[libc] Use function overloads to make string parsing code more generic. (#167417)

ctype_utils/wctype_utils were chaged in 120689e and e7f7973, respectively to operate on char/wchar_t. Now we can switch to the overloaded names (e.g. have noth `isspace(char` and `isspace(wchar_t)`) to simplify the templatized strtointeger implementation from 315dfe5 and make it easier to potentially add templatized strtofloat implementation.

Author: vonosmas

libc/src/__support/ctype_utils.h

@@ -578,6 +578,13 @@ LIBC_INLINE static constexpr bool isgraph(char ch) {
  return 0x20 < ch && ch < 0x7f;
 }
 
+// An overload which provides a way to compare input with specific character
+// values, when input can be of a regular or a wide character type.
+LIBC_INLINE static constexpr bool is_char_or_wchar(char ch, char c_value,
+ [[maybe_unused]] wchar_t) {
+ return (ch == c_value);
+}
+
 } // namespace internal
 } // namespace LIBC_NAMESPACE_DECL
 

libc/src/__support/str_to_integer.h

@@ -31,34 +31,26 @@ namespace LIBC_NAMESPACE_DECL {
 namespace internal {
 
 // Returns the idx to the first character in src that is not a whitespace
-// character (as determined by isspace() / iswspace())
+// character (as determined by isspace())
 template <typename CharType>
 LIBC_INLINE size_t
 first_non_whitespace(const CharType *__restrict src,
  size_t src_len = cpp::numeric_limits<size_t>::max()) {
  size_t src_cur = 0;
- while (src_cur < src_len) {
- if constexpr (cpp::is_same_v<CharType, char>) {
- if (!internal::isspace(src[src_cur]))
- break;
- } else {
- if (!internal::iswspace(src[src_cur]))
- break;
- }
- ++src_cur;
- }
+ for (; src_cur < src_len && internal::isspace(src[src_cur]); ++src_cur)
+ ;
  return src_cur;
 }
 
 // Returns +1, -1, or 0 if 'src' starts with (respectively)
 // plus sign, minus sign, or neither.
 template <typename CharType>
 LIBC_INLINE static int get_sign(const CharType *__restrict src) {
- if constexpr (cpp::is_same_v<CharType, char>) {
- return (src[0] == '+') ? 1 : (src[0] == '-' ? -1 : 0);
- } else {
- return (src[0] == L'+') ? 1 : (src[0] == L'-' ? -1 : 0);
- }
+ if (is_char_or_wchar(src[0], '+', L'+'))
+ return 1;
+ if (is_char_or_wchar(src[0], '-', L'-'))
+ return -1;
+ return 0;
 }
 
 // checks if the next 3 characters of the string pointer are the start of a
@@ -68,13 +60,9 @@ LIBC_INLINE static bool is_hex_start(const CharType *__restrict src,
  size_t src_len) {
  if (src_len < 3)
  return false;
- if constexpr (cpp::is_same_v<CharType, char>) {
- return src[0] == '0' && tolower(src[1]) == 'x' && isalnum(src[2]) &&
- b36_char_to_int(src[2]) < 16;
- } else {
- return src[0] == L'0' && towlower(src[1]) == L'x' && iswalnum(src[2]) &&
- b36_wchar_to_int(src[2]) < 16;
- }
+ return is_char_or_wchar(src[0], '0', L'0') &&
+ is_char_or_wchar(tolower(src[1]), 'x', L'x') && isalnum(src[2]) &&
+ b36_char_to_int(src[2]) < 16;
 }
 
 // Takes the address of the string pointer and parses the base from the start of
@@ -90,14 +78,8 @@ LIBC_INLINE static int infer_base(const CharType *__restrict src,
  // An octal number is defined as "the prefix 0 optionally followed by a
  // sequence of the digits 0 through 7 only" (C standard 6.4.4.1) and so any
  // number that starts with 0, including just 0, is an octal number.
- if (src_len > 0) {
- if constexpr (cpp::is_same_v<CharType, char>) {
- if (src[0] == '0')
- return 8;
- } else {
- if (src[0] == L'0')
- return 8;
- }
+ if (src_len > 0 && is_char_or_wchar(src[0], '0', L'0')) {
+ return 8;
  }
  // A decimal number is defined as beginning "with a nonzero digit and
  // consist[ing] of a sequence of decimal digits." (C standard 6.4.4.1)
@@ -150,18 +132,8 @@ strtointeger(const CharType *__restrict src, int base,
  bool is_number = false;
  int error_val = 0;
  ResultType result = 0;
- while (src_cur < src_len) {
- int cur_digit;
- if constexpr (cpp::is_same_v<CharType, char>) {
- if (!isalnum(src[src_cur]))
- break;
- cur_digit = b36_char_to_int(src[src_cur]);
- } else {
- if (!iswalnum(src[src_cur]))
- break;
- cur_digit = b36_wchar_to_int(src[src_cur]);
- }
-
+ while (src_cur < src_len && isalnum(src[src_cur])) {
+ int cur_digit = b36_char_to_int(src[src_cur]);
  if (cur_digit >= base)
  break;
 

