RewriteRule.cpp
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//===--- Transformer.cpp - Transformer library implementation ---*- 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
//
//===----------------------------------------------------------------------===//
#include "clang/Tooling/Transformer/RewriteRule.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Tooling/Transformer/SourceCode.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/Error.h"
#include <map>
#include <string>
#include <utility>
#include <vector>
using namespace clang;
using namespace transformer;
using ast_matchers::MatchFinder;
using ast_matchers::internal::DynTypedMatcher;
using MatchResult = MatchFinder::MatchResult;
static Expected<SmallVector<transformer::Edit, 1>>
translateEdits(const MatchResult &Result, ArrayRef<ASTEdit> ASTEdits) {
SmallVector<transformer::Edit, 1> Edits;
for (const auto &E : ASTEdits) {
Expected<CharSourceRange> Range = E.TargetRange(Result);
if (!Range)
return Range.takeError();
llvm::Optional<CharSourceRange> EditRange =
tooling::getRangeForEdit(*Range, *Result.Context);
// FIXME: let user specify whether to treat this case as an error or ignore
// it as is currently done.
if (!EditRange)
return SmallVector<Edit, 0>();
auto Replacement = E.Replacement->eval(Result);
if (!Replacement)
return Replacement.takeError();
transformer::Edit T;
T.Range = *EditRange;
T.Replacement = std::move(*Replacement);
T.Metadata = E.Metadata;
Edits.push_back(std::move(T));
}
return Edits;
}
EditGenerator transformer::editList(SmallVector<ASTEdit, 1> Edits) {
return [Edits = std::move(Edits)](const MatchResult &Result) {
return translateEdits(Result, Edits);
};
}
EditGenerator transformer::edit(ASTEdit Edit) {
return [Edit = std::move(Edit)](const MatchResult &Result) {
return translateEdits(Result, {Edit});
};
}
ASTEdit transformer::changeTo(RangeSelector Target, TextGenerator Replacement) {
ASTEdit E;
E.TargetRange = std::move(Target);
E.Replacement = std::move(Replacement);
return E;
}
namespace {
/// A \c TextGenerator that always returns a fixed string.
class SimpleTextGenerator : public MatchComputation<std::string> {
std::string S;
public:
SimpleTextGenerator(std::string S) : S(std::move(S)) {}
llvm::Error eval(const ast_matchers::MatchFinder::MatchResult &,
std::string *Result) const override {
Result->append(S);
return llvm::Error::success();
}
std::string toString() const override {
return (llvm::Twine("text(\"") + S + "\")").str();
}
};
} // namespace
ASTEdit transformer::remove(RangeSelector S) {
return change(std::move(S), std::make_shared<SimpleTextGenerator>(""));
}
RewriteRule transformer::makeRule(ast_matchers::internal::DynTypedMatcher M,
EditGenerator Edits,
TextGenerator Explanation) {
return RewriteRule{{RewriteRule::Case{
std::move(M), std::move(Edits), std::move(Explanation), {}}}};
}
void transformer::addInclude(RewriteRule &Rule, StringRef Header,
IncludeFormat Format) {
for (auto &Case : Rule.Cases)
Case.AddedIncludes.emplace_back(Header.str(), Format);
}
#ifndef NDEBUG
// Filters for supported matcher kinds. FIXME: Explicitly list the allowed kinds
// (all node matcher types except for `QualType` and `Type`), rather than just
// banning `QualType` and `Type`.
static bool hasValidKind(const DynTypedMatcher &M) {
return !M.canConvertTo<QualType>();
}
#endif
// Binds each rule's matcher to a unique (and deterministic) tag based on
// `TagBase` and the id paired with the case. All of the returned matchers have
// their traversal kind explicitly set, either based on a pre-set kind or to the
// provided `DefaultTraversalKind`.
static std::vector<DynTypedMatcher> taggedMatchers(
StringRef TagBase,
const SmallVectorImpl<std::pair<size_t, RewriteRule::Case>> &Cases,
ast_type_traits::TraversalKind DefaultTraversalKind) {
std::vector<DynTypedMatcher> Matchers;
Matchers.reserve(Cases.size());
for (const auto &Case : Cases) {
std::string Tag = (TagBase + Twine(Case.first)).str();
// HACK: Many matchers are not bindable, so ensure that tryBind will work.
