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gh-116: Fix SPLIT handling of empty delimiter. #117

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Merged
python-processing-unit merged 1 commit into from
Apr 1, 2026
Merged

gh-116: Fix SPLIT handling of empty delimiter. #117

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20 changes: 11 additions & 9 deletions src/builtins.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4952,6 +4952,9 @@ static Value builtin_split(Interpreter* interp, Value* args, int argc, Expr** ar
if (argc >= 2) {
EXPECT_STR(args[1], "SPLIT", interp, line, col);
sep = args[1].as.s;
if (sep[0] == '\0') {
RUNTIME_ERROR(interp, "SPLIT expects a non-empty delimiter", line, col);
}
}
const char* s = args[0].as.s;
// simple separator: if sep==NULL split on whitespace, else split on sep exactly
Expand Down Expand Up @@ -4984,16 +4987,15 @@ static Value builtin_split(Interpreter* interp, Value* args, int argc, Expr** ar
free(piece);
cur = found + seplen;
}
// last piece
if (*cur != '\0') {
if (count + 1 > cap) { cap *= 2; items = realloc(items, sizeof(Value) * cap); }
items[count++] = value_str(cur);
}
// last piece, including empty trailing fields
size_t len = strlen(cur);
char* piece = malloc(len + 1);
Comment on lines 4955 to +4992
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Copilot AI Apr 1, 2026

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This change introduces new SPLIT behaviors that should be covered by the existing builtin test suite (tests/test2.pre): (1) empty delimiter now raises a runtime error, and (2) empty trailing fields are now preserved (e.g., splitting "a," by "," should include a final empty string). Adding explicit assertions will prevent regressions and clarify intended semantics (including the "" input case).

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memcpy(piece, cur, len);
piece[len] = '\0';
if (count + 1 > cap) { cap *= 2; items = realloc(items, sizeof(Value) * cap); }
items[count++] = value_str(piece);
free(piece);
Comment on lines +4991 to +4997
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Copilot AI Apr 1, 2026

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The newly added last-piece handling allocates piece with malloc(len + 1) but never checks for allocation failure before memcpy, which can dereference NULL on OOM. Since value_str() already duplicates its input, you can avoid this allocation entirely by passing cur directly; otherwise add an explicit NULL check and clean up (free(copy), free(items)) before raising the runtime error.

Suggested change
size_t len = strlen(cur);
char* piece = malloc(len + 1);
memcpy(piece, cur, len);
piece[len] = '\0';
if (count + 1 > cap) { cap *= 2; items = realloc(items, sizeof(Value) * cap); }
items[count++] = value_str(piece);
free(piece);
if (count + 1 > cap) { cap *= 2; items = realloc(items, sizeof(Value) * cap); }
items[count++] = value_str(cur);

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Comment on lines +4990 to +4997
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Copilot AI Apr 1, 2026

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The PR title mentions fixing empty-delimiter handling, but this hunk also changes SPLIT semantics by always appending the final field (including empty trailing fields, and changing the result for an empty input string). If that broader behavior change is intentional, consider reflecting it in the PR description/title and/or documenting it in the SPLIT comment/spec so the change is discoverable for users.

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free(copy);
if (count == 0) {
free(items);
return value_tns_new(TYPE_STR, 1, (const size_t[]){0});
}
size_t shape[1] = { count };
Value out = value_tns_from_values(TYPE_STR, 1, shape, items, count);
for (size_t i = 0; i < count; i++) value_free(items[i]);
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