LibHTML: Start building a simple code generator for CSS properties

Code for parsing and stringifying CSS properties is now generated based
on LibHTML/CSS/Properties.json

At the moment, the file tells us three things:

- The name of a property
- Its initial value
- Whether it's inherited

Also, for shorthand properties, it provides a list of all the longhand
properties it may expand too. This is not actually used in the engine
yet though.

This *finally* makes layout tree dumps show the names of CSS properties
in effect, instead of "CSS::PropertyID(32)" and such. :^)

Libraries/LibHTML/CodeGenerators/Generate_CSS_PropertyID_h/Generate_CSS_PropertyID_h.cpp

@@ -0,0 +1,61 @@
+#include <AK/JsonObject.h>
+#include <AK/StringBuilder.h>
+#include <LibCore/CFile.h>
+#include <ctype.h>
+#include <stdio.h>
+
+static String title_casify(const String& dashy_name)
+{
+    auto parts = dashy_name.split('-');
+    StringBuilder builder;
+    for (auto& part : parts) {
+        if (part.is_empty())
+            continue;
+        builder.append(toupper(part[0]));
+        if (part.length() == 1)
+            continue;
+        builder.append(part.substring_view(1, part.length() - 1));
+    }
+    return builder.to_string();
+}
+
+int main(int argc, char** argv)
+{
+    if (argc != 2) {
+        fprintf(stderr, "usage: %s <path/to/CSS/Properties.json>\n", argv[0]);
+        return 1;
+    }
+    auto file = CFile::construct(argv[1]);
+    if (!file->open(CIODevice::ReadOnly))
+        return 1;
+
+    auto json = JsonValue::from_string(file->read_all());
+    ASSERT(json.is_object());
+
+    dbg() << "#pragma once";
+    dbg() << "#include <AK/StringView.h>";
+    dbg() << "#include <AK/Traits.h>";
+
+    dbg() << "namespace CSS {";
+    dbg() << "enum class PropertyID {";
+    dbg() << "    Invalid,";
+
+    json.as_object().for_each_member([&](auto& name, auto& value) {
+        ASSERT(value.is_object());
+        dbg() << "    " << title_casify(name) << ",";
+    });
+
+    dbg() << "};\n\
+PropertyID property_id_from_string(const StringView&);\n\
+const char* string_from_property_id(PropertyID);\n\
+}\n\
+\n\
+namespace AK {\n\
+template<>\n\
+struct Traits<CSS::PropertyID> : public GenericTraits<CSS::PropertyID> {\n\
+    static unsigned hash(CSS::PropertyID property_id) { return int_hash((unsigned)property_id); }\n\
+};\n\
+}\n";
+
+    return 0;
+}

Libraries/LibHTML/CodeGenerators/Generate_CSS_PropertyID_h/Makefile

@@ -0,0 +1,33 @@
+PROGRAM = Generate_CSS_PropertyID_h
+
+OBJS = \
+    Generate_CSS_PropertyID_h.o \
+    $(SERENITY_ROOT)/AK/String.o \
+    $(SERENITY_ROOT)/AK/StringImpl.o \
+    $(SERENITY_ROOT)/AK/StringBuilder.o \
+    $(SERENITY_ROOT)/AK/StringView.o \
+    $(SERENITY_ROOT)/AK/JsonValue.o \
+    $(SERENITY_ROOT)/AK/JsonParser.o \
+    $(SERENITY_ROOT)/AK/LogStream.o \
+    $(SERENITY_ROOT)/Libraries/LibCore/CIODevice.o \
+    $(SERENITY_ROOT)/Libraries/LibCore/CFile.o \
+    $(SERENITY_ROOT)/Libraries/LibCore/CObject.o \
+    $(SERENITY_ROOT)/Libraries/LibCore/CEvent.o \
+    $(SERENITY_ROOT)/Libraries/LibCore/CSocket.o \
+    $(SERENITY_ROOT)/Libraries/LibCore/CLocalSocket.o \
+    $(SERENITY_ROOT)/Libraries/LibCore/CNotifier.o \
+    $(SERENITY_ROOT)/Libraries/LibCore/CLocalServer.o \
+    $(SERENITY_ROOT)/Libraries/LibCore/CEventLoop.o
+
+all: $(PROGRAM)
+
+CXXFLAGS = -std=c++17 -Wall -Wextra
+
+%.o: %.cpp
+	$(PRE_CXX) $(CXX) $(CXXFLAGS) -I../ -I$(SERENITY_ROOT)/ -I$(SERENITY_ROOT)/Libraries/ -o $@ -c $<
+
+$(PROGRAM): $(OBJS)
+	$(CXX) $(LDFLAGS) -I../ -I$(SERENITY_ROOT)/ -I$(SERENITY_ROOT)/Libraries/ -o $(PROGRAM) $(OBJS)
+
+clean:
+	rm -f $(PROGRAM) $(OBJS)