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// Copyright (C) 2019-2024 Aleo Systems Inc.
// This file is part of the Leo library.

// The Leo library is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// The Leo library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with the Leo library. If not, see <https://www.gnu.org/licenses/>.

use crate::{Assigner, TypeTable};

use leo_ast::{Expression, Identifier, Node, NodeBuilder, Statement, TupleExpression};
use leo_span::Symbol;

use indexmap::IndexMap;

pub struct Destructurer<'a> {
    /// A mapping between node IDs and their types.
    pub(crate) type_table: &'a TypeTable,
    /// A counter used to generate unique node IDs.
    pub(crate) node_builder: &'a NodeBuilder,
    /// A struct used to construct (unique) assignment statements.
    pub(crate) assigner: &'a Assigner,
    /// A mapping between variables and flattened tuple expressions.
    pub(crate) tuples: IndexMap<Symbol, TupleExpression>,
    /// Whether or not we are currently traversing an async function block.
    pub(crate) is_async: bool,
}

impl<'a> Destructurer<'a> {
    pub(crate) fn new(type_table: &'a TypeTable, node_builder: &'a NodeBuilder, assigner: &'a Assigner) -> Self {
        Self { type_table, node_builder, assigner, tuples: IndexMap::new(), is_async: false }
    }

    /// A wrapper around `assigner.simple_assign_statement` that tracks the type of the lhs.
    pub(crate) fn simple_assign_statement(&mut self, lhs: Identifier, rhs: Expression) -> Statement {
        // Update the type table.
        let type_ = match self.type_table.get(&rhs.id()) {
            Some(type_) => type_,
            None => unreachable!("Type checking guarantees that all expressions have a type."),
        };
        self.type_table.insert(lhs.id(), type_);
        // Construct the statement.
        self.assigner.simple_assign_statement(lhs, rhs, self.node_builder.next_id())
    }
}