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// Copyright (c) 2016 Ryan Prichard
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
// Efficient integer->string conversion and string concatenation. The
// hexadecimal conversion may optionally have leading zeros. Other ways to
// convert integers to strings in C++ suffer these drawbacks:
//
// * std::stringstream: Inefficient, even more so than stdio.
//
// * std::to_string: No hexadecimal output, tends to use heap allocation, not
// supported on Cygwin.
//
// * stdio routines: Requires parsing a format string (inefficient). The
// caller *must* know how large the content is for correctness. The
// string-printf functions are extremely inconsistent on Windows. In
// particular, 64-bit integers, wide strings, and return values are
// problem areas.
//
// StringBuilderTest.cc is a standalone program that tests this header.
#ifndef WINPTY_STRING_BUILDER_H
#define WINPTY_STRING_BUILDER_H
#include <array>
#include <string>
#include <type_traits>
#ifdef STRING_BUILDER_TESTING
#include <assert.h>
#define STRING_BUILDER_CHECK(cond) assert(cond)
#else
#define STRING_BUILDER_CHECK(cond)
#endif // STRING_BUILDER_TESTING
#include "WinptyAssert.h"
template <typename C, size_t sz>
struct ValueString {
std::array<C, sz> m_array;
size_t m_offset;
size_t m_size;
const C *c_str() const { return m_array.data() + m_offset; }
const C *data() const { return m_array.data() + m_offset; }
size_t size() const { return m_size; }
std::basic_string<C> str() const {
return std::basic_string<C>(data(), m_size);
}
};
#ifdef _MSC_VER
// Disable an MSVC /SDL error that forbids unsigned negation. Signed negation
// invokes undefined behavior for INTxx_MIN, so unsigned negation is simpler to
// reason about. (We assume twos-complement in any case.)
#define STRING_BUILDER_ALLOW_UNSIGNED_NEGATE(x) \
( \
__pragma(warning(push)) \
__pragma(warning(disable:4146)) \
(x) \
__pragma(warning(pop)) \
)
#else
#define STRING_BUILDER_ALLOW_UNSIGNED_NEGATE(x) (x)
#endif
// Formats an integer as decimal without leading zeros.
template <typename C, typename I>
ValueString<C, sizeof(I) * 3 + 1 + 1> gdecOfInt(const I value) {
typedef typename std::make_unsigned<I>::type U;
auto unsValue = static_cast<U>(value);
const bool isNegative = (value < 0);
if (isNegative) {
unsValue = STRING_BUILDER_ALLOW_UNSIGNED_NEGATE(-unsValue);
}
decltype(gdecOfInt<C, I>(value)) out;
auto &arr = out.m_array;
C *const endp = arr.data() + arr.size();
C *outp = endp;
*(--outp) = '\0';
STRING_BUILDER_CHECK(outp >= arr.data());
do {
const int digit = unsValue % 10;
unsValue /= 10;
*(--outp) = '0' + digit;
STRING_BUILDER_CHECK(outp >= arr.data());
} while (unsValue != 0);
if (isNegative) {
*(--outp) = '-';
STRING_BUILDER_CHECK(outp >= arr.data());
}
out.m_offset = outp - arr.data();
out.m_size = endp - outp - 1;
return out;
}
template <typename I> decltype(gdecOfInt<char, I>(0)) decOfInt(I i) {
return gdecOfInt<char>(i);
}
template <typename I> decltype(gdecOfInt<wchar_t, I>(0)) wdecOfInt(I i) {
return gdecOfInt<wchar_t>(i);
}
// Formats an integer as hexadecimal, with or without leading zeros.
