// 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.
 
#nullable disable
 
using System;
using System.Threading;
 
namespace Microsoft.CodeAnalysis.FlowAnalysis;
 
/// <summary>
/// Analyzer to execute custom dataflow analysis on a control flow graph.
/// </summary>
/// <typeparam name="TBlockAnalysisData">Custom data tracked for each basic block with values at start of the block.</typeparam>
internal abstract class DataFlowAnalyzer<TBlockAnalysisData> : IDisposable
{
    /// <summary>
    /// Gets current analysis data for the given basic block, or an empty analysis data.
    /// </summary>
    public abstract TBlockAnalysisData GetCurrentAnalysisData(BasicBlock basicBlock);
 
    /// <summary>
    /// Gets empty analysis data for first analysis pass on a basic block.
    /// </summary>
    public abstract TBlockAnalysisData GetEmptyAnalysisData();
 
    /// <summary>
    /// Updates the current analysis data for the given basic block.
    /// </summary>
    public abstract void SetCurrentAnalysisData(BasicBlock basicBlock, TBlockAnalysisData data, CancellationToken cancellationToken);
 
    /// <summary>
    /// Analyze the given basic block and return the block analysis data at the end of the block for its successors.
    /// </summary>
    public abstract TBlockAnalysisData AnalyzeBlock(BasicBlock basicBlock, CancellationToken cancellationToken);
 
    /// <summary>
    /// Analyze the non-conditional fallthrough successor branch for the given basic block
    /// and return the block analysis data for the branch destination.
    /// </summary>
    public abstract TBlockAnalysisData AnalyzeNonConditionalBranch(BasicBlock basicBlock, TBlockAnalysisData currentAnalysisData, CancellationToken cancellationToken);
 
    /// <summary>
    /// Analyze the given conditional branch for the given basic block and return the
    /// block analysis data for the branch destinations for the fallthrough and
    /// conditional successor branches.
    /// </summary>
    public abstract (TBlockAnalysisData fallThroughSuccessorData, TBlockAnalysisData conditionalSuccessorData) AnalyzeConditionalBranch(
        BasicBlock basicBlock, TBlockAnalysisData currentAnalysisData, CancellationToken cancellationToken);
 
    /// <summary>
    /// Merge the given block analysis data instances to produce the resultant merge data.
    /// </summary>
    public abstract TBlockAnalysisData Merge(TBlockAnalysisData analysisData1, TBlockAnalysisData analysisData2, CancellationToken cancellationToken);
 
    /// <summary>
    /// Returns true if both the given block analysis data instances should be considered equivalent by analysis.
    /// </summary>
    public abstract bool IsEqual(TBlockAnalysisData analysisData1, TBlockAnalysisData analysisData2);
 
    /// <summary>
    /// Flag indicating if the dataflow analysis should run on unreachable blocks.
    /// </summary>
    public abstract bool AnalyzeUnreachableBlocks { get; }
 
    public virtual void Dispose()
    {
    }
}