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// Licensed under the MIT License.
using System.Collections;
using System.Collections.Generic;
using System.Management.Automation.Internal;
namespace System.Management.Automation
{
/// <summary>
/// Implements the help provider for alias help.
/// </summary>
/// <remarks>
/// Unlike other help providers, AliasHelpProvider directly inherits from HelpProvider
/// instead of HelpProviderWithCache. This is because alias can be created/removed/updated
/// in a Microsoft Command Shell session. And thus caching may result in old alias being cached.
///
/// The real information for alias is stored in command help. To retrieve the real
/// help information, help forwarding is needed.
/// </remarks>
internal class AliasHelpProvider : HelpProvider
{
/// <summary>
/// Initializes a new instance of AliasHelpProvider class.
/// </summary>
internal AliasHelpProvider(HelpSystem helpSystem) : base(helpSystem)
{
_sessionState = helpSystem.ExecutionContext.SessionState;
_commandDiscovery = helpSystem.ExecutionContext.CommandDiscovery;
_context = helpSystem.ExecutionContext;
}
private readonly ExecutionContext _context;
/// <summary>
/// Session state for current Microsoft Command Shell session.
/// </summary>
/// <remarks>
/// _sessionState is mainly used for alias help search in the case
/// of wildcard search patterns. This is currently not achievable
/// through _commandDiscovery.
/// </remarks>
private readonly SessionState _sessionState;
/// <summary>
/// Command Discovery object for current session.
/// </summary>
/// <remarks>
/// _commandDiscovery is mainly used for exact match help for alias.
/// The AliasInfo object returned from _commandDiscovery is essential
/// in creating AliasHelpInfo.
/// </remarks>
private readonly CommandDiscovery _commandDiscovery;
#region Common Properties
/// <summary>
/// Name of alias help provider.
/// </summary>
/// <value>Name of alias help provider</value>
internal override string Name
{
get
{
return "Alias Help Provider";
}
}
/// <summary>
/// Help category of alias help provider, which is a constant: HelpCategory.Alias.
/// </summary>
/// <value>Help category of alias help provider.</value>
internal override HelpCategory HelpCategory
{
get
{
return HelpCategory.Alias;
}
}
#endregion
#region Help Provider Interface
/// <summary>
/// Exact match an alias help target.
/// </summary>
/// <remarks>
/// This will
/// a. use _commandDiscovery object to retrieve AliasInfo object.
/// b. Create AliasHelpInfo object based on AliasInfo object
/// </remarks>
/// <param name="helpRequest">Help request object.</param>
/// <returns>Help info found.</returns>
internal override IEnumerable<HelpInfo> ExactMatchHelp(HelpRequest helpRequest)
{
CommandInfo commandInfo = null;
try
{
commandInfo = _commandDiscovery.LookupCommandInfo(helpRequest.Target);
}
catch (CommandNotFoundException)
{
// CommandNotFoundException is expected here if target doesn't match any
// commandlet. Just ignore this exception and bail out.
}
if ((commandInfo != null) && (commandInfo.CommandType == CommandTypes.Alias))
{
AliasInfo aliasInfo = (AliasInfo)commandInfo;
HelpInfo helpInfo = AliasHelpInfo.GetHelpInfo(aliasInfo);
if (helpInfo != null)
{
yield return helpInfo;
}
}
}
/// <summary>
/// Search an alias help target.
/// </summary>
/// <remarks>
/// This will,
/// a. use _sessionState object to get a list of alias that match the target.
/// b. for each alias, retrieve help info as in ExactMatchHelp.
/// </remarks>
/// <param name="helpRequest">Help request object.</param>
/// <param name="searchOnlyContent">
/// If true, searches for pattern in the help content. Individual
/// provider can decide which content to search in.
///
/// If false, searches for pattern in the command names.
