Simplify str_copy_decimal_str.

pandas/_libs/src/parser/tokenizer.c

@@ -1778,128 +1778,49 @@ double precise_xstrtod(const char *str, char **endptr, char decimal,
     return number;
 }
 
-/* copy a decimal number string in form `decimal` and `tsep` and `sci` as
-   decimal point, thousands separator and sci exponent character to a an
-   equivalent c-locale decimal string (striping tsep, replacing `decimal`
-   with '.'). Return NULL if nothing could be copied.
+/* copy a decimal number string with `decimal`, `tsep` as decimal point
+   and thousands separator to an equivalent c-locale decimal string (striping
+   `tsep`, replacing `decimal` with '.'). The returned memory should be free-d
+   with a call to `free`.
 */
 
-char* str_copy_decimal_str_c(const char *s, char **endpos, char decimal,
-                             char tsep, char sci) {
-    #define IS_TSEP(c) (tsep != '\0' && c == tsep)
-    ssize_t size = 0;
-    ssize_t num_digits = 0;
-    char has_exponent = 0;
+char* _str_copy_decimal_str_c(const char *s, char **endpos, char decimal,
+                              char tsep) {
     const char *p = s;
-    // First count how many characters we can consume.
-    // Leading sign
-    if (*p == '+' || *p == '-') p++;
-    // Integer part
-    while (isdigit_ascii(*p)) {
-        p++;
-        p += IS_TSEP(*p);
-        num_digits++;
-    }
-    // Fractional part
-    if (*p == decimal) {
-        p++;
-        while (isdigit_ascii(*p)) {
-            p++;
-            num_digits++;
-        }
-    }
-    if (num_digits == 0) {
-        if (endpos != NULL) {
-            *endpos = (char *)s;
-        }
-        return NULL;
-    }
-    // Exponent part
-    if (toupper_ascii(*p) == toupper_ascii(sci)) {
-        const char * p_at_e = p;
-        num_digits = 0;
-        p++;
-        // Exponent sign
-        if (*p == '+' || *p == '-') p++;
-        // Exponent
-        while (isdigit_ascii(*p)) {
-            p++;
-            num_digits++;
-        }
-        if (num_digits == 0) {
-            // no digits after exponent; un-consume the (+|-)?
-            p = p_at_e;
-            has_exponent = 0;
-        } else {
-            has_exponent = 1;
-        }
-    }
-
-    size = p - s;
-    char *pc = malloc(size + 1);
-    memcpy(pc, p, size);
-    pc[size] = '\0';
-    char *dst = pc;
-    p = s;
-    num_digits = 0;
-    // Copy leading sign
+    size_t length = strlen(s);
+    char *s_copy = malloc(length + 1);
+    char *dst = s_copy;
+    // Copy Leading sign
     if (*p == '+' || *p == '-') {
         *dst++ = *p++;
     }
-    // Copy integer part
+    // Copy integer part dropping `tsep`
     while (isdigit_ascii(*p)) {
         *dst++ = *p++;
-        p += IS_TSEP(*p);
-        num_digits++;
+        p += (tsep != '\0' && *p == tsep);
     }
-    // Copy factional part, replacing `decimal` with '.'
+    // Replace `decimal` with '.'
     if (*p == decimal) {
-        *dst++ = '.';
-        p++;
-        while (isdigit_ascii(*p)) {
-            *dst++ = *p++;
-            num_digits++;
-        }
-    }
-    assert(num_digits > 0);
-    // Copy exponent
-    if (has_exponent && toupper_ascii(*p) == toupper_ascii(sci)) {
-        num_digits = 0;
-        *dst++ = *p++;
-        // Copy leading exponent sign
-        if (*p == '+' || *p == '-') {
-            *dst++ = *p++;
-        }
-        // Exponent
-        while (isdigit_ascii(*p)) {
-            *dst++ = *p++;
-            num_digits++;
-        }
-        assert(num_digits > 0);
-    }
-    *dst = '\0';
-    if (endpos != NULL) {
-        *endpos = (char *)p;
-    }
-    return pc;
-    #undef IS_TSEP
+       *dst++ = '.';
+       p++;
+    }
+    // Copy the remainder of the string as is.
+    memcpy(dst, p, length + 1 - (p - s));
+    s_copy[length] = '\0';
+    if (endpos != NULL)
+        *endpos = (char *)(s + length);
+    return s_copy;
 }
 
+
 double round_trip(const char *p, char **q, char decimal, char sci, char tsep,
                   int skip_trailing, int *error, int *maybe_int) {
     char *pc = NULL;
     // 'normalize' representation to C-locale; replace decimal with '.' and
     // remove t(housand)sep.
     char *endptr = NULL;
     if (decimal != '.' || tsep != '\0') {
-        pc = str_copy_decimal_str_c(p, &endptr, decimal, tsep, sci);
-        if (pc == NULL) {
-            if (q != NULL) {
-                *q = (char *)p;
-            }
-            *error = -1;
-            return 0.0;
-        }
+        pc = _str_copy_decimal_str_c(p, &endptr, decimal, tsep);
     }
     // This is called from a nogil block in parsers.pyx
     // so need to explicitly get GIL before Python calls