CmdletParameterBinderController.cs

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Management.Automation.Internal;
using System.Management.Automation.Host;
using System.Management.Automation.Language;
using System.Management.Automation.Runspaces;
using System.Text;
using System.Globalization;
using System.Diagnostics.CodeAnalysis;

namespace System.Management.Automation
{
    /// <summary>
    /// This is the interface between the CommandProcessor and the various
    /// parameter binders required to bind parameters to a cmdlet.
    /// </summary>
    internal class CmdletParameterBinderController : ParameterBinderController
    {
        #region tracer

        [TraceSource("ParameterBinderController", "Controls the interaction between the command processor and the parameter binder(s).")]
        private static readonly PSTraceSource s_tracer = PSTraceSource.GetTracer("ParameterBinderController", "Controls the interaction between the command processor and the parameter binder(s).");

        #endregion tracer

        #region ctor

        /// <summary>
        /// Initializes the cmdlet parameter binder controller for
        /// the specified cmdlet and engine context
        /// </summary>
        /// <param name="cmdlet">
        /// The cmdlet that the parameters will be bound to.
        /// </param>
        /// <param name="commandMetadata">
        /// The metadata about the cmdlet.
        /// </param>
        /// <param name="parameterBinder">
        /// The default parameter binder to use.
        /// </param>
        internal CmdletParameterBinderController(
            Cmdlet cmdlet,
            CommandMetadata commandMetadata,
            ParameterBinderBase parameterBinder)
            : base(
                cmdlet.MyInvocation,
                cmdlet.Context,
                parameterBinder)
        {
            if (cmdlet == null)
            {
                throw PSTraceSource.NewArgumentNullException("cmdlet");
            }

            if (commandMetadata == null)
            {
                throw PSTraceSource.NewArgumentNullException("commandMetadata");
            }

            this.Command = cmdlet;
            _commandRuntime = (MshCommandRuntime)cmdlet.CommandRuntime;
            _commandMetadata = commandMetadata;

            // Add the static parameter metadata to the bindable parameters
            // And add them to the unbound parameters list

            if (commandMetadata.ImplementsDynamicParameters)
            {
                // ReplaceMetadata makes a copy for us, so we can use that collection as is.
                this.UnboundParameters = this.BindableParameters.ReplaceMetadata(commandMetadata.StaticCommandParameterMetadata);
            }
            else
            {
                _bindableParameters = commandMetadata.StaticCommandParameterMetadata;

                // Must make a copy of the list because we'll modify it.
                this.UnboundParameters = new List<MergedCompiledCommandParameter>(_bindableParameters.BindableParameters.Values);
            }
        }

        #endregion ctor

        #region helper_methods

        /// <summary>
        /// Binds the specified command-line parameters to the target
        /// </summary>
        /// <param name="arguments">
        /// Parameters to the command.
        /// </param>
        /// <exception cref="ParameterBindingException">
        /// If any parameters fail to bind,
        /// or
        /// If any mandatory parameters are missing.
        /// </exception>
        /// <exception cref="MetadataException">
        /// If there is an error generating the metadata for dynamic parameters.
        /// </exception>
        internal void BindCommandLineParameters(Collection<CommandParameterInternal> arguments)
        {
            s_tracer.WriteLine("Argument count: {0}", arguments.Count);

            BindCommandLineParametersNoValidation(arguments);

            // Is pipeline input expected?
            bool isPipelineInputExpected = !(_commandRuntime.IsClosed && _commandRuntime.InputPipe.Empty);

            int validParameterSetCount;

            if (!isPipelineInputExpected)
            {
                // Since pipeline input is not expected, ensure that we have a single
                // parameter set and that all the mandatory
                // parameters for the working parameter set are specified, or prompt

                validParameterSetCount = ValidateParameterSets(false, true);
            }
            else
            {
                // Use ValidateParameterSets to get the number of valid parameter
                // sets.

