Meta: Replace GenerateCSSEnvironmentVariable with a python generator

Author: https://github.com/AtkinsSJ
Commit: https://github.com/LadybirdBrowser/ladybird/commit/f6a3ff388b3
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/9083

Meta/CMake/libweb_generators.cmake

@@ -20,9 +20,9 @@ function (generate_css_implementation)
         arguments -j "${LIBWEB_INPUT_FOLDER}/CSS/Enums.json"
     )
 
-    invoke_cpp_generator(
+    invoke_py_generator(
         "EnvironmentVariable.cpp"
-        Lagom::GenerateCSSEnvironmentVariable
+        "generate_libweb_css_environment_variables.py"
         "${LIBWEB_INPUT_FOLDER}/CSS/EnvironmentVariables.json"
         "CSS/EnvironmentVariable.h"
         "CSS/EnvironmentVariable.cpp"

Meta/Generators/generate_libweb_css_environment_variables.py

@@ -0,0 +1,157 @@
+#!/usr/bin/env python3
+
+# Copyright (c) 2025-2026, Sam Atkins <sam@ladybird.org>
+# Copyright (c) 2026-present, the Ladybird developers.
+#
+# SPDX-License-Identifier: BSD-2-Clause
+
+import argparse
+import json
+import sys
+
+from pathlib import Path
+from typing import TextIO
+
+sys.path.append(str(Path(__file__).resolve().parent.parent))
+
+from Utils.utils import title_casify
+from Utils.utils import underlying_type_for_enum
+
+
+def verify_alphabetical(data: dict, path: str) -> None:
+    most_recent_name = ""
+    for name in data:
+        if name < most_recent_name:
+            print(
+                f"`{name}` is in the wrong position in `{path}`. Please keep this list alphabetical!", file=sys.stderr
+            )
+            sys.exit(1)
+        most_recent_name = name
+
+
+def write_header_file(out: TextIO, environment_variables: dict) -> None:
+    underlying_type = underlying_type_for_enum(len(environment_variables))
+    out.write(f"""
+#pragma once
+
+#include <AK/Optional.h>
+#include <AK/StringView.h>
+#include <LibWeb/CSS/ValueType.h>
+
+namespace Web::CSS {{
+
+enum class EnvironmentVariable : {underlying_type} {{
+""")
+
+    for name in environment_variables:
+        out.write(f"    {title_casify(name)},\n")
+
+    out.write("""
+};
+
+Optional<EnvironmentVariable> environment_variable_from_string(StringView);
+StringView to_string(EnvironmentVariable);
+
+ValueType environment_variable_type(EnvironmentVariable);
+u32 environment_variable_dimension_count(EnvironmentVariable);
+}
+""")
+
+
+def write_implementation_file(out: TextIO, environment_variables: dict) -> None:
+    out.write("""
+#include <LibWeb/CSS/EnvironmentVariable.h>
+
+namespace Web::CSS {
+
+Optional<EnvironmentVariable> environment_variable_from_string(StringView string)
+{
+""")
+    for name in environment_variables:
+        out.write(f"""
+    if (string.equals_ignoring_ascii_case("{name}"sv))
+        return EnvironmentVariable::{title_casify(name)};
+""")
+
+    out.write("""
+
+    return {};
+}
+
+StringView to_string(EnvironmentVariable environment_variable)
+{
+    switch (environment_variable) {
+""")
+
+    for name in environment_variables:
+        out.write(f"""
+    case EnvironmentVariable::{title_casify(name)}:
+        return "{name}"sv;
+""")
+
+    out.write("""
+    }
+    VERIFY_NOT_REACHED();
+}
+
+ValueType environment_variable_type(EnvironmentVariable environment_variable)
+{
+    switch (environment_variable) {
+""")
+
+    for name, variable in environment_variables.items():
+        value_type = variable["type"].strip("<>")
+        out.write(f"""
+    case EnvironmentVariable::{title_casify(name)}:
+        return ValueType::{title_casify(value_type)};
+""")
+
+    out.write("""
+    }
+    VERIFY_NOT_REACHED();
+}
+
+u32 environment_variable_dimension_count(EnvironmentVariable environment_variable)
+{
+    switch (environment_variable) {
+""")
+
+    for name, variable in environment_variables.items():
+        out.write(f"""
+    case EnvironmentVariable::{title_casify(name)}:
+        return {variable["dimensions"]};
+""")
+
+    out.write("""
+    }
+    VERIFY_NOT_REACHED();
+}
+
+}
+""")
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Generate CSS EnvironmentVariable", add_help=False)
+    parser.add_argument("--help", action="help", help="Show this help message and exit")
+    parser.add_argument("-h", "--header", required=True, help="Path to the EnvironmentVariable header file to generate")
+    parser.add_argument(
+        "-c", "--implementation", required=True, help="Path to the EnvironmentVariable implementation file to generate"
+    )
+    parser.add_argument("-j", "--json", required=True, help="Path to the JSON file to read from")
+    args = parser.parse_args()
+
+    with open(args.json, "r", encoding="utf-8") as input_file:
+        environment_variables = json.load(input_file)
+
+    verify_alphabetical(environment_variables, args.json)
+
+    with open(args.header, "w", encoding="utf-8") as output_file:
+        write_header_file(output_file, environment_variables)
+
+    with open(args.implementation, "w", encoding="utf-8") as output_file:
+        write_implementation_file(output_file, environment_variables)
+
+
+if __name__ == "__main__":
+    main()

