From 2e3b74cacebc66c2abd0c89cf76440bcfd14b084 Mon Sep 17 00:00:00 2001
From: Jan Haller <bromeon@gmail.com>
Date: Fri, 7 Apr 2023 23:38:16 +0200
Subject: [PATCH] Support engine class constants

---
 godot-codegen/src/api_parser.rs      | 11 ++++++++---
 godot-codegen/src/class_generator.rs | 23 ++++++++++++++++++++---
 godot-codegen/src/util.rs            | 11 ++++++++++-
 itest/rust/src/codegen_test.rs       |  8 +++++++-
 4 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/godot-codegen/src/api_parser.rs b/godot-codegen/src/api_parser.rs
index 3561a672c..6a67760cf 100644
--- a/godot-codegen/src/api_parser.rs
+++ b/godot-codegen/src/api_parser.rs
@@ -41,7 +41,7 @@ pub struct BuiltinClass {
     pub indexing_return_type: Option<String>,
     pub is_keyed: bool,
     pub members: Option<Vec<Member>>,
-    pub constants: Option<Vec<Constant>>,
+    // pub constants: Option<Vec<BuiltinConstant>>,
     pub enums: Option<Vec<BuiltinClassEnum>>, // no bitfield
     pub operators: Vec<Operator>,
     pub methods: Option<Vec<BuiltinClassMethod>>,
@@ -56,7 +56,7 @@ pub struct Class {
     pub is_instantiable: bool,
     pub inherits: Option<String>,
     // pub api_type: String,
-    // pub constants: Option<Vec<Constant>>,
+    pub constants: Option<Vec<ClassConstant>>,
     pub enums: Option<Vec<Enum>>,
     pub methods: Option<Vec<ClassMethod>>,
     // pub properties: Option<Vec<Property>>,
@@ -100,13 +100,18 @@ pub struct EnumConstant {
     pub value: i32,
 }
 
+pub type ClassConstant = EnumConstant;
+
+/*
+// Constants of builtin types have a string value like "Vector2(1, 1)", hence also a type field
 #[derive(DeJson)]
-pub struct Constant {
+pub struct BuiltinConstant {
     pub name: String,
     #[nserde(rename = "type")]
     pub type_: String,
     pub value: String,
 }
+*/
 
 #[derive(DeJson)]
 pub struct Operator {
diff --git a/godot-codegen/src/class_generator.rs b/godot-codegen/src/class_generator.rs
index b27eb91a9..1fd9baf44 100644
--- a/godot-codegen/src/class_generator.rs
+++ b/godot-codegen/src/class_generator.rs
@@ -173,6 +173,7 @@ fn make_class(class: &Class, class_name: &TyName, ctx: &mut Context) -> Generate
     let constructor = make_constructor(class, ctx);
     let methods = make_methods(&class.methods, class_name, ctx);
     let enums = make_enums(&class.enums, class_name, ctx);
+    let constants = make_constants(&class.constants, class_name, ctx);
     let inherits_macro = format_ident!("inherits_transitive_{}", class_name.rust_ty);
     let all_bases = ctx.inheritance_tree().collect_all_bases(class_name);
     let virtual_trait = make_virtual_methods_trait(class, &all_bases, &virtual_trait_str, ctx);
@@ -205,6 +206,7 @@ fn make_class(class: &Class, class_name: &TyName, ctx: &mut Context) -> Generate
             impl #class_name {
                 #constructor
                 #methods
+                #constants
             }
             impl crate::obj::GodotClass for #class_name {
                 type Base = #base;
@@ -420,9 +422,8 @@ fn make_builtin_methods(
 }
 
 fn make_enums(enums: &Option<Vec<Enum>>, _class_name: &TyName, _ctx: &Context) -> TokenStream {
-    let enums = match enums {
-        Some(e) => e,
-        None => return TokenStream::new(),
+    let Some(enums) = enums else {
+        return TokenStream::new();
     };
 
     let definitions = enums.iter().map(util::make_enum_definition);
@@ -432,6 +433,22 @@ fn make_enums(enums: &Option<Vec<Enum>>, _class_name: &TyName, _ctx: &Context) -
     }
 }
 
+fn make_constants(
+    constants: &Option<Vec<ClassConstant>>,
+    _class_name: &TyName,
+    _ctx: &Context,
+) -> TokenStream {
+    let Some(constants) = constants else {
+        return TokenStream::new();
+    };
+
+    let definitions = constants.iter().map(util::make_constant_definition);
+
+    quote! {
+        #( #definitions )*
+    }
+}
+
 /// Depending on the built-in class, adds custom constructors and methods.
 fn make_special_builtin_methods(class_name: &TyName, _ctx: &Context) -> TokenStream {
     if class_name.godot_ty == "Array" {
diff --git a/godot-codegen/src/util.rs b/godot-codegen/src/util.rs
index d3b4735f0..8a3c39d49 100644
--- a/godot-codegen/src/util.rs
+++ b/godot-codegen/src/util.rs
@@ -4,7 +4,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-use crate::api_parser::Enum;
+use crate::api_parser::{ClassConstant, Enum};
 use crate::special_cases::is_builtin_scalar;
 use crate::{Context, ModName, RustTy, TyName};
 use proc_macro2::{Ident, Literal, TokenStream};
@@ -106,6 +106,15 @@ pub fn make_enum_definition(enum_: &Enum) -> TokenStream {
     }
 }
 
+pub fn make_constant_definition(constant: &ClassConstant) -> TokenStream {
+    let ClassConstant { name, value } = constant;
+    let name = ident(name);
+
+    quote! {
+        pub const #name: i32 = #value;
+    }
+}
+
 fn make_enum_name(enum_name: &str) -> Ident {
     // TODO clean up enum name
 
diff --git a/itest/rust/src/codegen_test.rs b/itest/rust/src/codegen_test.rs
index 14a7fd0dc..d292acc8c 100644
--- a/itest/rust/src/codegen_test.rs
+++ b/itest/rust/src/codegen_test.rs
@@ -9,7 +9,7 @@
 
 use crate::itest;
 use godot::builtin::inner::{InnerColor, InnerString};
-use godot::engine::{FileAccess, HttpRequest, HttpRequestVirtual};
+use godot::engine::{FileAccess, HttpRequest, HttpRequestVirtual, Image};
 use godot::prelude::*;
 
 #[itest]
@@ -50,6 +50,12 @@ fn codegen_static_class_method() {
     // see also object_test for reference count verification
 }
 
+#[itest]
+fn codegen_constants() {
+    assert_eq!(Image::MAX_WIDTH, 16777216);
+    // assert_eq!(Material::RENDER_PRIORITY_MIN, -128);
+}
+
 // ----------------------------------------------------------------------------------------------------------------------------------------------
 
 #[derive(GodotClass)]