Initial implementation of a code-completion interface in Clang. In

essence, code completion is triggered by a magic "code completion"
token produced by the lexer [*], which the parser recognizes at
certain points in the grammar. The parser then calls into the Action
object with the appropriate CodeCompletionXXX action.

Sema implements the CodeCompletionXXX callbacks by performing minimal
translation, then forwarding them to a CodeCompletionConsumer
subclass, which uses the results of semantic analysis to provide
code-completion results. At present, only a single, "printing" code
completion consumer is available, for regression testing and
debugging. However, the design is meant to permit other
code-completion consumers.

This initial commit contains two code-completion actions: one for
member access, e.g., "x." or "p->", and one for
nested-name-specifiers, e.g., "std::". More code-completion actions
will follow, along with improved gathering of code-completion results
for the various contexts.

[*] In the current -code-completion-dump testing/debugging mode, the
file is truncated at the completion point and EOF is translated into
"code completion".


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@82166 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 183 insertions, 0 deletions

diff --git a/include/clang/Sema/CodeCompleteConsumer.h b/include/clang/Sema/CodeCompleteConsumer.h
new file mode 100644
index 0000000000..c9e989e3cc
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+++ b/include/clang/Sema/CodeCompleteConsumer.h
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+//===---- CodeCompleteConsumer.h - Code Completion Interface ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the CodeCompleteConsumer class.
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_CLANG_SEMA_CODECOMPLETECONSUMER_H
+#define LLVM_CLANG_SEMA_CODECOMPLETECONSUMER_H
+
+#include "clang/AST/DeclarationName.h"
+#include "clang/AST/Type.h"
+#include <list>
+#include <map>
+#include <vector>
+
+namespace llvm {
+class raw_ostream;
+}
+
+namespace clang {
+  
+class DeclContext;
+class NamedDecl;
+class Scope;
+class Sema;
+  
+/// \brief Abstract interface for a consumer of code-completion 
+/// information.
+class CodeCompleteConsumer {
+  /// \brief The semantic-analysis object to which this code-completion
+  /// consumer is attached.
+  Sema &SemaRef;
+  
+public:
+  /// \brief Captures a result of code completion.
+  struct Result {
+    /// \brief Describes the kind of result generated.
+    enum ResultKind {
+      RK_Declaration = 0, //< Refers to a declaration
+      RK_Keyword,        //< Refers to a keyword or symbol.
+    };
+    
+    /// \brief The kind of result stored here.
+    ResultKind Kind;
+    
+    union {
+      /// \brief When Kind == RK_Declaration, the declaration we are referring
+      /// to.
+      NamedDecl *Declaration;
+      
+      /// \brief When Kind == RK_Keyword, the string representing the keyword 
+      /// or symbol's spelling.
+      const char *Keyword;
+    };
+    
+    /// \brief Describes how good this result is, with zero being the best
+    /// result and progressively higher numbers representing poorer results.
+    unsigned Rank;
+    
+    /// \brief Whether this result is hidden by another name.
+    bool Hidden : 1;
+    
+    /// \brief Build a result that refers to a declaration.
+    Result(NamedDecl *Declaration, unsigned Rank)
+      : Kind(RK_Declaration), Declaration(Declaration), Rank(Rank), 
+        Hidden(false) { }
+    
+    /// \brief Build a result that refers to a keyword or symbol.
+    Result(const char *Keyword, unsigned Rank)
+      : Kind(RK_Keyword), Keyword(Keyword), Rank(Rank), Hidden(false) { }
+  };
+  
+  /// \brief A container of code-completion results.
+  class ResultSet {
+    /// \brief The actual results we have found.
+    std::vector<Result> Results;
+
+    /// \brief A mapping from declaration names to the declarations that have
+    /// this name within a particular scope and their index within the list of
+    /// results.
+    typedef std::multimap<DeclarationName, 
+                          std::pair<NamedDecl *, unsigned> > ShadowMap;
+    
+    /// \brief A list of shadow maps, which is used to model name hiding at
+    /// different levels of, e.g., the inheritance hierarchy.
+    std::list<ShadowMap> ShadowMaps;
+    
+  public:
+    typedef std::vector<Result>::iterator iterator;
+    iterator begin() { return Results.begin(); }
+    iterator end() { return Results.end(); }
+    
+    Result *data() { return Results.empty()? 0 : &Results.front(); }
+    unsigned size() const { return Results.size(); }
+    bool empty() const { return Results.empty(); }
+    
+    /// \brief Add a new result to this result set (if it isn't already in one
+    /// of the shadow maps), or replace an existing result (for, e.g., a 
+    /// redeclaration).
+    void MaybeAddResult(Result R);
+    
+    /// \brief Enter into a new scope.
+    void EnterNewScope();
+    
+    /// \brief Exit from the current scope.
+    void ExitScope();
+  };
+  
+  /// \brief Create a new code-completion consumer and registers it with
+  /// the given semantic-analysis object.
+  explicit CodeCompleteConsumer(Sema &S);
+  
+  /// \brief Deregisters and destroys this code-completion consumer.
+  virtual ~CodeCompleteConsumer();
+  
+  /// \brief Retrieve the semantic-analysis object to which this code-completion
+  /// consumer is attached.
+  Sema &getSema() const { return SemaRef; }
+  
+  /// \name Code-completion callbacks
+  //@{
+  
+  /// \brief Process the finalized code-completion results.
+  virtual void ProcessCodeCompleteResults(Result *Results, 
+                                          unsigned NumResults) { }
+  
+  /// \brief Code completion for a member access expression, e.g., "x->" or
+  /// "x.".
+  ///
+  /// \param S is the scope in which code-completion occurs.
+  ///
+  /// \param BaseType is the type whose members are being accessed.
+  ///
+  /// \param IsArrow whether this member referenced was written with an
+  /// arrow ("->") or a period (".").
+  virtual void CodeCompleteMemberReferenceExpr(Scope *S, QualType BaseType,
+                                               bool IsArrow);
+  
+  /// \brief Code completion for a qualified-id, e.g., "std::"
+  ///
+  /// \param S the scope in which the nested-name-specifier occurs.
+  ///
+  /// \param NNS the nested-name-specifier before the code-completion location.
+  ///
+  /// \param EnteringContext whether the parser will be entering the scope of
+  /// the qualified-id.
+  virtual void CodeCompleteQualifiedId(Scope *S, NestedNameSpecifier *NNS,
+                                       bool EnteringContext);
+  //@}
+  
+  /// \name Utility functions
+  //@{
+  unsigned CollectMemberResults(DeclContext *Ctx, unsigned InitialRank, 
+                                ResultSet &Results);
+  //@}
+};
+  
+/// \brief A simple code-completion consumer that prints the results it 
+/// receives in a simple format.
+class PrintingCodeCompleteConsumer : public CodeCompleteConsumer {
+  /// \brief The raw output stream.
+  llvm::raw_ostream &OS;
+  
+public:
+  /// \brief Create a new printing code-completion consumer that prints its
+  /// results to the given raw output stream.
+  PrintingCodeCompleteConsumer(Sema &S, llvm::raw_ostream &OS)
+    : CodeCompleteConsumer(S), OS(OS) { }
+  
+  /// \brief Prints the finalized code-completion results.
+  virtual void ProcessCodeCompleteResults(Result *Results, 
+                                          unsigned NumResults);
+};
+  
+} // end namespace clang
+
+#endif // LLVM_CLANG_SEMA_CODECOMPLETECONSUMER_H