Meta/Lagom/Tools/CodeGenerators/LibWeb/CMakeLists.txt

@@ -1,7 +1,6 @@
 set(SOURCES "") # avoid pulling SOURCES from parent scope
 
 lagom_tool(GenerateCSSDescriptors           SOURCES GenerateCSSDescriptors.cpp LIBS LibMain)
-lagom_tool(GenerateCSSEnvironmentVariable   SOURCES GenerateCSSEnvironmentVariable.cpp LIBS LibMain)
 lagom_tool(GenerateCSSKeyword               SOURCES GenerateCSSKeyword.cpp LIBS LibMain)
 lagom_tool(GenerateCSSMathFunctions         SOURCES GenerateCSSMathFunctions.cpp LIBS LibMain)
 lagom_tool(GenerateCSSMediaFeatureID        SOURCES GenerateCSSMediaFeatureID.cpp LIBS LibMain)

Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSEnvironmentVariable.cpp

@@ -1,197 +0,0 @@
-/*
- * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#include "GeneratorUtil.h"
-#include <AK/SourceGenerator.h>
-#include <LibCore/ArgsParser.h>
-#include <LibMain/Main.h>
-
-ErrorOr<void> generate_header_file(JsonObject const& environment_variables, Core::File& file);
-ErrorOr<void> generate_implementation_file(JsonObject const& environment_variables, Core::File& file);
-
-ErrorOr<int> ladybird_main(Main::Arguments arguments)
-{
-    StringView generated_header_path;
-    StringView generated_implementation_path;
-    StringView json_path;
-
-    Core::ArgsParser args_parser;
-    args_parser.add_option(generated_header_path, "Path to the EnvironmentVariable header file to generate", "generated-header-path", 'h', "generated-header-path");
-    args_parser.add_option(generated_implementation_path, "Path to the EnvironmentVariable implementation file to generate", "generated-implementation-path", 'c', "generated-implementation-path");
-    args_parser.add_option(json_path, "Path to the JSON file to read from", "json-path", 'j', "json-path");
-    args_parser.parse(arguments);
-
-    auto read_json_object = [](auto& path) -> ErrorOr<JsonObject> {
-        auto json = TRY(read_entire_file_as_json(path));
-        VERIFY(json.is_object());
-
-        // Check we're in alphabetical order
-        String most_recent_name;
-        json.as_object().for_each_member([&](auto& name, auto&) {
-            if (name < most_recent_name) {
-                warnln("`{}` is in the wrong position in `{}`. Please keep this list alphabetical!", name, path);
-                VERIFY_NOT_REACHED();
-            }
-            most_recent_name = name;
-        });
-
-        return json.as_object();
-    };
-
-    auto environment_variables = TRY(read_json_object(json_path));
-
-    auto generated_header_file = TRY(Core::File::open(generated_header_path, Core::File::OpenMode::Write));
-    auto generated_implementation_file = TRY(Core::File::open(generated_implementation_path, Core::File::OpenMode::Write));
-
-    TRY(generate_header_file(environment_variables, *generated_header_file));
-    TRY(generate_implementation_file(environment_variables, *generated_implementation_file));
-
-    return 0;
-}
-
-ErrorOr<void> generate_header_file(JsonObject const& environment_variables, Core::File& file)
-{
-    StringBuilder builder;
-    SourceGenerator generator { builder };
-
-    generator.set("environment_variable_underlying_type", underlying_type_for_enum(environment_variables.size()));
-
-    generator.append(R"~~~(
-#pragma once
-
-#include <AK/Optional.h>
-#include <AK/StringView.h>
-#include <LibWeb/CSS/ValueType.h>
-
-namespace Web::CSS {
-
-enum class EnvironmentVariable : @environment_variable_underlying_type@ {
-)~~~");
-
-    environment_variables.for_each_member([&](auto& name, JsonValue const&) {
-        auto member_generator = generator.fork();
