Add a StringBuilder class that resembles an efficient std::stringstream
This commit is contained in:
Ryan Prichard
parent
ba0e3a49fd
commit
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198
src/shared/StringBuilder.h
Executable file
198
src/shared/StringBuilder.h
Executable file
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// Copyright (c) 2016 Ryan Prichard
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to
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// deal in the Software without restriction, including without limitation the
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// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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// sell copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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// IN THE SOFTWARE.
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// Efficient integer->string conversion and string concatenation. The
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// hexadecimal conversion may optionally have leading zeros. Other ways to
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// convert integers to strings in C++ suffer these drawbacks:
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//
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// * std::stringstream: Inefficient, even more so than stdio.
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//
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// * std::to_string: No hexadecimal output, tends to use heap allocation, not
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// supported on Cygwin.
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//
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// * stdio routines: Requires parsing a format string (inefficient). The
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// caller *must* know how large the content is for correctness. The
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// string-printf functions are extremely inconsistent on Windows. In
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// particular, 64-bit integers, wide strings, and return values are
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// problem areas.
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//
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// StringBuilderTest.cc is a standalone program that tests this header.
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#ifndef WINPTY_STRING_BUILDER_H
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#define WINPTY_STRING_BUILDER_H
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#include <array>
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#include <string>
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namespace winpty_shared {
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#ifdef STRING_BUILDER_TESTING
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#include <assert.h>
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#define STRING_BUILDER_CHECK(cond) assert(cond)
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#else
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#define STRING_BUILDER_CHECK(cond)
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#endif // STRING_BUILDER_TESTING
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template <typename C, size_t sz>
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struct ValueString {
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std::array<C, sz> m_array;
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size_t m_offset;
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size_t m_size;
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const C *c_str() const { return m_array.data() + m_offset; }
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const C *data() const { return m_array.data() + m_offset; }
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size_t size() const { return m_size; }
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std::basic_string<C> str() const {
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return std::basic_string<C>(data(), m_size);
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}
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};
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// Formats an integer as decimal without leading zeros.
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template <typename C, typename I>
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ValueString<C, sizeof(I) * 3 + 1 + 1> gdecOfInt(const I value) {
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typedef typename std::make_unsigned<I>::type U;
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auto unsValue = static_cast<U>(value);
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const bool isNegative = (value < 0);
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if (isNegative) {
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unsValue = -unsValue;
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}
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decltype(gdecOfInt<C, I>(value)) out;
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auto &arr = out.m_array;
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C *const endp = arr.data() + arr.size();
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C *outp = endp;
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*(--outp) = '\0';
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STRING_BUILDER_CHECK(outp >= arr.data());
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do {
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const int digit = unsValue % 10;
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unsValue /= 10;
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*(--outp) = '0' + digit;
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STRING_BUILDER_CHECK(outp >= arr.data());
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} while (unsValue != 0);
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if (isNegative) {
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*(--outp) = '-';
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STRING_BUILDER_CHECK(outp >= arr.data());
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}
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out.m_offset = outp - arr.data();
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out.m_size = endp - outp - 1;
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return out;
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}
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template <typename I> decltype(gdecOfInt<char, I>(0)) decOfInt(I i) {
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return gdecOfInt<char>(i);
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}
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template <typename I> decltype(gdecOfInt<wchar_t, I>(0)) wdecOfInt(I i) {
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return gdecOfInt<wchar_t>(i);
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}
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// Formats an integer as hexadecimal, with or without leading zeros.
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template <typename C, bool leadingZeros=false, typename I>
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ValueString<C, sizeof(I) * 2 + 1> ghexOfInt(const I value) {
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typedef typename std::make_unsigned<I>::type U;
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const auto unsValue = static_cast<U>(value);
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static const C hex[16] = {'0','1','2','3','4','5','6','7',
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'8','9','a','b','c','d','e','f'};
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decltype(ghexOfInt<C, leadingZeros, I>(value)) out;
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auto &arr = out.m_array;
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C *outp = arr.data();
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int inIndex = 0;
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int shift = sizeof(I) * 8 - 4;
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const int len = sizeof(I) * 2;
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if (!leadingZeros) {
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for (; inIndex < len - 1; ++inIndex, shift -= 4) {
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STRING_BUILDER_CHECK(shift >= 0 && shift < sizeof(unsValue) * 8);
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const int digit = (unsValue >> shift) & 0xF;
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if (digit != 0) {
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break;
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}
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}
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}
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for (; inIndex < len; ++inIndex, shift -= 4) {
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const int digit = (unsValue >> shift) & 0xF;
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*(outp++) = hex[digit];
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STRING_BUILDER_CHECK(outp <= arr.data() + arr.size());
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}
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*(outp++) = '\0';
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STRING_BUILDER_CHECK(outp <= arr.data() + arr.size());
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out.m_offset = 0;
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out.m_size = outp - arr.data() - 1;
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return out;
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}
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template <bool leadingZeros=false, typename I>
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decltype(ghexOfInt<char, leadingZeros, I>(0)) hexOfInt(I i) {
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return ghexOfInt<char, leadingZeros, I>(i);
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}
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template <bool leadingZeros=false, typename I>
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decltype(ghexOfInt<wchar_t, leadingZeros, I>(0)) whexOfInt(I i) {
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return ghexOfInt<wchar_t, leadingZeros, I>(i);
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}
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template <typename C>
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class GStringBuilder {
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public:
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typedef std::basic_string<C> StringType;
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GStringBuilder() {}
