObj.c: [FRQ 3396731] inline string reverse
-
 2011-08-19  Don Porter  <dgp@users.sourceforge.net>
 
 	* generic/tclIORTrans.c: [Bugs 3393279, 3393280] ReflectClose(.) is
diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c
index 993a694..ab62359 100644
--- a/generic/tclStringObj.c
+++ b/generic/tclStringObj.c
@@ -2657,96 +2657,96 @@ Tcl_Obj *
 TclStringObjReverse(
     Tcl_Obj *objPtr)
 {
-    char *src, *dest;
-    Tcl_Obj *resultPtr = objPtr;
-    char c;
+    String *stringPtr;
+    char *src = NULL, *dest = NULL;
+    Tcl_UniChar *usrc = NULL, *udest = NULL;
+    Tcl_Obj *resultPtr = NULL;
 
-    src = TclGetString(objPtr);
-    if (Tcl_IsShared(objPtr)) {
-	resultPtr = Tcl_NewObj();
-	Tcl_SetObjLength(resultPtr, objPtr->length);
-	dest = TclGetString(resultPtr);
-	memcpy(dest, src, objPtr->length);
-    } else {
-	TclFreeIntRep(objPtr);
-	dest = src;
-    }
+    SetStringFromAny(NULL, objPtr);
+    stringPtr = GET_STRING(objPtr);
 
-    src = dest + objPtr->length;
+    if (stringPtr->hasUnicode == 0) {
+	if (stringPtr->numChars == -1) {
+	    TclNumUtfChars(stringPtr->numChars, objPtr->bytes, objPtr->length);
+	}
+	if (stringPtr->numChars <= 1) {
+	    return objPtr;
+	}
+	if (stringPtr->numChars == objPtr->length) {
+	    /*
+	     * All one-byte chars. Reverse in objPtr->bytes.
+	     */
 
-    /* Pass 1: reverse individual bytes of UTF-8 representation. */
-    while (dest < src) {
-	Tcl_UniChar ch = 0;
-	switch (Tcl_UtfToUniChar(dest, &ch)) {
-	case 1: {
-		++dest;
-		break;
-	    }
-	case 2: {
-		c = dest[0];
-		dest[0] = dest[1];
-		dest[1] = c;
-		dest += 2;
-		break;
-	    }
-	case 3: {
-		c = dest[0];
-		dest[0] = dest[2];
-		dest[2] = c;
-		dest += 3;
-		break;
-	    }
-#if TCL_UTF_MAX > 4
-	case 5: {
-		c = dest[0];
-		dest[0] = dest[4];
-		dest[4] = c;
-		c = dest[1];
-		dest[1] = dest[3];
-		dest[3] = c;
-		dest += 5;
-		break;
-	    }
-#endif
-#if TCL_UTF_MAX > 5
-	case 6: {
-		c = dest[0];
-		dest[0] = dest[5];
-		dest[5] = c;
-		c = dest[1];
-		dest[1] = dest[4];
-		dest[4] = c;
-		c = dest[0];
-		dest[2] = dest[3];
-		dest[3] = c;
-		dest += 6;
-		break;
+	    if (Tcl_IsShared(objPtr)) {
+		resultPtr = Tcl_NewObj();
+		Tcl_SetObjLength(resultPtr, objPtr->length);
+		dest = TclGetString(resultPtr);
+		src = objPtr->bytes + objPtr->length - 1;
+		while (src >= objPtr->bytes) {
+		    *dest++ = *src--;
+		}
+		return resultPtr;
 	    }
-#endif
-	default: {
-#if TCL_UTF_MAX > 3
-		c = dest[0];
-		dest[0] = dest[3];
-		dest[3] = c;
-		c = dest[1];
-		dest[1] = dest[2];
-		dest[2] = c;
-		dest += 4;
-#endif
-		break;
+
+	    /*
+	     * Unshared. Reverse objPtr->bytes in place.
+	     */
+
+	    dest = objPtr->bytes;
+	    src = dest + objPtr->length - 1;
+	    while (dest < src) {
+		char tmp = *src;
+
+		*src-- = *dest;
+		*dest++ = tmp;
 	    }
+	    return objPtr;
 	}
+	FillUnicodeRep(objPtr);
+	stringPtr = GET_STRING(objPtr);
+    }
+    if (stringPtr->numChars <= 1) {
+	return objPtr;
     }
 
-	/* Pass 2: Reverse byte string. */
-	dest = TclGetString(resultPtr);
+    /*
+     * Reverse the Unicode rep.
+     */
+
+    if (Tcl_IsShared(objPtr)) {
+	Tcl_UniChar ch = 0;
+
+	/*
+	 * Create a non-empty, pure unicode value, so we can coax
+	 * Tcl_SetObjLength into growing the unicode rep buffer.
+	 */
 
-	while (dest < --src) {
-		c = *src;
-		*src = *dest;
-		*dest++ = c;
+	resultPtr = Tcl_NewUnicodeObj(&ch, 1);
+	Tcl_SetObjLength(resultPtr, stringPtr->numChars);
+	udest = Tcl_GetUnicode(resultPtr);
+	usrc = stringPtr->unicode + stringPtr->numChars - 1;
+	while (usrc >= stringPtr->unicode) {
+	    *udest++ = *usrc--;
 	}
-    return resultPtr;
+	return resultPtr;
+    }
+
+    /*
+     * Unshared. Reverse objPtr->bytes in place.
+     */
+
+    udest = stringPtr->unicode;
+    usrc = udest + stringPtr->numChars - 1;
+    while (udest < usrc) {
+	Tcl_UniChar tmp = *usrc;
+
+	*usrc-- = *udest;
+	*udest++ = tmp;
+    }
+
+    TclInvalidateStringRep(objPtr);
+    stringPtr->allocated = 0;
+    return objPtr;
 }
 
 /*