mirror of
https://github.com/jart/cosmopolitan.git
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e38a6e7996
The mangled name of a C++ function will typically not vary by const-ness of a by-value parameter; in other words, there is no meaning to a const- qualified by-value parameter in a function prototype. However, the const keyword _does_ matter at function _definition_ time, like it does with a variable declared in the body. So for prototypes, we strip out const for by-value parameters; but for definitions, we leave them alone. At function definition (as opposed to prototype), we add const to values in parameters by default, unless we’re going to mutate them. This commit also changes a couple of const string_view& to be simply by- value string_view. A string_view is only two words; it rarely ever makes sense to pass one by reference if it’s not going to be mutated.
357 lines
7.9 KiB
C++
357 lines
7.9 KiB
C++
// -*-mode:c++;indent-tabs-mode:nil;c-basic-offset:4;tab-width:8;coding:utf-8-*-
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// vi: set et ft=cpp ts=4 sts=4 sw=4 fenc=utf-8 :vi
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#ifndef COSMOPOLITAN_CTL_STRING_H_
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#define COSMOPOLITAN_CTL_STRING_H_
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#include "string_view.h"
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namespace ctl {
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class string;
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string strcat(string_view, string_view) noexcept __wur;
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namespace __ {
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constexpr size_t string_size = 3 * sizeof(size_t);
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constexpr size_t sso_max = string_size - 1;
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constexpr size_t big_mask = ~(1ull << (8ull * sizeof(size_t) - 1ull));
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struct small_string
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{
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char buf[sso_max];
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// interpretation is: size == sso_max - rem
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unsigned char rem;
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#if 0
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size_t rem : 7;
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size_t big : 1 /* = 0 */;
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#endif
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};
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struct big_string
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{
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char* p;
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size_t n;
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// interpretation is: capacity == c & big_mask
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size_t c;
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#if 0
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size_t c : sizeof(size_t) * 8 - 1;
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size_t big : 1 /* = 1 */;
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#endif
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};
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} // namespace __
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class string
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{
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public:
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using iterator = char*;
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using const_iterator = const char*;
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static constexpr size_t npos = -1;
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~string() /* noexcept */;
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string(string_view) noexcept;
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string(const char*) noexcept;
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string(const string&) noexcept;
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string(const char*, size_t) noexcept;
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explicit string(size_t, char = 0) noexcept;
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string& operator=(string) noexcept;
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const char* c_str() const noexcept;
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void pop_back() noexcept;
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void grow(size_t) noexcept;
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void reserve(size_t) noexcept;
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void resize(size_t, char = 0) noexcept;
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void append(char) noexcept;
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void append(char, size_t) noexcept;
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void append(unsigned long) noexcept;
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void append(const void*, size_t) noexcept;
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string& insert(size_t, string_view) noexcept;
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string& erase(size_t = 0, size_t = npos) noexcept;
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string substr(size_t = 0, size_t = npos) const noexcept;
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string& replace(size_t, size_t, string_view) noexcept;
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bool operator==(string_view) const noexcept;
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bool operator!=(string_view) const noexcept;
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bool contains(string_view) const noexcept;
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bool ends_with(string_view) const noexcept;
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bool starts_with(string_view) const noexcept;
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size_t find(char, size_t = 0) const noexcept;
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size_t find(string_view, size_t = 0) const noexcept;
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string() noexcept
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{
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__builtin_memset(blob, 0, sizeof(size_t) * 2);
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// equivalent to set_small_size(0) but also zeroes memory
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*(((size_t*)blob) + 2) = __::sso_max << (sizeof(size_t) - 1) * 8;
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}
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void swap(string& s) noexcept
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{
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char tmp[__::string_size];
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__builtin_memcpy(tmp, blob, __::string_size);
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__builtin_memcpy(blob, s.blob, __::string_size);
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__builtin_memcpy(s.blob, tmp, __::string_size);
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}
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string(string&& s) noexcept
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{
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__builtin_memcpy(blob, s.blob, __::string_size);
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s.set_small_size(0);
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}
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void clear() noexcept
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{
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if (isbig()) {
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big()->n = 0;
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} else {
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set_small_size(0);
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}
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}
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bool empty() const noexcept
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{
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return isbig() ? !big()->n : small()->rem >= __::sso_max;
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}
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inline char* data() noexcept
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{
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return isbig() ? big()->p : small()->buf;
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}
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inline const char* data() const noexcept
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{
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return isbig() ? big()->p : small()->buf;
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}
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inline size_t size() const noexcept
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{
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#if 0
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if (!isbig() && small()->rem > __::sso_max)
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__builtin_trap();
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#endif
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return isbig() ? big()->n : __::sso_max - small()->rem;
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}
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size_t length() const noexcept
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{
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return size();
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}
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size_t capacity() const noexcept
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{
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#if 0
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if (isbig() && big()->c <= __::sso_max)
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__builtin_trap();
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#endif
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return isbig() ? __::big_mask & big()->c : __::string_size;
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}
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iterator begin() noexcept
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{
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return data();
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}
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iterator end() noexcept
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{
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return data() + size();
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}
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const_iterator cbegin() const noexcept
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{
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return data();
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}
