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//===--- MacroExpander.cpp - Format C++ code --------------------*- 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file contains the implementation of MacroExpander, which handles macro
/// configuration and expansion while formatting.
///
//===----------------------------------------------------------------------===//
#include "Macros.h"
#include "Encoding.h"
#include "FormatToken.h"
#include "FormatTokenLexer.h"
#include "clang/Basic/TokenKinds.h"
#include "clang/Format/Format.h"
#include "clang/Lex/HeaderSearch.h"
#include "clang/Lex/HeaderSearchOptions.h"
#include "clang/Lex/Lexer.h"
#include "clang/Lex/ModuleLoader.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Lex/PreprocessorOptions.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/Support/ErrorHandling.h"
namespace clang {
namespace format {
struct MacroExpander::Definition {
StringRef Name;
SmallVector<FormatToken *, 8> Params;
SmallVector<FormatToken *, 8> Body;
// Map from each argument's name to its position in the argument list.
// With "M(x, y) x + y":
// x -> 0
// y -> 1
llvm::StringMap<size_t> ArgMap;
bool ObjectLike = true;
};
class MacroExpander::DefinitionParser {
public:
DefinitionParser(ArrayRef<FormatToken *> Tokens) : Tokens(Tokens) {
assert(!Tokens.empty());
Current = Tokens[0];
}
// Parse the token stream and return the corresponding Definition object.
// Returns an empty definition object with a null-Name on error.
MacroExpander::Definition parse() {
if (!Current->is(tok::identifier))
return {};
Def.Name = Current->TokenText;
nextToken();
if (Current->is(tok::l_paren)) {
Def.ObjectLike = false;
if (!parseParams())
return {};
}
if (!parseExpansion())
return {};
return Def;
}
private:
bool parseParams() {
assert(Current->is(tok::l_paren));
nextToken();
while (Current->is(tok::identifier)) {
Def.Params.push_back(Current);
Def.ArgMap[Def.Params.back()->TokenText] = Def.Params.size() - 1;
nextToken();
if (Current->isNot(tok::comma))
break;
nextToken();
}
if (Current->isNot(tok::r_paren))
return false;
nextToken();
return true;
}
bool parseExpansion() {
if (!Current->isOneOf(tok::equal, tok::eof))
return false;
if (Current->is(tok::equal))
nextToken();
parseTail();
return true;
}
void parseTail() {
while (Current->isNot(tok::eof)) {
Def.Body.push_back(Current);
nextToken();
}
Def.Body.push_back(Current);
}
void nextToken() {
if (Pos + 1 < Tokens.size())
++Pos;
Current = Tokens[Pos];
Current->Finalized = true;
}
size_t Pos = 0;
FormatToken *Current = nullptr;
Definition Def;
ArrayRef<FormatToken *> Tokens;
};
MacroExpander::MacroExpander(
const std::vector<std::string> &Macros, clang::SourceManager &SourceMgr,
const FormatStyle &Style,
llvm::SpecificBumpPtrAllocator<FormatToken> &Allocator,
IdentifierTable &IdentTable)
: SourceMgr(SourceMgr), Style(Style), Allocator(Allocator),
IdentTable(IdentTable) {
for (const std::string &Macro : Macros) {
parseDefinition(Macro);
}
}
MacroExpander::~MacroExpander() = default;
void MacroExpander::parseDefinition(const std::string &Macro) {
Buffers.push_back(
llvm::MemoryBuffer::getMemBufferCopy(Macro, "<scratch space>"));
clang::FileID FID = SourceMgr.createFileID(Buffers.back()->getMemBufferRef());
FormatTokenLexer Lex(SourceMgr, FID, 0, Style, encoding::Encoding_UTF8,
Allocator, IdentTable);
const auto Tokens = Lex.lex();
if (!Tokens.empty()) {
DefinitionParser Parser(Tokens);
auto Definition = Parser.parse();
Definitions[Definition.Name] = std::move(Definition);
}
}
bool MacroExpander::defined(llvm::StringRef Name) const {
return Definitions.find(Name) != Definitions.end();
}
bool MacroExpander::objectLike(llvm::StringRef Name) const {
return Definitions.find(Name)->second.ObjectLike;
}
llvm::SmallVector<FormatToken *, 8> MacroExpander::expand(FormatToken *ID,
ArgsList Args) const {
assert(defined(ID->TokenText));
SmallVector<FormatToken *, 8> Result;
const Definition &Def = Definitions.find(ID->TokenText)->second;
// Expand each argument at most once.
llvm::StringSet<> ExpandedArgs;
// Adds the given token to Result.
auto pushToken = [&](FormatToken *Tok) {
Tok->MacroCtx->ExpandedFrom.push_back(ID);
Result.push_back(Tok);
};
// If Tok references a parameter, adds the corresponding argument to Result.
// Returns false if Tok does not reference a parameter.
auto expandArgument = [&](FormatToken *Tok) -> bool {
// If the current token references a parameter, expand the corresponding
// argument.
if (!Tok->is(tok::identifier) || ExpandedArgs.contains(Tok->TokenText))
return false;
ExpandedArgs.insert(Tok->TokenText);
auto I = Def.ArgMap.find(Tok->TokenText);
if (I == Def.ArgMap.end())
return false;
// If there are fewer arguments than referenced parameters, treat the
// parameter as empty.
// FIXME: Potentially fully abort the expansion instead.
if (I->getValue() >= Args.size())
return true;
for (FormatToken *Arg : Args[I->getValue()]) {
// A token can be part of a macro argument at multiple levels.
// For example, with "ID(x) x":
// in ID(ID(x)), 'x' is expanded first as argument to the inner
// ID, then again as argument to the outer ID. We keep the macro
// role the token had from the inner expansion.
if (!Arg->MacroCtx)
Arg->MacroCtx = MacroExpansion(MR_ExpandedArg);
pushToken(Arg);
}
return true;
};
// Expand the definition into Result.
for (FormatToken *Tok : Def.Body) {
if (expandArgument(Tok))
continue;
// Create a copy of the tokens from the macro body, i.e. were not provided
// by user code.
FormatToken *New = new (Allocator.Allocate()) FormatToken;
New->copyFrom(*Tok);
assert(!New->MacroCtx);
// Tokens that are not part of the user code are not formatted.
New->MacroCtx = MacroExpansion(MR_Hidden);
pushToken(New);
}
assert(Result.size() >= 1 && Result.back()->is(tok::eof));
if (Result.size() > 1) {
++Result[0]->MacroCtx->StartOfExpansion;
++Result[Result.size() - 2]->MacroCtx->EndOfExpansion;
}
return Result;
}
} // namespace format
} // namespace clang
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