bpo-37388: Add PyUnicode_Decode(str, 0) fast-path (GH-14385)

vstinner · web-flow · commit ed076ed46726 · 2019-06-26T01:49:32.000+02:00
Add a fast-path to PyUnicode_Decode() for size equals to 0.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
@@ -3354,6 +3354,10 @@ PyUnicode_Decode(const char *s,
         return NULL;
     }
 
+    if (size == 0) {
+        _Py_RETURN_UNICODE_EMPTY();
+    }
+
     if (encoding == NULL) {
         return PyUnicode_DecodeUTF8Stateful(s, size, errors, NULL);
     }

Original file line number	Diff line number	Diff line change
`@@ -3354,6 +3354,10 @@ PyUnicode_Decode(const char *s,`
`3354`	`3354`	`return NULL;`
`3355`	`3355`	`}`
`3356`	`3356`
	`3357`	`+ if (size == 0) {`
	`3358`	`+ _Py_RETURN_UNICODE_EMPTY();`
	`3359`	`+ }`
	`3360`	`+`
`3357`	`3361`	`if (encoding == NULL) {`
`3358`	`3362`	`return PyUnicode_DecodeUTF8Stateful(s, size, errors, NULL);`
`3359`	`3363`	`}`