                // NTRAID#Windows Out Of Band Releases-2005/11/07-923917-JonN
                validParameterSetCount = ValidateParameterSets(true, false);
            }

            // If the parameter set is determined and the default parameters are not used
            // we try the default parameter binding again because it may contain some mandatory
            // parameters
            if (validParameterSetCount == 1 && !DefaultParameterBindingInUse)
            {
                ApplyDefaultParameterBinding("Mandatory Checking", false);
            }

            // If there are multiple valid parameter sets and we are expecting pipeline inputs,
            // we should filter out those parameter sets that cannot take pipeline inputs anymore.
            if (validParameterSetCount > 1 && isPipelineInputExpected)
            {
                uint filteredValidParameterSetFlags = FilterParameterSetsTakingNoPipelineInput();
                if (filteredValidParameterSetFlags != _currentParameterSetFlag)
                {
                    _currentParameterSetFlag = filteredValidParameterSetFlags;
                    // The valid parameter set flag is narrowed down, we get the new validParameterSetCount
                    validParameterSetCount = ValidateParameterSets(true, false);
                }
            }

            using (ParameterBinderBase.bindingTracer.TraceScope(
                "MANDATORY PARAMETER CHECK on cmdlet [{0}]",
                _commandMetadata.Name))
            {
                try
                {
                    // The missingMandatoryParameters out parameter is used for error reporting when binding from the pipeline.
                    // We're not binding from the pipeline here, and if a mandatory non-pipeline parameter is missing, it will
                    // be prompted for, or an exception will be raised, so we can ignore the missingMandatoryParameters out parameter.
                    Collection<MergedCompiledCommandParameter> missingMandatoryParameters;

                    // We shouldn't prompt for mandatory parameters if this command is private.
                    bool promptForMandatoryParameters = (Command.CommandInfo.Visibility == SessionStateEntryVisibility.Public);
                    HandleUnboundMandatoryParameters(validParameterSetCount, true, promptForMandatoryParameters, isPipelineInputExpected, out missingMandatoryParameters);

                    if (DefaultParameterBinder is ScriptParameterBinder)
                    {
                        BindUnboundScriptParameters();
                    }
                }
                catch (ParameterBindingException pbex)
                {
                    if (!DefaultParameterBindingInUse)
                    {
                        throw;
                    }

                    ThrowElaboratedBindingException(pbex);
                }
            }

            // If there is no more expected input, ensure there is a single
            // parameter set selected

            if (!isPipelineInputExpected)
            {
                VerifyParameterSetSelected();
            }

            // Set the prepipeline parameter set flags so that they can be restored
            // between each pipeline object.

            _prePipelineProcessingParameterSetFlags = _currentParameterSetFlag;
        }

        /// <summary>
        /// Binds the unbound arguments to parameters but does not
        /// perform mandatory parameter validation or parameter set validation.
        /// </summary>
        internal void BindCommandLineParametersNoValidation(Collection<CommandParameterInternal> arguments)
        {
            var psCompiledScriptCmdlet = this.Command as PSScriptCmdlet;
            if (psCompiledScriptCmdlet != null)
            {
                psCompiledScriptCmdlet.PrepareForBinding(this.CommandLineParameters);
            }

            // Add the passed in arguments to the unboundArguments collection

            foreach (CommandParameterInternal argument in arguments)
            {
                UnboundArguments.Add(argument);
            }

            CommandMetadata cmdletMetadata = _commandMetadata;
            // Clear the warningSet at the beginning.
            _warningSet.Clear();
            // Parse $PSDefaultParameterValues to get all valid <parameter, value> pairs
            _allDefaultParameterValuePairs = this.GetDefaultParameterValuePairs(true);
            // Set to false at the beginning
            DefaultParameterBindingInUse = false;
            // Clear the bound default parameters at the beginning
            BoundDefaultParameters.Clear();

            // Reparse the arguments based on the merged metadata
            ReparseUnboundArguments();

            using (ParameterBinderBase.bindingTracer.TraceScope(
                "BIND NAMED cmd line args [{0}]",
                _commandMetadata.Name))
            {
                // Bind the actual arguments
                UnboundArguments = BindParameters(_currentParameterSetFlag, this.UnboundArguments);
            }

            ParameterBindingException reportedBindingException;
            ParameterBindingException currentBindingException;

            using (ParameterBinderBase.bindingTracer.TraceScope(
                "BIND POSITIONAL cmd line args [{0}]",
                _commandMetadata.Name))
            {
                // Now that we know the parameter set, bind the positional parameters
                UnboundArguments =
                    BindPositionalParameters(
                        UnboundArguments,
                        _currentParameterSetFlag,
                        cmdletMetadata.DefaultParameterSetFlag,
                        out currentBindingException);

                reportedBindingException = currentBindingException;
            }

            // Try applying the default parameter binding after POSITIONAL BIND so that the default parameter
            // values can influence the parameter set selection earlier than the default parameter set.
            ApplyDefaultParameterBinding("POSITIONAL BIND", false);

            // We need to make sure there is at least one valid parameter set. Its
            // OK to allow more than one as long as one of them takes pipeline input.

