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d94bcd2889
The StringView::substr now accepts a substring starting position and its length instead of previous non-standard `from` & `to` positions. All uses of two argument StringView::substr are in MicrosoftDemangler and have 0 as a starting position, so no changes are necessary. This also fixes a bug where attempting to extract a suffix with substr (a `to` position equal to size) would return a substring without the last character. Fixing the issue should not introduce observable changes in the demangler, since as currently used, a second argument to StringView::substr is either: 1) a result of a successful call to StringView::find and so necessarily smaller than size., or 2) in the case of Demangler::demangleCharLiteral potentially equal to size, but with demangler expecting more data to follow later on and failing either way. Reviewed By: #libc_abi, ldionne, erik.pilkington Differential Revision: https://reviews.llvm.org/D100246
120 lines
3.1 KiB
C++
120 lines
3.1 KiB
C++
//===--- StringView.h -------------------------------------------*- 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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//
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// FIXME: Use std::string_view instead when we support C++17.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_DEMANGLE_STRINGVIEW_H
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#define LLVM_DEMANGLE_STRINGVIEW_H
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#include "DemangleConfig.h"
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#include <algorithm>
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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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return StringView(begin() + Pos, std::min(Len, size() - Pos));
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}
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size_t find(char C, size_t From = 0) const {
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size_t FindBegin = std::min(From, size());
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// Avoid calling memchr with nullptr.
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if (FindBegin < 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 + FindBegin, C, size() - FindBegin))
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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::equal(Str.begin(), Str.end(), begin());
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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::equal(LHS.begin(), LHS.end(), RHS.begin());
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}
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DEMANGLE_NAMESPACE_END
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#endif
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