/// </param>
/// <returns>A IEnumerable of helpinfo object.</returns>
internal override IEnumerable<HelpInfo> SearchHelp(HelpRequest helpRequest, bool searchOnlyContent)
{
// aliases do not have help content...so doing nothing in that case
if (!searchOnlyContent)
{
string target = helpRequest.Target;
string pattern = target;
var allAliases = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
if (!WildcardPattern.ContainsWildcardCharacters(target))
{
pattern += "*";
}
WildcardPattern matcher = WildcardPattern.Get(pattern, WildcardOptions.IgnoreCase);
IDictionary<string, AliasInfo> aliasTable = _sessionState.Internal.GetAliasTable();
foreach (string name in aliasTable.Keys)
{
if (matcher.IsMatch(name))
{
HelpRequest exactMatchHelpRequest = helpRequest.Clone();
exactMatchHelpRequest.Target = name;
// Duplicates??
foreach (HelpInfo helpInfo in ExactMatchHelp(exactMatchHelpRequest))
{
// Component/Role/Functionality match is done only for SearchHelp
// as "get-help * -category alias" should not forward help to
// CommandHelpProvider..(ExactMatchHelp does forward help to
// CommandHelpProvider)
if (!Match(helpInfo, helpRequest))
{
continue;
}
if (allAliases.Contains(name))
{
continue;
}
allAliases.Add(name);
yield return helpInfo;
}
}
}
CommandSearcher searcher =
new CommandSearcher(
pattern,
SearchResolutionOptions.ResolveAliasPatterns, CommandTypes.Alias,
_context);
while (searcher.MoveNext())
{
CommandInfo current = ((IEnumerator<CommandInfo>)searcher).Current;
if (_context.CurrentPipelineStopping)
{
yield break;
}
AliasInfo alias = current as AliasInfo;
if (alias != null)
{
string name = alias.Name;
HelpRequest exactMatchHelpRequest = helpRequest.Clone();
exactMatchHelpRequest.Target = name;
// Duplicates??
foreach (HelpInfo helpInfo in ExactMatchHelp(exactMatchHelpRequest))
{
// Component/Role/Functionality match is done only for SearchHelp
// as "get-help * -category alias" should not forward help to
// CommandHelpProvider..(ExactMatchHelp does forward help to
// CommandHelpProvider)
if (!Match(helpInfo, helpRequest))
{
continue;
}
if (allAliases.Contains(name))
{
continue;
}
allAliases.Add(name);
yield return helpInfo;
}
}
}
foreach (CommandInfo current in ModuleUtils.GetMatchingCommands(pattern, _context, helpRequest.CommandOrigin))
{
if (_context.CurrentPipelineStopping)
{
yield break;
}
AliasInfo alias = current as AliasInfo;
if (alias != null)
{
string name = alias.Name;
HelpInfo helpInfo = AliasHelpInfo.GetHelpInfo(alias);
if (allAliases.Contains(name))
{
continue;
}
allAliases.Add(name);
yield return helpInfo;
}
}
}
}
private static bool Match(HelpInfo helpInfo, HelpRequest helpRequest)
{
if (helpRequest == null)
return true;
if ((helpRequest.HelpCategory & helpInfo.HelpCategory) == 0)
{
return false;
}
if (!Match(helpInfo.Component, helpRequest.Component))
{
return false;
}
if (!Match(helpInfo.Role, helpRequest.Role))
{
return false;
}
if (!Match(helpInfo.Functionality, helpRequest.Functionality))
{
return false;
}
return true;
}
private static bool Match(string target, string[] patterns)
{
// patterns should never be null as shell never accepts
// empty inputs. Keeping this check as a safe measure.
if (patterns == null || patterns.Length == 0)
return true;
foreach (string pattern in patterns)
{
if (Match(target, pattern))
{
// we have a match so return true
return true;
}
}
// We dont have a match so far..so return false
return false;
}
private static bool Match(string target, string pattern)
{
if (string.IsNullOrEmpty(pattern))
return true;
if (string.IsNullOrEmpty(target))
target = string.Empty;
WildcardPattern matcher = WildcardPattern.Get(pattern, WildcardOptions.IgnoreCase);
return matcher.IsMatch(target);
}
#endregion
}
}
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