[libTooling] Move `RewriteRule` abstraction into its own header and impl.

Summary: Move the `RewriteRule` class and related declarations into its own set
of files (header, implementation). Only the `Transformer` class is left in the
Transformer-named files. This change clarifies the distinction between the
`RewriteRule` class, which is essential to the Transformer library, and the
`Transformer` class, which is only one possible `RewriteRule` interpreter
(compare to `TransformerClangTidyCheck`, a clang-tidy based interpreter).

Reviewers: gribozavr

Subscribers: jfb, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D68795

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@374558 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Tooling/Transformer/RewriteRule.h

@@ -0,0 +1,288 @@
+//===--- RewriteRule.h - RewriteRule class ----------------------*- 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
+///  Defines the RewriteRule class and related functions for creating,
+///  modifying and interpreting RewriteRules.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLING_TRANSFORMER_REWRITE_RULE_H_
+#define LLVM_CLANG_TOOLING_TRANSFORMER_REWRITE_RULE_H_
+
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/ASTMatchers/ASTMatchersInternal.h"
+#include "clang/Tooling/Refactoring/AtomicChange.h"
+#include "clang/Tooling/Transformer/MatchConsumer.h"
+#include "clang/Tooling/Transformer/RangeSelector.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/Error.h"
+#include <functional>
+#include <string>
+#include <utility>
+
+namespace clang {
+namespace tooling {
+using TextGenerator = MatchConsumer<std::string>;
+
+/// Wraps a string as a TextGenerator.
+inline TextGenerator text(std::string M) {
+  return [M](const ast_matchers::MatchFinder::MatchResult &)
+             -> Expected<std::string> { return M; };
+}
+
+// Description of a source-code edit, expressed in terms of an AST node.
+// Includes: an ID for the (bound) node, a selector for source related to the
+// node, a replacement and, optionally, an explanation for the edit.
+//
+// * Target: the source code impacted by the rule. This identifies an AST node,
+//   or part thereof (\c Part), whose source range indicates the extent of the
+//   replacement applied by the replacement term.  By default, the extent is the
+//   node matched by the pattern term (\c NodePart::Node). Target's are typed
+//   (\c Kind), which guides the determination of the node extent.
+//
+// * Replacement: a function that produces a replacement string for the target,
+//   based on the match result.
+//
+// * Note: (optional) a note specifically for this edit, potentially referencing
+//   elements of the match.  This will be displayed to the user, where possible;
+//   for example, in clang-tidy diagnostics.  Use of notes should be rare --
+//   explanations of the entire rewrite should be set in the rule
+//   (`RewriteRule::Explanation`) instead.  Notes serve the rare cases wherein
+//   edit-specific diagnostics are required.
+//
+// `ASTEdit` should be built using the `change` convenience functions. For
+// example,
+// \code
+//   change(name(fun), text("Frodo"))
+// \endcode
+// Or, if we use Stencil for the TextGenerator:
+// \code
+//   using stencil::cat;
+//   change(statement(thenNode), cat("{", thenNode, "}"))
+//   change(callArgs(call), cat(x, ",", y))
+// \endcode
+// Or, if you are changing the node corresponding to the rule's matcher, you can
+// use the single-argument override of \c change:
+// \code
+//   change(cat("different_expr"))
+// \endcode
+struct ASTEdit {
+  RangeSelector TargetRange;
+  TextGenerator Replacement;
+  TextGenerator Note;
+};
+
+/// Format of the path in an include directive -- angle brackets or quotes.
+enum class IncludeFormat {
+  Quoted,
+  Angled,
+};
+
+/// Description of a source-code transformation.
+//
+// A *rewrite rule* describes a transformation of source code. A simple rule
+// contains each of the following components:
+//
+// * Matcher: the pattern term, expressed as clang matchers (with Transformer
+//   extensions).
+//
+// * Edits: a set of Edits to the source code, described with ASTEdits.
+//
+// * Explanation: explanation of the rewrite.  This will be displayed to the
+//   user, where possible; for example, in clang-tidy diagnostics.
+//
