Enable SignatureHelp (#187)

Author: 16bit-ykiko

include/Feature/SignatureHelp.h

@@ -4,6 +4,7 @@
 #include <cstdint>
 
 #include "llvm/ADT/StringRef.h"
+#include "Protocol/Feature/SignatureHelp.h"
 
 namespace clice {
 
@@ -17,12 +18,8 @@ struct SignatureHelpOption {};
 
 namespace feature {
 
-struct SignatureHelpItem {};
-
-using SignatureHelpResult = std::vector<SignatureHelpItem>;
-
-SignatureHelpResult signatureHelp(CompilationParams& params,
-                                  const config::SignatureHelpOption& option);
+proto::SignatureHelp signature_help(CompilationParams& params,
+                                    const config::SignatureHelpOption& option);
 
 }  // namespace feature
 

include/Protocol/Basic.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <array>
 #include <string>
 #include <vector>
 #include <cstdint>

include/Protocol/Feature/SignatureHelp.h

@@ -4,8 +4,47 @@
 
 namespace clice::proto {
 
-struct SignatureHelpClientCapabilities {};
+struct SignatureHelpClientCapabilities {
+    /**
+     * The client supports the `activeParameter` property on
+     * `SignatureInformation` literal.
+     *
+     * @since 3.16.0
+     */
+};
 
-struct SignatureHelpOptions {};
+struct SignatureHelpOptions {
+    /// The characters that trigger signature help automatically.
+    array<string> triggerCharacters;
+
+    /// List of characters that re-trigger signature help.
+    ///
+    /// These trigger characters are only active when signature help is already
+    /// showing. All trigger characters are also counted as re-trigger
+    /// characters.
+    array<string> retriggerCharacters;
+};
+
+using SignatureHelpParams = TextDocumentPositionParams;
+
+struct ParameterInformation {
+    std::array<uinteger, 2> label;
+};
+
+struct SignatureInformation {
+    string label;
+
+    MarkupContent document;
+
+    array<ParameterInformation> parameters;
+
+    uinteger activeParameter;
+};
+
+struct SignatureHelp {
+    array<SignatureInformation> signatures;
+
+    uinteger activeSignature;
+};
 
 }  // namespace clice::proto

include/Protocol/Lifecycle.h

@@ -85,7 +85,7 @@ struct ServerCapabilities {
     HoverOptions hoverProvider;
 
     /// The server provides signature help support.
-    /// FIXME: SignatureHelpOptions signatureHelpProvider;
+    SignatureHelpOptions signatureHelpProvider;
 
     /// The server provides go to declaration support.
     /// FIXME: DeclarationOptions declarationProvider;

include/Server/Server.h

@@ -200,6 +200,8 @@ class Server {
 
     async::Task<json::Value> on_hover(proto::HoverParams params);
 
+    async::Task<json::Value> on_signature_help(proto::SignatureHelpParams params);
+
     async::Task<json::Value> on_document_symbol(proto::DocumentSymbolParams params);
 
     async::Task<json::Value> on_document_link(proto::DocumentLinkParams params);

include/Test/Tester.h

@@ -31,7 +31,7 @@ struct Tester {
         sources.add_sources(content);
     }
 
-    bool compile(llvm::StringRef standard = "-std=c++20") {
+    void prepare(llvm::StringRef standard = "-std=c++20") {
         auto command = std::format("clang++ {} {} -fms-extensions", standard, src_path);
 
         database.update_command("fake", src_path, command);
@@ -46,6 +46,10 @@ struct Tester {
                 params.add_remapped_file(path, source.content);
             }
         }
+    }
+
+    bool compile(llvm::StringRef standard = "-std=c++20") {
+        prepare(standard);
 
         auto info = clice::compile(params);
         if(!info) {

src/AST/Utility.cpp

@@ -281,34 +281,32 @@ const clang::NamedDecl* decl_of_impl(const void* T) {
 }
 
 auto decl_of(clang::QualType type) -> const clang::NamedDecl* {
+    if(auto TST = type->getAs<clang::TemplateSpecializationType>()) {
+        auto decl = TST->getTemplateName().getAsTemplateDecl();
+        if(type->isDependentType()) {
+            return decl;
+        }
+
+        /// For a template specialization type, the template name is possibly a `ClassTemplateDecl`
+        ///  `TypeAliasTemplateDecl` or `TemplateTemplateParmDecl` and `BuiltinTemplateDecl`.
+        if(llvm::isa<clang::TypeAliasTemplateDecl>(decl)) {
+            return decl->getTemplatedDecl();
+        }
+
+        if(llvm::isa<clang::TemplateTemplateParmDecl, clang::BuiltinTemplateDecl>(decl)) {
+            return decl;
+        }
+
+        return instantiated_from(TST->getAsCXXRecordDecl());
+    }
+
     switch(type->getTypeClass()) {
 #define ABSTRACT_TYPE(TY, BASE)
 #define TYPE(TY, BASE)                                                                             \
     case clang::Type::TY: return decl_of_impl(llvm::cast<clang::TY##Type>(type));
 #include "clang/AST/TypeNodes.inc"
     }
 
-    /// FIXME: Handle Template Specialization type in the future
-    /// if(auto TST = type->getAs<clang::TemplateSpecializationType>()) {
-    ///    auto decl = TST->getTemplateName().getAsTemplateDecl();
-    ///    if(type->isDependentType()) {
-    ///        return decl;
-    ///    }
-    ///
-    ///    /// For a template specialization type, the template name is possibly a
-    ///    `ClassTemplateDecl`
-    ///    ///  `TypeAliasTemplateDecl` or `TemplateTemplateParmDecl` and `BuiltinTemplateDecl`.
-    ///    if(llvm::isa<clang::TypeAliasTemplateDecl>(decl)) {
-    ///        return decl->getTemplatedDecl();
-    ///    }
-    ///
-    ///    if(llvm::isa<clang::TemplateTemplateParmDecl, clang::BuiltinTemplateDecl>(decl)) {
-    ///        return decl;
-    ///    }
-    ///
-    ///    return instantiated_from(TST->getAsCXXRecordDecl());
-    ///}
-
     return nullptr;
 }