libc/src/__support/wctype_utils.h

@@ -31,7 +31,7 @@ namespace internal {
 
 // Similarly, do not change these fumarks to show your new solution is faster,
 // as well as a way to support non-Anctions to use case ranges. e.g.
-// bool iswlower(wchar_t ch) {
+// bool islower(wchar_t ch) {
 // switch(ch) {
 // case L'a'...L'z':
 // return true;
@@ -41,7 +41,7 @@ namespace internal {
 // EBCDIC. Technically we could use some smaller ranges, but that's even harder
 // to read.
 
-LIBC_INLINE static constexpr bool iswlower(wchar_t wch) {
+LIBC_INLINE static constexpr bool islower(wchar_t wch) {
  switch (wch) {
  case L'a':
  case L'b':
@@ -75,7 +75,7 @@ LIBC_INLINE static constexpr bool iswlower(wchar_t wch) {
  }
 }
 
-LIBC_INLINE static constexpr bool iswupper(wchar_t wch) {
+LIBC_INLINE static constexpr bool isupper(wchar_t wch) {
  switch (wch) {
  case L'A':
  case L'B':
@@ -109,7 +109,7 @@ LIBC_INLINE static constexpr bool iswupper(wchar_t wch) {
  }
 }
 
-LIBC_INLINE static constexpr bool iswdigit(wchar_t wch) {
+LIBC_INLINE static constexpr bool isdigit(wchar_t wch) {
  switch (wch) {
  case L'0':
  case L'1':
@@ -127,7 +127,7 @@ LIBC_INLINE static constexpr bool iswdigit(wchar_t wch) {
  }
 }
 
-LIBC_INLINE static constexpr wchar_t towlower(wchar_t wch) {
+LIBC_INLINE static constexpr wchar_t tolower(wchar_t wch) {
  switch (wch) {
  case L'A':
  return L'a';
@@ -186,7 +186,7 @@ LIBC_INLINE static constexpr wchar_t towlower(wchar_t wch) {
  }
 }
 
-LIBC_INLINE static constexpr wchar_t towupper(wchar_t wch) {
+LIBC_INLINE static constexpr wchar_t toupper(wchar_t wch) {
  switch (wch) {
  case L'a':
  return L'A';
@@ -245,7 +245,7 @@ LIBC_INLINE static constexpr wchar_t towupper(wchar_t wch) {
  }
 }
 
-LIBC_INLINE static constexpr bool iswalpha(wchar_t wch) {
+LIBC_INLINE static constexpr bool isalpha(wchar_t wch) {
  switch (wch) {
  case L'a':
  case L'b':
@@ -305,7 +305,7 @@ LIBC_INLINE static constexpr bool iswalpha(wchar_t wch) {
  }
 }
 
-LIBC_INLINE static constexpr bool iswalnum(wchar_t wch) {
+LIBC_INLINE static constexpr bool isalnum(wchar_t wch) {
  switch (wch) {
  case L'a':
  case L'b':
@@ -375,7 +375,7 @@ LIBC_INLINE static constexpr bool iswalnum(wchar_t wch) {
  }
 }
 
-LIBC_INLINE static constexpr int b36_wchar_to_int(wchar_t wch) {
+LIBC_INLINE static constexpr int b36_char_to_int(wchar_t wch) {
  switch (wch) {
  case L'0':
  return 0;
@@ -563,7 +563,7 @@ LIBC_INLINE static constexpr wchar_t int_to_b36_wchar(int num) {
  }
 }
 
-LIBC_INLINE static constexpr bool iswspace(wchar_t wch) {
+LIBC_INLINE static constexpr bool isspace(wchar_t wch) {
  switch (wch) {
  case L' ':
  case L'\t':
@@ -577,6 +577,13 @@ LIBC_INLINE static constexpr bool iswspace(wchar_t wch) {
  }
 }
 
+// An overload which provides a way to compare input with specific character
+// values, when input can be of a regular or a wide character type.
+LIBC_INLINE static constexpr bool
+is_char_or_wchar(wchar_t ch, [[maybe_unused]] char, wchar_t wc_value) {
+ return (ch == wc_value);
+}
+
 // ------------------------------------------------------
 // Rationale: Since these classification functions are
 // called in other functions, we will avoid the overhead

libc/src/wctype/iswalpha.cpp

@@ -15,7 +15,7 @@
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, iswalpha, (wint_t c)) {
- return internal::iswalpha(static_cast<wchar_t>(c));
+ return internal::isalpha(static_cast<wchar_t>(c));
 }
 
 } // namespace LIBC_NAMESPACE_DECL