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Diffstat (limited to 'src/google/protobuf/stubs/strutil.cc')
| -rw-r--r-- | src/google/protobuf/stubs/strutil.cc | 1121 |
1 files changed, 1121 insertions, 0 deletions
diff --git a/src/google/protobuf/stubs/strutil.cc b/src/google/protobuf/stubs/strutil.cc new file mode 100644 index 00000000..07caaf76 --- /dev/null +++ b/src/google/protobuf/stubs/strutil.cc @@ -0,0 +1,1121 @@ +// Protocol Buffers - Google's data interchange format +// Copyright 2008 Google Inc. +// http://code.google.com/p/protobuf/ +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +// from google3/strings/strutil.cc + +#include <google/protobuf/stubs/strutil.h> +#include <errno.h> +#include <float.h> // FLT_DIG and DBL_DIG +#include <limits> +#include <limits.h> + +#ifdef _WIN32 +// MSVC has only _snprintf, not snprintf. +// +// MinGW has both snprintf and _snprintf, but they appear to be different +// functions. The former is buggy. When invoked like so: +// char buffer[32]; +// snprintf(buffer, 32, "%.*g\n", FLT_DIG, 1.23e10f); +// it prints "1.23000e+10". This is plainly wrong: %g should never print +// trailing zeros after the decimal point. For some reason this bug only +// occurs with some input values, not all. In any case, _snprintf does the +// right thing, so we use it. +#define snprintf _snprintf +#endif + +namespace google { +namespace protobuf { + +inline bool IsNaN(double value) { + // NaN is never equal to anything, even itself. + return value != value; +} + +// The definitions of these in ctype.h change based on locale. Since our +// string manipulation is all in relation to the protocol buffer and C++ +// languages, we always want to use the C locale. So, we re-define these +// exactly as we want them. +static bool isxdigit(char c) { + return ('0' <= c && c <= '9') || + ('a' <= c && c <= 'f') || + ('A' <= c && c <= 'F'); +} + +static bool isprint(char c) { + return c >= 0x20 && c <= 0x7E; +} + +// ---------------------------------------------------------------------- +// StripString +// Replaces any occurrence of the character 'remove' (or the characters +// in 'remove') with the character 'replacewith'. +// ---------------------------------------------------------------------- +void StripString(string* s, const char* remove, char replacewith) { + const char * str_start = s->c_str(); + const char * str = str_start; + for (str = strpbrk(str, remove); + str != NULL; + str = strpbrk(str + 1, remove)) { + (*s)[str - str_start] = replacewith; + } +} + +// ---------------------------------------------------------------------- +// StringReplace() +// Replace the "old" pattern with the "new" pattern in a string, +// and append the result to "res". If replace_all is false, +// it only replaces the first instance of "old." +// ---------------------------------------------------------------------- + +void StringReplace(const string& s, const string& oldsub, + const string& newsub, bool replace_all, + string* res) { + if (oldsub.empty()) { + res->append(s); // if empty, append the given string. + return; + } + + string::size_type start_pos = 0; + string::size_type pos; + do { + pos = s.find(oldsub, start_pos); + if (pos == string::npos) { + break; + } + res->append(s, start_pos, pos - start_pos); + res->append(newsub); + start_pos = pos + oldsub.size(); // start searching again after the "old" + } while (replace_all); + res->append(s, start_pos, s.length() - start_pos); +} + +// ---------------------------------------------------------------------- +// StringReplace() +// Give me a string and two patterns "old" and "new", and I replace +// the first instance of "old" in the string with "new", if it +// exists. If "global" is true; call this repeatedly until it +// fails. RETURN a new string, regardless of whether the replacement +// happened or not. +// ---------------------------------------------------------------------- + +string StringReplace(const string& s, const string& oldsub, + const string& newsub, bool replace_all) { + string ret; + StringReplace(s, oldsub, newsub, replace_all, &ret); + return ret; +} + +// ---------------------------------------------------------------------- +// SplitStringUsing() +// Split a string using a character delimiter. Append the components +// to 'result'. +// +// Note: For multi-character delimiters, this routine will split on *ANY* of +// the characters in the string, not the entire string as a single delimiter. +// ---------------------------------------------------------------------- +template <typename ITR> +static inline +void SplitStringToIteratorUsing(const string& full, + const