LanguageServers/Cpp: Support jumping to declaration of preprocessor

.. definitions.

Userland/DevTools/HackStudio/LanguageServers/ClientConnection.cpp

@@ -135,6 +135,7 @@ void ClientConnection::handle(const Messages::LanguageServer::FindDeclaration& m
         dbgln("could not find declaration");
         return;
     }
+
     dbgln_if(LANGUAGE_SERVER_DEBUG, "declaration location: {} {}:{}", location.value().file, location.value().line, location.value().column);
     post_message(Messages::LanguageClient::DeclarationLocation(GUI::AutocompleteProvider::ProjectLocation { location.value().file, location.value().line, location.value().column }));
 }

Userland/DevTools/HackStudio/LanguageServers/Cpp/ParserAutoComplete.cpp

@@ -343,10 +343,26 @@ Optional<GUI::AutocompleteProvider::ProjectLocation> ParserAutoComplete::find_de
         return {};
     }
     auto decl = find_declaration_of(document, *node);
-    if (!decl)
-        return {};
-
+    if (decl)
         return GUI::AutocompleteProvider::ProjectLocation { decl->filename(), decl->start().line, decl->start().column };
+
+    return find_preprocessor_definition(document, identifier_position);
+}
+
+Optional<GUI::AutocompleteProvider::ProjectLocation> ParserAutoComplete::find_preprocessor_definition(const DocumentData& document, const GUI::TextPosition& text_position)
+{
+    Position cpp_position { text_position.line(), text_position.column() };
+
+    // Search for a replaced preprocessor token that intersects with text_position
+    for (auto& replaced_token : document.parser().replaced_preprocessor_tokens()) {
+        if (replaced_token.token.start() > cpp_position)
+            continue;
+        if (replaced_token.token.end() < cpp_position)
+            continue;
+
+        return GUI::AutocompleteProvider::ProjectLocation { replaced_token.preprocessor_value.filename, replaced_token.preprocessor_value.line, replaced_token.preprocessor_value.column };
+    }
+    return {};
 }
 
 RefPtr<Declaration> ParserAutoComplete::find_declaration_of(const DocumentData& document_data, const ASTNode& node) const
@@ -409,7 +425,7 @@ OwnPtr<ParserAutoComplete::DocumentData> ParserAutoComplete::create_document_dat
     auto document_data = make<DocumentData>();
     document_data->m_filename = move(filename);
     document_data->m_text = move(text);
-    document_data->m_preprocessor = make<Preprocessor>(document_data->text());
+    document_data->m_preprocessor = make<Preprocessor>(document_data->m_filename, document_data->text());
     document_data->preprocessor().process();
 
     Preprocessor::Definitions all_definitions;

Userland/DevTools/HackStudio/LanguageServers/Cpp/ParserAutoComplete.h

@@ -106,6 +106,7 @@ private:
     String document_path_from_include_path(const StringView& include_path) const;
     void update_declared_symbols(const DocumentData&);
     GUI::AutocompleteProvider::DeclarationType type_of_declaration(const Declaration&);
+    Optional<GUI::AutocompleteProvider::ProjectLocation> find_preprocessor_definition(const DocumentData&, const GUI::TextPosition&);
 
     OwnPtr<DocumentData> create_document_data(String&& text, const String& filename);
 

Userland/Libraries/LibCpp/Parser.cpp

@@ -54,6 +54,7 @@ Parser::Parser(const StringView& program, const String& filename, Preprocessor::
     }
 #endif
 }
+
 void Parser::initialize_program_tokens(const StringView& program)
 {
     Lexer lexer(program);
@@ -63,6 +64,7 @@ void Parser::initialize_program_tokens(const StringView& program)
         if (token.type() == Token::Type::Identifier) {
             if (auto defined_value = m_definitions.find(text_of_token(token)); defined_value != m_definitions.end()) {
                 add_tokens_for_preprocessor(token, defined_value->value);
+                m_replaced_preprocessor_tokens.append({ token, defined_value->value });
                 continue;
             }
         }

Userland/Libraries/LibCpp/Parser.h

@@ -56,6 +56,12 @@ public:
     Vector<String> errors() const { return m_errors; }
     const Preprocessor::Definitions& definitions() const { return m_definitions; }
 
+    struct TokenAndPreprocessorDefinition {
+        Token token;
+        Preprocessor::DefinedValue preprocessor_value;
+    };
+    const Vector<TokenAndPreprocessorDefinition>& replaced_preprocessor_tokens() const { return m_replaced_preprocessor_tokens; }
+
 private:
     enum class DeclarationType {
         Function,
@@ -171,6 +177,8 @@ private:
     RefPtr<TranslationUnit> m_root_node;
     NonnullRefPtrVector<ASTNode> m_nodes;
     Vector<String> m_errors;
+
+    Vector<TokenAndPreprocessorDefinition> m_replaced_preprocessor_tokens;
 };
 
 }

Userland/Libraries/LibCpp/Preprocessor.cpp

@@ -31,8 +31,9 @@
 #include <ctype.h>
 
 namespace Cpp {
-Preprocessor::Preprocessor(const StringView& program)
-    : m_program(program)
+Preprocessor::Preprocessor(const String& filename, const StringView& program)
+    : m_filename(filename)
+    , m_program(program)
 {
     m_lines = m_program.split_view('\n', true);
 }
@@ -107,6 +108,7 @@ void Preprocessor::handle_preprocessor_line(const StringView& line)
             consume_whitespace();
 
             DefinedValue value;
+            value.filename = m_filename;
             value.line = m_line_index;
 
             auto string_value = lexer.consume_all();

Userland/Libraries/LibCpp/Preprocessor.h

@@ -26,6 +26,7 @@
 
 #pragma once
 
+#include <AK/FlyString.h>
 #include <AK/HashMap.h>
 #include <AK/Optional.h>
 #include <AK/String.h>
@@ -36,13 +37,14 @@ namespace Cpp {
 class Preprocessor {
 
 public:
-    explicit Preprocessor(const StringView&);
+    explicit Preprocessor(const String& filename, const StringView& program);
     const String& process();
     const String& processed_text();
     Vector<StringView> included_paths() const { return m_included_paths; }
 
     struct DefinedValue {
         Optional<StringView> value;
+        FlyString filename;
         size_t line { 0 };
         size_t column { 0 };
     };
@@ -54,6 +56,7 @@ private:
     void handle_preprocessor_line(const StringView&);
 
     Definitions m_definitions;
+    const String m_filename;
     const StringView m_program;
     StringBuilder m_builder;
     Vector<StringView> m_lines;

Userland/Utilities/PreprocessorTest.cpp

@@ -35,6 +35,6 @@ int main(int, char**)
         exit(1);
     }
     auto content = file->read_all();
-    Cpp::Preprocessor cpp(StringView { content });
+    Cpp::Preprocessor cpp("other.h", StringView { content });
     dbgln("{}", cpp.process());
 }