+// However, rules can also consist of (sub)rules, where the first that matches
+// is applied and the rest are ignored.  So, the above components are gathered
+// as a `Case` and a rule is a list of cases.
+//
+// Rule cases have an additional, implicit, component: the parameters. These are
+// portions of the pattern which are left unspecified, yet bound in the pattern
+// so that we can reference them in the edits.
+//
+// The \c Transformer class can be used to apply the rewrite rule and obtain the
+// corresponding replacements.
+struct RewriteRule {
+  struct Case {
+    ast_matchers::internal::DynTypedMatcher Matcher;
+    SmallVector<ASTEdit, 1> Edits;
+    TextGenerator Explanation;
+    // Include paths to add to the file affected by this case.  These are
+    // bundled with the `Case`, rather than the `RewriteRule`, because each case
+    // might have different associated changes to the includes.
+    std::vector<std::pair<std::string, IncludeFormat>> AddedIncludes;
+  };
+  // We expect RewriteRules will most commonly include only one case.
+  SmallVector<Case, 1> Cases;
+
+  // ID used as the default target of each match. The node described by the
+  // matcher is should always be bound to this id.
+  static constexpr llvm::StringLiteral RootID = "___root___";
+};
+
+/// Convenience function for constructing a simple \c RewriteRule.
+RewriteRule makeRule(ast_matchers::internal::DynTypedMatcher M,
+                     SmallVector<ASTEdit, 1> Edits,
+                     TextGenerator Explanation = nullptr);
+
+/// Convenience overload of \c makeRule for common case of only one edit.
+inline RewriteRule makeRule(ast_matchers::internal::DynTypedMatcher M,
+                            ASTEdit Edit,
+                            TextGenerator Explanation = nullptr) {
+  SmallVector<ASTEdit, 1> Edits;
+  Edits.emplace_back(std::move(Edit));
+  return makeRule(std::move(M), std::move(Edits), std::move(Explanation));
+}
+
+/// For every case in Rule, adds an include directive for the given header. The
+/// common use is assumed to be a rule with only one case. For example, to
+/// replace a function call and add headers corresponding to the new code, one
+/// could write:
+/// \code
+///   auto R = makeRule(callExpr(callee(functionDecl(hasName("foo")))),
+///            change(text("bar()")));
+///   AddInclude(R, "path/to/bar_header.h");
+///   AddInclude(R, "vector", IncludeFormat::Angled);
+/// \endcode
+void addInclude(RewriteRule &Rule, llvm::StringRef Header,
+                IncludeFormat Format = IncludeFormat::Quoted);
+
+/// Applies the first rule whose pattern matches; other rules are ignored.  If
+/// the matchers are independent then order doesn't matter. In that case,
+/// `applyFirst` is simply joining the set of rules into one.
+//
+// `applyFirst` is like an `anyOf` matcher with an edit action attached to each
+// of its cases. Anywhere you'd use `anyOf(m1.bind("id1"), m2.bind("id2"))` and
+// then dispatch on those ids in your code for control flow, `applyFirst` lifts
+// that behavior to the rule level.  So, you can write `applyFirst({makeRule(m1,
+// action1), makeRule(m2, action2), ...});`
+//
+// For example, consider a type `T` with a deterministic serialization function,
+// `serialize()`.  For performance reasons, we would like to make it
+// non-deterministic.  Therefore, we want to drop the expectation that
+// `a.serialize() = b.serialize() iff a = b` (although we'll maintain
+// `deserialize(a.serialize()) = a`).
+//
+// We have three cases to consider (for some equality function, `eq`):
+// ```
+// eq(a.serialize(), b.serialize()) --> eq(a,b)
+// eq(a, b.serialize())             --> eq(deserialize(a), b)
+// eq(a.serialize(), b)             --> eq(a, deserialize(b))
+// ```
+//
+// `applyFirst` allows us to specify each independently:
+// ```
+// auto eq_fun = functionDecl(...);
+// auto method_call = cxxMemberCallExpr(...);
+//
+// auto two_calls = callExpr(callee(eq_fun), hasArgument(0, method_call),
+//                           hasArgument(1, method_call));
+// auto left_call =
+//     callExpr(callee(eq_fun), callExpr(hasArgument(0, method_call)));
+// auto right_call =
+//     callExpr(callee(eq_fun), callExpr(hasArgument(1, method_call)));
+//
+// RewriteRule R = applyFirst({makeRule(two_calls, two_calls_action),
+//                             makeRule(left_call, left_call_action),