            // NTRAID#Windows Out Of Band Releases-2006/02/14-928660-JonN
            // Pipeline input fails to bind to pipeline enabled parameter
            // second parameter changed from true to false
            ValidateParameterSets(true, false);

            // Always get the dynamic parameters as there may be mandatory parameters there

            // Now try binding the dynamic parameters
            HandleCommandLineDynamicParameters(out currentBindingException);

            // Try binding the default parameters again. After dynamic binding, new parameter metadata are
            // included, so it's possible a previously unsuccessful binding will succeed.
            ApplyDefaultParameterBinding("DYNAMIC BIND", true);

            // If this generated an exception (but we didn't have one from the non-dynamic
            // parameters, report on this one.
            if (reportedBindingException == null)
                reportedBindingException = currentBindingException;

            // If the cmdlet implements a ValueFromRemainingArguments parameter (VarArgs)
            // bind the unbound arguments to that parameter.
            HandleRemainingArguments();

            VerifyArgumentsProcessed(reportedBindingException);
        }

        /// <summary>
        /// Process all valid parameter sets, and filter out those that don't take any pipeline input
        /// </summary>
        /// <returns>
        /// The new valid parameter set flags
        /// </returns>
        private uint FilterParameterSetsTakingNoPipelineInput()
        {
            uint parameterSetsTakingPipeInput = 0;
            bool findPipeParameterInAllSets = false;

            foreach (KeyValuePair<MergedCompiledCommandParameter, DelayedScriptBlockArgument> entry in _delayBindScriptBlocks)
            {
                parameterSetsTakingPipeInput |= entry.Key.Parameter.ParameterSetFlags;
            }

            foreach (MergedCompiledCommandParameter parameter in UnboundParameters)
            {
                // If a parameter doesn't take pipeline input at all, we can skip it
                if (!parameter.Parameter.IsPipelineParameterInSomeParameterSet)
                {
                    continue;
                }

                var matchingParameterSetMetadata =
                    parameter.Parameter.GetMatchingParameterSetData(_currentParameterSetFlag);

                foreach (ParameterSetSpecificMetadata parameterSetMetadata in matchingParameterSetMetadata)
                {
                    if (parameterSetMetadata.ValueFromPipeline || parameterSetMetadata.ValueFromPipelineByPropertyName)
                    {
                        if (parameterSetMetadata.ParameterSetFlag == 0 && parameterSetMetadata.IsInAllSets)
                        {
                            // The parameter takes pipeline input and is in all sets, we don't change the _currentParameterSetFlag
                            parameterSetsTakingPipeInput = 0;
                            findPipeParameterInAllSets = true;
                            break;
                        }
                        else
                        {
                            parameterSetsTakingPipeInput |= parameterSetMetadata.ParameterSetFlag;
                        }
                    }
                }

                if (findPipeParameterInAllSets)
                    break;
            }

            // If parameterSetsTakingPipeInput is 0, then no parameter set from the _currentParameterSetFlag can take piped objects.
            // Then we just leave what it was, and the pipeline binding deal with the error later
            if (parameterSetsTakingPipeInput != 0)
                return _currentParameterSetFlag & parameterSetsTakingPipeInput;
            else
                return _currentParameterSetFlag;
        }

        /// <summary>
        /// Apply the binding for the default parameter defined by the user
        /// </summary>
        /// <param name="bindingStage">
        /// Dictate which binding stage this default binding happens
        /// </param>
        /// <param name="isDynamic">
        /// Special operation needed if the default binding happens at the dynamic binding stage
        /// </param>
        /// <returns></returns>
        private void ApplyDefaultParameterBinding(string bindingStage, bool isDynamic)
        {
            if (!_useDefaultParameterBinding)
            {
                return;
            }

            if (isDynamic)
            {
                // Get user defined default parameter value pairs again, so that the
                // dynamic parameter value pairs could be involved.
                _allDefaultParameterValuePairs = GetDefaultParameterValuePairs(false);
            }

