hakorune/src/mir/builder/exprs_lambda.rs

use super::ValueId;
use crate::ast::ASTNode;

impl super::MirBuilder {
    // Lambda lowering to FunctionNew
    pub(super) fn build_lambda_expression(
        &mut self,
        params: Vec<String>,
        body: Vec<ASTNode>,
    ) -> Result<ValueId, String> {
        use std::collections::HashSet;
        let mut used: HashSet<String> = HashSet::new();
        let mut locals: HashSet<String> = HashSet::new();
        for p in &params { locals.insert(p.clone()); }
        fn collect_vars(ast: &ASTNode, used: &mut std::collections::HashSet<String>, locals: &mut std::collections::HashSet<String>) {
            match ast {
                ASTNode::Variable { name, .. } => { if !locals.contains(name) { used.insert(name.clone()); } }
                ASTNode::Assignment { target, value, .. } => { collect_vars(target, used, locals); collect_vars(value, used, locals); }
                ASTNode::BinaryOp { left, right, .. } => { collect_vars(left, used, locals); collect_vars(right, used, locals); }
                ASTNode::UnaryOp { operand, .. } => { collect_vars(operand, used, locals); }
                ASTNode::MethodCall { object, arguments, .. } => { collect_vars(object, used, locals); for a in arguments { collect_vars(a, used, locals); } }
                ASTNode::FunctionCall { arguments, .. } => { for a in arguments { collect_vars(a, used, locals); } }
                ASTNode::Call { callee, arguments, .. } => { collect_vars(callee, used, locals); for a in arguments { collect_vars(a, used, locals); } }
                ASTNode::FieldAccess { object, .. } => { collect_vars(object, used, locals); }
                ASTNode::New { arguments, .. } => { for a in arguments { collect_vars(a, used, locals); } }
                ASTNode::If { condition, then_body, else_body, .. } => {
                    collect_vars(condition, used, locals);
                    for st in then_body { collect_vars(st, used, locals); }
                    if let Some(eb) = else_body { for st in eb { collect_vars(st, used, locals); } }
                }
                ASTNode::Loop { condition, body, .. } => { collect_vars(condition, used, locals); for st in body { collect_vars(st, used, locals); } }
                ASTNode::TryCatch { try_body, catch_clauses, finally_body, .. } => {
                    for st in try_body { collect_vars(st, used, locals); }
                    for c in catch_clauses { for st in &c.body { collect_vars(st, used, locals); } }
                    if let Some(fb) = finally_body { for st in fb { collect_vars(st, used, locals); } }
                }
                ASTNode::Throw { expression, .. } => { collect_vars(expression, used, locals); }
                ASTNode::Print { expression, .. } => { collect_vars(expression, used, locals); }
                ASTNode::Return { value, .. } => { if let Some(v) = value { collect_vars(v, used, locals); } }
                ASTNode::AwaitExpression { expression, .. } => { collect_vars(expression, used, locals); }
                ASTNode::PeekExpr { scrutinee, arms, else_expr, .. } => {
                    collect_vars(scrutinee, used, locals);
                    for (_, e) in arms { collect_vars(e, used, locals); }
                    collect_vars(else_expr, used, locals);
                }
                ASTNode::Program { statements, .. } => { for st in statements { collect_vars(st, used, locals); } }
                ASTNode::FunctionDeclaration { params, body, .. } => {
                    let mut inner = locals.clone();
                    for p in params { inner.insert(p.clone()); }
                    for st in body { collect_vars(st, used, &mut inner); }
                }
                _ => {}
            }
        }
        for st in body.iter() { collect_vars(st, &mut used, &mut locals); }
        let mut captures: Vec<(String, ValueId)> = Vec::new();
        for name in used.into_iter() {
            if let Some(&vid) = self.variable_map.get(&name) { captures.push((name, vid)); }
        }
        let me = self.variable_map.get("me").copied();
        let dst = self.value_gen.next();
        self.emit_instruction(super::MirInstruction::FunctionNew { dst, params: params.clone(), body: body.clone(), captures, me })?;
        self.value_types.insert(dst, crate::mir::MirType::Box("FunctionBox".to_string()));
        Ok(dst)
    }
}