forked from OSchip/llvm-project
100 lines
2.6 KiB
C++
100 lines
2.6 KiB
C++
//===-- Standalone implementation std::string_view --------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_UTILS_CPP_STRINGVIEW_H
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#define LLVM_LIBC_UTILS_CPP_STRINGVIEW_H
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#include <stddef.h>
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namespace __llvm_libc {
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namespace cpp {
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// This is very simple alternate of the std::string_view class. There is no
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// bounds check performed in any of the methods. The callers are expected to
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// do the checks before invoking the methods.
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//
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// This class will be extended as needed in future.
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class StringView {
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private:
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const char *Data;
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size_t Len;
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public:
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StringView() : Data(nullptr), Len(0) {}
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// Assumes Str is a null-terminated string. The length of the string does
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// not include the terminating null character.
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explicit StringView(const char *Str) : Data(Str), Len(0) {
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if (Str == nullptr)
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return;
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for (const char *D = Data; *D != '\0'; ++D, ++Len)
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;
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if (Len == 0)
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Data = nullptr;
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}
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explicit StringView(const char *Str, size_t N)
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: Data(N ? Str : nullptr), Len(Str == nullptr ? 0 : N) {}
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const char *data() const { return Data; }
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size_t size() { return Len; }
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const char &operator[](size_t Index) const { return Data[Index]; }
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StringView remove_prefix(size_t N) const {
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if (N >= Len)
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return StringView();
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return StringView(Data + N, Len - N);
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}
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StringView remove_suffix(size_t N) const {
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if (N >= Len)
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return StringView();
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return StringView(Data, Len - N);
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}
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// An equivalent method is not available in std::string_view.
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StringView trim(char C) const {
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if (Len == 0)
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return StringView();
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const char *NewStart = Data;
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size_t PrefixLen = 0;
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for (; PrefixLen < Len; ++NewStart, ++PrefixLen) {
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if (*NewStart != C)
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break;
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}
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size_t SuffixLen = 0;
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const char *NewEnd = Data + Len - 1;
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for (; SuffixLen < Len; --NewEnd, ++SuffixLen) {
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if (*NewEnd != C)
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break;
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}
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return remove_prefix(PrefixLen).remove_suffix(SuffixLen);
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}
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// An equivalent method is not available in std::string_view.
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bool equals(StringView Other) const {
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if (Len != Other.Len)
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return false;
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for (size_t I = 0; I < Len; ++I) {
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if (Data[I] != Other.Data[I])
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return false;
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}
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return true;
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}
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};
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} // namespace cpp
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} // namespace __llvm_libc
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#endif // LLVM_LIBC_UTILS_CPP_STRINGVIEW_H
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