124 lines
3.4 KiB
C++
124 lines
3.4 KiB
C++
//===--- StringView.h ----------------*- mode:c++;eval:(read-only-mode) -*-===//
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// Do not edit! See README.txt.
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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-FileCopyrightText: Part of the LLVM Project
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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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//
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// FIXME: Use std::string_view instead when we support C++17.
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// There are two copies of this file in the source tree. The one under
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// libcxxabi is the original and the one under llvm is the copy. Use
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// cp-to-llvm.sh to update the copy. See README.txt for more details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef DEMANGLE_STRINGVIEW_H
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#define DEMANGLE_STRINGVIEW_H
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#include "DemangleConfig.h"
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#include <cassert>
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#include <cstring>
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DEMANGLE_NAMESPACE_BEGIN
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class StringView {
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const char *First;
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const char *Last;
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public:
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static const size_t npos = ~size_t(0);
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template <size_t N>
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StringView(const char (&Str)[N]) : First(Str), Last(Str + N - 1) {}
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StringView(const char *First_, const char *Last_)
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: First(First_), Last(Last_) {}
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StringView(const char *First_, size_t Len)
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: First(First_), Last(First_ + Len) {}
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StringView(const char *Str) : First(Str), Last(Str + std::strlen(Str)) {}
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StringView() : First(nullptr), Last(nullptr) {}
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StringView substr(size_t Pos, size_t Len = npos) const {
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assert(Pos <= size());
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if (Len > size() - Pos)
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Len = size() - Pos;
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return StringView(begin() + Pos, Len);
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}
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size_t find(char C, size_t From = 0) const {
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// Avoid calling memchr with nullptr.
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if (From < size()) {
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// Just forward to memchr, which is faster than a hand-rolled loop.
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if (const void *P = ::memchr(First + From, C, size() - From))
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return size_t(static_cast<const char *>(P) - First);
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}
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return npos;
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}
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StringView dropFront(size_t N = 1) const {
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if (N >= size())
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N = size();
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return StringView(First + N, Last);
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}
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StringView dropBack(size_t N = 1) const {
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if (N >= size())
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N = size();
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return StringView(First, Last - N);
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}
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char front() const {
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assert(!empty());
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return *begin();
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}
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char back() const {
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assert(!empty());
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return *(end() - 1);
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}
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char popFront() {
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assert(!empty());
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return *First++;
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}
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bool consumeFront(char C) {
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if (!startsWith(C))
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return false;
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*this = dropFront(1);
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return true;
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}
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bool consumeFront(StringView S) {
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if (!startsWith(S))
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return false;
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*this = dropFront(S.size());
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return true;
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}
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bool startsWith(char C) const { return !empty() && *begin() == C; }
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bool startsWith(StringView Str) const {
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if (Str.size() > size())
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return false;
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return std::strncmp(Str.begin(), begin(), Str.size()) == 0;
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}
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const char &operator[](size_t Idx) const { return *(begin() + Idx); }
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const char *begin() const { return First; }
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const char *end() const { return Last; }
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size_t size() const { return static_cast<size_t>(Last - First); }
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bool empty() const { return First == Last; }
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};
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inline bool operator==(const StringView &LHS, const StringView &RHS) {
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return LHS.size() == RHS.size() &&
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std::strncmp(LHS.begin(), RHS.begin(), LHS.size()) == 0;
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}
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DEMANGLE_NAMESPACE_END
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#endif
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