mirror of
https://github.com/fmtlib/fmt.git
synced 2025-10-31 06:01:41 +01:00
369 lines
9.3 KiB
C++
369 lines
9.3 KiB
C++
/*
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Small, safe and fast string formatting library for C++
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Author: Victor Zverovich
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*/
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#include "format.h"
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#include <stdint.h>
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#include <cassert>
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#include <climits>
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#include <cstring>
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#include <algorithm>
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using std::size_t;
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namespace {
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// Flags.
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enum { PLUS_FLAG = 1, ZERO_FLAG = 2, HEX_PREFIX_FLAG = 4 };
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// Throws Exception(message) if format contains '}', otherwise throws
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// FormatError reporting unmatched '{'. The idea is that unmatched '{'
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// should override other errors.
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void ReportError(const char *s, const std::string &message) {
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for (int num_open_braces = 1; *s; ++s) {
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if (*s == '{') {
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++num_open_braces;
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} else if (*s == '}') {
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if (--num_open_braces == 0)
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throw fmt::FormatError(message);
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}
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}
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throw fmt::FormatError("unmatched '{' in format");
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}
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void ReportUnknownType(char code, const char *type) {
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if (std::isprint(code)) {
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throw fmt::FormatError(
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str(fmt::Format("unknown format code '{0}' for {1}") << code << type));
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}
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throw fmt::FormatError(
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str(fmt::Format("unknown format code '\\x{0:02x}' for {1}")
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<< static_cast<unsigned>(code) << type));
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}
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// Parses an unsigned integer advancing s to the end of the parsed input.
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// This function assumes that the first character of s is a digit.
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unsigned ParseUInt(const char *&s) {
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assert('0' <= *s && *s <= '9');
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unsigned value = 0;
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do {
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unsigned new_value = value * 10 + (*s++ - '0');
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if (new_value < value) // Check if value wrapped around.
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ReportError(s, "number is too big in format");
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value = new_value;
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} while ('0' <= *s && *s <= '9');
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return value;
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}
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// Maps an integer type T to its unsigned counterpart.
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template <typename T>
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struct GetUnsigned;
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template <>
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struct GetUnsigned<int> {
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typedef unsigned Type;
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};
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template <>
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struct GetUnsigned<unsigned> {
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typedef unsigned Type;
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};
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template <>
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struct GetUnsigned<long> {
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typedef unsigned long Type;
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};
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template <>
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struct GetUnsigned<unsigned long> {
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typedef unsigned long Type;
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};
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template <typename T>
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struct IsLongDouble { enum {VALUE = 0}; };
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template <>
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struct IsLongDouble<long double> { enum {VALUE = 1}; };
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}
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template <typename T>
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void fmt::Formatter::FormatInt(T value, unsigned flags, int width, char type) {
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int size = 0;
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char sign = 0;
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typedef typename GetUnsigned<T>::Type UnsignedType;
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UnsignedType abs_value = value;
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if (value < 0) {
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sign = '-';
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++size;
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abs_value = -value;
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} else if ((flags & PLUS_FLAG) != 0) {
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sign = '+';
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++size;
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}
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char fill = (flags & ZERO_FLAG) != 0 ? '0' : ' ';
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size_t start = buffer_.size();
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char *p = 0;
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switch (type) {
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case 0: case 'd': {
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UnsignedType n = abs_value;
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do {
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++size;
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} while ((n /= 10) != 0);
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width = std::max(width, size);
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p = GrowBuffer(width) + width - 1;
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n = abs_value;
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do {
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*p-- = '0' + (n % 10);
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} while ((n /= 10) != 0);
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break;
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}
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case 'x': case 'X': {
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UnsignedType n = abs_value;
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bool print_prefix = (flags & HEX_PREFIX_FLAG) != 0;
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if (print_prefix) size += 2;
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do {
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++size;
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} while ((n >>= 4) != 0);
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width = std::max(width, size);
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p = GrowBuffer(width) + width - 1;
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n = abs_value;
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const char *digits = type == 'x' ? "0123456789abcdef" : "0123456789ABCDEF";
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do {
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*p-- = digits[n & 0xf];
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} while ((n >>= 4) != 0);
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if (print_prefix) {
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*p-- = type;
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*p-- = '0';
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}
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break;
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}
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case 'o': {
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UnsignedType n = abs_value;
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do {
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++size;
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} while ((n >>= 3) != 0);
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width = std::max(width, size);
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p = GrowBuffer(width) + width - 1;
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n = abs_value;
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do {
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*p-- = '0' + (n & 7);
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} while ((n >>= 3) != 0);
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break;
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}
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default:
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ReportUnknownType(type, "integer");
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break;
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}
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if (sign) {
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if ((flags & ZERO_FLAG) != 0)
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buffer_[start++] = sign;
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else
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*p-- = sign;
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}
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std::fill(&buffer_[start], p + 1, fill);
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}
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template <typename T>
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void fmt::Formatter::FormatDouble(
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T value, unsigned flags, int width, int precision, char type) {
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// Check type.
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switch (type) {
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case 0:
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type = 'g';
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break;
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case 'e': case 'E': case 'f': case 'F': case 'g': case 'G':
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break;
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default:
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ReportUnknownType(type, "double");
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break;
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}
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// Build format string.
