[assembler] Support superscript and subscript solidus (slash).

Author: youngman-g

assembler/src/asmlib/lexer.rs

@@ -123,7 +123,7 @@ pub(crate) enum Token {
 
     /// Solidus is often called "slash" but people often confuse slash
     /// and backslash.  So we don't call it either.
-    Solidus,
+    Solidus(Script),
 
     // @plus@ is actually not the correct glyph name, following sub.py.
     Plus(Script),
@@ -191,7 +191,7 @@ impl Display for Token {
             Token::GreaterThan => f.write_char('>'),
             Token::Intersection => f.write_char('∩'),
             Token::Union => f.write_char('∪'),
-            Token::Solidus => f.write_char('/'),
+            Token::Solidus(script) => write_elevated(script, "/"),
             Token::Plus(script) => write_elevated(script, "+"),
             Token::Minus(script) => write_elevated(script, "-"),
             Token::Times => f.write_char('×'),
@@ -495,7 +495,7 @@ mod lexer_impl_new {
             GlyphShape::DoublePipe => {
                 todo!("double-pipe (which is a symex terminator) does not yet have a token")
             }
-            GlyphShape::Solidus => only_normal(Token::Solidus),
+            GlyphShape::Solidus => Some(Token::Solidus(script)),
             GlyphShape::Times => only_normal(Token::Times),
             GlyphShape::Hash => Some(Token::Hash(script)),
             GlyphShape::Arrow => Some(match script {

assembler/src/asmlib/lexer/tests.rs

@@ -922,7 +922,22 @@ fn test_union() {
 
 #[test]
 fn test_solidus() {
-    assert_eq!(scan_tokens_only("/"), Ok(vec![Token::Solidus,]));
+    assert_eq!(
+        scan_tokens_only("/"),
+        Ok(vec![Token::Solidus(Script::Normal)])
+    );
+    assert_eq!(
+        scan_tokens_only("@solidus@"),
+        Ok(vec![Token::Solidus(Script::Normal)])
+    );
+    assert_eq!(
+        scan_tokens_only("@sup_solidus@"),
+        Ok(vec![Token::Solidus(Script::Super)])
+    );
+    assert_eq!(
+        scan_tokens_only("@sub_solidus@"),
+        Ok(vec![Token::Solidus(Script::Sub)])
+    );
 }
 
 #[test]

assembler/src/asmlib/parser.rs

@@ -201,8 +201,7 @@ where
     select! {
         // Solidus ("/") is used for divide.  See section 6-2.7
         // "Word Assembly" for details.
-        // TODO: support subscript/superscript for '/'
-        Tok::Solidus if script_required == Script::Normal => Operator::Divide,
+        Tok::Solidus(script) if script_required == script => Operator::Divide,
         Tok::Plus(Script::Normal) => Operator::Add,
         // TODO: support subscript/superscript for times
         Tok::Times if script_required == Script::Normal => Operator::Multiply,
@@ -324,7 +323,7 @@ where
         just(Tok::GreaterThan).to('>'),
         just(Tok::Intersection).to('∩'),
         just(Tok::Union).to('∪'),
-        just(Tok::Solidus).to('/'),
+        just(Tok::Solidus(Script::Normal)).to('/'),
         just(Tok::Times).to('×'),
         just(Tok::LogicalOr(Script::Normal)).to('∨'),
         just(Tok::LogicalAnd(Script::Normal)).to('∧'),