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//===--- StringView.h -------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// FIXME: Use std::string_view instead when we support C++17.
//
//===----------------------------------------------------------------------===//
#ifndef DEMANGLE_STRINGVIEW_H
#define DEMANGLE_STRINGVIEW_H
#include "DemangleConfig.h"
#include <algorithm>
#include <cassert>
#include <cstring>
DEMANGLE_NAMESPACE_BEGIN
class StringView {
const char *First;
const char *Last;
public:
static const size_t npos = ~size_t(0);
template <size_t N>
StringView(const char (&Str)[N]) : First(Str), Last(Str + N - 1) {}
StringView(const char *First_, const char *Last_)
: First(First_), Last(Last_) {}
StringView(const char *First_, size_t Len)
: First(First_), Last(First_ + Len) {}
StringView(const char *Str) : First(Str), Last(Str + std::strlen(Str)) {}
StringView() : First(nullptr), Last(nullptr) {}
StringView substr(size_t Pos, size_t Len = npos) const {
assert(Pos <= size());
return StringView(begin() + Pos, std::min(Len, size() - Pos));
}
size_t find(char C, size_t From = 0) const {
size_t FindBegin = std::min(From, size());
// Avoid calling memchr with nullptr.
if (FindBegin < size()) {
// Just forward to memchr, which is faster than a hand-rolled loop.
if (const void *P = ::memchr(First + FindBegin, C, size() - FindBegin))
return size_t(static_cast<const char *>(P) - First);
}
return npos;
}
StringView dropFront(size_t N = 1) const {
if (N >= size())
N = size();
return StringView(First + N, Last);
}
StringView dropBack(size_t N = 1) const {
if (N >= size())
N = size();
return StringView(First, Last - N);
}
char front() const {
assert(!empty());
return *begin();
}
char back() const {
assert(!empty());
return *(end() - 1);
}
char popFront() {
assert(!empty());
return *First++;
}
bool consumeFront(char C) {
if (!startsWith(C))
return false;
*this = dropFront(1);
return true;
}
bool consumeFront(StringView S) {
if (!startsWith(S))
return false;
*this = dropFront(S.size());
return true;
}
bool startsWith(char C) const { return !empty() && *begin() == C; }
bool startsWith(StringView Str) const {
if (Str.size() > size())
return false;
return std::equal(Str.begin(), Str.end(), begin());
}
const char &operator[](size_t Idx) const { return *(begin() + Idx); }
const char *begin() const { return First; }
const char *end() const { return Last; }
size_t size() const { return static_cast<size_t>(Last - First); }
bool empty() const { return First == Last; }
};
inline bool operator==(const StringView &LHS, const StringView &RHS) {
return LHS.size() == RHS.size() &&
std::equal(LHS.begin(), LHS.end(), RHS.begin());
}
DEMANGLE_NAMESPACE_END
#endif
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