MegaBites-AI/Windows-powershell

1/* ****************************************************************************2 *3 * Copyright (c) Microsoft Corporation.4 *5 * This source code is subject to terms and conditions of the Apache License, Version 2.0. A6 * copy of the license can be found in the License.html file at the root of this distribution. If7 * you cannot locate the Apache License, Version 2.0, please send an email to8 * dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound9 * by the terms of the Apache License, Version 2.0.10 *11 * You must not remove this notice, or any other, from this software.12 *13 *14 * ***************************************************************************/15 16using System.Diagnostics;17using System.Collections.Generic;18using System.Globalization;19 20namespace System.Management.Automation.Interpreter21{22    internal readonly struct RuntimeLabel23    {24        public readonly int Index;25        public readonly int StackDepth;26        public readonly int ContinuationStackDepth;27 28        public RuntimeLabel(int index, int continuationStackDepth, int stackDepth)29        {30            Index = index;31            ContinuationStackDepth = continuationStackDepth;32            StackDepth = stackDepth;33        }34 35        public override string ToString()36        {37            return string.Format(CultureInfo.InvariantCulture, "->{0} C({1}) S({2})", Index, ContinuationStackDepth, StackDepth);38        }39    }40 41    internal sealed class BranchLabel42    {43        internal const int UnknownIndex = Int32.MinValue;44        internal const int UnknownDepth = Int32.MinValue;45 46        internal int _labelIndex = UnknownIndex;47        internal int _targetIndex = UnknownIndex;48        internal int _stackDepth = UnknownDepth;49        internal int _continuationStackDepth = UnknownDepth;50 51        // Offsets of forward branching instructions targeting this label52        // that need to be updated after we emit the label.53        private List<int> _forwardBranchFixups;54 55        public BranchLabel()56        {57        }58 59        internal int LabelIndex60        {61            get { return _labelIndex; }62 63            set { _labelIndex = value; }64        }65 66        internal bool HasRuntimeLabel67        {68            get { return _labelIndex != UnknownIndex; }69        }70 71        internal int TargetIndex72        {73            get { return _targetIndex; }74        }75 76        internal int StackDepth77        {78            get { return _stackDepth; }79        }80 81        internal RuntimeLabel ToRuntimeLabel()82        {83            Debug.Assert(_targetIndex != UnknownIndex && _stackDepth != UnknownDepth && _continuationStackDepth != UnknownDepth);84            return new RuntimeLabel(_targetIndex, _continuationStackDepth, _stackDepth);85        }86 87        internal void Mark(InstructionList instructions)88        {89            // ContractUtils.Requires(_targetIndex == UnknownIndex && _stackDepth == UnknownDepth && _continuationStackDepth == UnknownDepth);90 91            _stackDepth = instructions.CurrentStackDepth;92            _continuationStackDepth = instructions.CurrentContinuationsDepth;93            _targetIndex = instructions.Count;94 95            if (_forwardBranchFixups != null)96            {97                foreach (var branchIndex in _forwardBranchFixups)98                {99                    FixupBranch(instructions, branchIndex);100                }101 102                _forwardBranchFixups = null;103            }104        }105 106        internal void AddBranch(InstructionList instructions, int branchIndex)107        {108            Debug.Assert(((_targetIndex == UnknownIndex) == (_stackDepth == UnknownDepth)));109            Debug.Assert(((_targetIndex == UnknownIndex) == (_continuationStackDepth == UnknownDepth)));110 111            if (_targetIndex == UnknownIndex)112            {113                _forwardBranchFixups ??= new List<int>();114 115                _forwardBranchFixups.Add(branchIndex);116            }117            else118            {119                FixupBranch(instructions, branchIndex);120            }121        }122 123        internal void FixupBranch(InstructionList instructions, int branchIndex)124        {125            Debug.Assert(_targetIndex != UnknownIndex);126            instructions.FixupBranch(branchIndex, _targetIndex - branchIndex);127        }128    }129}130