Reorganize godot-macros file structure

Organize by semantics, grouping class-related macros together.
Also move helper types into their own data_models directory.

Author: Bromeon

godot-macros/src/class/data_models/field.rs

@@ -0,0 +1,36 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+use crate::class::{FieldExport, FieldVar};
+use proc_macro2::{Ident, TokenStream};
+
+pub struct Field {
+    pub name: Ident,
+    pub ty: venial::TyExpr,
+    pub default: Option<TokenStream>,
+    pub var: Option<FieldVar>,
+    pub export: Option<FieldExport>,
+}
+
+impl Field {
+    pub fn new(field: &venial::NamedField) -> Self {
+        Self {
+            name: field.name.clone(),
+            ty: field.ty.clone(),
+            default: None,
+            var: None,
+            export: None,
+        }
+    }
+}
+
+pub struct Fields {
+    /// All fields except `base_field`.
+    pub all_fields: Vec<Field>,
+
+    /// The field annotated with `#[base]`.
+    pub base_field: Option<Field>,
+}

godot-macros/src/derive_godot_class/property/field_export.rs renamed to godot-macros/src/class/data_models/field_export.rs

@@ -4,14 +4,13 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
+use proc_macro2::{Ident, TokenStream};
+use quote::quote;
 use std::collections::HashSet;
 
+use crate::class::FieldHint;
 use crate::util::{KvParser, ListParser};
 use crate::ParseResult;
-use proc_macro2::{Ident, TokenStream};
-use quote::quote;
-
-use super::FieldHint;
 
 /// Store info from `#[export]` attribute.
 pub enum FieldExport {

godot-macros/src/derive_godot_class/property/field_var.rs renamed to godot-macros/src/class/data_models/field_var.rs

@@ -4,14 +4,15 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-use crate::derive_godot_class::{make_existence_check, Field, FieldHint};
-use crate::method_registration::make_method_registration;
-use crate::method_registration::FuncDefinition;
-use crate::util::KvParser;
-use crate::{util, ParseResult};
 use proc_macro2::{Ident, TokenStream};
 use quote::{format_ident, quote};
 
+use crate::class::{
+    make_existence_check, make_method_registration, Field, FieldHint, FuncDefinition,
+};
+use crate::util::KvParser;
+use crate::{util, ParseResult};
+
 /// Store info from `#[var]` attribute.
 #[derive(Default, Clone, Debug)]
 pub struct FieldVar {
@@ -144,7 +145,7 @@ impl GetSet {
 }
 
 #[derive(Clone, Debug)]
-pub(super) struct GetterSetterImpl {
+pub struct GetterSetterImpl {
     pub function_name: Ident,
     pub function_impl: TokenStream,
     pub export_token: TokenStream,