char* delim, + ITR& result) { + // Optimize the common case where delim is a single character. + if (delim[0] != '\0' && delim[1] == '\0') { + char c = delim[0]; + const char* p = full.data(); + const char* end = p + full.size(); + while (p != end) { + if (*p == c) { + ++p; + } else { + const char* start = p; + while (++p != end && *p != c); + *result++ = string(start, p - start); + } + } + return; + } + + string::size_type begin_index, end_index; + begin_index = full.find_first_not_of(delim); + while (begin_index != string::npos) { + end_index = full.find_first_of(delim, begin_index); + if (end_index == string::npos) { + *result++ = full.substr(begin_index); + return; + } + *result++ = full.substr(begin_index, (end_index - begin_index)); + begin_index = full.find_first_not_of(delim, end_index); + } +} + +void SplitStringUsing(const string& full, + const char* delim, + vector<string>* result) { + back_insert_iterator< vector<string> > it(*result); + SplitStringToIteratorUsing(full, delim, it); +} + +// ---------------------------------------------------------------------- +// JoinStrings() +// This merges a vector of string components with delim inserted +// as separaters between components. +// +// ---------------------------------------------------------------------- +template <class ITERATOR> +static void JoinStringsIterator(const ITERATOR& start, + const ITERATOR& end, + const char* delim, + string* result) { + GOOGLE_CHECK(result != NULL); + result->clear(); + int delim_length = strlen(delim); + + // Precompute resulting length so we can reserve() memory in one shot. + int length = 0; + for (ITERATOR iter = start; iter != end; ++iter) { + if (iter != start) { + length += delim_length; + } + length += iter->size(); + } + result->reserve(length); + + // Now combine everything. + for (ITERATOR iter = start; iter != end; ++iter) { + if (iter != start) { + result->append(delim, delim_length); + } + result->append(iter->data(), iter->size()); + } +} + +void JoinStrings(const vector<string>& components, + const char* delim, + string * result) { + JoinStringsIterator(components.begin(), components.end(), delim, result); +} + +// ---------------------------------------------------------------------- +// UnescapeCEscapeSequences() +// This does all the unescaping that C does: \ooo, \r, \n, etc +// Returns length of resulting string. +// The implementation of \x parses any positive number of hex digits, +// but it is an error if the value requires more than 8 bits, and the +// result is truncated to 8 bits. +// +// The second call stores its errors in a supplied string vector. +// If the string vector pointer is NULL, it reports the errors with LOG(). +// ---------------------------------------------------------------------- + +#define IS_OCTAL_DIGIT(c) (((c) >= '0') && ((c) <= '7')) + +inline int hex_digit_to_int(char c) { + /* Assume ASCII. */ + assert('0' == 0x30 && 'A' == 0x41 && 'a' == 0x61); + assert(isxdigit(c)); + int x = static_cast<unsigned char>(c); + if (x > '9') { + x += 9; + } + return x & 0xf; +} + +// Protocol buffers doesn't ever care about errors, but I don't want to remove +// the code. +#define LOG_STRING(LEVEL, VECTOR) GOOGLE_LOG_IF(LEVEL, false) + +int UnescapeCEscapeSequences(const char* source, char* dest) { + return UnescapeCEscapeSequences(source, dest, NULL); +} + +int UnescapeCEscapeSequences(const char* source, char* dest, + vector<string> *errors) { + GOOGLE_DCHECK(errors == NULL) << "Error reporting not implemented."; + + char* d = dest; + const char* p = source; + + // Small optimization for case where source = dest and there's no escaping + while ( p == d && *p != '\0' && *p != '\\' ) + p++, d++; + + while (*p != '\0') { + if (*p != '\\') { + *d++ = *p++; + } else { + switch ( *++p ) { // skip past the '\\' + case '\0': + LOG_STRING(ERROR, errors) << "String cannot end with \\"; + *d = '\0'; + return d - dest; // we're done with p + case 'a': *d++ = '\a'; break; + case 'b': *d++ = '\b'; break; + case 'f': *d++ = '\f'; break; + case 'n': *d++ = '\n'; break; + case 'r': *d++ = '\r'; break; + case 't': *d++ = '\t'; break; + case 'v': *d++ = '\v'; break; + case '\\': *d++ = '\\'; break; + case '?': *d++ = '\?'; break; // \? Who knew? + case '\'': *d++ = '\''; break; + case '"': *d++ = '\"'; break; + case '0': case '1': case '2': case '3': // octal digit: 1 to 3 digits + case '4': case '5': case '6': case '7': { + char ch = *p - '0'; + if ( IS_OCTAL_DIGIT(p[1]) ) + ch = ch * 8 + *++p - '0'; + if ( IS_OCTAL_DIGIT(p[1]) ) // safe (and easy) to do this twice + ch = ch * 8 + *++p - '0'; // now points at last digit + *d++ = ch; + break; + } + case 