            Dictionary<MergedCompiledCommandParameter, object> qualifiedParameterValuePairs = GetQualifiedParameterValuePairs(_currentParameterSetFlag, _allDefaultParameterValuePairs);
            if (qualifiedParameterValuePairs != null)
            {
                bool isSuccess = false;
                using (ParameterBinderBase.bindingTracer.TraceScope(
                    "BIND DEFAULT <parameter, value> pairs after [{0}] for [{1}]",
                    bindingStage, _commandMetadata.Name))
                {
                    isSuccess = BindDefaultParameters(_currentParameterSetFlag, qualifiedParameterValuePairs);
                    if (isSuccess && !DefaultParameterBindingInUse)
                    {
                        DefaultParameterBindingInUse = true;
                    }
                }

                s_tracer.WriteLine("BIND DEFAULT after [{0}] result [{1}]", bindingStage, isSuccess);
            }
            return;
        }

        /// <summary>
        /// Bind the default parameter value pairs
        /// </summary>
        /// <param name="validParameterSetFlag">validParameterSetFlag</param>
        /// <param name="defaultParameterValues">default value pairs</param>
        /// <returns>
        /// true if there is at least one default parameter bound successfully
        /// false if there is no default parameter bound successfully
        /// </returns>
        private bool BindDefaultParameters(uint validParameterSetFlag, Dictionary<MergedCompiledCommandParameter, object> defaultParameterValues)
        {
            bool ret = false;
            foreach (var pair in defaultParameterValues)
            {
                MergedCompiledCommandParameter parameter = pair.Key;
                object argumentValue = pair.Value;
                string parameterName = parameter.Parameter.Name;

                try
                {
                    ScriptBlock scriptBlockArg = argumentValue as ScriptBlock;
                    if (scriptBlockArg != null)
                    {
                        // Get the current binding state, and pass it to the ScriptBlock as the argument
                        // The 'arg' includes HashSet properties 'BoundParameters', 'BoundPositionalParameters',
                        // 'BoundDefaultParameters', and 'LastBindingStage'. So the user can set value
                        // to a parameter depending on the current binding state.
                        PSObject arg = WrapBindingState();
                        Collection<PSObject> results = scriptBlockArg.Invoke(arg);
                        if (results == null || results.Count == 0)
                        {
                            continue;
                        }
                        else if (results.Count == 1)
                        {
                            argumentValue = results[0];
                        }
                        else
                        {
                            argumentValue = results;
                        }
                    }

                    CommandParameterInternal bindableArgument =
                        CommandParameterInternal.CreateParameterWithArgument(
                           /*parameterAst*/null, parameterName, "-" + parameterName + ":",
                           /*argumentAst*/null, argumentValue, false);

                    bool bindResult =
                            BindParameter(
                                validParameterSetFlag,
                                bindableArgument,
                                parameter,
                                ParameterBindingFlags.ShouldCoerceType | ParameterBindingFlags.DelayBindScriptBlock);

                    if (bindResult && !ret)
                    {
                        ret = true;
                    }

                    if (bindResult)
                    {
                        BoundDefaultParameters.Add(parameterName);
                    }
                }
                catch (ParameterBindingException ex)
                {
                    // We don't want the failures in default binding affect the command line binding,
                    // so we write out a warning and ignore this binding failure
                    if (!_warningSet.Contains(_commandMetadata.Name + Separator + parameterName))
                    {
                        string message = String.Format(CultureInfo.InvariantCulture,
                            ParameterBinderStrings.FailToBindDefaultParameter,
                            LanguagePrimitives.IsNull(argumentValue) ? "null" : argumentValue.ToString(),
                            parameterName, ex.Message);
                        _commandRuntime.WriteWarning(message);
                        _warningSet.Add(_commandMetadata.Name + Separator + parameterName);
                    }
                    continue;
                }
            }

            return ret;
        }

        /// <summary>
        /// Wrap up current binding state to provide more information to the user
        /// </summary>
        /// <returns></returns>
        private PSObject WrapBindingState()
        {
            HashSet<string> boundParameterNames = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            HashSet<string> boundPositionalParameterNames =
                this.DefaultParameterBinder.CommandLineParameters.CopyBoundPositionalParameters();
            HashSet<string> boundDefaultParameterNames = new HashSet<string>(StringComparer.OrdinalIgnoreCase);

            foreach (string paramName in BoundParameters.Keys)
            {
                boundParameterNames.Add(paramName);
            }

            foreach (string paramName in BoundDefaultParameters)
            {
                boundDefaultParameterNames.Add(paramName);
            }