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const_iterator cend() const noexcept
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{
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return data() + size();
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}
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char& front()
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{
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if (!size())
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__builtin_trap();
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return data()[0];
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}
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const char& front() const
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{
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if (!size())
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__builtin_trap();
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return data()[0];
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}
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char& back()
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{
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if (!size())
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__builtin_trap();
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return data()[size() - 1];
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}
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const char& back() const
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{
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if (!size())
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__builtin_trap();
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return data()[size() - 1];
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}
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char& operator[](size_t i) noexcept
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{
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if (i >= size())
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__builtin_trap();
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return data()[i];
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}
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const char& operator[](const size_t i) const noexcept
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{
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if (i >= size())
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__builtin_trap();
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return data()[i];
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}
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void push_back(const char ch) noexcept
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{
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append(ch);
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}
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void append(const string_view s) noexcept
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{
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append(s.p, s.n);
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}
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inline operator string_view() const noexcept
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{
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return string_view(data(), size());
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}
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string& operator=(const char* s) noexcept
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{
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clear();
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append(s);
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return *this;
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}
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string& operator=(const string_view s) noexcept
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{
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clear();
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append(s);
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return *this;
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}
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string& operator+=(const char x) noexcept
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{
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append(x);
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return *this;
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}
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string& operator+=(const string_view s) noexcept
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{
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append(s);
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return *this;
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}
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string operator+(const string_view s) const noexcept
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{
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return strcat(*this, s);
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}
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int compare(const string_view s) const noexcept
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{
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return strcmp(*this, s);
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}
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bool operator<(const string_view s) const noexcept
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{
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return compare(s) < 0;
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}
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bool operator<=(const string_view s) const noexcept
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{
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return compare(s) <= 0;
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}
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bool operator>(const string_view s) const noexcept
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{
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return compare(s) > 0;
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}
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bool operator>=(const string_view s) const noexcept
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{
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return compare(s) >= 0;
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}
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private:
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inline bool isbig() const noexcept
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{
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return *(blob + __::sso_max) & 0x80;
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}
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inline void set_small_size(const size_t size) noexcept
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{
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if (size > __::sso_max)
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__builtin_trap();
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*(blob + __::sso_max) = (__::sso_max - size);
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}
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inline void set_big_string(char* const p,
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const size_t n,
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const size_t c2) noexcept
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{
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if (c2 > __::big_mask)
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__builtin_trap();
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*(char**)blob = p;
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*(((size_t*)blob) + 1) = n;
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*(((size_t*)blob) + 2) = c2 | ~__::big_mask;
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}
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inline __::small_string* small() noexcept
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{
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if (isbig())
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__builtin_trap();
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return reinterpret_cast<__::small_string*>(blob);
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}
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inline const __::small_string* small() const noexcept
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{
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if (isbig())
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__builtin_trap();
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return reinterpret_cast<const __::small_string*>(blob);
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}
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inline __::big_string* big() noexcept
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{
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if (!isbig())
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__builtin_trap();
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return reinterpret_cast<__::big_string*>(blob);
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}
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inline const __::big_string* big() const noexcept
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{
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if (!isbig())
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__builtin_trap();
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return reinterpret_cast<const __::big_string*>(blob);
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}
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friend string strcat(string_view, string_view);
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alignas(union {
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__::big_string a;
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__::small_string b;
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}) char blob[__::string_size];
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};
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static_assert(sizeof(string) == __::string_size);
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static_assert(sizeof(__::small_string) == __::string_size);
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static_assert(sizeof(__::big_string) == __::string_size);
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} // namespace ctl
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wliteral-suffix"
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inline ctl::string
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operator"" s(const char* s, size_t n)
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{
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return ctl::string(s, n);
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}
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#pragma GCC diagnostic pop
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#endif // COSMOPOLITAN_CTL_STRING_H_
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