'x': case 'X': { + if (!isxdigit(p[1])) { + if (p[1] == '\0') { + LOG_STRING(ERROR, errors) << "String cannot end with \\x"; + } else { + LOG_STRING(ERROR, errors) << + "\\x cannot be followed by non-hex digit: \\" << *p << p[1]; + } + break; + } + unsigned int ch = 0; + const char *hex_start = p; + while (isxdigit(p[1])) // arbitrarily many hex digits + ch = (ch << 4) + hex_digit_to_int(*++p); + if (ch > 0xFF) + LOG_STRING(ERROR, errors) << "Value of " << + "\\" << string(hex_start, p+1-hex_start) << " exceeds 8 bits"; + *d++ = ch; + break; + } +#if 0 // TODO(kenton): Support \u and \U? Requires runetochar(). + case 'u': { + // \uhhhh => convert 4 hex digits to UTF-8 + char32 rune = 0; + const char *hex_start = p; + for (int i = 0; i < 4; ++i) { + if (isxdigit(p[1])) { // Look one char ahead. + rune = (rune << 4) + hex_digit_to_int(*++p); // Advance p. + } else { + LOG_STRING(ERROR, errors) + << "\\u must be followed by 4 hex digits: \\" + << string(hex_start, p+1-hex_start); + break; + } + } + d += runetochar(d, &rune); + break; + } + case 'U': { + // \Uhhhhhhhh => convert 8 hex digits to UTF-8 + char32 rune = 0; + const char *hex_start = p; + for (int i = 0; i < 8; ++i) { + if (isxdigit(p[1])) { // Look one char ahead. + // Don't change rune until we're sure this + // is within the Unicode limit, but do advance p. + char32 newrune = (rune << 4) + hex_digit_to_int(*++p); + if (newrune > 0x10FFFF) { + LOG_STRING(ERROR, errors) + << "Value of \\" + << string(hex_start, p + 1 - hex_start) + << " exceeds Unicode limit (0x10FFFF)"; + break; + } else { + rune = newrune; + } + } else { + LOG_STRING(ERROR, errors) + << "\\U must be followed by 8 hex digits: \\" + << string(hex_start, p+1-hex_start); + break; + } + } + d += runetochar(d, &rune); + break; + } +#endif + default: + LOG_STRING(ERROR, errors) << "Unknown escape sequence: \\" << *p; + } + p++; // read past letter we escaped + } + } + *d = '\0'; + return d - dest; +} + +// ---------------------------------------------------------------------- +// UnescapeCEscapeString() +// This does the same thing as UnescapeCEscapeSequences, but creates +// a new string. The caller does not need to worry about allocating +// a dest buffer. This should be used for non performance critical +// tasks such as printing debug messages. It is safe for src and dest +// to be the same. +// +// The second call stores its errors in a supplied string vector. +// If the string vector pointer is NULL, it reports the errors with LOG(). +// +// In the first and second calls, the length of dest is returned. In the +// the third call, the new string is returned. +// ---------------------------------------------------------------------- +int UnescapeCEscapeString(const string& src, string* dest) { + return UnescapeCEscapeString(src, dest, NULL); +} + +int UnescapeCEscapeString(const string& src, string* dest, + vector<string> *errors) { + scoped_array<char> unescaped(new char[src.size() + 1]); + int len = UnescapeCEscapeSequences(src.c_str(), unescaped.get(), errors); + GOOGLE_CHECK(dest); + dest->assign(unescaped.get(), len); + return len; +} + +string UnescapeCEscapeString(const string& src) { + scoped_array<char> unescaped(new char[src.size() + 1]); + int len = UnescapeCEscapeSequences(src.c_str(), unescaped.get(), NULL); + return string(unescaped.get(), len); +} + +// ---------------------------------------------------------------------- +// CEscapeString() +// CHexEscapeString() +// Copies 'src' to 'dest', escaping dangerous characters using +// C-style escape sequences. This is very useful for preparing query +// flags. 'src' and 'dest' should not overlap. The 'Hex' version uses +// hexadecimal rather than octal sequences. +// Returns the number of bytes written to 'dest' (not including the \0) +// or -1 if there was insufficient space. +// +// Currently only \n, \r, \t, ", ', \ and !isprint() chars are escaped. +// ---------------------------------------------------------------------- +static int CEscapeInternal(const char* src, int src_len, char* dest, + int dest_len, bool use_hex) { + const char* src_end = src + src_len; + int used = 0; + bool last_hex_escape = false; // true if last output char was \xNN + + for (; src < src_end; src++) { + if (dest_len - used < 2) // Need space for two letter escape + return -1; + + bool is_hex_escape = false; + switch (*src) { + case '\n': dest[used++] = '\\'; dest[used++] = 'n'; break; + case '\r': dest[used++] = '\\'; dest[used++] = 'r'; break; + case '\t': dest[used++] = '\\'; dest[used++] = 't'; break; + case '\"': dest[used++] = '\\'; dest[used++] = '\"'; break; + case '\'': dest[used++] = '\\'; dest[used++] = '\''; break; + case '\\': dest[used++] = '\\'; dest[used++] = '\\'; break; + default: + // Note that if we emit \xNN and the src character after that is a hex + // digit then that digit must be escaped too to prevent it being + // interpreted as part of the character code by C. + if (!isprint(*src) || (last_hex_escape && isxdigit(*src))) { + if (dest_len - used < 4) // need space for 4 letter escape + return -1; + sprintf(dest + used, (use_hex ? "\\x%02x" : "\\%03o"), + static_cast<uint8>(*src)); + is_hex_escape = use_hex; + used += 4; + } else { + dest[used++] = *src; break; + } + } + last_hex_escape = is_hex_escape; + } + + if (dest_len - used < 1) // make sure that there is room for \0 + return -1; + + dest[used] = '\0'; // doesn't count towards return value though + return used; +} + +int CEscapeString(const char* src, int src_len, char* dest, int dest_len) { + return CEscapeInternal(src, src_len, dest, dest_len, false); +} + +// ---------------------------------------------------------------------- +// CEscape() +// CHexEscape() +// Copies 'src' to result, escaping dangerous characters using +// C-style escape sequences. This is very useful for preparing query +// flags. 'src' and 'dest' should not overlap. The 'Hex' version +// hexadecimal rather than octal sequences. +// +// Currently only \n, \r, \t, ", ', \ and !isprint() chars are escaped. +// ---------------------------------------------------------------------- +string CEscape(const string& src) { + const int dest_length = src.size() * 4 + 1; // Maximum possible expansion + scoped_array<char> dest(new char[dest_length]); + const int len = CEscapeInternal(src.data(), src.size(), + dest.get(), dest_length, false); + GOOGLE_DCHECK_GE(len, 0); + return string(dest.get(), len); +} + +// ---------------------------------------------------------------------- +// strto32_adaptor() +// strtou32_adaptor() +// Implementation of strto[u]l replacements that have identical +// overflow and underflow characteristics for both ILP-32 and LP-64 +// platforms, including errno preservation in error-free calls. +// ---------------------------------------------------------------------- + +int32 strto32_adaptor(const char *nptr, char **endptr, int base) { + const int saved_errno = errno; + errno = 0; + const long result = strtol(nptr, endptr, base); + if (errno == ERANGE && result == LONG_MIN) { + return kint32min; + } else if (errno == ERANGE && result == LONG_MAX) { + return kint32max; + } else if (errno == 0 && result < kint32min) { + errno = ERANGE; + return kint32min; + } else if (errno == 0 && result > kint32max) { + errno = ERANGE; + return kint32max; + } + if (errno == 0) + errno = saved_errno; + return static_cast<int32>(result); +} + +uint32 strtou32_adaptor(const char *nptr, char **endptr, int base) { + const int saved_errno = errno; + errno = 0; + const unsigned long result = strtoul(nptr, endptr, base); + if (errno == ERANGE && result == ULONG_MAX) { + return kuint32max; + } else if (errno == 0 && result > kuint32max) { + errno = ERANGE; + return kuint32max; + } + if (errno == 0) + errno = saved_errno; + return static_cast<uint32>(result); +} + +// ---------------------------------------------------------------------- +// FastIntToBuffer() +// FastInt64ToBuffer() +// FastHexToBuffer() +// FastHex64ToBuffer() +// FastHex32ToBuffer() +// ---------------------------------------------------------------------- + +// Offset into buffer where FastInt64ToBuffer places the end of string +// null character. Also used by FastInt64ToBufferLeft. +static const int kFastInt64ToBufferOffset = 21; + +char *FastInt64ToBuffer(int64 i, char* buffer) { + // We could collapse the positive and negative sections, but that + // would be slightly slower for positive numbers... + // 22 bytes is enough to store -2**64, -18446744073709551616. + char* p = buffer + kFastInt64ToBufferOffset; + *p-- = '\0'; + if (i >= 0) { + do { + *p-- = '0' + i % 10; + i /= 10; + } while (i > 0); + return p + 1; + } else { + // On different platforms, % and / have different behaviors for + // negative numbers, so we need to jump through hoops to make sure + // we don't divide negative numbers. + if (i > -10) { + i = -i; + *p-- = '0' + i; + *p = '-'; + return p; + } else { + // Make sure we aren't at MIN_INT, in which case we can't say i = -i + i = i + 10; + i = -i; + *p-- = '0' + i % 10; + // Undo what we did a moment ago + i = i / 10 + 1; + do { + *p-- = '0' + i % 10; + i /= 10; + } while (i > 0); + *p = '-'; + return p; + } + } +} + +// Offset into buffer where FastInt32ToBuffer places the end of string +// null