Feat: UI / UX

crates/forth/src/compiler.rs

@@ -160,6 +160,12 @@ fn compile(tokens: &[Token], dict: &Dictionary) -> Result<Vec<Op>, String> {
                         ops.push(Op::Branch(else_ops.len()));
                         ops.extend(else_ops);
                     }
+                } else if word == "case" {
+                    let (case_ops, consumed) = compile_case(&tokens[i + 1..], dict)?;
+                    i += consumed;
+                    ops.extend(case_ops);
+                } else if word == "of" || word == "endof" || word == "endcase" {
+                    return Err(format!("unexpected '{word}'"));
                 } else if !compile_word(word, Some(*span), &mut ops, dict) {
                     return Err(format!("unknown word: {word}"));
                 }
@@ -300,3 +306,69 @@ fn compile_if(
 
     Ok((then_ops, else_ops, then_pos + 1, then_span, else_span))
 }
+
+fn compile_case(tokens: &[Token], dict: &Dictionary) -> Result<(Vec<Op>, usize), String> {
+    let mut depth = 1;
+    let mut endcase_pos = None;
+    let mut clauses: Vec<(usize, usize)> = Vec::new();
+    let mut last_of = None;
+
+    for (i, tok) in tokens.iter().enumerate() {
+        if let Token::Word(w, _) = tok {
+            match w.as_str() {
+                "case" => depth += 1,
+                "endcase" => {
+                    depth -= 1;
+                    if depth == 0 {
+                        endcase_pos = Some(i);
+                        break;
+                    }
+                }
+                "of" if depth == 1 => last_of = Some(i),
+                "endof" if depth == 1 => {
+                    let of_pos = last_of.ok_or("'endof' without matching 'of'")?;
+                    clauses.push((of_pos, i));
+                    last_of = None;
+                }
+                _ => {}
+            }
+        }
+    }
+
+    let endcase_pos = endcase_pos.ok_or("missing 'endcase'")?;
+
+    let mut ops = Vec::new();
+    let mut branch_fixups: Vec<usize> = Vec::new();
+    let mut clause_start = 0;
+
+    for &(of_pos, endof_pos) in &clauses {
+        let test_ops = compile(&tokens[clause_start..of_pos], dict)?;
+        let body_ops = compile(&tokens[of_pos + 1..endof_pos], dict)?;
+
+        ops.extend(test_ops);
+        ops.push(Op::Over);
+        ops.push(Op::Eq);
+        ops.push(Op::BranchIfZero(body_ops.len() + 2, None, None));
+        ops.push(Op::Drop);
+        ops.extend(body_ops);
+        branch_fixups.push(ops.len());
+        ops.push(Op::Branch(0));
+
+        clause_start = endof_pos + 1;
+    }
+
+    let default_tokens = &tokens[clause_start..endcase_pos];
+    if !default_tokens.is_empty() {
+        let default_ops = compile(default_tokens, dict)?;
+        ops.extend(default_ops);
+    }
+
+    ops.push(Op::Drop);
+
+    let end = ops.len();
+    for pos in branch_fixups {
+        ops[pos] = Op::Branch(end - pos - 1);
+    }
+
+    Ok((ops, endcase_pos + 1))
+}

crates/forth/src/ops.rs

@@ -64,6 +64,7 @@ pub enum Op {
     Emit,
     Get,
     Set,
+    SetKeep,
     GetContext(&'static str),
     Rand(Option<SourceSpan>),
     ExpRand(Option<SourceSpan>),

crates/forth/src/vm.rs

@@ -637,6 +637,16 @@ impl Forth {
                         .expect("var_writes taken")
                         .insert(name, val);
                 }
+                Op::SetKeep => {
+                    let name = pop(stack)?;
+                    let name = name.as_str()?.to_string();
+                    let val = stack.last().ok_or("Stack underflow")?.clone();
+                    var_writes_cell
+                        .borrow_mut()
+                        .as_mut()
+                        .expect("var_writes taken")
+                        .insert(name, val);
+                }
 
                 Op::GetContext(name) => {
                     let val = match *name {

crates/forth/src/words/compile.rs

@@ -272,6 +272,14 @@ pub(crate) fn compile_word(
         }
     }
 
+    if let Some(var_name) = name.strip_prefix(',') {
+        if !var_name.is_empty() {
+            ops.push(Op::PushStr(Arc::from(var_name), span));
+            ops.push(Op::SetKeep);
+            return true;
+        }
+    }
+
     if let Some(midi) = parse_note_name(name) {
         ops.push(Op::PushInt(midi, span));
         return true;

crates/forth/src/words/core.rs

@@ -558,6 +558,16 @@ pub(super) const WORDS: &[Word] = &[
         compile: Simple,
         varargs: false,
     },
+    Word {
+        name: ",<var>",
+        aliases: &[],
+        category: "Variables",
+        stack: "(val -- val)",
+        desc: "Store value in variable, keep on stack",
+        example: "440 ,freq => 440",
+        compile: Simple,
+        varargs: false,
+    },
     // Definitions
     Word {
         name: ":",