1 files changed, 178 insertions, 0 deletions
diff --git a/lib/Tooling/Transformer/RewriteRule.cpp b/lib/Tooling/Transformer/RewriteRule.cpp
new file mode 100644
index 000000000000..6fa558f7b2ee
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+++ b/lib/Tooling/Transformer/RewriteRule.cpp
@@ -0,0 +1,178 @@
+//===--- 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 ast_type_traits::ASTNodeKind;
+
+using MatchResult = MatchFinder::MatchResult;
+
+Expected<SmallVector<transformer::detail::Transformation, 1>>
+transformer::detail::translateEdits(const MatchResult &Result,
+                                llvm::ArrayRef<ASTEdit> Edits) {
+  SmallVector<transformer::detail::Transformation, 1> Transformations;
+  for (const auto &Edit : Edits) {
+    Expected<CharSourceRange> Range = Edit.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<Transformation, 0>();
+    auto Replacement = Edit.Replacement(Result);
+    if (!Replacement)
+      return Replacement.takeError();
+    transformer::detail::Transformation T;
+    T.Range = *EditRange;
+    T.Replacement = std::move(*Replacement);
+    Transformations.push_back(std::move(T));
+  }
+  return Transformations;
+}
+
+ASTEdit transformer::change(RangeSelector S, TextGenerator Replacement) {
+  ASTEdit E;
+  E.TargetRange = std::move(S);
+  E.Replacement = std::move(Replacement);
+  return E;
+}
+
+RewriteRule transformer::makeRule(DynTypedMatcher M, SmallVector<ASTEdit, 1> 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.
+static std::vector<DynTypedMatcher> taggedMatchers(
+    StringRef TagBase,
+    const SmallVectorImpl<std::pair<size_t, RewriteRule::Case>> &Cases) {
+  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(*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]);
+  }
+
+  std::vector<DynTypedMatcher> Matchers;
+  for (const auto &Bucket : Buckets) {
+    DynTypedMatcher M = DynTypedMatcher::constructVariadic(
+        DynTypedMatcher::VO_AnyOf, Bucket.first,
+        taggedMatchers("Tag", Bucket.second));
+    M.setAllowBind(true);
+    // `tryBind` is guaranteed to succeed, because `AllowBind` was set to true.
+    Matchers.push_back(*M.tryBind(RewriteRule::RootID));
+  }
+  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;