character. Also used by FastInt32ToBufferLeft +static const int kFastInt32ToBufferOffset = 11; + +// Yes, this is a duplicate of FastInt64ToBuffer. But, we need this for the +// compiler to generate 32 bit arithmetic instructions. It's much faster, at +// least with 32 bit binaries. +char *FastInt32ToBuffer(int32 i, char* buffer) { + // We could collapse the positive and negative sections, but that + // would be slightly slower for positive numbers... + // 12 bytes is enough to store -2**32, -4294967296. + char* p = buffer + kFastInt32ToBufferOffset; + *p-- = '\0'; + if (i >= 0) { + do { + *p-- = '0' + i % 10; + i /= 10; + } while (i > 0); + return p + 1; + } else { + // On different platforms, % and / have different behaviors for + // negative numbers, so we need to jump through hoops to make sure + // we don't divide negative numbers. + if (i > -10) { + i = -i; + *p-- = '0' + i; + *p = '-'; + return p; + } else { + // Make sure we aren't at MIN_INT, in which case we can't say i = -i + i = i + 10; + i = -i; + *p-- = '0' + i % 10; + // Undo what we did a moment ago + i = i / 10 + 1; + do { + *p-- = '0' + i % 10; + i /= 10; + } while (i > 0); + *p = '-'; + return p; + } + } +} + +char *FastHexToBuffer(int i, char* buffer) { + GOOGLE_CHECK(i >= 0) << "FastHexToBuffer() wants non-negative integers, not " << i; + + static const char *hexdigits = "0123456789abcdef"; + char *p = buffer + 21; + *p-- = '\0'; + do { + *p-- = hexdigits[i & 15]; // mod by 16 + i >>= 4; // divide by 16 + } while (i > 0); + return p + 1; +} + +char *InternalFastHexToBuffer(uint64 value, char* buffer, int num_byte) { + static const char *hexdigits = "0123456789abcdef"; + buffer[num_byte] = '\0'; + for (int i = num_byte - 1; i >= 0; i--) { + buffer[i] = hexdigits[uint32(value) & 0xf]; + value >>= 4; + } + return buffer; +} + +char *FastHex64ToBuffer(uint64 value, char* buffer) { + return InternalFastHexToBuffer(value, buffer, 16); +} + +char *FastHex32ToBuffer(uint32 value, char* buffer) { + return InternalFastHexToBuffer(value, buffer, 8); +} + +static inline char* PlaceNum(char* p, int num, char prev_sep) { + *p-- = '0' + num % 10; + *p-- = '0' + num / 10; + *p-- = prev_sep; + return p; +} + +// ---------------------------------------------------------------------- +// FastInt32ToBufferLeft() +// FastUInt32ToBufferLeft() +// FastInt64ToBufferLeft() +// FastUInt64ToBufferLeft() +// +// Like the Fast*ToBuffer() functions above, these are intended for speed. +// Unlike the Fast*ToBuffer() functions, however, these functions write +// their output to the beginning of the buffer (hence the name, as the +// output is left-aligned). The caller is responsible for ensuring that +// the buffer has enough space to hold the output. +// +// Returns a pointer to the end of the string (i.e. the null character +// terminating the string). +// ---------------------------------------------------------------------- + +static const char two_ASCII_digits[100][2] = { + {'0','0'}, {'0','1'}, {'0','2'}, {'0','3'}, {'0','4'}, + {'0','5'}, {'0','6'}, {'0','7'}, {'0','8'}, {'0','9'}, + {'1','0'}, {'1','1'}, {'1','2'}, {'1','3'}, {'1','4'}, + {'1','5'}, {'1','6'}, {'1','7'}, {'1','8'}, {'1','9'}, + {'2','0'}, {'2','1'}, {'2','2'}, {'2','3'}, {'2','4'}, + {'2','5'}, {'2','6'}, {'2','7'}, {'2','8'}, {'2','9'}, + {'3','0'}, {'3','1'}, {'3','2'}, {'3','3'}, {'3','4'}, + {'3','5'}, {'3','6'}, {'3','7'}, {'3','8'}, {'3','9'}, + {'4','0'}, {'4','1'}, {'4','2'}, {'4','3'}, {'4','4'}, + {'4','5'}, {'4','6'}, {'4','7'}, {'4','8'}, {'4','9'}, + {'5','0'}, {'5','1'}, {'5','2'}, {'5','3'}, {'5','4'}, + {'5','5'}, {'5','6'}, {'5','7'}, {'5','8'}, {'5','9'}, + {'6','0'}, {'6','1'}, {'6','2'}, {'6','3'}, {'6','4'}, + {'6','5'}, {'6','6'}, {'6','7'}, {'6','8'}, {'6','9'}, + {'7','0'}, {'7','1'}, {'7','2'}, {'7','3'}, {'7','4'}, + {'7','5'}, {'7','6'}, {'7','7'}, {'7','8'}, {'7','9'}, + {'8','0'}, {'8','1'}, {'8','2'}, {'8','3'}, {'8','4'}, + {'8','5'}, {'8','6'}, {'8','7'}, {'8','8'}, {'8','9'}, + {'9','0'}, {'9','1'}, {'9','2'}, {'9','3'}, {'9','4'}, + {'9','5'}, {'9','6'}, {'9','7'}, {'9','8'}, {'9','9'} +}; + +char* FastUInt32ToBufferLeft(uint32 u, char* buffer) { + int digits; + const char *ASCII_digits = NULL; + // The idea of this implementation is to trim the number of divides to as few + // as possible by using multiplication and subtraction rather than mod (%), + // and by outputting two digits at a time rather than one. + // The huge-number case is first, in the hopes that the compiler will output + // that case in one branch-free block of code, and only output conditional + // branches into it from below. + if (u >= 