// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use std::collections::HashMap;
use std::cmp::max;
use std::slice;
use std::iter;

use super::{ControlFlowGraph, GraphPredecessors, GraphSuccessors};

pub struct TestGraph {
    num_nodes: usize,
    start_node: usize,
    successors: HashMap<usize, Vec<usize>>,
    predecessors: HashMap<usize, Vec<usize>>,
}

impl TestGraph {
    pub fn new(start_node: usize, edges: &[(usize, usize)]) -> Self {
        let mut graph = TestGraph {
            num_nodes: start_node + 1,
            start_node,
            successors: HashMap::new(),
            predecessors: HashMap::new(),
        };
        for &(source, target) in edges {
            graph.num_nodes = max(graph.num_nodes, source + 1);
            graph.num_nodes = max(graph.num_nodes, target + 1);
            graph.successors.entry(source).or_insert(vec![]).push(target);
            graph.predecessors.entry(target).or_insert(vec![]).push(source);
        }
        for node in 0..graph.num_nodes {
            graph.successors.entry(node).or_insert(vec![]);
            graph.predecessors.entry(node).or_insert(vec![]);
        }
        graph
    }
}

impl ControlFlowGraph for TestGraph {
    type Node = usize;

    fn start_node(&self) -> usize {
        self.start_node
    }

    fn num_nodes(&self) -> usize {
        self.num_nodes
    }

    fn predecessors<'graph>(&'graph self,
                            node: usize)
                            -> <Self as GraphPredecessors<'graph>>::Iter {
        self.predecessors[&node].iter().cloned()
    }

    fn successors<'graph>(&'graph self, node: usize) -> <Self as GraphSuccessors<'graph>>::Iter {
        self.successors[&node].iter().cloned()
    }
}

impl<'graph> GraphPredecessors<'graph> for TestGraph {
    type Item = usize;
    type Iter = iter::Cloned<slice::Iter<'graph, usize>>;
}

impl<'graph> GraphSuccessors<'graph> for TestGraph {
    type Item = usize;
    type Iter = iter::Cloned<slice::Iter<'graph, usize>>;
}