+//                             makeRule(right_call, right_call_action)});
+// ```
+RewriteRule applyFirst(ArrayRef<RewriteRule> Rules);
+
+/// Replaces a portion of the source text with \p Replacement.
+ASTEdit change(RangeSelector Target, TextGenerator Replacement);
+
+/// Replaces the entirety of a RewriteRule's match with \p Replacement.  For
+/// example, to replace a function call, one could write:
+/// \code
+///   makeRule(callExpr(callee(functionDecl(hasName("foo")))),
+///            change(text("bar()")))
+/// \endcode
+inline ASTEdit change(TextGenerator Replacement) {
+  return change(node(RewriteRule::RootID), std::move(Replacement));
+}
+
+/// Inserts \p Replacement before \p S, leaving the source selected by \S
+/// unchanged.
+inline ASTEdit insertBefore(RangeSelector S, TextGenerator Replacement) {
+  return change(before(std::move(S)), std::move(Replacement));
+}
+
+/// Inserts \p Replacement after \p S, leaving the source selected by \S
+/// unchanged.
+inline ASTEdit insertAfter(RangeSelector S, TextGenerator Replacement) {
+  return change(after(std::move(S)), std::move(Replacement));
+}
+
+/// Removes the source selected by \p S.
+inline ASTEdit remove(RangeSelector S) {
+  return change(std::move(S), text(""));
+}
+
+/// The following three functions are a low-level part of the RewriteRule
+/// API. We expose them for use in implementing the fixtures that interpret
+/// RewriteRule, like Transformer and TransfomerTidy, or for more advanced
+/// users.
+//
+// FIXME: These functions are really public, if advanced, elements of the
+// RewriteRule API.  Recast them as such.  Or, just declare these functions
+// public and well-supported and move them out of `detail`.
+namespace detail {
+/// Builds a single matcher for the rule, covering all of the rule's cases.
+/// Only supports Rules whose cases' matchers share the same base "kind"
+/// (`Stmt`, `Decl`, etc.)  Deprecated: use `buildMatchers` instead, which
+/// supports mixing matchers of different kinds.
+ast_matchers::internal::DynTypedMatcher buildMatcher(const RewriteRule &Rule);
+
+/// Builds a set of matchers that cover the rule (one for each distinct node
+/// matcher base kind: Stmt, Decl, etc.). Node-matchers for `QualType` and
+/// `Type` are not permitted, since such nodes carry no source location
+/// information and are therefore not relevant for rewriting. If any such
+/// matchers are included, will return an empty vector.
+std::vector<ast_matchers::internal::DynTypedMatcher>
+buildMatchers(const RewriteRule &Rule);
+
+/// Gets the beginning location of the source matched by a rewrite rule. If the
+/// match occurs within a macro expansion, returns the beginning of the
+/// expansion point. `Result` must come from the matching of a rewrite rule.
+SourceLocation
+getRuleMatchLoc(const ast_matchers::MatchFinder::MatchResult &Result);
+
+/// Returns the \c Case of \c Rule that was selected in the match result.
+/// Assumes a matcher built with \c buildMatcher.
+const RewriteRule::Case &
+findSelectedCase(const ast_matchers::MatchFinder::MatchResult &Result,
+                 const RewriteRule &Rule);
+
+/// A source "transformation," represented by a character range in the source to
+/// be replaced and a corresponding replacement string.
+struct Transformation {
+  CharSourceRange Range;
+  std::string Replacement;
+};
+
+/// Attempts to translate `Edits`, which are in terms of AST nodes bound in the
+/// match `Result`, into Transformations, which are in terms of the source code
+/// text.
+///
+/// Returns an empty vector if any of the edits apply to portions of the source
+/// that are ineligible for rewriting (certain interactions with macros, for
+/// example).  Fails if any invariants are violated relating to bound nodes in
+/// the match.  However, it does not fail in the case of conflicting edits --
+/// conflict handling is left to clients.  We recommend use of the \c
+/// AtomicChange or \c Replacements classes for assistance in detecting such
+/// conflicts.
+Expected<SmallVector<Transformation, 1>>
+translateEdits(const ast_matchers::MatchFinder::MatchResult &Result,
+               llvm::ArrayRef<ASTEdit> Edits);
+} // namespace detail
+} // namespace tooling
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLING_TRANSFORMER_REWRITE_RULE_H_

