blob: 917b3e9fb06e378d00f39994f09a8f2309204ebe [file] [log] [blame]
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// http://code.google.com/p/protobuf/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// 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>
#include <stdio.h>
#include <iterator>
#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;
}
// These are defined as macros on some platforms. #undef them so that we can
// redefine them.
#undef isxdigit
#undef isprint
// 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.
inline bool isxdigit(char c) {
return ('0' <= c && c <= '9') ||
('a' <= c && c <= 'f') ||
('A' <= c && c <= 'F');
}
inline 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);
}
// Split a string using a character delimiter. Append the components
// to 'result'. If there are consecutive delimiters, this function
// will return corresponding empty strings. The string is split into
// at most the specified number of pieces greedily. This means that the
// last piece may possibly be split further. To split into as many pieces
// as possible, specify 0 as the number of pieces.
//
// If "full" is the empty string, yields an empty string as the only value.
//
// If "pieces" is negative for some reason, it returns the whole string
// ----------------------------------------------------------------------
template <typename StringType, typename ITR>
static inline
void SplitStringToIteratorAllowEmpty(const StringType& full,
const char* delim,
int pieces,
ITR& result) {
string::size_type begin_index, end_index;
begin_index = 0;
for (int i = 0; (i < pieces-1) || (pieces == 0); i++) {
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 = end_index + 1;
}
*result++ = full.substr(begin_index);
}
void SplitStringAllowEmpty(const string& full, const char* delim,
vector<string>* result) {
back_insert_iterator<vector<string> > it(*result);
SplitStringToIteratorAllowEmpty(full, delim, 0, 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.
// ----------------------------------------------------------------------
int CEscapeInternal(const char* src, int src_len, char* dest,
int dest_len, bool use_hex, bool utf8_safe) {
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 ((!utf8_safe || static_cast<uint8>(*src) < 0x80) &&
(!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, 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, false);
GOOGLE_DCHECK_GE(len, 0);
return string(dest.get(), len);
}
namespace strings {
string Utf8SafeCEscape(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, true);
GOOGLE_DCHECK_GE(len, 0);
return string(dest.get(), len);
}
string CHexEscape(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, true, false);
GOOGLE_DCHECK_GE(len, 0);
return string(dest.get(), len);
}
} // namespace strings
// ----------------------------------------------------------------------
// 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--) {
#ifdef _M_X64
// MSVC x64 platform has a bug optimizing the uint32(value) in the #else
// block. Given that the uint32 cast was to improve performance on 32-bit
// platforms, we use 64-bit '&' directly.
buffer[i] = hexdigits[value & 0xf];
#else
buffer[i] = hexdigits[uint32(value) & 0xf];
#endif
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
#if defined(_WIN32) || defined (__hpux) // 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