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use super::*;
impl Codegen {
/// Emit the single `call_method` dispatcher: one arm per (class, method),
/// each checking arity at runtime — filling defaults and packing the variadic
/// tail — before calling the method wrapper. A non-`Object` receiver (a List or
/// Dict method, or a method on any other value) is forwarded to the runtime's
/// `builtin_method`. Emitted only when the script defines an object or calls a
/// method somewhere.
pub(super) fn dispatcher(
&self,
classes: &[Class],
uses_method_call: bool,
emit: &Emit,
) -> Result<String, Diagnostic> {
if classes.is_empty() && !uses_method_call {
return Ok(String::new());
}
let mut out = String::new();
out.push_str(
"\nfn call_method(recv: Value, name: &str, mut args: Vec<Value>, env: &mut Env) -> DogeResult<Value> {\n",
);
out.push_str(
" if !matches!(recv, Value::Object(_)) { return builtin_method(&recv, name, args); }\n",
);
out.push_str(" match (object_class_id(&recv)?, name) {\n");
for class in classes {
// Every method callable on this class — its own and every one inherited
// — each dispatching to the ancestor `def` that actually defines it.
for (method, def, params) in effective_methods(classes, class) {
out.push_str(&format!(
" ({}u32, \"{}\") => {{\n",
class.id,
escape_str(method)
));
let err = format!(
"method_arity_error(\"{}\", \"{}\", {}usize, {}, args.len())",
escape_str(&class.name),
escape_str(method),
params.required(),
max_repr(params),
);
out.push_str(&self.dispatch_arg_setup(params, &err, emit)?);
let count = params.params.len() + params.has_vararg() as usize;
let mut call_args = vec!["recv".to_string()];
for _ in 0..count {
call_args.push("args.remove(0)".to_string());
}
call_args.push("env".to_string());
out.push_str(&format!(
" {METHOD_PREFIX}{}_{method}({})\n",
def.id,
call_args.join(", ")
));
out.push_str(" }\n");
}
}
out.push_str(" _ => Err(no_such_method(&recv, name)),\n");
out.push_str(" }\n");
out.push_str("}\n");
Ok(out)
}
/// The `call_function` dispatcher: one arm per materialized `fn_id`, each
/// checking arity before calling the target — a user function's
/// recursion-guarded wrapper, or a builtin/module function directly. Emitted
/// only when the script calls something through a value.
pub(super) fn function_dispatcher(&self, emit: &Emit) -> Result<String, Diagnostic> {
if !emit.uses_call_function.get() {
return Ok(String::new());
}
let mut ids: Vec<u32> = emit.materialized.borrow().iter().copied().collect();
ids.sort_unstable();
let mut out = String::new();
out.push_str(
"\nfn call_function(f: &FunctionData, mut args: Vec<Value>, env: &mut Env) -> DogeResult<Value> {\n",
);
out.push_str(" match f.fn_id {\n");
for id in ids {
let arm = &emit.analysis.registry[id as usize];
out.push_str(&self.function_arm(id, arm, emit)?);
}
// Unreachable for any value the runtime built, since `callee_function`
// rejects non-functions before dispatch — but keep it non-panicking.
out.push_str(
" _ => Err(DogeError::type_error(\"very confuse. much function.\")),\n",
);
out.push_str(" }\n");
out.push_str("}\n");
Ok(out)
}
/// The `call_value` shim every indirect call goes through: a bound method
/// routes back through `call_method` (so it dispatches exactly like a direct
/// `a.speak(...)`), and any other value unwraps to its `FunctionData` and goes
/// through `call_function`. Emitted whenever the program calls a value.
pub(super) fn call_value_fn(&self, emit: &Emit) -> String {
if !emit.uses_call_function.get() {
return String::new();
}
let mut out = String::new();
out.push_str(
"\nfn call_value(callee: Value, args: Vec<Value>, env: &mut Env) -> DogeResult<Value> {\n",
);
out.push_str(" if let Value::BoundMethod(m) = &callee {\n");
out.push_str(" return call_method(m.receiver.clone(), &m.method, args, env);\n");
out.push_str(" }\n");
// `&*` derefs the `Rc<FunctionData>` explicitly: relying on deref coercion
// through the `?` here trips rustc's expected-type propagation.