include/clang/Tooling/Transformer/Transformer.h

@@ -1,292 +1,24 @@
-//===--- Transformer.h - Clang source-rewriting library ---------*- C++ -*-===//
+//===--- Transformer.h - Transformer class ----------------------*- 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
-///  Defines a library supporting the concise specification of clang-based
-///  source-to-source transformations.
-///
-//===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_TOOLING_TRANSFORMER_TRANSFORMER_H_
 #define LLVM_CLANG_TOOLING_TRANSFORMER_TRANSFORMER_H_
 
 #include "clang/ASTMatchers/ASTMatchFinder.h"
-#include "clang/ASTMatchers/ASTMatchers.h"
-#include "clang/ASTMatchers/ASTMatchersInternal.h"
 #include "clang/Tooling/Refactoring/AtomicChange.h"
-#include "clang/Tooling/Transformer/MatchConsumer.h"
-#include "clang/Tooling/Transformer/RangeSelector.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SmallVector.h"
+#include "clang/Tooling/Transformer/RewriteRule.h"
 #include "llvm/Support/Error.h"
-#include <deque>
 #include <functional>
-#include <string>
-#include <type_traits>
 #include <utility>
 
 namespace clang {
 namespace tooling {
-
-using TextGenerator = MatchConsumer<std::string>;
-
-/// Wraps a string as a TextGenerator.
-inline TextGenerator text(std::string M) {
-  return [M](const ast_matchers::MatchFinder::MatchResult &)
-             -> Expected<std::string> { return M; };
-}
-
-// Description of a source-code edit, expressed in terms of an AST node.
-// Includes: an ID for the (bound) node, a selector for source related to the
-// node, a replacement and, optionally, an explanation for the edit.
-//
-// * Target: the source code impacted by the rule. This identifies an AST node,
-//   or part thereof (\c Part), whose source range indicates the extent of the
-//   replacement applied by the replacement term.  By default, the extent is the
-//   node matched by the pattern term (\c NodePart::Node). Target's are typed
-//   (\c Kind), which guides the determination of the node extent.
-//
-// * Replacement: a function that produces a replacement string for the target,
-//   based on the match result.
-//
-// * Note: (optional) a note specifically for this edit, potentially referencing
-//   elements of the match.  This will be displayed to the user, where possible;
-//   for example, in clang-tidy diagnostics.  Use of notes should be rare --
-//   explanations of the entire rewrite should be set in the rule
-//   (`RewriteRule::Explanation`) instead.  Notes serve the rare cases wherein
-//   edit-specific diagnostics are required.
-//
-// `ASTEdit` should be built using the `change` convenience functions. For
-// example,
-// \code
-//   change(name(fun), text("Frodo"))
-// \endcode
-// Or, if we use Stencil for the TextGenerator:
-// \code
-//   using stencil::cat;
-//   change(statement(thenNode), cat("{", thenNode, "}"))
-//   change(callArgs(call), cat(x, ",", y))
-// \endcode
-// Or, if you are changing the node corresponding to the rule's matcher, you can
-// use the single-argument override of \c change:
-// \code
-//   change(cat("different_expr"))
-// \endcode
-struct ASTEdit {
-  RangeSelector TargetRange;
-  TextGenerator Replacement;
-  TextGenerator Note;
-};
-
-/// Format of the path in an include directive -- angle brackets or quotes.
-enum class IncludeFormat {
-  Quoted,
-  Angled,
-};
-
-/// Description of a source-code transformation.
-//
-// A *rewrite rule* describes a transformation of source code. A simple rule
-// contains each of the following components:
-//
-// * Matcher: the pattern term, expressed as clang matchers (with Transformer
-//   extensions).
-//
-// * Edits: a set of Edits to the source code, described with ASTEdits.
-//
-// * Explanation: explanation of the rewrite.  This will be displayed to the
-//   user, where possible; for example, in clang-tidy diagnostics.
-//
-// However, rules can also consist of (sub)rules, where the first that matches
-// is applied and the rest are ignored.  So, the above components are gathered
-// as a `Case` and a rule is a list of cases.
-//
-// Rule cases have an additional, implicit, component: the parameters. These are
-// portions of the pattern which are left unspecified, yet bound in the pattern
