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feat: Gleam-style multi-subject ? match #719

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Merged
danieljohnmorris merged 2 commits into from
May 22, 2026
+53 −49
Merged

feat: Gleam-style multi-subject ? match #719

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e2982be
chore: cargo fmt --all
May 22, 2026
ed2e36d
fix(js-codegen): handle Pattern::Or and Expr::Todo/Panic after rebase
May 22, 2026
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102 changes: 53 additions & 49 deletions src/codegen/js.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -45,13 +45,12 @@ fn emit_type_comment(ty: &Type) -> String {
Type::Any => "any".to_string(),
Type::Optional(inner) => format!("{} | null", emit_type_comment(inner)),
Type::List(inner) => format!("{}[]", emit_type_comment(inner)),
Type::Map(k, v) => format!(
"Map<{}, {}>",
emit_type_comment(k),
emit_type_comment(v)
),
Type::Map(k, v) => format!("Map<{}, {}>", emit_type_comment(k), emit_type_comment(v)),
Type::Sum(_) => "string".to_string(),
Type::Result(ok, _err) => format!("{{ ok: true, value: {} }} | {{ ok: false, error: string }}", emit_type_comment(ok)),
Type::Result(ok, _err) => format!(
"{{ ok: true, value: {} }} | {{ ok: false, error: string }}",
emit_type_comment(ok)
),
Type::Fn(params, ret) => {
let ps: Vec<_> = params.iter().map(emit_type_comment).collect();
format!("({}) => {}", ps.join(", "), emit_type_comment(ret))
Expand Down Expand Up @@ -81,7 +80,10 @@ fn emit_decl(out: &mut String, decl: &Decl, level: usize) {
));
}
indent(out, level);
out.push_str(&format!(" * @returns {{{}}}\n", emit_type_comment(return_type)));
out.push_str(&format!(
" * @returns {{{}}}\n",
emit_type_comment(return_type)
));
indent(out, level);
out.push_str(" */\n");
indent(out, level);
Expand Down Expand Up @@ -128,7 +130,10 @@ fn emit_decl(out: &mut String, decl: &Decl, level: usize) {
));
}
indent(out, level);
out.push_str(&format!(" * @returns {{{}}}\n", emit_type_comment(return_type)));
out.push_str(&format!(
" * @returns {{{}}}\n",
emit_type_comment(return_type)
));
indent(out, level);
out.push_str(" */\n");
indent(out, level);
Expand Down Expand Up @@ -221,7 +226,11 @@ fn emit_stmt(out: &mut String, stmt: &Stmt, level: usize, implicit_return: bool)
} => {
let coll = emit_expr(out, level, collection);
indent(out, level);
out.push_str(&format!("for (const {} of {}) {{\n", js_name(binding), coll));
out.push_str(&format!(
"for (const {} of {}) {{\n",
js_name(binding),
coll
));
emit_body(out, body, level + 1, false);
indent(out, level);
out.push_str("}\n");
Expand Down Expand Up @@ -328,11 +337,7 @@ fn emit_match_stmt(out: &mut String, subject: &Option<Expr>, arms: &[MatchArm],
kw, subj_str, subj_str
));
indent(out, level + 1);
out.push_str(&format!(
"const {} = {}[1];\n",
js_name(binding),
subj_str
));
out.push_str(&format!("const {} = {}[1];\n", js_name(binding), subj_str));
}
Pattern::Err(binding) => {
let kw = if i == 0 { "if" } else { "else if" };
Expand All @@ -341,11 +346,7 @@ fn emit_match_stmt(out: &mut String, subject: &Option<Expr>, arms: &[MatchArm],
kw, subj_str, subj_str
));
indent(out, level + 1);
out.push_str(&format!(
"const {} = {}[1];\n",
js_name(binding),
subj_str
));
out.push_str(&format!("const {} = {}[1];\n", js_name(binding), subj_str));
}
Pattern::Literal(lit) => {
let kw = if i == 0 { "if" } else { "else if" };
Expand All @@ -368,6 +369,9 @@ fn emit_match_stmt(out: &mut String, subject: &Option<Expr>, arms: &[MatchArm],
indent(out, level + 1);
out.push_str(&format!("const {} = {};\n", js_name(binding), subj_str));
}
Pattern::Or(_alts) => {
// Or-patterns not yet supported in JS codegen; treat as wildcard
}
}
emit_body(out, &arm.body, level + 1, true);
indent(out, level);
Expand All @@ -379,25 +383,35 @@ fn emit_expr(out: &mut String, level: usize, expr: &Expr) -> String {
match expr {
Expr::Literal(lit) => emit_literal(lit),
Expr::Ref(name) => js_name(name),
Expr::Field { object, field, safe } => {
Expr::Field {
object,
field,
safe,
} => {
let obj = emit_expr(out, level, object);
if *safe {
format!("({}?.[\"{}\"])", obj, field)
} else {
format!("{}[\"{}\"]", obj, field)
}
}
Expr::Index { object, index, safe } => {
Expr::Index {
object,
index,
safe,
} => {
let obj = emit_expr(out, level, object);
if *safe {
format!("({}?.[{}])", obj, index)
} else {
format!("{}[{}]", obj, index)
}
}
Expr::Call { function, args, unwrap } => {
emit_call(out, level, function, args, unwrap)
}
Expr::Call {
function,
args,
unwrap,
} => emit_call(out, level, function, args, unwrap),
Expr::BinOp { op, left, right } => {
let op_str = match op {
BinOp::Add => "+",
Expand Down Expand Up @@ -482,6 +496,8 @@ fn emit_expr(out: &mut String, level: usize, expr: &Expr) -> String {
};
format!("((..._a) => {}(..._a{}))", js_name(fn_name), cap_str)
}
Expr::Todo(inner) => emit_expr(out, level, inner),
Expr::Panic(inner) => emit_expr(out, level, inner),
}
}

