Rust: refactor pre_emit! and post_emit! to a trait

Author: redsun82

rust/ast-generator/src/main.rs

@@ -52,6 +52,32 @@ fn property_name(type_name: &str, field_name: &str) -> String {
     name.to_owned()
 }
 
+fn has_special_emission(type_name: &str) -> bool {
+    matches!(
+        type_name,
+        "Item"
+            | "AssocItem"
+            | "ExternItem"
+            | "Meta"
+            | "MacroCall"
+            | "Fn"
+            | "Struct"
+            | "Enum"
+            | "Union"
+            | "Trait"
+            | "Module"
+            | "Variant"
+            | "PathExpr"
+            | "RecordExpr"
+            | "PathPat"
+            | "RecordPat"
+            | "TupleStructPat"
+            | "MethodCallExpr"
+            | "PathSegment"
+            | "Const"
+    )
+}
+
 fn to_lower_snake_case(s: &str) -> String {
     let mut buf = String::with_capacity(s.len());
     let mut prev = false;
@@ -355,6 +381,7 @@ struct ExtractorEnumInfo {
     snake_case_name: String,
     ast_name: String,
     variants: Vec<EnumVariantInfo>,
+    has_special_emission: bool,
 }
 
 #[derive(Serialize, Default)]
@@ -376,6 +403,7 @@ struct ExtractorNodeInfo {
     ast_name: String,
     fields: Vec<ExtractorNodeFieldInfo>,
     has_attrs: bool,
+    has_special_emission: bool,
 }
 
 #[derive(Serialize)]
@@ -406,6 +434,7 @@ fn enum_to_extractor_info(node: &AstEnumSrc) -> Option<ExtractorEnumInfo> {
                 }
             })
             .collect(),
+        has_special_emission: has_special_emission(&node.name),
     })
 }
 
@@ -460,6 +489,7 @@ fn node_to_extractor_info(node: &AstNodeSrc) -> ExtractorNodeInfo {
         ast_name: node.name.clone(),
         fields,
         has_attrs,
+        has_special_emission: has_special_emission(&node.name),
     }
 }
 

rust/ast-generator/templates/extractor.mustache

@@ -1,8 +1,7 @@
 //! Generated by `ast-generator`, do not edit by hand.
 
 use super::base::Translator;
-use super::mappings::TextValue;
-use crate::{pre_emit,post_emit};
+use super::mappings::{TextValue, HasTrapClass, Emission};
 use crate::generated;
 use crate::trap::{Label, TrapId};
 use ra_ap_syntax::ast::{
@@ -13,29 +12,23 @@ use ra_ap_syntax::ast::{
 use ra_ap_syntax::{AstNode, ast};
 
 impl Translator<'_> {
-    fn emit_else_branch(&mut self, node: &ast::ElseBranch) -> Option<Label<generated::Expr>> {
-        match node {
-            ast::ElseBranch::IfExpr(inner) => self.emit_if_expr(inner).map(Into::into),
-            ast::ElseBranch::Block(inner) => self.emit_block_expr(inner).map(Into::into),
-        }
-    }
     {{#enums}}
 
     pub(crate) fn emit_{{snake_case_name}}(&mut self, node: &ast::{{ast_name}}) -> Option<Label<generated::{{name}}>> {
-        pre_emit!({{name}}, self, node);
+        {{>pre_emission}}
         let label = match node {
             {{#variants}}
             ast::{{ast_name}}::{{variant_ast_name}}(inner) => self.emit_{{snake_case_name}}(inner).map(Into::into),
             {{/variants}}
         }?;
-        post_emit!({{name}}, self, node, label);
+        {{>post_emission}}
         Some(label)
     }
     {{/enums}}
     {{#nodes}}
 
     pub(crate) fn emit_{{snake_case_name}}(&mut self, node: &ast::{{ast_name}}) -> Option<Label<generated::{{name}}>> {
-        pre_emit!({{name}}, self, node);
+        {{>pre_emission}}
         {{#has_attrs}}
         if self.should_be_excluded(node) { return None; }
         {{/has_attrs}}
@@ -65,9 +58,15 @@ impl Translator<'_> {
             {{/fields}}
         });
         self.emit_location(label, node);
-        post_emit!({{name}}, self, node, label);
+        {{>post_emission}}
         self.emit_tokens(node, label.into(), node.syntax().children_with_tokens());
         Some(label)
     }
     {{/nodes}}
 }
+{{#enums}}
+{{>trap_class_mapping}}
+{{/enums}}
+{{#nodes}}
+{{>trap_class_mapping}}
+{{/nodes}}

rust/ast-generator/templates/post_emission.mustache

@@ -0,0 +1,3 @@
+{{#has_special_emission}}
+self.post_emit(node, label);
+{{/has_special_emission}}

rust/ast-generator/templates/pre_emission.mustache

@@ -0,0 +1,5 @@
+{{#has_special_emission}}
+if let Some(label) = self.pre_emit(node) {
+  return Some(label);
+}
+{{/has_special_emission}}

rust/ast-generator/templates/trap_class_mapping.mustache

@@ -0,0 +1,6 @@
+{{#has_special_emission}}
+
+impl HasTrapClass for ast::{{ast_name}} {
+    type TrapClass = generated::{{name}};
+}
+{{/has_special_emission}}