@used_as_key dsl

src/comment_ast.rs

@@ -11,6 +11,7 @@ pub struct RuleMetadata {
     pub name: Option<String>,
     pub is_newtype: bool,
     pub no_alias: bool,
+    pub used_as_key: bool,
 }
 
 pub fn merge_metadata(r1: &RuleMetadata, r2: &RuleMetadata) -> RuleMetadata {
@@ -24,6 +25,7 @@ pub fn merge_metadata(r1: &RuleMetadata, r2: &RuleMetadata) -> RuleMetadata {
         },
         is_newtype: r1.is_newtype || r2.is_newtype,
         no_alias: r1.no_alias || r2.no_alias,
+        used_as_key: r1.used_as_key || r2.used_as_key,
     };
     merged.verify();
     merged
@@ -33,6 +35,7 @@ enum ParseResult {
     NewType,
     Name(String),
     DontGenAlias,
+    UsedAsKey,
 }
 
 impl RuleMetadata {
@@ -54,6 +57,10 @@ impl RuleMetadata {
                 ParseResult::DontGenAlias => {
                     base.no_alias = true;
                 }
+
+                ParseResult::UsedAsKey => {
+                    base.used_as_key = true;
+                }
             }
         }
         base.verify();
@@ -88,9 +95,15 @@ fn tag_no_alias(input: &str) -> IResult<&str, ParseResult> {
     Ok((input, ParseResult::DontGenAlias))
 }
 
+fn tag_used_as_key(input: &str) -> IResult<&str, ParseResult> {
+    let (input, _) = tag("@used_as_key")(input)?;
+
+    Ok((input, ParseResult::UsedAsKey))
+}
+
 fn whitespace_then_tag(input: &str) -> IResult<&str, ParseResult> {
     let (input, _) = take_while(char::is_whitespace)(input)?;
-    let (input, result) = alt((tag_name, tag_newtype, tag_no_alias))(input)?;
+    let (input, result) = alt((tag_name, tag_newtype, tag_no_alias, tag_used_as_key))(input)?;
 
     Ok((input, result))
 }
@@ -130,6 +143,7 @@ fn parse_comment_name() {
                 name: Some("foo".to_string()),
                 is_newtype: false,
                 no_alias: false,
+                used_as_key: false,
             }
         ))
     );
@@ -145,6 +159,7 @@ fn parse_comment_newtype() {
                 name: None,
                 is_newtype: true,
                 no_alias: false,
+                used_as_key: false,
             }
         ))
     );
@@ -160,6 +175,39 @@ fn parse_comment_newtype_and_name() {
                 name: Some("foo".to_string()),
                 is_newtype: true,
                 no_alias: false,
+                used_as_key: false,
+            }
+        ))
+    );
+}
+
+#[test]
+fn parse_comment_newtype_and_name_and_used_as_key() {
+    assert_eq!(
+        rule_metadata("@newtype @used_as_key @name foo"),
+        Ok((
+            "",
+            RuleMetadata {
+                name: Some("foo".to_string()),
+                is_newtype: true,
+                no_alias: false,
+                used_as_key: true,
+            }
+        ))
+    );
+}
+
+#[test]
+fn parse_comment_used_as_key() {
+    assert_eq!(
+        rule_metadata("@used_as_key"),
+        Ok((
+            "",
+            RuleMetadata {
+                name: None,
+                is_newtype: false,
+                no_alias: false,
+                used_as_key: true,
             }
         ))
     );
@@ -175,6 +223,7 @@ fn parse_comment_newtype_and_name_inverse() {
                 name: Some("foo".to_string()),
                 is_newtype: true,
                 no_alias: false,
+                used_as_key: false,
             }
         ))
     );
@@ -190,6 +239,7 @@ fn parse_comment_name_noalias() {
                 name: Some("foo".to_string()),
                 is_newtype: false,
                 no_alias: true,
+                used_as_key: false,
             }
         ))
     );

src/intermediate.rs

@@ -547,7 +547,10 @@ impl<'a> IntermediateTypes<'a> {
                 domain.visit_types(self, &mut |ty| mark_used_as_key(ty, &mut used_as_key));
             }
         }
-        self.used_as_key = used_as_key;
+        // we use a separate one here to get around the borrow checker in the above visit_types
+        for ident in used_as_key {
+            self.mark_used_as_key(ident);
+        }
     }
 
     pub fn visit_types<F: FnMut(&ConceptualRustType)>(&self, f: &mut F) {
@@ -657,6 +660,10 @@ impl<'a> IntermediateTypes<'a> {
         self.used_as_key.contains(name)
     }
 
+    pub fn mark_used_as_key(&mut self, name: RustIdent) {
+        self.used_as_key.insert(name);
+    }
+
     pub fn print_info(&self) {
         if !self.plain_groups.is_empty() {
             println!("\n\nPlain groups:");

src/parsing.rs

@@ -456,6 +456,9 @@ fn parse_type(
         &RuleMetadata::from(type1.comments_after_type.as_ref()),
         &RuleMetadata::from(type_choice.comments_after_type.as_ref()),
     );
+    if rule_metadata.used_as_key {
+        types.mark_used_as_key(type_name.clone());
+    }
     match &type1.type2 {
         Type2::Typename {
             ident,