-// so that we can reference them in the edits.
-//
-// The \c Transformer class can be used to apply the rewrite rule and obtain the
-// corresponding replacements.
-struct RewriteRule {
-  struct Case {
-    ast_matchers::internal::DynTypedMatcher Matcher;
-    SmallVector<ASTEdit, 1> Edits;
-    TextGenerator Explanation;
-    // Include paths to add to the file affected by this case.  These are
-    // bundled with the `Case`, rather than the `RewriteRule`, because each case
-    // might have different associated changes to the includes.
-    std::vector<std::pair<std::string, IncludeFormat>> AddedIncludes;
-  };
-  // We expect RewriteRules will most commonly include only one case.
-  SmallVector<Case, 1> Cases;
-
-  // ID used as the default target of each match. The node described by the
-  // matcher is should always be bound to this id.
-  static constexpr llvm::StringLiteral RootID = "___root___";
-};
-
-/// Convenience function for constructing a simple \c RewriteRule.
-RewriteRule makeRule(ast_matchers::internal::DynTypedMatcher M,
-                     SmallVector<ASTEdit, 1> Edits,
-                     TextGenerator Explanation = nullptr);
-
-/// Convenience overload of \c makeRule for common case of only one edit.
-inline RewriteRule makeRule(ast_matchers::internal::DynTypedMatcher M,
-                            ASTEdit Edit,
-                            TextGenerator Explanation = nullptr) {
-  SmallVector<ASTEdit, 1> Edits;
-  Edits.emplace_back(std::move(Edit));
-  return makeRule(std::move(M), std::move(Edits), std::move(Explanation));
-}
-
-/// For every case in Rule, adds an include directive for the given header. The
-/// common use is assumed to be a rule with only one case. For example, to
-/// replace a function call and add headers corresponding to the new code, one
-/// could write:
-/// \code
-///   auto R = makeRule(callExpr(callee(functionDecl(hasName("foo")))),
-///            change(text("bar()")));
-///   AddInclude(R, "path/to/bar_header.h");
-///   AddInclude(R, "vector", IncludeFormat::Angled);
-/// \endcode
-void addInclude(RewriteRule &Rule, llvm::StringRef Header,
-                IncludeFormat Format = IncludeFormat::Quoted);
-
-/// Applies the first rule whose pattern matches; other rules are ignored.  If
-/// the matchers are independent then order doesn't matter. In that case,
-/// `applyFirst` is simply joining the set of rules into one.
-//
-// `applyFirst` is like an `anyOf` matcher with an edit action attached to each
-// of its cases. Anywhere you'd use `anyOf(m1.bind("id1"), m2.bind("id2"))` and
-// then dispatch on those ids in your code for control flow, `applyFirst` lifts
-// that behavior to the rule level.  So, you can write `applyFirst({makeRule(m1,
-// action1), makeRule(m2, action2), ...});`
-//
-// For example, consider a type `T` with a deterministic serialization function,
-// `serialize()`.  For performance reasons, we would like to make it
-// non-deterministic.  Therefore, we want to drop the expectation that
-// `a.serialize() = b.serialize() iff a = b` (although we'll maintain
-// `deserialize(a.serialize()) = a`).
-//
-// We have three cases to consider (for some equality function, `eq`):
-// ```
-// eq(a.serialize(), b.serialize()) --> eq(a,b)
-// eq(a, b.serialize())             --> eq(deserialize(a), b)
-// eq(a.serialize(), b)             --> eq(a, deserialize(b))
-// ```
-//
-// `applyFirst` allows us to specify each independently:
-// ```
-// auto eq_fun = functionDecl(...);
-// auto method_call = cxxMemberCallExpr(...);
-//
-// auto two_calls = callExpr(callee(eq_fun), hasArgument(0, method_call),
-//                           hasArgument(1, method_call));
-// auto left_call =
-//     callExpr(callee(eq_fun), callExpr(hasArgument(0, method_call)));
-// auto right_call =
-//     callExpr(callee(eq_fun), callExpr(hasArgument(1, method_call)));
-//
-// RewriteRule R = applyFirst({makeRule(two_calls, two_calls_action),
-//                             makeRule(left_call, left_call_action),
-//                             makeRule(right_call, right_call_action)});
-// ```
-RewriteRule applyFirst(ArrayRef<RewriteRule> Rules);
-
-/// Replaces a portion of the source text with \p Replacement.
-ASTEdit change(RangeSelector Target, TextGenerator Replacement);
