[assembler] Support super/subscript identical-to sign (≡).

Author: youngman-g

assembler/src/asmlib/lexer.rs

@@ -114,7 +114,7 @@ pub(crate) enum Token {
 
     Pipe(Script),
     ProperSuperset,
-    IdenticalTo,
+    IdenticalTo(Script),
     Tilde(Script),
     LessThan,
     GreaterThan,
@@ -185,7 +185,7 @@ impl Display for Token {
             Token::Equals(script) => write_elevated(script, "="),
             Token::Pipe(script) => write_elevated(script, "|"),
             Token::ProperSuperset => f.write_char('⊃'),
-            Token::IdenticalTo => f.write_char('≡'),
+            Token::IdenticalTo(script) => write_elevated(script, "≡"),
             Token::Tilde(script) => write_elevated(script, "~"),
             Token::LessThan => f.write_char('<'),
             Token::GreaterThan => f.write_char('>'),
@@ -535,7 +535,7 @@ mod lexer_impl_new {
             GlyphShape::Tilde => Some(Token::Tilde(script)),
             GlyphShape::LeftBrace => only_normal(Token::LeftBrace),
             GlyphShape::RightBrace => only_normal(Token::RightBrace),
-            GlyphShape::IdenticalTo => only_normal(Token::IdenticalTo),
+            GlyphShape::IdenticalTo => Some(Token::IdenticalTo(script)),
             GlyphShape::Equals => Some(Token::Equals(script)),
             GlyphShape::Apostrophe => make_symex(),
             GlyphShape::Asterisk => only_normal(Token::Asterisk),

assembler/src/asmlib/lexer/tests.rs

@@ -936,8 +936,20 @@ fn test_proper_superset() {
 
 #[test]
 fn test_identical_to() {
-    assert_eq!(scan_tokens_only("≡"), Ok(vec![Token::IdenticalTo,]));
-    assert_eq!(scan_tokens_only("@hamb@"), Ok(vec![Token::IdenticalTo,]));
+    use Script::*;
+    assert_eq!(scan_tokens_only("≡"), Ok(vec![Token::IdenticalTo(Normal),]));
+    assert_eq!(
+        scan_tokens_only("@hamb@"),
+        Ok(vec![Token::IdenticalTo(Normal),])
+    );
+    assert_eq!(
+        scan_tokens_only("@sup_hamb@"),
+        Ok(vec![Token::IdenticalTo(Super),])
+    );
+    assert_eq!(
+        scan_tokens_only("@sub_hamb@"),
+        Ok(vec![Token::IdenticalTo(Sub),])
+    );
 }
 
 #[test]

assembler/src/asmlib/parser.rs

@@ -316,7 +316,7 @@ where
         just(Tok::Arrow(Script::Normal)).to('→'),
         just(Tok::Pipe(Script::Normal)).to('|'),
         just(Tok::ProperSuperset).to('⊃'),
-        just(Tok::IdenticalTo).to('≡'),
+        just(Tok::IdenticalTo(Script::Normal)).to('≡'),
         just(Tok::Tilde(Script::Normal)).to('~'),
         just(Tok::LessThan).to('<'),
         just(Tok::GreaterThan).to('>'),
@@ -327,6 +327,7 @@ where
         just(Tok::LogicalOr(Script::Normal)).to('∨'),
         just(Tok::LogicalAnd(Script::Normal)).to('∧'),
     ))
+    .labelled("macro terminator")
 }
 
 fn macro_argument<'a, I>() -> impl Parser<'a, I, MacroArgument, Extra<'a>>