From a4cf80a89007bdcce2edf8024785f80a071320db Mon Sep 17 00:00:00 2001
From: Myriad-Dreamin <camiyoru@gmail.com>
Date: Sat, 6 Sep 2025 22:36:54 +0000
Subject: [PATCH] Add initial implementation of definition feature

---
 include/Feature/Definition.h      | 107 ++++++++++++++++++++++++++++++
 src/Feature/Definition.cpp        |   2 +
 tests/unit/Feature/Definition.cpp |  96 +++++++++++++++++++++++++++
 3 files changed, 205 insertions(+)
 create mode 100644 include/Feature/Definition.h
 create mode 100644 src/Feature/Definition.cpp
 create mode 100644 tests/unit/Feature/Definition.cpp

diff --git a/include/Feature/Definition.h b/include/Feature/Definition.h
new file mode 100644
index 00000000..4af44125
--- /dev/null
+++ b/include/Feature/Definition.h
@@ -0,0 +1,107 @@
+#pragma once
+
+#include <vector>
+#include <cstdint>
+
+#include "AST/SourceCode.h"
+#include "llvm/ADT/StringRef.h"
+
+namespace clice {
+
+struct CompilationParams;
+
+namespace config {
+
+struct DefinitionOption {
+    /// 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
+
+namespace feature {
+
+enum class CompletionItemKind {
+    None = 0,
+    Text,
+    Method,
+    Function,
+    Constructor,
+    Field,
+    Variable,
+    Class,
+    Interface,
+    Module,
+    Property,
+    Unit,
+    Value,
+    Enum,
+    Keyword,
+    Snippet,
+    Color,
+    File,
+    Reference,
+    Folder,
+    EnumMember,
+    Constant,
+    Struct,
+    Event,
+    Operator,
+    TypeParameter
+};
+
+/// Represents a single code completion item to be presented to the user.
+struct CompletionItem {
+    /// 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;
+
+    /// 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>;
+
+std::vector<CompletionItem> definition(CompilationParams& params,
+                                       const config::DefinitionOption& option);
+
+}  // namespace feature
+
+}  // namespace clice
+
diff --git a/src/Feature/Definition.cpp b/src/Feature/Definition.cpp
new file mode 100644
index 00000000..43e583e8
--- /dev/null
+++ b/src/Feature/Definition.cpp
@@ -0,0 +1,2 @@
+
+namespace clice::feature {}
diff --git a/tests/unit/Feature/Definition.cpp b/tests/unit/Feature/Definition.cpp
new file mode 100644
index 00000000..5cac1845
--- /dev/null
+++ b/tests/unit/Feature/Definition.cpp
@@ -0,0 +1,96 @@
+#include "Test/Tester.h"
+#include "Feature/Definition.h"
+
+namespace clice::testing {
+
+namespace {
+
+suite<"Definition"> goto_definition = [] {
+    std::vector<feature::CompletionItem> items;
+
+    auto definition = [&](llvm::StringRef code) {
+        CompilationParams params;
+        auto annotation = AnnotatedSource::from(code);
+        params.arguments = {"clang++", "-std=c++20", "main.cpp"};
+        params.completion = {"main.cpp", annotation.offsets["pos"]};
+        params.add_remapped_file("main.cpp", annotation.content);
+
+        config::DefinitionOption options = {};
+        items = feature::definition(params, options);
+    };
+
+    using enum feature::CompletionItemKind;
+
+    test("Score") = [&] {
+        definition(R"cpp(
+int foooo(int x);
+int x = fo$(pos)
+)cpp");
+        expect(that % items.size() == 1);
+        expect(items.front().label == "foooo");
+        expect(items.front().kind == Function);
+    };
+
+    test("Snippet") = [&] {
+        definition(R"cpp(
+int x = tru$(pos)
+)cpp");
+    };
+
+    test("Overload") = [&] {
+        definition(R"cpp(
+int foooo(int x);
+int foooo(int x, int y);
+int x = fooo$(pos)
+)cpp");
+    };
+
+    test("Unqualified") = [&] {
+        definition(R"cpp(
+namespace A { 
+    void fooooo(); 
+}
+
+void bar() {
+    fo$(pos)
+}
+)cpp");
+
+        /// EXPECT: "A::fooooo"
+        /// To implement this we need to search code completion result from index
+        /// or traverse AST to collect interesting names.
+    };
+
+    test("Functor") = [&] {
+        definition(R"cpp(
+    struct X {
+        void operator() () {}
+    };
+    
+void bar() {
+    X foo;
+    fo$(pos);
+}
+)cpp");
+
+        /// TODO:
+        /// complete lambda as it is a variable.
+    };
+
+    test("Lambda") = [&] {
+        definition(R"cpp(
+void bar() {
+    auto foo = [](int x){ };
+    fo$(pos);
+}
+)cpp");
+
+        /// TODO:
+        /// complete lambda as it is a function.
+    };
+};
+
+}  // namespace
+
+}  // namespace clice::testing
+