-
-/// Replaces the entirety of a RewriteRule's match with \p Replacement.  For
-/// example, to replace a function call, one could write:
-/// \code
-///   makeRule(callExpr(callee(functionDecl(hasName("foo")))),
-///            change(text("bar()")))
-/// \endcode
-inline ASTEdit change(TextGenerator Replacement) {
-  return change(node(RewriteRule::RootID), std::move(Replacement));
-}
-
-/// Inserts \p Replacement before \p S, leaving the source selected by \S
-/// unchanged.
-inline ASTEdit insertBefore(RangeSelector S, TextGenerator Replacement) {
-  return change(before(std::move(S)), std::move(Replacement));
-}
-
-/// Inserts \p Replacement after \p S, leaving the source selected by \S
-/// unchanged.
-inline ASTEdit insertAfter(RangeSelector S, TextGenerator Replacement) {
-  return change(after(std::move(S)), std::move(Replacement));
-}
-
-/// Removes the source selected by \p S.
-inline ASTEdit remove(RangeSelector S) {
-  return change(std::move(S), text(""));
-}
-
-/// The following three functions are a low-level part of the RewriteRule
-/// API. We expose them for use in implementing the fixtures that interpret
-/// RewriteRule, like Transformer and TransfomerTidy, or for more advanced
-/// users.
-//
-// FIXME: These functions are really public, if advanced, elements of the
-// RewriteRule API.  Recast them as such.  Or, just declare these functions
-// public and well-supported and move them out of `detail`.
-namespace detail {
-/// Builds a single matcher for the rule, covering all of the rule's cases.
-/// Only supports Rules whose cases' matchers share the same base "kind"
-/// (`Stmt`, `Decl`, etc.)  Deprecated: use `buildMatchers` instead, which
-/// supports mixing matchers of different kinds.
-ast_matchers::internal::DynTypedMatcher buildMatcher(const RewriteRule &Rule);
-
-/// Builds a set of matchers that cover the rule (one for each distinct node
-/// matcher base kind: Stmt, Decl, etc.). Node-matchers for `QualType` and
-/// `Type` are not permitted, since such nodes carry no source location
-/// information and are therefore not relevant for rewriting. If any such
-/// matchers are included, will return an empty vector.
-std::vector<ast_matchers::internal::DynTypedMatcher>
-buildMatchers(const RewriteRule &Rule);
-
-/// Gets the beginning location of the source matched by a rewrite rule. If the
-/// match occurs within a macro expansion, returns the beginning of the
-/// expansion point. `Result` must come from the matching of a rewrite rule.
-SourceLocation
-getRuleMatchLoc(const ast_matchers::MatchFinder::MatchResult &Result);
-
-/// Returns the \c Case of \c Rule that was selected in the match result.
-/// Assumes a matcher built with \c buildMatcher.
-const RewriteRule::Case &
-findSelectedCase(const ast_matchers::MatchFinder::MatchResult &Result,
-                 const RewriteRule &Rule);
-
-/// A source "transformation," represented by a character range in the source to
-/// be replaced and a corresponding replacement string.
-struct Transformation {
-  CharSourceRange Range;
-  std::string Replacement;
-};
-
-/// Attempts to translate `Edits`, which are in terms of AST nodes bound in the
-/// match `Result`, into Transformations, which are in terms of the source code
-/// text.
-///
-/// Returns an empty vector if any of the edits apply to portions of the source
-/// that are ineligible for rewriting (certain interactions with macros, for
-/// example).  Fails if any invariants are violated relating to bound nodes in
-/// the match.  However, it does not fail in the case of conflicting edits --
-/// conflict handling is left to clients.  We recommend use of the \c
-/// AtomicChange or \c Replacements classes for assistance in detecting such
-/// conflicts.
-Expected<SmallVector<Transformation, 1>>
-translateEdits(const ast_matchers::MatchFinder::MatchResult &Result,
-               llvm::ArrayRef<ASTEdit> Edits);
-} // namespace detail
-
-/// Handles the matcher and callback registration for a single rewrite rule, as
+/// Handles the matcher and callback registration for a single `RewriteRule`, as
 /// defined by the arguments of the constructor.
 class Transformer : public ast_matchers::MatchFinder::MatchCallback {
 public:

lib/Tooling/Transformer/CMakeLists.txt

@@ -2,6 +2,7 @@ set(LLVM_LINK_COMPONENTS Support)
 
 add_clang_library(clangTransformer
   RangeSelector.cpp
+  RewriteRule.cpp
   SourceCode.cpp
   SourceCodeBuilders.cpp
   Stencil.cpp

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 tooling;
+
+using ast_matchers::MatchFinder;
+using ast_matchers::internal::DynTypedMatcher;
+using ast_type_traits::ASTNodeKind;
+
+using MatchResult = MatchFinder::MatchResult;
+
+Expected<SmallVector<tooling::detail::Transformation, 1>>
+tooling::detail::translateEdits(const MatchResult &Result,
+                                llvm::ArrayRef<ASTEdit> Edits) {
+  SmallVector<tooling::detail::Transformation, 1> Transformations;
+  for (const auto &Edit : Edits) {
+    Expected<CharSourceRange> Range = Edit.TargetRange(Result);
+    if (!Range)
+      return Range.takeError();
+    llvm::Optional<CharSourceRange> EditRange =
+        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();
+    tooling::detail::Transformation T;
+    T.Range = *EditRange;
+    T.Replacement = std::move(*Replacement);
+    Transformations.push_back(std::move(T));
+  }
+  return Transformations;
+}
+
+ASTEdit tooling::change(RangeSelector S, TextGenerator Replacement) {
+  ASTEdit E;
+  E.TargetRange = std::move(S);
+  E.Replacement = std::move(Replacement);
+  return E;
+}
+
+RewriteRule tooling::makeRule(DynTypedMatcher M, SmallVector<ASTEdit, 1> Edits,
+                              TextGenerator Explanation) {
+  return RewriteRule{{RewriteRule::Case{
+      std::move(M), std::move(Edits), std::move(Explanation), {}}}};
+}
+
+void tooling::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 tooling::applyFirst(ArrayRef<RewriteRule> Rules) {
+  RewriteRule R;
+  for (auto &Rule : Rules)
+    R.Cases.append(Rule.Cases.begin(), Rule.Cases.end());
+  return R;
+}
+
+std::vector<DynTypedMatcher>
+tooling::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 tooling::detail::buildMatcher(const RewriteRule &Rule) {
+  std::vector<DynTypedMatcher> Ms = buildMatchers(Rule);
+  assert(Ms.size() == 1 && "Cases must have compatible matchers.");
+  return Ms[0];
+}
+
+SourceLocation tooling::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 = 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 &
+tooling::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;