1000000000) { // >= 1,000,000,000 + digits = u / 100000000; // 100,000,000 + ASCII_digits = two_ASCII_digits[digits]; + buffer[0] = ASCII_digits[0]; + buffer[1] = ASCII_digits[1]; + buffer += 2; +sublt100_000_000: + u -= digits * 100000000; // 100,000,000 +lt100_000_000: + digits = u / 1000000; // 1,000,000 + ASCII_digits = two_ASCII_digits[digits]; + buffer[0] = ASCII_digits[0]; + buffer[1] = ASCII_digits[1]; + buffer += 2; +sublt1_000_000: + u -= digits * 1000000; // 1,000,000 +lt1_000_000: + digits = u / 10000; // 10,000 + ASCII_digits = two_ASCII_digits[digits]; + buffer[0] = ASCII_digits[0]; + buffer[1] = ASCII_digits[1]; + buffer += 2; +sublt10_000: + u -= digits * 10000; // 10,000 +lt10_000: + digits = u / 100; + ASCII_digits = two_ASCII_digits[digits]; + buffer[0] = ASCII_digits[0]; + buffer[1] = ASCII_digits[1]; + buffer += 2; +sublt100: + u -= digits * 100; +lt100: + digits = u; + ASCII_digits = two_ASCII_digits[digits]; + buffer[0] = ASCII_digits[0]; + buffer[1] = ASCII_digits[1]; + buffer += 2; +done: + *buffer = 0; + return buffer; + } + + if (u < 100) { + digits = u; + if (u >= 10) goto lt100; + *buffer++ = '0' + digits; + goto done; + } + if (u < 10000) { // 10,000 + if (u >= 1000) goto lt10_000; + digits = u / 100; + *buffer++ = '0' + digits; + goto sublt100; + } + if (u < 1000000) { // 1,000,000 + if (u >= 100000) goto lt1_000_000; + digits = u / 10000; // 10,000 + *buffer++ = '0' + digits; + goto sublt10_000; + } + if (u < 100000000) { // 100,000,000 + if (u >= 10000000) goto lt100_000_000; + digits = u / 1000000; // 1,000,000 + *buffer++ = '0' + digits; + goto sublt1_000_000; + } + // we already know that u < 1,000,000,000 + digits = u / 100000000; // 100,000,000 + *buffer++ = '0' + digits; + goto sublt100_000_000; +} + +char* FastInt32ToBufferLeft(int32 i, char* buffer) { + uint32 u = i; + if (i < 0) { + *buffer++ = '-'; + u = -i; + } + return FastUInt32ToBufferLeft(u, buffer); +} + +char* FastUInt64ToBufferLeft(uint64 u64, char* buffer) { + int digits; + const char *ASCII_digits = NULL; + + uint32 u = static_cast<uint32>(u64); + if (u == u64) return FastUInt32ToBufferLeft(u, buffer); + + uint64 top_11_digits = u64 / 1000000000; + buffer = FastUInt64ToBufferLeft(top_11_digits, buffer); + u = u64 - (top_11_digits * 1000000000); + + digits = u / 10000000; // 10,000,000 + GOOGLE_DCHECK_LT(digits, 100); + ASCII_digits = two_ASCII_digits[digits]; + buffer[0] = ASCII_digits[0]; + buffer[1] = ASCII_digits[1]; + buffer += 2; + u -= digits * 10000000; // 10,000,000 + digits = u / 100000; // 100,000 + ASCII_digits = two_ASCII_digits[digits]; + buffer[0] = ASCII_digits[0]; + buffer[1] = ASCII_digits[1]; + buffer += 2; + u -= digits * 100000; // 100,000 + digits = u / 1000; // 1,000 + ASCII_digits = two_ASCII_digits[digits]; + buffer[0] = ASCII_digits[0]; + buffer[1] = ASCII_digits[1]; + buffer += 2; + u -= digits * 1000; // 1,000 + digits = u / 10; + ASCII_digits = two_ASCII_digits[digits]; + buffer[0] = ASCII_digits[0]; + buffer[1] = ASCII_digits[1]; + buffer += 2; + u -= digits * 10; + digits = u; + *buffer++ = '0' + digits; + *buffer = 0; + return buffer; +} + +char* FastInt64ToBufferLeft(int64 i, char* buffer) { + uint64 u = i; + if (i < 0) { + *buffer++ = '-'; + u = -i; + } + return FastUInt64ToBufferLeft(u, buffer); +} + +// ---------------------------------------------------------------------- +// SimpleItoa() +// Description: converts an integer to a string. +// +// Return value: string +// ---------------------------------------------------------------------- + +string SimpleItoa(int i) { + char buffer[kFastToBufferSize]; + return (sizeof(i) == 4) ? + FastInt32ToBuffer(i, buffer) : + FastInt64ToBuffer(i, buffer); +} + +string SimpleItoa(unsigned int i) { + char buffer[kFastToBufferSize]; + return string(buffer, (sizeof(i) == 4) ? + FastUInt32ToBufferLeft(i, buffer) : + FastUInt64ToBufferLeft(i, buffer)); +} + +string SimpleItoa(long i) { + char buffer[kFastToBufferSize]; + return (sizeof(i) == 4) ? + FastInt32ToBuffer(i, buffer) : + FastInt64ToBuffer(i, buffer); +} + +string SimpleItoa(unsigned long i) { + char buffer[kFastToBufferSize]; + return string(buffer, (sizeof(i) == 4) ? + FastUInt32ToBufferLeft(i, buffer) : + FastUInt64ToBufferLeft(i, buffer)); +} + +string SimpleItoa(long long i) { + char buffer[kFastToBufferSize]; + return (sizeof(i) == 4) ? + FastInt32ToBuffer(i, buffer) : + FastInt64ToBuffer(i, buffer); +} + +string SimpleItoa(unsigned long long i) { + char buffer[kFastToBufferSize]; + return string(buffer, (sizeof(i) == 