Added initial code completion support for the `expr` command

Summary:
This patch adds initial code completion support for the `expr` command.

We now have a completion handler in the expression CommandObject that
essentially just attempts to parse the given user expression with Clang with
an attached code completion consumer. We filter and prepare the
code completions provided by Clang and send them back to the completion
API.

The current completion is limited to variables that are in the current scope.
This includes local variables and all types used by local variables. We however
don't do any completion of symbols that are not used in the local scope (or
in some other way already in the ASTContext).

This is partly because there is not yet any code that manually searches for additiona
information in the debug information. Another cause is that for some reason the existing
code for loading these additional symbols when requested by Clang doesn't seem to work.
This will be fixed in a future patch.

Reviewers: jingham, teemperor

Reviewed By: teemperor

Subscribers: labath, aprantl, JDevlieghere, friss, lldb-commits

Differential Revision: https://reviews.llvm.org/D48465

llvm-svn: 341086

1 files changed, 34 insertions, 0 deletions

diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.h b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.h
index 6b17c6d5fb3..7fdc9c121ef 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.h
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.h
@@ -20,6 +20,10 @@
 #include <string>
 #include <vector>
 
+namespace clang {
+class CodeCompleteConsumer;
+}
+
 namespace lldb_private {
 
 class IRExecutionUnit;
@@ -58,6 +62,9 @@ public:
   //------------------------------------------------------------------
   ~ClangExpressionParser() override;
 
+  bool Complete(StringList &matches, unsigned line, unsigned pos,
+                unsigned typed_pos) override;
+
   //------------------------------------------------------------------
   /// Parse a single expression and convert it to IR using Clang.  Don't wrap
   /// the expression in anything at all.
@@ -143,6 +150,33 @@ public:
   std::string GetClangTargetABI(const ArchSpec &target_arch);
 
 private:
+  //------------------------------------------------------------------
+  /// Parses the expression.
+  ///
+  /// @param[in] diagnostic_manager
+  ///     The diagnostic manager that should receive the diagnostics
+  ///     from the parsing process.
+  ///
+  /// @param[in] completion
+  ///     The completion consumer that should be used during parsing
+  ///     (or a nullptr if no consumer should be attached).
+  ///
+  /// @param[in] completion_line
+  ///     The line in which the completion marker should be placed.
+  ///     The first line is represented by the value 0.
+  ///
+  /// @param[in] completion_column
+  ///     The column in which the completion marker should be placed.
+  ///     The first column is represented by the value 0.
+  ///
+  /// @return
+  ///    The number of parsing errors.
+  //-------------------------------------------------------------------
+  unsigned ParseInternal(DiagnosticManager &diagnostic_manager,
+                         clang::CodeCompleteConsumer *completion = nullptr,
+                         unsigned completion_line = 0,
+                         unsigned completion_column = 0);
+
   std::unique_ptr<llvm::LLVMContext>
       m_llvm_context; ///< The LLVM context to generate IR into
   std::unique_ptr<clang::FileManager>