projjal commented on a change in pull request #7641:
URL: https://github.com/apache/arrow/pull/7641#discussion_r458053012
##########
File path: cpp/src/gandiva/precompiled/string_ops.cc
##########
@@ -305,21 +342,104 @@ const char* trim_utf8(gdv_int64 context, const char*
data, gdv_int32 data_len,
--end;
}
- // string with no leading/trailing spaces, return original string
- if (start == 0 && end == data_len - 1) {
- *out_len = data_len;
- return data;
+ // string has some leading/trailing spaces and some non-space characters
+ *out_len = end - start + 1;
+ return data + start;
+}
+
+// Trims characters present in the trim text from the left end of the base text
+FORCE_INLINE
+const char* ltrim_utf8_utf8(gdv_int64 context, const char* basetext,
+ gdv_int32 basetext_len, const char* trimtext,
+ gdv_int32 trimtext_len, int32_t* out_len) {
+ if (basetext_len == 0) {
+ *out_len = 0;
+ return "";
+ } else if (trimtext_len == 0) {
+ *out_len = basetext_len;
+ return basetext;
+ }
+
+ gdv_int32 start_ptr, char_len;
+ // scan the base text from left to right and increment the start pointer till
+ // there is a character which is not present in the trim text
+ for (start_ptr = 0; start_ptr < basetext_len; start_ptr += char_len) {
+ char_len = utf8_char_length(basetext[start_ptr]);
+ if (!is_substr_utf8_utf8(trimtext, trimtext_len, basetext + start_ptr,
char_len)) {
+ break;
+ }
+ }
+
+ *out_len = basetext_len - start_ptr;
+ return basetext + start_ptr;
+}
+
+// Trims characters present in the trim text from the right end of the base
text
+FORCE_INLINE
+const char* rtrim_utf8_utf8(gdv_int64 context, const char* basetext,
+ gdv_int32 basetext_len, const char* trimtext,
+ gdv_int32 trimtext_len, int32_t* out_len) {
+ if (basetext_len == 0) {
+ *out_len = 0;
+ return "";
+ } else if (trimtext_len == 0) {
+ *out_len = basetext_len;
+ return basetext;
+ }
+
+ gdv_int32 char_len, end_ptr;
+ // scan the base text from right to left and decrement the end pointer till
+ // there is a character which is not present in the trim text
+ for (end_ptr = basetext_len - 1; end_ptr >= 0; --end_ptr) {
+ char_len = utf8_char_length(basetext[end_ptr]);
+ if (char_len == 0) { // trailing bytes of multibyte character
+ continue;
+ }
+ if (!is_substr_utf8_utf8(trimtext, trimtext_len, basetext + end_ptr,
char_len)) {
+ break;
+ }
}
- // string with all spaces
- if (start > end) {
+ end_ptr += utf8_char_length(basetext[end_ptr]); // point to the next
character
Review comment:
here end_ptr can be -1 and will be buffer overflow. You need to
separately handle that case.
##########
File path: cpp/src/gandiva/precompiled/string_ops.cc
##########
@@ -305,21 +342,104 @@ const char* trim_utf8(gdv_int64 context, const char*
data, gdv_int32 data_len,
--end;
}
- // string with no leading/trailing spaces, return original string
- if (start == 0 && end == data_len - 1) {
- *out_len = data_len;
- return data;
+ // string has some leading/trailing spaces and some non-space characters
+ *out_len = end - start + 1;
+ return data + start;
+}
+
+// Trims characters present in the trim text from the left end of the base text
+FORCE_INLINE
+const char* ltrim_utf8_utf8(gdv_int64 context, const char* basetext,
Review comment:
You need to handle the cases when the input is a malformed utf8 string.
Currently the code might give buffer overflow if last character is incomplete
multibyte character or the ltrim() might go into an infinite loop if there is
an invalid byte in the middle.
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