lib/Tooling/Transformer/Transformer.cpp

@@ -7,20 +7,11 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/Tooling/Transformer/Transformer.h"
-#include "clang/AST/Expr.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
-#include "clang/ASTMatchers/ASTMatchers.h"
-#include "clang/Basic/Diagnostic.h"
+#include "clang/ASTMatchers/ASTMatchersInternal.h"
 #include "clang/Basic/SourceLocation.h"
-#include "clang/Rewrite/Core/Rewriter.h"
 #include "clang/Tooling/Refactoring/AtomicChange.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>
 
@@ -28,168 +19,13 @@ using namespace clang;
 using namespace tooling;
 
 using ast_matchers::MatchFinder;
-using ast_matchers::internal::DynTypedMatcher;
-using ast_type_traits::ASTNodeKind;
-using ast_type_traits::DynTypedNode;
-using llvm::Error;
-using llvm::StringError;
-
-using MatchResult = MatchFinder::MatchResult;
-
-Expected<SmallVector<tooling::detail::Transformation, 1>>
-tooling::detail::translateEdits(const MatchResult &Result,
-                                llvm::ArrayRef<ASTEdit> Edits) {
-  SmallVector<tooling::detail::Transformation, 1> Transformations;
-  for (const auto &Edit : Edits) {
-    Expected<CharSourceRange> Range = Edit.TargetRange(Result);
-    if (!Range)
-      return Range.takeError();
-    llvm::Optional<CharSourceRange> EditRange =
-        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();
-    tooling::detail::Transformation T;
-    T.Range = *EditRange;
-    T.Replacement = std::move(*Replacement);
-    Transformations.push_back(std::move(T));
-  }
-  return Transformations;
-}
-
-ASTEdit tooling::change(RangeSelector S, TextGenerator Replacement) {
-  ASTEdit E;
-  E.TargetRange = std::move(S);
-  E.Replacement = std::move(Replacement);
-  return E;
-}
-
-RewriteRule tooling::makeRule(DynTypedMatcher M, SmallVector<ASTEdit, 1> Edits,
-                              TextGenerator Explanation) {
-  return RewriteRule{{RewriteRule::Case{
-      std::move(M), std::move(Edits), std::move(Explanation), {}}}};
-}
-
-void tooling::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 tooling::applyFirst(ArrayRef<RewriteRule> Rules) {
-  RewriteRule R;
-  for (auto &Rule : Rules)
-    R.Cases.append(Rule.Cases.begin(), Rule.Cases.end());
-  return R;
-}
-
-std::vector<DynTypedMatcher>
-tooling::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 tooling::detail::buildMatcher(const RewriteRule &Rule) {
-  std::vector<DynTypedMatcher> Ms = buildMatchers(Rule);
-  assert(Ms.size() == 1 && "Cases must have compatible matchers.");
-  return Ms[0];
-}
-
-SourceLocation tooling::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 = 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 &
-tooling::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;
 
 void Transformer::registerMatchers(MatchFinder *MatchFinder) {
   for (auto &Matcher : tooling::detail::buildMatchers(Rule))
     MatchFinder->addDynamicMatcher(Matcher, this);
 }
 
-void Transformer::run(const MatchResult &Result) {
+void Transformer::run(const MatchFinder::MatchResult &Result) {
   if (Result.Context->getDiagnostics().hasErrorOccurred())
     return;
 
@@ -202,7 +38,7 @@ void Transformer::run(const MatchResult &Result) {
 
   if (Transformations->empty()) {
     // No rewrite applied (but no error encountered either).
-    detail::getRuleMatchLoc(Result).print(
+    tooling::detail::getRuleMatchLoc(Result).print(
         llvm::errs() << "note: skipping match at loc ", *Result.SourceManager);
     llvm::errs() << "\n";
     return;