[PATCH] D56267: [clangd] Interfaces for writing code actions

[Sam McCall via Phabricator via cfe-commits]

sammccall added a comment.

Offline discussion:

- CRTP doesn't buy anything. Simple inheritance is less clean than current function-passing version but probably more familiar.
- `Tweak` is a good name: short, evocative but not commonly used, works as a noun and a verb.
- Registry might be a good enough fit to use directly

Here's the result of my local, er, tweaking to `ActionProvider.h`.

  //===--- Tweak.h -------------------------------------------------*- C++-*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  // A tweak is a small context-sensitive refactoring-like action that is
  // triggered at a cursor location, examines the AST and produces a set of edits.
  //
  // It has two main pieces of logic:
  //   - prepare() quickly checks whether the action is applicable at the cursor.
  //     It must be cheap as all tweaks are prepared to list them for the user.
  //   - apply() computes the actual edits.
  //     This can be more expensive, only the chosen tweak is applied.
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_REFACTOR_ACTIONS_ACTIONPROVIDER_H
  #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_REFACTOR_ACTIONS_ACTIONPROVIDER_H
  
  #include "ClangdUnit.h"
  #include "Protocol.h"
  #include "llvm/ADT/Optional.h"
  #include "llvm/ADT/StringRef.h"
  namespace clang {
  namespace clangd {
  
  // Abstract base for small context-sensitive refactoring actions.
  class Tweak {
  public:
    // Information about the location where the tweak was triggered.
    struct Selection {
      // The path of an active document the action was invoked in.
      llvm::StringRef File;
      // The text of the active document.
      llvm::StringRef Code;
      // Parsed AST of the active file.
      ParsedAST *
      // A location of the cursor in the editor.
      SourceLocation Cursor;
      // FIXME: full selection bounds.
      // FIXME: AST node under cursor.
      // FIXME: allow tweaks to specify matchers, and include match results.
      // FIXME: allow access to index and other source files.
    };
  
    // Tweaks must have a no-op default constructor.
    virtual ~Tweak() = default;
  
    virtual const char* id() = 0;
    // Determines whether this tweak can run at the selection.
    // This function may record information to be used later.
    // It should run as fast as possible, particularly when returning false.
    virtual bool prepare(const Selection &) = 0;
  
    // Generate the edits for this tweak.
    // REQUIRES: prepare() was called and returned true.
    virtual llvm::Expected<tooling::Replacements>
    apply(const Selection &) = 0;
  
    // Description of this tweak at the selected location.
    // e.g. "Out-line definition of toString()".
    // REQUIRES: prepare() was called and returned true.
    virtual std::string describe() const;
  };
  
  // All tweaks must be registered, next to their definition.
  #define REGISTER_TWEAK(Subclass)                                               \
    static ::llvm::Registry<::clang::clangd::Tweak>::Add<Subclass>                 \
        TweakRegistrationFor##Subclass(Subclass{}.id(), #Subclass);
  
  // Calls prepare() on all tweaks, returning those that can run on the selection.
  std::vector<std::unique_ptr<Tweak>> prepareTweaks(const Tweak::Selection &);
  // Calls prepare() on the tweak with a given ID.
  // If prepare() returns false, returns an error.
  Expected<std::unique_ptr<Tweak>> prepareTweak(StringRef ID,
                                                const Tweak::Selection &);
  
  } // namespace clangd
  } // namespace clang
  
  #endif


Repository:
  rCTE Clang Tools Extra

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  https://reviews.llvm.org/D56267/new/

https://reviews.llvm.org/D56267