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authordgp <dgp@users.sourceforge.net>2017-06-16 19:54:57 (GMT)
committerdgp <dgp@users.sourceforge.net>2017-06-16 19:54:57 (GMT)
commitb4133af5ee0c655f627443f04d50f492eedc58fa (patch)
treee09b228582d7f4d68adba9ab644f83f6d6370e0b
parent5425edf173bf9efcf17955623e5be64196eae2fa (diff)
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Another reworking, now with comments.
-rw-r--r--generic/tclStringObj.c79
1 files changed, 43 insertions, 36 deletions
diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c
index 51d6c13..41dad65 100644
--- a/generic/tclStringObj.c
+++ b/generic/tclStringObj.c
@@ -2947,65 +2947,72 @@ TclStringCatObjv(
}
} while (--oc);
} else {
- Tcl_Obj *pendingPtr = NULL;
-
/* Result will be concat of string reps. Pre-size it. */
ov = objv; oc = objc;
do {
- /* assert ( pendingPtr == NULL ) */
- /* assert ( length == 0 ) */
+ Tcl_Obj *pendingPtr = NULL;
- Tcl_Obj *objPtr = *ov++;
+ /*
+ * Loop until a possibly non-empty value is reached.
+ * Keep string rep generation pending when possible.
+ */
- if (objPtr->bytes == NULL) {
- /* No string rep; Take the chance we can avoid making it */
- pendingPtr = objPtr;
- } else {
- Tcl_GetStringFromObj(objPtr, &length); /* PANIC? */
- }
- } while (--oc && (length == 0) && (pendingPtr == NULL));
+ do {
+ /* assert ( pendingPtr == NULL ) */
+ /* assert ( length == 0 ) */
- first = last = objc - oc - 1;
+ Tcl_Obj *objPtr = *ov++;
- while (oc && (length == 0)) {
- int numBytes;
- Tcl_Obj *objPtr = *ov++;
+ if (objPtr->bytes == NULL) {
+ /* No string rep; Take the chance we can avoid making it */
+ pendingPtr = objPtr;
+ } else {
+ Tcl_GetStringFromObj(objPtr, &length); /* PANIC? */
+ }
+ } while (--oc && (length == 0) && (pendingPtr == NULL));
+
+ /*
+ * Either we found a possibly non-empty value, and we
+ * remember this index as the first and last such value so
+ * far seen, or (oc == 0) and all values are known empty,
+ * so first = last = objc - 1 signals the right quick return.
+ */
- /* assert ( pendingPtr != NULL ) <-- aiming for */
+ first = last = objc - oc - 1;
- if ((length == 0) && (objPtr->bytes == NULL) && !pendingPtr) {
- /* No string rep; Take the chance we can avoid making it */
+ if (oc && (length == 0)) {
+ int numBytes;
- last = objc - oc;
- first = last;
- pendingPtr = objPtr;
- } else {
+ /* assert ( pendingPtr != NULL ) */
+
+ /*
+ * There's a pending value followed by more values.
+ * Loop over remaining values generating strings until
+ * a non-empty value is found, or the pending value gets
+ * its string generated.
+ */
+
+ do {
+ Tcl_Obj *objPtr = *ov++;
+ Tcl_GetStringFromObj(objPtr, &numBytes); /* PANIC? */
+ } while (--oc && numBytes == 0 && pendingPtr->bytes == NULL);
- Tcl_GetStringFromObj(objPtr, &numBytes); /* PANIC? */
if (numBytes) {
- last = objc - oc;
- } else if (pendingPtr == NULL || pendingPtr->bytes == NULL) {
- --oc;
- continue;
+ last = objc -oc -1;
}
- if (pendingPtr) {
- Tcl_GetStringFromObj(pendingPtr, &length); /* PANIC? */
- pendingPtr = NULL;
+ if (oc || numBytes) {
+ Tcl_GetStringFromObj(pendingPtr, &length);
}
if (length == 0) {
if (numBytes) {
first = last;
- } else {
- first = objc - 1;
- last = 0;
}
} else if (numBytes > INT_MAX - length) {
goto overflow;
}
length += numBytes;
}
- --oc;
- }
+ } while (oc && (length == 0));
while (oc) {
int numBytes;