4) ? + FastUInt32ToBufferLeft(i, buffer) : + FastUInt64ToBufferLeft(i, buffer)); +} + +// ---------------------------------------------------------------------- +// SimpleDtoa() +// SimpleFtoa() +// DoubleToBuffer() +// FloatToBuffer() +// We want to print the value without losing precision, but we also do +// not want to print more digits than necessary. This turns out to be +// trickier than it sounds. Numbers like 0.2 cannot be represented +// exactly in binary. If we print 0.2 with a very large precision, +// e.g. "%.50g", we get "0.2000000000000000111022302462515654042363167". +// On the other hand, if we set the precision too low, we lose +// significant digits when printing numbers that actually need them. +// It turns out there is no precision value that does the right thing +// for all numbers. +// +// Our strategy is to first try printing with a precision that is never +// over-precise, then parse the result with strtod() to see if it +// matches. If not, we print again with a precision that will always +// give a precise result, but may use more digits than necessary. +// +// An arguably better strategy would be to use the algorithm described +// in "How to Print Floating-Point Numbers Accurately" by Steele & +// White, e.g. as implemented by David M. Gay's dtoa(). It turns out, +// however, that the following implementation is about as fast as +// DMG's code. Furthermore, DMG's code locks mutexes, which means it +// will not scale well on multi-core machines. DMG's code is slightly +// more accurate (in that it will never use more digits than +// necessary), but this is probably irrelevant for most users. +// +// Rob Pike and Ken Thompson also have an implementation of dtoa() in +// third_party/fmt/fltfmt.cc. Their implementation is similar to this +// one in that it makes guesses and then uses strtod() to check them. +// Their implementation is faster because they use their own code to +// generate the digits in the first place rather than use snprintf(), +// thus avoiding format string parsing overhead. However, this makes +// it considerably more complicated than the following implementation, +// and it is embedded in a larger library. If speed turns out to be +// an issue, we could re-implement this in terms of their +// implementation. +// ---------------------------------------------------------------------- + +string SimpleDtoa(double value) { + char buffer[kDoubleToBufferSize]; + return DoubleToBuffer(value, buffer); +} + +string SimpleFtoa(float value) { + char buffer[kFloatToBufferSize]; + return FloatToBuffer(value, buffer); +} + +static inline bool IsValidFloatChar(char c) { + return ('0' <= c && c <= '9') || + c == 'e' || c == 'E' || + c == '+' || c == '-'; +} + +void DelocalizeRadix(char* buffer) { + // Fast check: if the buffer has a normal decimal point, assume no + // translation is needed. + if (strchr(buffer, '.') != NULL) return; + + // Find the first unknown character. + while (IsValidFloatChar(*buffer)) ++buffer; + + if (*buffer == '\0') { + // No radix character found. + return; + } + + // We are now pointing at the locale-specific radix character. Replace it + // with '.'. + *buffer = '.'; + ++buffer; + + if (!IsValidFloatChar(*buffer) && *buffer != '\0') { + // It appears the radix was a multi-byte character. We need to remove the + // extra bytes. + char* target = buffer; + do { ++buffer; } while (!IsValidFloatChar(*buffer) && *buffer != '\0'); + memmove(target, buffer, strlen(buffer) + 1); + } +} + +char* DoubleToBuffer(double value, char* buffer) { + // DBL_DIG is 15 for IEEE-754 doubles, which are used on almost all + // platforms these days. Just in case some system exists where DBL_DIG + // is significantly larger -- and risks overflowing our buffer -- we have + // this assert. + GOOGLE_COMPILE_ASSERT(DBL_DIG < 20, DBL_DIG_is_too_big); + + if (value == numeric_limits<double>::infinity()) { + strcpy(buffer, "inf"); + return buffer; + } else if (value == -numeric_limits<double>::infinity()) { + strcpy(buffer, "-inf"); + return buffer; + } else if (IsNaN(value)) { + strcpy(buffer, "nan"); + return buffer; + } + + int snprintf_result = + snprintf(buffer, kDoubleToBufferSize, "%.*g", DBL_DIG, value); + + // The snprintf should never overflow because the buffer is significantly + // larger than the precision we asked for. + GOOGLE_DCHECK(snprintf_result > 0 && snprintf_result < kDoubleToBufferSize); + + // We need to make parsed_value volatile in order to force the compiler to + // write it out to the stack. Otherwise, it may keep the value in a + // register, and if it does that, it may keep it as a long double instead + // of a double. This long double may have extra bits that make it compare + // unequal to "value" even though it would be exactly equal if it were + // truncated to a double. + volatile double parsed_value = strtod(buffer, NULL); + if (parsed_value != value) { + int snprintf_result = + snprintf(buffer, kDoubleToBufferSize, "%.