Fix [Bug 2008248] and make dict->list->dict round trip efficient to boot.

1 files changed, 55 insertions, 2 deletions

diff --git a/generic/tclListObj.c b/generic/tclListObj.c
index d04fb45..6cf903b 100644
--- a/generic/tclListObj.c
+++ b/generic/tclListObj.c
@@ -10,7 +10,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclListObj.c,v 1.50 2008/04/27 22:21:30 dkf Exp $
+ * RCS: @(#) $Id: tclListObj.c,v 1.51 2008/07/20 17:55:51 dkf Exp $
  */
 
 #include "tclInt.h"
@@ -1658,6 +1658,58 @@ SetListFromAny(
     List *listRepPtr;
 
     /*
+     * Dictionaries are a special case; they have a string representation such
+     * that *all* valid dictionaries are valid lists. Hence we can convert
+     * more directly.
+     */
+
+    if (objPtr->typePtr == &tclDictType) {
+	Tcl_Obj *keyPtr, *valuePtr;
+	Tcl_DictSearch search;
+	int done, size;
+
+	/*
+	 * Create the new list representation. Note that we do not need to do
+	 * anything with the string representation as the transformation (and
+	 * the reverse back to a dictionary) are both order-preserving. Also
+	 * note that since we know we've got a valid dictionary (by
+	 * representation) we also know that fetching the size of the
+	 * dictionary or iterating over it will not fail.
+	 */
+
+	Tcl_DictObjSize(NULL, objPtr, &size);
+	listRepPtr = NewListIntRep(size > 0 ? 2*size : 1, NULL);
+	if (!listRepPtr) {
+	    Tcl_SetResult(interp,
+		    "insufficient memory to allocate list working space",
+		    TCL_STATIC);
+	    return TCL_ERROR;
+	}
+	listRepPtr->elemCount = 2 * size;
+
+	/*
+	 * Populate the list representation.
+	 */
+
+	elemPtrs = &listRepPtr->elements;
+	Tcl_DictObjFirst(NULL, objPtr, &search, &keyPtr, &valuePtr, &done);
+	i = 0;
+	while (!done) {
+	    elemPtrs[i++] = keyPtr;
+	    elemPtrs[i++] = valuePtr;
+	    Tcl_IncrRefCount(keyPtr);
+	    Tcl_IncrRefCount(valuePtr);
+	    Tcl_DictObjNext(&search, &keyPtr, &valuePtr, &done);
+	}
+
+	/*
+	 * Swap the representations.
+	 */
+
+	goto commitRepresentation;
+    }
+
+    /*
      * Get the string representation. Make it up-to-date if necessary.
      */
 
@@ -1742,9 +1794,10 @@ SetListFromAny(
      * Tcl_GetStringFromObj, to use that old internalRep.
      */
 
+  commitRepresentation:
     listRepPtr->refCount++;
     TclFreeIntRep(objPtr);
-    objPtr->internalRep.twoPtrValue.ptr1 = (void *) listRepPtr;
+    objPtr->internalRep.twoPtrValue.ptr1 = listRepPtr;
     objPtr->internalRep.twoPtrValue.ptr2 = NULL;
     objPtr->typePtr = &tclListType;
     return TCL_OK;