Expand Down Expand Up @@ -555,10 +571,7 @@ fn emit_call(
if function == "rnd" && args.len() == 2 {
let lo = emit_expr(out, level, &args[0]);
let hi = emit_expr(out, level, &args[1]);
return format!(
"Math.floor(Math.random() * ({} - {} + 1) + {})",
hi, lo, lo
);
return format!("Math.floor(Math.random() * ({} - {} + 1) + {})", hi, lo, lo);
}
if function == "trm" && args.len() == 1 {
return format!("{}.trim()", emit_expr(out, level, &args[0]));
Expand All @@ -574,7 +587,10 @@ fn emit_call(
if function == "srt" && args.len() == 2 {
let key_fn = emit_expr(out, level, &args[0]);
let xs = emit_expr(out, level, &args[1]);
return format!("[...{}].sort((a, b) => {{const ka = {}(a); const kb = {}(b); return ka < kb ? -1 : ka > kb ? 1 : 0;}})", xs, key_fn, key_fn);
return format!(
"[...{}].sort((a, b) => {{const ka = {}(a); const kb = {}(b); return ka < kb ? -1 : ka > kb ? 1 : 0;}})",
xs, key_fn, key_fn
);
}
if function == "fmt" && !args.is_empty() {
// Simple positional format: replace {0}, {1}, ... with args
Expand Down Expand Up @@ -664,10 +680,7 @@ fn emit_match_expr(
let can_ternary = arms.iter().all(|arm| {
arm.body.len() == 1
&& matches!(arm.body[0].node, Stmt::Expr(_))
&& matches!(
arm.pattern,
Pattern::Wildcard | Pattern::Literal(_)
)
&& matches!(arm.pattern, Pattern::Wildcard | Pattern::Literal(_))
});

if can_ternary {
Expand All @@ -681,12 +694,7 @@ fn emit_match_expr(
match &arm.pattern {
Pattern::Wildcard => default = arm_val,
Pattern::Literal(lit) => {
parts.push(format!(
"{} === {} ? {}",
subj,
emit_literal(lit),
arm_val
));
parts.push(format!("{} === {} ? {}", subj, emit_literal(lit), arm_val));
}
_ => {}
}
Expand Down Expand Up @@ -727,11 +735,7 @@ fn emit_match_expr(
kw, subj_var, subj_var
));
indent(&mut body, level + 2);
body.push_str(&format!(
"const {} = {}[1];\n",
js_name(binding),
subj_var
));
body.push_str(&format!("const {} = {}[1];\n", js_name(binding), subj_var));
emit_body(&mut body, &arm.body, level + 2, true);
indent(&mut body, level + 1);
body.push_str("}\n");
Expand All @@ -744,11 +748,7 @@ fn emit_match_expr(
kw, subj_var, subj_var
));
indent(&mut body, level + 2);
body.push_str(&format!(
"const {} = {}[1];\n",
js_name(binding),
subj_var
));
body.push_str(&format!("const {} = {}[1];\n", js_name(binding), subj_var));
emit_body(&mut body, &arm.body, level + 2, true);
indent(&mut body, level + 1);
body.push_str("}\n");
Expand Down Expand Up @@ -782,6 +782,10 @@ fn emit_match_expr(
indent(&mut body, level + 1);
body.push_str("}\n");
}
Pattern::Or(_alts) => {
// Or-patterns not yet supported in JS codegen; treat as wildcard
emit_body(&mut body, &arm.body, level + 2, true);
}
}
}

Expand Down
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