*g", DBL_DIG+2, value); + + // Should never overflow; see above. + GOOGLE_DCHECK(snprintf_result > 0 && snprintf_result < kDoubleToBufferSize); + } + + DelocalizeRadix(buffer); + return buffer; +} + +bool safe_strtof(const char* str, float* value) { + char* endptr; + errno = 0; // errno only gets set on errors +#ifdef _WIN32 // has no strtof() + *value = strtod(str, &endptr); +#else + *value = strtof(str, &endptr); +#endif + return *str != 0 && *endptr == 0 && errno == 0; +} + +char* FloatToBuffer(float value, char* buffer) { + // FLT_DIG is 6 for IEEE-754 floats, which are used on almost all + // platforms these days. Just in case some system exists where FLT_DIG + // is significantly larger -- and risks overflowing our buffer -- we have + // this assert. + GOOGLE_COMPILE_ASSERT(FLT_DIG < 10, FLT_DIG_is_too_big); + + if (value == numeric_limits<double>::infinity()) { + strcpy(buffer, "inf"); + return buffer; + } else if (value == -numeric_limits<double>::infinity()) { + strcpy(buffer, "-inf"); + return buffer; + } else if (IsNaN(value)) { + strcpy(buffer, "nan"); + return buffer; + } + + int snprintf_result = + snprintf(buffer, kFloatToBufferSize, "%.*g", FLT_DIG, value); + + // The snprintf should never overflow because the buffer is significantly + // larger than the precision we asked for. + GOOGLE_DCHECK(snprintf_result > 0 && snprintf_result < kFloatToBufferSize); + + float parsed_value; + if (!safe_strtof(buffer, &parsed_value) || parsed_value != value) { + int snprintf_result = + snprintf(buffer, kFloatToBufferSize, "%.*g", FLT_DIG+2, value); + + // Should never overflow; see above. + GOOGLE_DCHECK(snprintf_result > 0 && snprintf_result < kFloatToBufferSize); + } + + DelocalizeRadix(buffer); + return buffer; +} + +// ---------------------------------------------------------------------- +// NoLocaleStrtod() +// This code will make you cry. +// ---------------------------------------------------------------------- + +// Returns a string identical to *input except that the character pointed to +// by radix_pos (which should be '.') is replaced with the locale-specific +// radix character. +string LocalizeRadix(const char* input, const char* radix_pos) { + // Determine the locale-specific radix character by calling sprintf() to + // print the number 1.5, then stripping off the digits. As far as I can + // tell, this is the only portable, thread-safe way to get the C library + // to divuldge the locale's radix character. No, localeconv() is NOT + // thread-safe. + char temp[16]; + int size = sprintf(temp, "%.1f", 1.5); + GOOGLE_CHECK_EQ(temp[0], '1'); + GOOGLE_CHECK_EQ(temp[size-1], '5'); + GOOGLE_CHECK_LE(size, 6); + + // Now replace the '.' in the input with it. + string result; + result.reserve(strlen(input) + size - 3); + result.append(input, radix_pos); + result.append(temp + 1, size - 2); + result.append(radix_pos + 1); + return result; +} + +double NoLocaleStrtod(const char* text, char** original_endptr) { + // We cannot simply set the locale to "C" temporarily with setlocale() + // as this is not thread-safe. Instead, we try to parse in the current + // locale first. If parsing stops at a '.' character, then this is a + // pretty good hint that we're actually in some other locale in which + // '.' is not the radix character. + + char* temp_endptr; + double result = strtod(text, &temp_endptr); + if (original_endptr != NULL) *original_endptr = temp_endptr; + if (*temp_endptr != '.') return result; + + // Parsing halted on a '.'. Perhaps we're in a different locale? Let's + // try to replace the '.' with a locale-specific radix character and + // try again. + string localized = LocalizeRadix(text, temp_endptr); + const char* localized_cstr = localized.c_str(); + char* localized_endptr; + result = strtod(localized_cstr, &localized_endptr); + if ((localized_endptr - localized_cstr) > + (temp_endptr - text)) { + // This attempt got further, so replacing the decimal must have helped. + // Update original_endptr to point at the right location. + if (original_endptr != NULL) { + // size_diff is non-zero if the localized radix has multiple bytes. + int size_diff = localized.size() - strlen(text); + // const_cast is necessary to match the strtod() interface. + *original_endptr = const_cast<char*>( + text + (localized_endptr - localized_cstr - size_diff)); + } + } + + return result; +} + +} // namespace protobuf +} // namespace google |