template <typename C, bool leadingZeros=false, typename I>
ValueString<C, sizeof(I) * 2 + 1> ghexOfInt(const I value) {
typedef typename std::make_unsigned<I>::type U;
const auto unsValue = static_cast<U>(value);
static const C hex[16] = {'0','1','2','3','4','5','6','7',
'8','9','a','b','c','d','e','f'};
decltype(ghexOfInt<C, leadingZeros, I>(value)) out;
auto &arr = out.m_array;
C *outp = arr.data();
int inIndex = 0;
int shift = sizeof(I) * 8 - 4;
const int len = sizeof(I) * 2;
if (!leadingZeros) {
for (; inIndex < len - 1; ++inIndex, shift -= 4) {
STRING_BUILDER_CHECK(shift >= 0 && shift < sizeof(unsValue) * 8);
const int digit = (unsValue >> shift) & 0xF;
if (digit != 0) {
break;
}
}
}
for (; inIndex < len; ++inIndex, shift -= 4) {
const int digit = (unsValue >> shift) & 0xF;
*(outp++) = hex[digit];
STRING_BUILDER_CHECK(outp <= arr.data() + arr.size());
}
*(outp++) = '\0';
STRING_BUILDER_CHECK(outp <= arr.data() + arr.size());
out.m_offset = 0;
out.m_size = outp - arr.data() - 1;
return out;
}
template <bool leadingZeros=false, typename I>
decltype(ghexOfInt<char, leadingZeros, I>(0)) hexOfInt(I i) {
return ghexOfInt<char, leadingZeros, I>(i);
}
template <bool leadingZeros=false, typename I>
decltype(ghexOfInt<wchar_t, leadingZeros, I>(0)) whexOfInt(I i) {
return ghexOfInt<wchar_t, leadingZeros, I>(i);
}
template <typename C>
class GStringBuilder {
public:
typedef std::basic_string<C> StringType;
GStringBuilder() {}
GStringBuilder(size_t capacity) {
m_out.reserve(capacity);
}
GStringBuilder &operator<<(C ch) { m_out.push_back(ch); return *this; }
GStringBuilder &operator<<(const C *str) { m_out.append(str); return *this; }
GStringBuilder &operator<<(const StringType &str) { m_out.append(str); return *this; }
template <size_t sz>
GStringBuilder &operator<<(const ValueString<C, sz> &str) {
m_out.append(str.data(), str.size());
return *this;
}
private:
// Forbid output of char/wchar_t for GStringBuilder if the type doesn't
// exactly match the builder element type. The code still allows
// signed char and unsigned char, but I'm a little worried about what
// happens if a user tries to output int8_t or uint8_t.
template <typename P>
typename std::enable_if<
(std::is_same<P, char>::value || std::is_same<P, wchar_t>::value) &&
!std::is_same<C, P>::value, GStringBuilder&>::type
operator<<(P ch) {
ASSERT(false && "Method was not supposed to be reachable.");
return *this;
}
public:
GStringBuilder &operator<<(short i) { return *this << gdecOfInt<C>(i); }
GStringBuilder &operator<<(unsigned short i) { return *this << gdecOfInt<C>(i); }
GStringBuilder &operator<<(int i) { return *this << gdecOfInt<C>(i); }
GStringBuilder &operator<<(unsigned int i) { return *this << gdecOfInt<C>(i); }
GStringBuilder &operator<<(long i) { return *this << gdecOfInt<C>(i); }
GStringBuilder &operator<<(unsigned long i) { return *this << gdecOfInt<C>(i); }
GStringBuilder &operator<<(long long i) { return *this << gdecOfInt<C>(i); }
GStringBuilder &operator<<(unsigned long long i) { return *this << gdecOfInt<C>(i); }
GStringBuilder &operator<<(const void *p) {
m_out.push_back(static_cast<C>('0'));
m_out.push_back(static_cast<C>('x'));
*this << ghexOfInt<C>(reinterpret_cast<uintptr_t>(p));
return *this;
}
StringType str() { return m_out; }
StringType str_moved() { return std::move(m_out); }
const C *c_str() const { return m_out.c_str(); }
private:
StringType m_out;
};
typedef GStringBuilder<char> StringBuilder;
typedef GStringBuilder<wchar_t> WStringBuilder;
#endif // WINPTY_STRING_BUILDER_H
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