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//---------------------------------------------------------------------
// <copyright file="UniqueIdentifierService.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner [....]
// @backupOwner [....]
//---------------------------------------------------------------------
using System.Diagnostics;
using System.Collections.Generic;
using System.Globalization;
namespace System.Data.Entity.Design.Common
{
/// <summary>
/// Service making names within a scope unique. Initialize a new instance
/// for every scope.
///
///
internal sealed class UniqueIdentifierService
{
internal UniqueIdentifierService(bool caseSensitive)
{
_knownIdentifiers = new Dictionary<string, bool>(caseSensitive ? StringComparer.Ordinal : StringComparer.OrdinalIgnoreCase);
_identifierToAdjustedIdentifier = new Dictionary<object, string>();
_transform = s => s;
}
internal UniqueIdentifierService(bool caseSensitive, Func<string, string> transform)
{
Debug.Assert(transform != null, "use the other constructor if you don't want any transform");
_knownIdentifiers = new Dictionary<string, bool>(caseSensitive ? StringComparer.Ordinal : StringComparer.OrdinalIgnoreCase);
_identifierToAdjustedIdentifier = new Dictionary<object, string>();
_transform = transform;
}
private readonly Dictionary<string, bool> _knownIdentifiers;
private readonly Dictionary<object, string> _identifierToAdjustedIdentifier;
private readonly Func<string, string> _transform;
/// <summary>
/// This method can be used in when you have an
/// identifier that you know can't be used, but you don't want
/// an adjusted version of it
/// </summary>
/// <param name="identifier"></param>
internal void RegisterUsedIdentifier(string identifier)
{
Debug.Assert(!_knownIdentifiers.ContainsKey(identifier), "don't register identifiers that already exist");
_knownIdentifiers.Add(identifier, true);
}
/// <summary>
/// Given an identifier, makes it unique within the scope by adding
/// a suffix (1, 2, 3, ...), and returns the adjusted identifier.
/// </summary>
/// <param name="identifier">Identifier. Must not be null or empty.</param>
/// <param name="value">Object associated with this identifier in case it is required to
/// retrieve the adjusted identifier. If not null, must not exist in the current scope already.</param>
/// <returns>Identifier adjusted to be unique within the scope.</returns>
internal string AdjustIdentifier(string identifier, object value)
{
Debug.Assert(!string.IsNullOrEmpty(identifier), "identifier is null or empty");
// find a unique name by adding suffix as necessary
int numberOfConflicts = 0;
string adjustedIdentifier = _transform(identifier);
while (_knownIdentifiers.ContainsKey(adjustedIdentifier))
{
++numberOfConflicts;
adjustedIdentifier = _transform(identifier) + numberOfConflicts.ToString(CultureInfo.InvariantCulture);
}
// remember the identifier in this scope
Debug.Assert(!_knownIdentifiers.ContainsKey(adjustedIdentifier), "we just made it unique");
_knownIdentifiers.Add(adjustedIdentifier, true);
if (null != value)
{
Debug.Assert(!_identifierToAdjustedIdentifier.ContainsKey(value), "should never register one value twice");
_identifierToAdjustedIdentifier.Add(value, adjustedIdentifier);
}
return adjustedIdentifier;
}
/// <summary>
/// Simple overload when you don't need to track back to an object
/// </summary>
/// <param name="identifier"></param>
/// <returns></returns>
internal string AdjustIdentifier(string identifier)
{
return AdjustIdentifier(identifier, null);
}
/// <summary>
/// Determines the adjusted name for an identifier if it has been registered in this scope.
/// </summary>
internal bool TryGetAdjustedName(object value, out string adjustedIdentifier)
{
return _identifierToAdjustedIdentifier.TryGetValue(value, out adjustedIdentifier);
}
}
}
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