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enum { MAX_FORMAT_SIZE = 9}; // longest format: %+0*.*Lg
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char format[MAX_FORMAT_SIZE];
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char *format_ptr = format;
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*format_ptr++ = '%';
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if ((flags & PLUS_FLAG) != 0)
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*format_ptr++ = '+';
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if ((flags & ZERO_FLAG) != 0)
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*format_ptr++ = '0';
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if (width > 0)
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*format_ptr++ = '*';
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if (precision >= 0) {
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*format_ptr++ = '.';
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*format_ptr++ = '*';
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}
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if (IsLongDouble<T>::VALUE)
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*format_ptr++ = 'L';
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*format_ptr++ = type;
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*format_ptr = '\0';
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// Format using snprintf.
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size_t offset = buffer_.size();
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for (;;) {
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size_t size = buffer_.capacity() - offset;
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int n = 0;
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if (width <= 0) {
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n = precision < 0 ?
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snprintf(&buffer_[offset], size, format, value) :
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snprintf(&buffer_[offset], size, format, precision, value);
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} else {
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n = precision < 0 ?
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snprintf(&buffer_[offset], size, format, width, value) :
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snprintf(&buffer_[offset], size, format, width, precision, value);
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}
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if (n >= 0 && offset + n < buffer_.capacity()) {
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GrowBuffer(n);
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return;
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}
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buffer_.reserve(n >= 0 ? offset + n + 1 : 2 * buffer_.capacity());
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}
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}
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void fmt::Formatter::DoFormat() {
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const char *start = format_;
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format_ = 0;
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const char *s = start;
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while (*s) {
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char c = *s++;
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if (c != '{' && c != '}') continue;
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if (*s == c) {
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buffer_.append(start, s);
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start = ++s;
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continue;
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}
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if (c == '}')
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throw FormatError("unmatched '}' in format");
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buffer_.append(start, s - 1);
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// Parse argument index.
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if (*s < '0' || *s > '9')
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ReportError(s, "missing argument index in format string");
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unsigned arg_index = ParseUInt(s);
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if (arg_index >= args_.size())
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ReportError(s, "argument index is out of range in format");
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const Arg &arg = *args_[arg_index];
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unsigned flags = 0;
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int width = 0;
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int precision = -1;
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char type = 0;
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if (*s == ':') {
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++s;
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if (*s == '+') {
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++s;
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if (arg.type > LAST_NUMERIC_TYPE)
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ReportError(s, "format specifier '+' requires numeric argument");
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if (arg.type == UINT || arg.type == ULONG) {
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ReportError(s,
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"format specifier '+' requires signed argument");
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}
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flags |= PLUS_FLAG;
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}
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if (*s == '0') {
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++s;
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if (arg.type > LAST_NUMERIC_TYPE)
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ReportError(s, "format specifier '0' requires numeric argument");
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flags |= ZERO_FLAG;
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}
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// Parse width.
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if ('0' <= *s && *s <= '9') {
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unsigned value = ParseUInt(s);
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if (value > INT_MAX)
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ReportError(s, "number is too big in format");
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width = value;
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}
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// Parse precision.
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if (*s == '.') {
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++s;
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precision = 0;
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if ('0' <= *s && *s <= '9') {
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unsigned value = ParseUInt(s);
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if (value > INT_MAX)
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ReportError(s, "number is too big in format");
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precision = value;
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} else {
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ReportError(s, "missing precision in format");
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}
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if (arg.type != DOUBLE && arg.type != LONG_DOUBLE) {
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ReportError(s,
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"precision specifier requires floating-point argument");
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}
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}
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// Parse type.
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if (*s != '}' && *s)
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type = *s++;
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}
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if (*s++ != '}')
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throw FormatError("unmatched '{' in format");
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start = s;
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// Format argument.
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switch (arg.type) {
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case INT:
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FormatInt(arg.int_value, flags, width, type);
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break;
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case UINT:
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FormatInt(arg.uint_value, flags, width, type);
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break;
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case LONG:
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FormatInt(arg.long_value, flags, width, type);
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break;
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case ULONG:
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FormatInt(arg.ulong_value, flags, width, type);
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break;
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case DOUBLE:
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FormatDouble(arg.double_value, flags, width, precision, type);
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break;
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case LONG_DOUBLE:
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FormatDouble(arg.long_double_value, flags, width, precision, type);
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break;
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case CHAR: {
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if (type && type != 'c')
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ReportUnknownType(type, "char");
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char *out = GrowBuffer(std::max(width, 1));
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*out++ = arg.int_value;
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if (width > 1)
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std::fill_n(out, width - 1, ' ');
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break;
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}
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case STRING: {
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if (type && type != 's')
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ReportUnknownType(type, "string");
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const char *str = arg.string_value;
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size_t size = arg.size;
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if (size == 0 && *str)
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size = std::strlen(str);
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char *out = GrowBuffer(std::max<size_t>(width, size));
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out = std::copy(str, str + size, out);
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if (width > size)
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std::fill_n(out, width - size, ' ');
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break;
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}
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case POINTER:
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if (type && type != 'p')
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ReportUnknownType(type, "pointer");
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FormatInt(reinterpret_cast<uintptr_t>(
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arg.pointer_value), HEX_PREFIX_FLAG, width, 'x');
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break;
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case CUSTOM:
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if (type)
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ReportUnknownType(type, "object");
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(this->*arg.format)(arg.custom_value, width);
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break;
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default:
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assert(false);
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break;
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}
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}
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buffer_.append(start, s + 1);
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buffer_.resize(buffer_.size() - 1); // Don't count the terminating zero.
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}
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