            PSObject result = new PSObject();
            result.Properties.Add(new PSNoteProperty("BoundParameters", boundParameterNames));
            result.Properties.Add(new PSNoteProperty("BoundPositionalParameters", boundPositionalParameterNames));
            result.Properties.Add(new PSNoteProperty("BoundDefaultParameters", boundDefaultParameterNames));

            return result;
        }

        /// <summary>
        /// Get all qualified default parameter value pairs based on the
        /// given currentParameterSetFlag.
        /// </summary>
        /// <param name="currentParameterSetFlag"></param>
        /// <param name="availableParameterValuePairs"></param>
        /// <returns>null if no qualified pair found</returns>
        private Dictionary<MergedCompiledCommandParameter, object> GetQualifiedParameterValuePairs(
            uint currentParameterSetFlag,
            Dictionary<MergedCompiledCommandParameter, object> availableParameterValuePairs)
        {
            if (availableParameterValuePairs == null)
            {
                return null;
            }

            Dictionary<MergedCompiledCommandParameter, object> result = new Dictionary<MergedCompiledCommandParameter, object>();

            uint possibleParameterFlag = uint.MaxValue;
            foreach (var pair in availableParameterValuePairs)
            {
                MergedCompiledCommandParameter param = pair.Key;
                if ((param.Parameter.ParameterSetFlags & currentParameterSetFlag) == 0 && !param.Parameter.IsInAllSets)
                {
                    continue;
                }

                if (BoundArguments.ContainsKey(param.Parameter.Name))
                {
                    continue;
                }

                // check if this param's set conflicts with other possible params.
                if (param.Parameter.ParameterSetFlags != 0)
                {
                    possibleParameterFlag &= param.Parameter.ParameterSetFlags;
                    if (possibleParameterFlag == 0)
                    {
                        return null;
                    }
                }

                result.Add(param, pair.Value);
            }

            if (result.Count > 0)
            {
                return result;
            }
            return null;
        }

        /// <summary>
        /// Get the aliases of the the current cmdlet
        /// </summary>
        /// <returns></returns>
        private List<string> GetAliasOfCurrentCmdlet()
        {
            var results = Context.SessionState.Internal.GetAliasesByCommandName(_commandMetadata.Name).ToList();

            return results.Count > 0 ? results : null;
        }

        /// <summary>
        /// Check if the passed-in aliasName matches an alias name in _aliasList
        /// </summary>
        /// <param name="aliasName"></param>
        /// <returns></returns>
        private bool MatchAnyAlias(string aliasName)
        {
            if (_aliasList == null)
            {
                return false;
            }

            bool result = false;
            WildcardPattern aliasPattern = WildcardPattern.Get(aliasName, WildcardOptions.IgnoreCase);
            foreach (string alias in _aliasList)
            {
                if (aliasPattern.IsMatch(alias))
                {
                    result = true;
                    break;
                }
            }

            return result;
        }

        internal IDictionary DefaultParameterValues { get; set; }
        /// <summary>
        /// Get all available default parameter value pairs
        /// </summary>
        /// <returns>return the available parameter value pairs. Otherwise return null</returns>
        private Dictionary<MergedCompiledCommandParameter, object> GetDefaultParameterValuePairs(bool needToGetAlias)
        {
            if (DefaultParameterValues == null)
            {
                _useDefaultParameterBinding = false;
                return null;
            }

            var availablePairs = new Dictionary<MergedCompiledCommandParameter, object>();

            if (needToGetAlias && DefaultParameterValues.Count > 0)
            {
                // Get all aliases of the current cmdlet
                _aliasList = GetAliasOfCurrentCmdlet();
            }

            // Set flag to true by default
            _useDefaultParameterBinding = true;

            string currentCmdletName = _commandMetadata.Name;