out.push_str(" let f = callee_function(&callee)?;\n");
out.push_str(" call_function(&*f, args, env)\n");
out.push_str("}\n");
out
}
/// The `class_has_method` gate a bound-method read consults: whether an
/// instance of `class_id` responds to `name` (its own methods or an inherited
/// one). One `(id, name)` pair per entry in every class's effective method set,
/// matching the `call_method` dispatcher's arms. Emitted whenever the program
/// reads a bare `obj.name` as a value; `false` when the program has no classes.
pub(super) fn class_has_method_fn(&self, classes: &[Class], emit: &Emit) -> String {
if !emit.uses_attr_read.get() {
return String::new();
}
let mut pairs = Vec::new();
for class in classes {
for (method, _, _) in effective_methods(classes, class) {
pairs.push(format!("({}u32, \"{}\")", class.id, escape_str(method)));
}
}
let body = if pairs.is_empty() {
"false".to_string()
} else {
format!("matches!((class_id, name), {})", pairs.join(" | "))
};
format!("\nfn class_has_method(class_id: u32, name: &str) -> bool {{ {body} }}\n")
}
/// One arm of the `call_function` dispatcher for a given `fn_id`.
pub(super) fn function_arm(
&self,
id: u32,
arm: &ArmSpec,
emit: &Emit,
) -> Result<String, Diagnostic> {
let mut out = String::new();
out.push_str(&format!(" {id}u32 => {{\n"));
match arm {
ArmSpec::TopFunc {
file_id,
name,
params,
} => {
let err = format!(
"function_arity_error(\"{}\", {}usize, {}, args.len())",
escape_str(name),
params.required(),
max_repr(params),
);
out.push_str(&self.dispatch_arg_setup(params, &err, emit)?);
let count = params.params.len() + params.has_vararg() as usize;
let mut call_args: Vec<String> =
(0..count).map(|_| "args.remove(0)".into()).collect();
call_args.push("&mut *env".into());
out.push_str(&format!(
" {}({})\n",
func_wrapper(*file_id, name),
call_args.join(", ")
));
}
ArmSpec::Closure {
name,
id,
params,
captures,
} => {
let err = format!(
"function_arity_error(\"{}\", {}usize, {}, args.len())",
escape_str(name),
params.required(),
max_repr(params),
);
out.push_str(&self.dispatch_arg_setup(params, &err, emit)?);
let count = params.params.len() + params.has_vararg() as usize;
let mut call_args: Vec<String> = (0..*captures)
.map(|i| format!("f.captures[{i}].clone()"))
.collect();
call_args.extend((0..count).map(|_| "args.remove(0)".into()));
call_args.push("&mut *env".into());
out.push_str(&format!(
" {CLOSURE_PREFIX}{id}({})\n",
call_args.join(", ")
));
}
ArmSpec::Builtin { name } => out.push_str(&self.builtin_arm(name)),
ArmSpec::Module {
name,
runtime_fn,
arity,
} => {
out.push_str(&Self::fixed_arity_guard(name, *arity));
let call_args: Vec<String> =
(0..*arity).map(|_| "&args.remove(0)".into()).collect();
out.push_str(&format!(
" {runtime_fn}({})\n",
call_args.join(", ")
));
}
ArmSpec::Ctor { file_id, name } => {
// Constructing through a value: check arity against the effective
// `init`, fill defaults / pack the variadic, then call `n_<id>`.
