QueryCheckerVisitor.cs :  » 2.6.4-mono-.net-core » System.Linq » System » Linq » C# / CSharp Open Source

#if NET_4_0
//
// QueryCheckerVisitor.cs
//
// Author:
//       Jrmie "Garuma" Laval <jeremie.laval@gmail.com>
//
// Copyright (c) 2010 Jrmie "Garuma" Laval
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

using System;
using System.Threading;

namespace System.Linq{
  using OptionsList = Tuple<ParallelMergeOptions?, ParallelExecutionMode?, CancellationToken?, int, CancellationTokenSource>;

  internal class QueryCheckerVisitor : INodeVisitor
  {
    // Information gathering
    ParallelMergeOptions? options = null;
    ParallelExecutionMode? mode = null;
    CancellationToken? token = null;
    int? degreeOfParallelism = null;
    bool useStrip;
    CancellationToken implementerToken = CancellationToken.None;

    int partitionCount;
    bool? behindOrderGuard = null;

    internal QueryCheckerVisitor (int partitionCount)
    {
      this.partitionCount = partitionCount;
    }

    #region INodeVisitor implementation
    public void Visit<T> (QueryBaseNode<T> node)
    {
      // Nothing to do atm. Later we can check if the node is a
      // Take or a Skip and set accordingly useStrip
    }

    public void Visit<U, V> (QueryChildNode<U, V> node)
    {
      node.Parent.Visit (this);
    }

    public void Visit<T> (QueryOptionNode<T> node)
    {
      MergeOptions (node.GetOptions ());

      Visit<T, T> ((QueryChildNode<T, T>)node);
    }

    public void Visit<T> (QueryStartNode<T> node)
    {
      if (behindOrderGuard == null)
        behindOrderGuard = false;
      if (degreeOfParallelism != null)
        partitionCount = degreeOfParallelism.Value;
    }

    public void Visit<T, TParent> (QueryStreamNode<T, TParent> node)
    {
      if (node.IsIndexed)
        useStrip = true;

      Visit<T, TParent> ((QueryChildNode<T, TParent>)node);
    }

    public void Visit<T> (QueryOrderGuardNode<T> node)
    {
      if (node.EnsureOrder && behindOrderGuard == null)
        behindOrderGuard = true;
    }

    public void Visit<TFirst, TSecond, TResult> (QueryMuxNode<TFirst, TSecond, TResult> node)
    {

      Visit<TResult, TFirst> ((QueryChildNode<TResult, TFirst>)node);
    }
    #endregion

    internal QueryOptions Options {
      get {
        return new QueryOptions (options, mode, token == null ? CancellationToken.None : token.Value,
                                 useStrip, behindOrderGuard, partitionCount, implementerToken);
      }
    }

    internal bool UseStrip {
      get {
        return useStrip;
      }
    }

    internal bool BehindOrderGuard {
      get {
        return behindOrderGuard.Value;
      }
    }

    void MergeOptions (OptionsList list)
    {
      if (list.Item1 != null) {
        if (options == null)
          options = list.Item1;
        else
          Throw ("WithMergeOptions");
      }

      if (list.Item2 != null) {
        if (mode == null)
          mode = list.Item2;
        else
          Throw ("WithExecutionMode");
      }

      if (list.Item3 != null) {
        if (token == null)
          token = list.Item3;
        else
          Throw ("WithCancellationToken");
      }

      if (list.Item4 != -1) {
        if (degreeOfParallelism == null)
          degreeOfParallelism = list.Item4;
        else
          Throw ("WithDegreeOfParallelism");
      }

      // That one is treated specially
      if (list.Item5 != null) {
        implementerToken = implementerToken.Chain (list.Item5);
      }
    }

    void Throw (string methName)
    {
      throw new InvalidOperationException ("You can't have more than one " + methName + " node in a query");
    }
  }
}
#endif