            IDictionary<string, MergedCompiledCommandParameter> bindableParameters = BindableParameters.BindableParameters;
            IDictionary<string, MergedCompiledCommandParameter> bindableAlias = BindableParameters.AliasedParameters;

            // Contains parameters that are set with different values by settings in $PSDefaultParameterValues.
            // We should ignore those settings and write out a warning
            var parametersToRemove = new HashSet<MergedCompiledCommandParameter>();
            var wildcardDefault = new Dictionary<string, object>();
            // Contains keys that are in bad format. For every bad format key, we should write out a warning message
            // the first time we encounter it, and remove it from the $PSDefaultParameterValues
            var keysToRemove = new List<object>();

            foreach (DictionaryEntry entry in DefaultParameterValues)
            {
                string key = entry.Key as string;
                if (key == null)
                {
                    continue;
                }

                key = key.Trim();
                string cmdletName = null;
                string parameterName = null;

                // The key is not in valid format
                if (!DefaultParameterDictionary.CheckKeyIsValid(key, ref cmdletName, ref parameterName))
                {
                    if (key.Equals("Disabled", StringComparison.OrdinalIgnoreCase) &&
                        LanguagePrimitives.IsTrue(entry.Value))
                    {
                        _useDefaultParameterBinding = false;
                        return null;
                    }
                    // Write out a warning message if the key is not 'Disabled'
                    if (!key.Equals("Disabled", StringComparison.OrdinalIgnoreCase))
                    {
                        keysToRemove.Add(entry.Key);
                    }
                    continue;
                }

                Diagnostics.Assert(cmdletName != null && parameterName != null, "The cmdletName and parameterName should be set in CheckKeyIsValid");

                if (WildcardPattern.ContainsWildcardCharacters(key))
                {
                    wildcardDefault.Add(cmdletName + Separator + parameterName, entry.Value);
                    continue;
                }

                // Continue to process this entry only if the specified cmdletName is the name
                // of the current cmdlet, or is an alias name of the current cmdlet.
                if (!cmdletName.Equals(currentCmdletName, StringComparison.OrdinalIgnoreCase) && !MatchAnyAlias(cmdletName))
                {
                    continue;
                }

                GetDefaultParameterValuePairsHelper(
                    cmdletName, parameterName, entry.Value,
                    bindableParameters, bindableAlias,
                    availablePairs, parametersToRemove);
            }

            foreach (KeyValuePair<string, object> wildcard in wildcardDefault)
            {
                string key = wildcard.Key;

                string cmdletName = key.Substring(0, key.IndexOf(Separator, StringComparison.OrdinalIgnoreCase));
                string parameterName = key.Substring(key.IndexOf(Separator, StringComparison.OrdinalIgnoreCase) + Separator.Length);

                WildcardPattern cmdletPattern = WildcardPattern.Get(cmdletName, WildcardOptions.IgnoreCase);
                // Continue to process this entry only if the cmdletName matches the name of the current
                // cmdlet, or matches an alias name of the current cmdlet
                if (!cmdletPattern.IsMatch(currentCmdletName) && !MatchAnyAlias(cmdletName))
                {
                    continue;
                }

                if (!WildcardPattern.ContainsWildcardCharacters(parameterName))
                {
                    GetDefaultParameterValuePairsHelper(
                        cmdletName, parameterName, wildcard.Value,
                        bindableParameters, bindableAlias,
                        availablePairs, parametersToRemove);

                    continue;
                }

                WildcardPattern parameterPattern = MemberMatch.GetNamePattern(parameterName);
                var matches = new List<MergedCompiledCommandParameter>();

                foreach (KeyValuePair<string, MergedCompiledCommandParameter> entry in bindableParameters)
                {
                    if (parameterPattern.IsMatch(entry.Key))
                    {
                        matches.Add(entry.Value);
                    }
                }

                foreach (KeyValuePair<string, MergedCompiledCommandParameter> entry in bindableAlias)
                {
                    if (parameterPattern.IsMatch(entry.Key))
                    {
                        matches.Add(entry.Value);
                    }
                }

                if (matches.Count > 1)
                {
                    // The parameterPattern matches more than one parameters, so we write out a warning message and ignore this setting
                    if (!_warningSet.Contains(cmdletName + Separator + parameterName))
                    {
                        _commandRuntime.WriteWarning(
                            String.Format(CultureInfo.InvariantCulture, ParameterBinderStrings.MultipleParametersMatched, parameterName));
                        _warningSet.Add(cmdletName + Separator + parameterName);
                    }
                    continue;
                }