let class = emit
.class_in(*file_id, name)
.expect("compiler bug: ctor arm for an unknown class");
let params = init_params(emit.classes, class);
let err = format!(
"function_arity_error(\"{}\", {}usize, {}, args.len())",
escape_str(name),
params.required(),
max_repr(params),
);
out.push_str(&self.dispatch_arg_setup(params, &err, emit)?);
let count = params.params.len() + params.has_vararg() as usize;
let mut call_args: Vec<String> =
(0..count).map(|_| "args.remove(0)".into()).collect();
call_args.push("&mut *env".into());
out.push_str(&format!(
" {CTOR_PREFIX}{}({})\n",
class.id,
call_args.join(", ")
));
}
}
out.push_str(" }\n");
Ok(out)
}
/// The statements that open a user-function or method arm: a range arity guard,
/// then a push of each unfilled optional parameter's default, then packing any
/// surplus arguments into the variadic List. They operate on the arm's `args`
/// vector so it holds exactly one value per binding slot afterward. `err` is
/// the runtime error constructor to raise when the count is out of range.
pub(super) fn dispatch_arg_setup(
&self,
params: &Params,
err: &str,
emit: &Emit,
) -> Result<String, Diagnostic> {
let n = params.params.len();
let required = params.required();
let mut out = String::new();
match params.max_positional() {
// Fixed arity: a single exact check reads clearest.
Some(max) if max == required => out.push_str(&format!(
" if args.len() != {required} {{ return Err({err}); }}\n"
)),
Some(max) => {
if required > 0 {
out.push_str(&format!(
" if args.len() < {required} {{ return Err({err}); }}\n"
));
}
out.push_str(&format!(
" if args.len() > {max} {{ return Err({err}); }}\n"
));
}
None => {
if required > 0 {
out.push_str(&format!(
" if args.len() < {required} {{ return Err({err}); }}\n"
));
}
}
}
for (i, param) in params.params.iter().enumerate().skip(required) {
let default = param
.default
.as_ref()
.expect("compiler bug: optional slot without a default");
let rust = self.expr(default, emit)?;
out.push_str(&format!(
" if args.len() < {} {{ args.push({rust}); }}\n",
i + 1
));
}
if params.has_vararg() {
out.push_str(&format!(
" let __rest = args.split_off({n}); args.push(Value::list(__rest));\n"
));
}
Ok(out)
}
/// The runtime arity check for a fixed-arity target (a builtin or stdlib
/// module function): an exact count, raising a single-count arity error.
pub(super) fn fixed_arity_guard(name: &str, arity: usize) -> String {
format!(
" if args.len() != {arity} {{ return Err(function_arity_error(\"{}\", {arity}usize, Some({arity}usize), args.len())); }}\n",
escape_str(name)
)
}
/// The body of a builtin dispatcher arm, honoring each builtin's own signature
/// (some are infallible, `range` takes one or two arguments).
pub(super) fn builtin_arm(&self, name: &str) -> String {
let builtin = crate::builtins::builtin(name)
.expect("compiler bug: dispatcher arm for a name that is not a builtin");
match builtin.shape {
BuiltinShape::Fallible => format!(
"{} {}(&args.remove(0))\n",
Self::fixed_arity_guard(name, 1),
builtin.runtime_fn
),
BuiltinShape::Infallible => format!(
"{} Ok({}(&args.remove(0)))\n",
Self::fixed_arity_guard(name, 1),
builtin.runtime_fn
),
BuiltinShape::Range => {
// `range` accepts one argument (0..n) or two (a..b).
" if args.len() != 1 && args.len() != 2 { return Err(function_arity_error(\"range\", 1usize, Some(2usize), args.len())); }\n\
\x20 if args.len() == 1 { range(&Value::int(0i64), &args.remove(0)) } else { range(&args.remove(0), &args.remove(0)) }\n".to_string()
}
BuiltinShape::Prompt => {
// `gib` accepts no argument (read a line) or one (a prompt first).
" if args.len() > 1 { return Err(function_arity_error(\"gib\", 0usize, Some(1usize), args.len())); }\n\
\x20 if args.is_empty() { gib(None) } else { gib(Some(&args.remove(0))) }\n".to_string()
}
}
}
}
/// The `Option<usize>` upper-bound literal a runtime arity error carries: `Some(n)`
/// for a fixed or defaulted header, `None` for a variadic one.
fn max_repr(params: &Params) -> String {
match params.max_positional() {
Some(max) => format!("Some({max}usize)"),
None => "None".to_string(),
}
}