kraken/stdlib/obj_lower.krak

import symbol:*
import tree:*
import vector:*
import map:*
import util:*
import string:*
import mem:*
import io:*
import ast_nodes:*
import ast_transformation:*
import pass_common:*

// Here's how we lower objects
// - first, we make sure that all functions, if statments, while loops and for loops have code blocks
//      as children, not just statements.
// - then, we "uglify" for loops and while loops so that functions that need pre and post statements always
//      have a code block to insert them into that makes sure that they get run.
// - then on the pass up the chain, at function calls we add in they copy_construct in and defer destruct out
//      temporaries.
// - this is also when we add in defer destructs for function parameters (inside the function) and declaration statements
fun obj_lower(name_ast_map: *map<string, pair<*tree<symbol>,*ast_node>>, ast_to_syntax: *map<*ast_node, *tree<symbol>>) {
    name_ast_map->for_each(fun(name: string, syntax_ast_pair: pair<*tree<symbol>,*ast_node>) {
        var helper_before = fun(node: *ast_node, parent_chain: *stack<*ast_node>) {
            match(*node) {
                ast_node::function(backing) if (backing.body_statement && !is_code_block(backing.body_statement)) backing.body_statement = ast_statement_ptr(ast_code_block_ptr(backing.body_statement))
                ast_node::if_statement(backing) {
                    if (!is_code_block(backing.then_part)) backing.then_part = ast_statement_ptr(ast_code_block_ptr(backing.then_part))
                    if (backing.else_part && !is_code_block(backing.else_part)) backing.else_part = ast_statement_ptr(ast_code_block_ptr(backing.else_part))
                }
                // no need for case because it's already been lowered
                ast_node::while_loop(backing) {
                    if (!is_code_block(backing.statement)) backing.statement = ast_code_block_ptr(backing.statement)
                    var condition = backing.condition
                    backing.condition = ast_value_ptr(string("true"), type_ptr(base_type::boolean()))
                    // objects do not coerce to booleans, so it should be ok for this not to be a ref
                    var condition_ident = ast_identifier_ptr("condition_temp", get_ast_type(condition), backing.statement)
                    backing.statement->code_block.children.add(0, ast_statement_ptr(ast_declaration_statement_ptr(condition_ident, condition, false)))
                    var condition_if = ast_if_statement_ptr(make_operator_call("!", vector(condition_ident)))
                    condition_if->if_statement.then_part = ast_statement_ptr(ast_branching_statement_ptr(branching_type::break_stmt()))
                    backing.statement->code_block.children.add(1, ast_statement_ptr(condition_if))
                }
                ast_node::for_loop(backing) {
                    if (!is_code_block(backing.body)) backing.body = ast_code_block_ptr(backing.body)
                    add_before_in(backing.init, parent_chain->top(), parent_chain->from_top(1)) 
                    backing.init = null<ast_node>()
                    // the do_update goes in the block above the for
                    var update_ident = ast_identifier_ptr("do_update", type_ptr(base_type::boolean()), parent_chain->from_top(1))
                    add_before_in(ast_statement_ptr(ast_declaration_statement_ptr(update_ident, ast_value_ptr(string("false"), type_ptr(base_type::boolean())), false)),
                            parent_chain->top(), parent_chain->from_top(1))
                    var update_if = ast_if_statement_ptr(update_ident)
                    update_if->if_statement.then_part = ast_statement_ptr(ast_code_block_ptr(backing.update))
                    backing.update = null<ast_node>()
                    backing.body->code_block.children.add(0, ast_statement_ptr(update_if))
                    backing.body->code_block.children.add(1, ast_statement_ptr(ast_assignment_statement_ptr(update_ident, ast_value_ptr(string("true"), type_ptr(base_type::boolean())))))

                    var condition = backing.condition
                    backing.condition = ast_value_ptr(string("true"), type_ptr(base_type::boolean()))
                    // objects do not coerce to booleans, so it should be ok for this not to be a ref
                    var condition_ident = ast_identifier_ptr("condition_temp", get_ast_type(condition), backing.body)
                    backing.body->code_block.children.add(2, ast_statement_ptr(ast_declaration_statement_ptr(condition_ident, condition, false)))
                    var condition_if = ast_if_statement_ptr(make_operator_call("!", vector(condition_ident)))
                    condition_if->if_statement.then_part = ast_statement_ptr(ast_branching_statement_ptr(branching_type::break_stmt()))
                    backing.body->code_block.children.add(3, ast_statement_ptr(condition_if))
                }
            }
        }
        var helper_after = fun(node: *ast_node, parent_chain: *stack<*ast_node>) {
            match(*node) {
                ast_node::function(backing) {
                    var order = 0;
                    backing.parameters.for_each(fun(param: *ast_node) {
                        var param_type = get_ast_type(param)
                        if (!param_type->is_ref && param_type->indirection == 0 && (param_type->is_object() && has_method(param_type->type_def, "destruct", vector<*type>()))) {
                            // the first pass ensures a code_block child
                            backing.body_statement->statement.child->code_block.children.add(order++,
                                ast_statement_ptr(ast_defer_statement_ptr(ast_statement_ptr(make_method_call(param, "destruct", vector<*ast_node>())))))
                        }
                    })
                }
                ast_node::declaration_statement(backing) {
                    var ident_type = get_ast_type(backing.identifier)
                    if (is_translation_unit(parent_chain->top()) || is_type_def(parent_chain->top()))
                        return;
                    if (!ident_type->is_ref && ident_type->indirection == 0 && (ident_type->is_object() && has_method(ident_type->type_def, "destruct", vector<*type>()))) {
                        // have to go up one because our parent is a statement
                        add_after_in(ast_statement_ptr(ast_defer_statement_ptr(ast_statement_ptr(make_method_call(backing.identifier, "destruct", vector<*ast_node>())))),
                                    parent_chain->top(), parent_chain->from_top(1))
                    }
                }
            }
        }
        run_on_tree(helper_before, helper_after, syntax_ast_pair.second)
    })
}