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llvm-mirror/include/llvm/TableGen/StringToOffsetTable.h
Benjamin Kramer 87d13166c7 Make llvm::StringRef to std::string conversions explicit.
This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.

This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.

This doesn't actually modify StringRef yet, I'll do that in a follow-up.
2020-01-28 23:25:25 +01:00

105 lines
3.1 KiB
C++

//===- StringToOffsetTable.h - Emit a big concatenated string ---*- 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
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TABLEGEN_STRINGTOOFFSETTABLE_H
#define LLVM_TABLEGEN_STRINGTOOFFSETTABLE_H
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/Support/raw_ostream.h"
#include <cctype>
namespace llvm {
/// StringToOffsetTable - This class uniques a bunch of nul-terminated strings
/// and keeps track of their offset in a massive contiguous string allocation.
/// It can then output this string blob and use indexes into the string to
/// reference each piece.
class StringToOffsetTable {
StringMap<unsigned> StringOffset;
std::string AggregateString;
public:
bool Empty() const { return StringOffset.empty(); }
unsigned GetOrAddStringOffset(StringRef Str, bool appendZero = true) {
auto IterBool =
StringOffset.insert(std::make_pair(Str, AggregateString.size()));
if (IterBool.second) {
// Add the string to the aggregate if this is the first time found.
AggregateString.append(Str.begin(), Str.end());
if (appendZero)
AggregateString += '\0';
}
return IterBool.first->second;
}
void EmitString(raw_ostream &O) {
// Escape the string.
SmallString<256> Str;
raw_svector_ostream(Str).write_escaped(AggregateString);
AggregateString = std::string(Str.str());
O << " \"";
unsigned CharsPrinted = 0;
for (unsigned i = 0, e = AggregateString.size(); i != e; ++i) {
if (CharsPrinted > 70) {
O << "\"\n \"";
CharsPrinted = 0;
}
O << AggregateString[i];
++CharsPrinted;
// Print escape sequences all together.
if (AggregateString[i] != '\\')
continue;
assert(i + 1 < AggregateString.size() && "Incomplete escape sequence!");
if (isdigit(AggregateString[i + 1])) {
assert(isdigit(AggregateString[i + 2]) &&
isdigit(AggregateString[i + 3]) &&
"Expected 3 digit octal escape!");
O << AggregateString[++i];
O << AggregateString[++i];
O << AggregateString[++i];
CharsPrinted += 3;
} else {
O << AggregateString[++i];
++CharsPrinted;
}
}
O << "\"";
}
/// Emit the string using character literals. MSVC has a limitation that
/// string literals cannot be longer than 64K.
void EmitCharArray(raw_ostream &O) {
assert(AggregateString.find(')') == std::string::npos &&
"can't emit raw string with closing parens");
int Count = 0;
O << ' ';
for (char C : AggregateString) {
O << " \'";
O.write_escaped(StringRef(&C, 1));
O << "\',";
Count++;
if (Count > 14) {
O << "\n ";
Count = 0;
}
}
O << '\n';
}
};
} // end namespace llvm
#endif