                if (matches.Count == 1)
                {
                    if (!availablePairs.ContainsKey(matches[0]))
                    {
                        availablePairs.Add(matches[0], wildcard.Value);
                        continue;
                    }

                    if (!wildcard.Value.Equals(availablePairs[matches[0]]))
                    {
                        if (!_warningSet.Contains(cmdletName + Separator + parameterName))
                        {
                            _commandRuntime.WriteWarning(
                                String.Format(CultureInfo.InvariantCulture, ParameterBinderStrings.DifferentValuesAssignedToSingleParameter, parameterName));
                            _warningSet.Add(cmdletName + Separator + parameterName);
                        }
                        parametersToRemove.Add(matches[0]);
                    }
                }
            }

            if (keysToRemove.Count > 0)
            {
                var keysInError = new StringBuilder();
                foreach (object badFormatKey in keysToRemove)
                {
                    if (DefaultParameterValues.Contains(badFormatKey))
                        DefaultParameterValues.Remove(badFormatKey);

                    keysInError.Append(badFormatKey.ToString() + ", ");
                }

                keysInError.Remove(keysInError.Length - 2, 2);
                var multipleKeys = keysToRemove.Count > 1;
                string formatString = multipleKeys
                                            ? ParameterBinderStrings.MultipleKeysInBadFormat
                                            : ParameterBinderStrings.SingleKeyInBadFormat;
                _commandRuntime.WriteWarning(
                    String.Format(CultureInfo.InvariantCulture, formatString, keysInError));
            }

            foreach (MergedCompiledCommandParameter param in parametersToRemove)
            {
                availablePairs.Remove(param);
            }

            if (availablePairs.Count > 0)
            {
                return availablePairs;
            }

            return null;
        }

        /// <summary>
        /// A helper method for GetDefaultParameterValuePairs
        /// </summary>
        /// <param name="cmdletName"></param>
        /// <param name="paramName"></param>
        /// <param name="paramValue"></param>
        /// <param name="bindableParameters"></param>
        /// <param name="bindableAlias"></param>
        /// <param name="result"></param>
        /// <param name="parametersToRemove"></param>
        private void GetDefaultParameterValuePairsHelper(
            string cmdletName, string paramName, object paramValue,
            IDictionary<string, MergedCompiledCommandParameter> bindableParameters,
            IDictionary<string, MergedCompiledCommandParameter> bindableAlias,
            Dictionary<MergedCompiledCommandParameter, object> result,
            HashSet<MergedCompiledCommandParameter> parametersToRemove)
        {
            // No exception should be thrown if we cannot find a match for the 'paramName',
            // because the 'paramName' could be a dynamic parameter name, and this dynamic parameter
            // hasn't been introduced at the current stage.
            bool writeWarning = false;
            MergedCompiledCommandParameter matchParameter;
            object resultObject;
            if (bindableParameters.TryGetValue(paramName, out matchParameter))
            {
                if (!result.TryGetValue(matchParameter, out resultObject))
                {
                    result.Add(matchParameter, paramValue);
                    return;
                }

                if (!paramValue.Equals(resultObject))
                {
                    writeWarning = true;
                    parametersToRemove.Add(matchParameter);
                }
            }
            else
            {
                if (bindableAlias.TryGetValue(paramName, out matchParameter))
                {
                    if (!result.TryGetValue(matchParameter, out resultObject))
                    {
                        result.Add(matchParameter, paramValue);
                        return;
                    }

                    if (!paramValue.Equals(resultObject))
                    {
                        writeWarning = true;
                        parametersToRemove.Add(matchParameter);
                    }
                }
            }

            if (writeWarning && !_warningSet.Contains(cmdletName + Separator + paramName))
            {
                _commandRuntime.WriteWarning(
                    String.Format(CultureInfo.InvariantCulture, ParameterBinderStrings.DifferentValuesAssignedToSingleParameter, paramName));
                _warningSet.Add(cmdletName + Separator + paramName);
            }
        }