-        member_generator.set("name:titlecase", title_casify(name));
-        member_generator.appendln("    @name:titlecase@,");
-    });
-    generator.append(R"~~~(
-};
-
-Optional<EnvironmentVariable> environment_variable_from_string(StringView);
-StringView to_string(EnvironmentVariable);
-
-ValueType environment_variable_type(EnvironmentVariable);
-u32 environment_variable_dimension_count(EnvironmentVariable);
-}
-)~~~");
-
-    TRY(file.write_until_depleted(generator.as_string_view().bytes()));
-    return {};
-}
-
-ErrorOr<void> generate_implementation_file(JsonObject const& environment_variables, Core::File& file)
-{
-    StringBuilder builder;
-    SourceGenerator generator { builder };
-
-    generator.append(R"~~~(
-#include <LibWeb/CSS/EnvironmentVariable.h>
-
-namespace Web::CSS {
-
-Optional<EnvironmentVariable> environment_variable_from_string(StringView string)
-{
-)~~~");
-    environment_variables.for_each_member([&](auto& name, JsonValue const&) {
-        auto member_generator = generator.fork();
-        member_generator.set("name", name);
-        member_generator.set("name:titlecase", title_casify(name));
-
-        member_generator.append(R"~~~(
-    if (string.equals_ignoring_ascii_case("@name@"sv))
-        return EnvironmentVariable::@name:titlecase@;
-)~~~");
-    });
-
-    generator.append(R"~~~(
-
-    return {};
-}
-
-StringView to_string(EnvironmentVariable environment_variable)
-{
-    switch (environment_variable) {
-)~~~");
-
-    environment_variables.for_each_member([&](auto& name, JsonValue const&) {
-        auto member_generator = generator.fork();
-        member_generator.set("name", name);
-        member_generator.set("name:titlecase", title_casify(name));
-
-        member_generator.append(R"~~~(
-    case EnvironmentVariable::@name:titlecase@:
-        return "@name@"sv;
-)~~~");
-    });
-
-    generator.append(R"~~~(
-    }
-    VERIFY_NOT_REACHED();
-}
-
-ValueType environment_variable_type(EnvironmentVariable environment_variable)
-{
-    switch (environment_variable) {
-)~~~");
-
-    environment_variables.for_each_member([&](auto& name, JsonValue const& value) {
-        auto& variable = value.as_object();
-        auto member_generator = generator.fork();
-        member_generator.set("name", name);
-        member_generator.set("name:titlecase", title_casify(name));
-
-        auto value_type = MUST(variable.get_string("type"sv)->trim("<>"sv));
-        member_generator.set("value_type:titlecase", title_casify(value_type));
-
-        member_generator.append(R"~~~(
-    case EnvironmentVariable::@name:titlecase@:
-        return ValueType::@value_type:titlecase@;
-)~~~");
-    });
-
-    generator.append(R"~~~(
-    }
-    VERIFY_NOT_REACHED();
-}
-
-u32 environment_variable_dimension_count(EnvironmentVariable environment_variable)
-{
-    switch (environment_variable) {
-)~~~");
-
-    environment_variables.for_each_member([&](auto& name, JsonValue const& value) {
-        auto& variable = value.as_object();
-        auto member_generator = generator.fork();
-        member_generator.set("name", name);
-        member_generator.set("name:titlecase", title_casify(name));
-        member_generator.set("dimension_count", String::number(variable.get_u32("dimensions"sv).value()));
-
-        member_generator.append(R"~~~(
-    case EnvironmentVariable::@name:titlecase@:
-        return @dimension_count@;
-)~~~");
-    });
-
-    generator.append(R"~~~(
-    }
-    VERIFY_NOT_REACHED();
-}
-
-}
-)~~~");
-
-    TRY(file.write_until_depleted(generator.as_string_view().bytes()));
-    return {};
-}