refactor(ast_codegen): abstract passes and generators behind Runner trait.

tasks/ast_codegen/src/generators/ast_builder.rs

@@ -20,7 +20,11 @@ use crate::{
     CodegenCtx, Generator, GeneratorOutput, TypeRef,
 };
 
-pub struct AstBuilderGenerator;
+use super::define_generator;
+
+define_generator! {
+    pub struct AstBuilderGenerator;
+}
 
 impl Generator for AstBuilderGenerator {
     fn name(&self) -> &'static str {

tasks/ast_codegen/src/generators/ast_kind.rs

@@ -7,9 +7,11 @@ use crate::{
     GeneratorOutput, TypeRef,
 };
 
-use super::generated_header;
+use super::{define_generator, generated_header};
 
-pub struct AstKindGenerator;
+define_generator! {
+    pub struct AstKindGenerator;
+}
 
 pub const BLACK_LIST: [&str; 61] = [
     "Expression",

tasks/ast_codegen/src/generators/impl_get_span.rs

@@ -9,9 +9,11 @@ use crate::{
     CodegenCtx, Generator, GeneratorOutput,
 };
 
-use super::generated_header;
+use super::{define_generator, generated_header};
 
-pub struct ImplGetSpanGenerator;
+define_generator! {
+    pub struct ImplGetSpanGenerator;
+}
 
 impl Generator for ImplGetSpanGenerator {
     fn name(&self) -> &'static str {

tasks/ast_codegen/src/generators/mod.rs

@@ -43,3 +43,27 @@ pub use ast_builder::AstBuilderGenerator;
 pub use ast_kind::AstKindGenerator;
 pub use impl_get_span::ImplGetSpanGenerator;
 pub use visit::{VisitGenerator, VisitMutGenerator};
+
+use crate::{CodegenCtx, GeneratorOutput};
+
+pub trait Generator {
+    fn name(&self) -> &'static str;
+    fn generate(&mut self, ctx: &CodegenCtx) -> GeneratorOutput;
+}
+
+macro_rules! define_generator {
+    ($vis:vis struct $ident:ident $($lifetime:lifetime)? $($rest:tt)*) => {
+        $vis struct $ident $($lifetime)? $($rest)*
+        impl $($lifetime)? $crate::Runner for $ident $($lifetime)? {
+            fn name(&self) -> &'static str {
+                $crate::Generator::name(self)
+            }
+
+            fn run(&mut self, ctx: &$crate::CodegenCtx) -> $crate::Result<$crate::GeneratorOutput> {
+                Ok(self.generate(ctx))
+            }
+        }
+    };
+}
+
+pub(crate) use define_generator;

tasks/ast_codegen/src/generators/visit.rs

@@ -17,10 +17,15 @@ use crate::{
     CodegenCtx, Generator, GeneratorOutput, TypeRef,
 };
 
-use super::generated_header;
+use super::{define_generator, generated_header};
 
-pub struct VisitGenerator;
-pub struct VisitMutGenerator;
+define_generator! {
+    pub struct VisitGenerator;
+}
+
+define_generator! {
+    pub struct VisitMutGenerator;
+}
 
 impl Generator for VisitGenerator {
     fn name(&self) -> &'static str {