77 lines
2.8 KiB
C++
77 lines
2.8 KiB
C++
//===- StringToOffsetTable.h - Emit a big concatenated string ---*- 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_TABLEGEN_STRINGTOOFFSETTABLE_H
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#define LLVM_TABLEGEN_STRINGTOOFFSETTABLE_H
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/ADT/StringMap.h"
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#include <optional>
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namespace llvm {
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/// StringToOffsetTable - This class uniques a bunch of nul-terminated strings
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/// and keeps track of their offset in a massive contiguous string allocation.
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/// It can then output this string blob and use indexes into the string to
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/// reference each piece.
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class StringToOffsetTable {
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StringMap<unsigned> StringOffset;
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std::string AggregateString;
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/// If this is to be a static class member, the prefix to use (i.e. class name
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/// plus ::)
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const StringRef ClassPrefix;
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const bool AppendZero;
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const bool UsePrefixForStorageMember;
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public:
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StringToOffsetTable(bool AppendZero = true, StringRef ClassPrefix = "",
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bool UsePrefixForStorageMember = true)
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: ClassPrefix(ClassPrefix), AppendZero(AppendZero),
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UsePrefixForStorageMember(UsePrefixForStorageMember) {
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// Ensure we always put the empty string at offset zero. That lets empty
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// initialization also be zero initialization for offsets into the table.
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GetOrAddStringOffset("");
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}
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bool empty() const { return StringOffset.empty(); }
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size_t size() const { return AggregateString.size(); }
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LLVM_ABI unsigned GetOrAddStringOffset(StringRef Str);
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// Returns the offset of `Str` in the table if its preset, else return
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// std::nullopt.
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std::optional<unsigned> GetStringOffset(StringRef Str) const {
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auto II = StringOffset.find(Str);
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if (II == StringOffset.end())
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return std::nullopt;
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return II->second;
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}
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// Emit a string table definition with the provided name.
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//
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// When possible, this uses string-literal concatenation to emit the string
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// contents in a readable and searchable way. However, for (very) large string
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// tables MSVC cannot reliably use string literals and so there we use a large
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// character array. We still use a line oriented emission and add comments to
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// provide searchability even in this case.
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//
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// The string table, and its input string contents, are always emitted as both
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// `static` and `constexpr`. Both `Name` and (`Name` + "Storage") must be
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// valid identifiers to declare.
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LLVM_ABI void EmitStringTableDef(raw_ostream &OS, const Twine &Name) const;
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// Emit the string as one single string.
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LLVM_ABI void EmitString(raw_ostream &O) const;
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};
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} // end namespace llvm
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#endif
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