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GStringBuilder(size_t capacity) {
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m_out.reserve(capacity);
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}
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GStringBuilder &operator<<(C ch) { m_out.push_back(ch); return *this; }
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GStringBuilder &operator<<(const C *str) { m_out.append(str); return *this; }
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GStringBuilder &operator<<(const StringType &str) { m_out.append(str); return *this; }
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template <size_t sz>
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GStringBuilder &operator<<(const ValueString<C, sz> &str) {
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m_out.append(str.data(), str.size());
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return *this;
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}
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GStringBuilder &operator<<(short i) { return *this << gdecOfInt<C>(i); }
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GStringBuilder &operator<<(unsigned short i) { return *this << gdecOfInt<C>(i); }
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GStringBuilder &operator<<(int i) { return *this << gdecOfInt<C>(i); }
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GStringBuilder &operator<<(unsigned int i) { return *this << gdecOfInt<C>(i); }
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GStringBuilder &operator<<(long i) { return *this << gdecOfInt<C>(i); }
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GStringBuilder &operator<<(unsigned long i) { return *this << gdecOfInt<C>(i); }
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GStringBuilder &operator<<(long long i) { return *this << gdecOfInt<C>(i); }
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GStringBuilder &operator<<(unsigned long long i) { return *this << gdecOfInt<C>(i); }
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GStringBuilder &operator<<(const void *p) {
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m_out.push_back(static_cast<C>('0'));
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m_out.push_back(static_cast<C>('x'));
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*this << ghexOfInt<C>(reinterpret_cast<uintptr_t>(p));
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return *this;
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}
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StringType str() { return m_out; }
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StringType str_moved() { return std::move(m_out); }
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const C *c_str() const { return m_out.c_str(); }
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private:
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StringType m_out;
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};
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typedef GStringBuilder<char> StringBuilder;
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typedef GStringBuilder<wchar_t> WStringBuilder;
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} // namespace winpty_shared
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#endif // WINPTY_STRING_BUILDER_H
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116
src/shared/StringBuilderTest.cc
Executable file
116
src/shared/StringBuilderTest.cc
Executable file
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// Copyright (c) 2016 Ryan Prichard
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to
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// deal in the Software without restriction, including without limitation the
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// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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// sell copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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// IN THE SOFTWARE.
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#define STRING_BUILDER_TESTING
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#include "StringBuilder.h"
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#include <stdio.h>
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#include <string.h>
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#include <iomanip>
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#include <sstream>
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using namespace winpty_shared;
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void display(const std::string &str) { fprintf(stderr, "%s", str.c_str()); }
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void display(const std::wstring &str) { fprintf(stderr, "%ls", str.c_str()); }
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#define CHECK_EQ(x, y) \
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do { \
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const auto xval = (x); \
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const auto yval = (y); \
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if (xval != yval) { \
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fprintf(stderr, "error: %s:%d: %s != %s: ", \
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__FILE__, __LINE__, #x, #y); \
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display(xval); \
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fprintf(stderr, " != "); \
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display(yval); \
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fprintf(stderr, "\n"); \
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} \
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} while(0)
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template <typename C, typename I>
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std::basic_string<C> decOfIntSS(const I value) {
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// std::to_string and std::to_wstring are missing in Cygwin as of this
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// writing (early 2016).
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std::basic_stringstream<C> ss;
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ss << +value; // We must promote char to print it as an integer.
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return ss.str();
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}
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template <typename C, bool leadingZeros=false, typename I>
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std::basic_string<C> hexOfIntSS(const I value) {
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typedef typename std::make_unsigned<I>::type U;
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const unsigned long long u64Value = value & static_cast<U>(~0);
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std::basic_stringstream<C> ss;
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if (leadingZeros) {
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ss << std::setfill(static_cast<C>('0')) << std::setw(sizeof(I) * 2);
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}
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ss << std::hex << u64Value;
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return ss.str();
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}
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template <typename I>
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void testValue(I value) {
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CHECK_EQ(decOfInt(value).str(), (decOfIntSS<char>(value)));
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CHECK_EQ(wdecOfInt(value).str(), (decOfIntSS<wchar_t>(value)));
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CHECK_EQ((hexOfInt<false>(value).str()), (hexOfIntSS<char, false>(value)));
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CHECK_EQ((hexOfInt<true>(value).str()), (hexOfIntSS<char, true>(value)));
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CHECK_EQ((whexOfInt<false>(value).str()), (hexOfIntSS<wchar_t, false>(value)));
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CHECK_EQ((whexOfInt<true>(value).str()), (hexOfIntSS<wchar_t, true>(value)));
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}
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template <typename I>
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void testType() {
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typedef typename std::make_unsigned<I>::type U;
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const U quarter = static_cast<U>(1) << (sizeof(U) * 8 - 2);
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for (unsigned quarterIndex = 0; quarterIndex < 4; ++quarterIndex) {
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for (int offset = -18; offset <= 18; ++offset) {
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const I value = quarter * quarterIndex + static_cast<U>(offset);
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testValue(value);
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}
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}
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testValue(static_cast<I>(42));
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testValue(static_cast<I>(123456));
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testValue(static_cast<I>(0xdeadfacecafebeefull));
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}
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int main() {
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testType<char>();
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testType<signed char>();
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testType<signed short>();
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testType<signed int>();
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testType<signed long>();
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testType<signed long long>();
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testType<unsigned char>();
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testType<unsigned short>();
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testType<unsigned int>();
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testType<unsigned long>();
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testType<unsigned long long>();
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StringBuilder() << static_cast<const void*>("TEST");
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WStringBuilder() << static_cast<const void*>("TEST");
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fprintf(stderr, "All tests completed!\n");
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}
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