Feat: lots of convenience stuff

crates/forth/src/compiler.rs

@@ -143,6 +143,19 @@ fn compile(tokens: &[Token], dict: &Dictionary) -> Result<Vec<Op>, String> {
                     ops.push(Op::Quotation(Arc::from(quote_ops), Some(body_span)));
                 } else if word == "}" {
                     return Err("unexpected }".into());
+                } else if word == "[" {
+                    let (bracket_ops, consumed, end_span) =
+                        compile_bracket(&tokens[i + 1..], dict)?;
+                    i += consumed;
+                    ops.push(Op::Mark);
+                    ops.extend(bracket_ops);
+                    let count_span = SourceSpan {
+                        start: span.start,
+                        end: end_span.end,
+                    };
+                    ops.push(Op::Count(Some(count_span)));
+                } else if word == "]" {
+                    return Err("unexpected ]".into());
                 } else if word == ":" {
                     let (consumed, name, body) = compile_colon_def(&tokens[i + 1..], dict)?;
                     i += consumed;
@@ -211,6 +224,38 @@ fn compile_quotation(
     Ok((quote_ops, end_idx + 1, end_span))
 }
 
+fn compile_bracket(
+    tokens: &[Token],
+    dict: &Dictionary,
+) -> Result<(Vec<Op>, usize, SourceSpan), String> {
+    let mut depth = 1;
+    let mut end_idx = None;
+
+    for (i, tok) in tokens.iter().enumerate() {
+        if let Token::Word(w, _) = tok {
+            match w.as_str() {
+                "[" => depth += 1,
+                "]" => {
+                    depth -= 1;
+                    if depth == 0 {
+                        end_idx = Some(i);
+                        break;
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+
+    let end_idx = end_idx.ok_or("missing ]")?;
+    let end_span = match &tokens[end_idx] {
+        Token::Word(_, span) => *span,
+        _ => unreachable!(),
+    };
+    let body_ops = compile(&tokens[..end_idx], dict)?;
+    Ok((body_ops, end_idx + 1, end_span))
+}
+
 fn token_span(tok: &Token) -> Option<SourceSpan> {
     match tok {
         Token::Int(_, s) | Token::Float(_, s) | Token::Str(_, s) | Token::Word(_, s) => Some(*s),