Code completion (from Sema) (#144)

include/Feature/CodeCompletion.h

@@ -12,7 +12,23 @@ struct CompilationParams;
 
 namespace config {
 
-struct CodeCompletionOption {};
+struct CodeCompletionOption {
+    /// Insert placeholder for keywords? function call parameters? template arguments?
+    bool enable_keyword_snippet = false;
+
+    /// Also apply for lambda ...
+    bool enable_function_arguments_snippet = false;
+    bool enable_template_arguments_snippet = false;
+
+    bool insert_paren_in_function_call = false;
+    /// TODO: Add more detailed option, see
+    /// https://github.com/llvm/llvm-project/issues/63565
+
+    bool bundle_overloads = true;
+
+    /// The limits of code completion, 0 is non limit.
+    std::uint32_t limit = 0;
+};
 
 };  // namespace config
 
@@ -47,30 +63,43 @@ enum class CompletionItemKind {
     TypeParameter
 };
 
+/// Represents a single code completion item to be presented to the user.
 struct CompletionItem {
-    /// The label displayed when user select the item.
+    /// The primary label displayed in the completion list.
     std::string label;
 
+    /// Additional details, like a function signature, shown next to the label.
     std::string detail;
 
-    /// TODO:
-    /// std::string sortText;
+    /// A short description of the item, typically its type or namespace.
+    std::string description;
 
+    /// Full documentation for the item, shown on selection or hover.
+    std::string document;
+
+    /// The kind of item (function, class, etc.), used for an icon.
     CompletionItemKind kind;
 
+    /// A score for ranking this item against others. Higher is better.
+    float score;
+
+    /// Whether this item is deprecated (often rendered with a strikethrough).
     bool deprecated;
 
+    /// The text edit to be applied when this item is accepted.
     struct Edit {
+        /// The new text to insert, which may be a snippet.
         std::string text;
 
+        /// The source range to be replaced by the new text.
         LocalSourceRange range;
     } edit;
 };
 
 using CodeCompletionResult = std::vector<CompletionItem>;
 
-CodeCompletionResult codeCompletion(CompilationParams& params,
-                                    const config::CodeCompletionOption& option);
+std::vector<CompletionItem> code_complete(CompilationParams& params,
+                                          const config::CodeCompletionOption& option);
 
 }  // namespace feature