DynTypedMatcher BoundMatcher(Case.second.Matcher);
BoundMatcher.setAllowBind(true);
auto M = *BoundMatcher.tryBind(Tag);
Matchers.push_back(!M.getTraversalKind()
? M.withTraversalKind(DefaultTraversalKind)
: std::move(M));
}
return Matchers;
}
// Simply gathers the contents of the various rules into a single rule. The
// actual work to combine these into an ordered choice is deferred to matcher
// registration.
RewriteRule transformer::applyFirst(ArrayRef<RewriteRule> Rules) {
RewriteRule R;
for (auto &Rule : Rules)
R.Cases.append(Rule.Cases.begin(), Rule.Cases.end());
return R;
}
std::vector<DynTypedMatcher>
transformer::detail::buildMatchers(const RewriteRule &Rule) {
// Map the cases into buckets of matchers -- one for each "root" AST kind,
// which guarantees that they can be combined in a single anyOf matcher. Each
// case is paired with an identifying number that is converted to a string id
// in `taggedMatchers`.
std::map<ASTNodeKind, SmallVector<std::pair<size_t, RewriteRule::Case>, 1>>
Buckets;
const SmallVectorImpl<RewriteRule::Case> &Cases = Rule.Cases;
for (int I = 0, N = Cases.size(); I < N; ++I) {
assert(hasValidKind(Cases[I].Matcher) &&
"Matcher must be non-(Qual)Type node matcher");
Buckets[Cases[I].Matcher.getSupportedKind()].emplace_back(I, Cases[I]);
}
// Each anyOf explicitly controls the traversal kind. The anyOf itself is set
// to `TK_AsIs` to ensure no nodes are skipped, thereby deferring to the kind
// of the branches. Then, each branch is either left as is, if the kind is
// already set, or explicitly set to `TK_IgnoreUnlessSpelledInSource`. We
// choose this setting, because we think it is the one most friendly to
// beginners, who are (largely) the target audience of Transformer.
std::vector<DynTypedMatcher> Matchers;
for (const auto &Bucket : Buckets) {
DynTypedMatcher M = DynTypedMatcher::constructVariadic(
DynTypedMatcher::VO_AnyOf, Bucket.first,
taggedMatchers("Tag", Bucket.second, TK_IgnoreUnlessSpelledInSource));
M.setAllowBind(true);
// `tryBind` is guaranteed to succeed, because `AllowBind` was set to true.
Matchers.push_back(
M.tryBind(RewriteRule::RootID)->withTraversalKind(TK_AsIs));
}
return Matchers;
}
DynTypedMatcher transformer::detail::buildMatcher(const RewriteRule &Rule) {
std::vector<DynTypedMatcher> Ms = buildMatchers(Rule);
assert(Ms.size() == 1 && "Cases must have compatible matchers.");
return Ms[0];
}
SourceLocation transformer::detail::getRuleMatchLoc(const MatchResult &Result) {
auto &NodesMap = Result.Nodes.getMap();
auto Root = NodesMap.find(RewriteRule::RootID);
assert(Root != NodesMap.end() && "Transformation failed: missing root node.");
llvm::Optional<CharSourceRange> RootRange = tooling::getRangeForEdit(
CharSourceRange::getTokenRange(Root->second.getSourceRange()),
*Result.Context);
if (RootRange)
return RootRange->getBegin();
// The match doesn't have a coherent range, so fall back to the expansion
// location as the "beginning" of the match.
return Result.SourceManager->getExpansionLoc(
Root->second.getSourceRange().getBegin());
}
// Finds the case that was "selected" -- that is, whose matcher triggered the
// `MatchResult`.
const RewriteRule::Case &
transformer::detail::findSelectedCase(const MatchResult &Result,
const RewriteRule &Rule) {
if (Rule.Cases.size() == 1)
return Rule.Cases[0];
auto &NodesMap = Result.Nodes.getMap();
for (size_t i = 0, N = Rule.Cases.size(); i < N; ++i) {
std::string Tag = ("Tag" + Twine(i)).str();
if (NodesMap.find(Tag) != NodesMap.end())
return Rule.Cases[i];
}
llvm_unreachable("No tag found for this rule.");
}
constexpr llvm::StringLiteral RewriteRule::RootID;
TextGenerator tooling::text(std::string M) {
return std::make_shared<SimpleTextGenerator>(std::move(M));
}