// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
 
namespace Microsoft.CodeAnalysis.FlowAnalysis;
 
internal static partial class ControlFlowGraphExtensions
{
    public static BasicBlock EntryBlock(this ControlFlowGraph cfg)
    {
        var firstBlock = cfg.Blocks[0];
        Debug.Assert(firstBlock.Kind == BasicBlockKind.Entry);
        return firstBlock;
    }
 
    public static BasicBlock ExitBlock(this ControlFlowGraph cfg)
    {
        var lastBlock = cfg.Blocks.Last();
        Debug.Assert(lastBlock.Kind == BasicBlockKind.Exit);
        return lastBlock;
    }
 
    public static IEnumerable<IOperation> DescendantOperations(this ControlFlowGraph cfg)
        => cfg.Blocks.SelectMany(b => b.DescendantOperations());
 
    public static IEnumerable<T> DescendantOperations<T>(this ControlFlowGraph cfg, OperationKind operationKind)
        where T : IOperation
        => cfg.DescendantOperations().Where(d => d?.Kind == operationKind).Cast<T>();
}