        /// <summary>
        /// Verify if all arguments from the command line are bound.
        /// </summary>
        /// <param name="originalBindingException">
        /// Previous binding exceptions that possibly causes the failure
        /// </param>
        private void VerifyArgumentsProcessed(ParameterBindingException originalBindingException)
        {
            // Now verify that all the arguments that were passed in were processed.

            if (UnboundArguments.Count > 0)
            {
                ParameterBindingException bindingException;
                CommandParameterInternal parameter = UnboundArguments[0];

                // Get the argument type that was specified

                Type specifiedType = null;
                object argumentValue = parameter.ArgumentValue;
                if (argumentValue != null && argumentValue != UnboundParameter.Value)
                {
                    specifiedType = argumentValue.GetType();
                }

                if (parameter.ParameterNameSpecified)
                {
                    bindingException =
                        new ParameterBindingException(
                            ErrorCategory.InvalidArgument,
                            this.Command.MyInvocation,
                            GetParameterErrorExtent(parameter),
                            parameter.ParameterName,
                            null,
                            specifiedType,
                            ParameterBinderStrings.NamedParameterNotFound,
                            "NamedParameterNotFound");
                }
                else
                {
                    // If this was a positional parameter, and we have the original exception,
                    // report on the original error
                    if (originalBindingException != null)
                    {
                        bindingException = originalBindingException;
                    }
                    // Otherwise, give a generic error.
                    else
                    {
                        string argument = StringLiterals.DollarNull;
                        if (parameter.ArgumentValue != null)
                        {
                            try
                            {
                                argument = parameter.ArgumentValue.ToString();
                            }
                            catch (Exception e)
                            {
                                bindingException =
                                    new ParameterBindingArgumentTransformationException(
                                        e,
                                        ErrorCategory.InvalidData,
                                        this.InvocationInfo,
                                        null,
                                        null,
                                        null,
                                        parameter.ArgumentValue.GetType(),
                                        ParameterBinderStrings.ParameterArgumentTransformationErrorMessageOnly,
                                        "ParameterArgumentTransformationErrorMessageOnly",
                                        e.Message);

                                if (!DefaultParameterBindingInUse)
                                {
                                    throw bindingException;
                                }
                                else
                                {
                                    ThrowElaboratedBindingException(bindingException);
                                }
                            }
                        }

                        bindingException =
                            new ParameterBindingException(
                                ErrorCategory.InvalidArgument,
                                this.Command.MyInvocation,
                                null,
                                argument,
                                null,
                                specifiedType,
                                ParameterBinderStrings.PositionalParameterNotFound,
                                "PositionalParameterNotFound");
                    }
                }
                if (!DefaultParameterBindingInUse)
                {
                    throw bindingException;
                }
                else
                {
                    ThrowElaboratedBindingException(bindingException);
                }
            }
        }

        /// <summary>
        /// Verifies that a single parameter set is selected and throws an exception if
        /// one of there are multiple and one of them is not the default parameter set.
        /// </summary>
        private void VerifyParameterSetSelected()
        {
            // Now verify that a parameter set has been selected if any parameter sets
            // were defined.

            if (this.BindableParameters.ParameterSetCount > 1)
            {
                if (_currentParameterSetFlag == uint.MaxValue)
                {
                    if ((_currentParameterSetFlag &
                         _commandMetadata.DefaultParameterSetFlag) != 0 &&
                         _commandMetadata.DefaultParameterSetFlag != uint.MaxValue)
                    {
                        ParameterBinderBase.bindingTracer.WriteLine(
                            "{0} valid parameter sets, using the DEFAULT PARAMETER SET: [{0}]",
                            this.BindableParameters.ParameterSetCount,
                            _commandMetadata.DefaultParameterSetName);

                        _currentParameterSetFlag =
                            _commandMetadata.DefaultParameterSetFlag;
                    }
                    else
                    {
                        ParameterBinderBase.bindingTracer.TraceError(
                            "ERROR: {0} valid parameter sets, but NOT DEFAULT PARAMETER SET.",
                            this.BindableParameters.ParameterSetCount);

                        // Throw an exception for ambiguous parameter set
                        ThrowAmbiguousParameterSetException(_currentParameterSetFlag, BindableParameters);
                    }
                }
            }
        }

        /// <summary>
        /// Restores the specified parameter to the original value.
        /// </summary>
        /// <param name="argumentToBind">
        /// The argument containing the value to restore.
        /// </param>