File: System\Data\Metadata\CacheForPrimitiveTypes.cs
Project: ndp\fx\src\DataEntity\System.Data.Entity.csproj (System.Data.Entity)
//---------------------------------------------------------------------
// <copyright file="CacheForPrimitiveTypes.cs" company="Microsoft">
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
//
// @owner       Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
 
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Data.EntityModel;
using System.Diagnostics;
using System.Text;
using System.Xml.Serialization;
using System.Xml;
using System.Xml.Schema;
using System.IO;
using System.Data.Common;
using System.Globalization;
 
namespace System.Data.Metadata.Edm
{
    internal class CacheForPrimitiveTypes
    {
        #region Fields
        // The primitive type kind is a list of enum which the EDM model 
        // Every specific instantiation of the model should map their 
        // primitive types to the edm primitive types.
 
        // In this class, primitive type is to be cached
 
        // Key for the cache: primitive type kind
        // Value for the cache: List<PrimitiveType>.  A list is used because there an be multiple types mapping to the
        // same primitive type kind.  For example, sqlserver has multiple string types.
 
        private List<PrimitiveType>[] _primitiveTypeMap = new List<PrimitiveType>[EdmConstants.NumPrimitiveTypes];
        #endregion
 
        #region Methods
        /// <summary>
        /// Add the given primitive type to the primitive type cache
        /// </summary>
        /// <param name="type">The primitive type to add</param>
        internal void Add(PrimitiveType type)
        {
            // Get to the list
            List<PrimitiveType> primitiveTypes = EntityUtil.CheckArgumentOutOfRange(_primitiveTypeMap, (int)type.PrimitiveTypeKind, "primitiveTypeKind");
 
            // If there isn't a list for the given model type, create one and add it
            if (primitiveTypes == null)
            {
                primitiveTypes = new List<PrimitiveType>();
                primitiveTypes.Add(type);
                _primitiveTypeMap[(int)type.PrimitiveTypeKind] = primitiveTypes;
            }
            else
            {
                primitiveTypes.Add(type);
            }
        }
 
        /// <summary>
        /// Try and get the mapped type for the given primitiveTypeKind in the given dataspace
        /// </summary>
        /// <param name="primitiveTypeKind">The primitive type kind of the primitive type to retrieve</param>
        /// <param name="facets">The facets to use in picking the primitive type</param>
        /// <param name="type">The resulting type</param>
        /// <returns>Whether a type was retrieved or not</returns>
        internal bool TryGetType(PrimitiveTypeKind primitiveTypeKind, IEnumerable<Facet> facets, out PrimitiveType type)
        {
            type = null;
 
            // Now, see if we have any types for this model type, if so, loop through to find the best matching one
            List<PrimitiveType> primitiveTypes = EntityUtil.CheckArgumentOutOfRange(_primitiveTypeMap, (int)primitiveTypeKind, "primitiveTypeKind");
            if ((null != primitiveTypes) && (0 < primitiveTypes.Count))
            {
                if (primitiveTypes.Count == 1)
                {
                    type = primitiveTypes[0];
                    return true;
                }
 
                if (facets == null)
                {
                    FacetDescription[] facetDescriptions = EdmProviderManifest.GetInitialFacetDescriptions(primitiveTypeKind);
                    if (facetDescriptions == null)
                    {
                        type = primitiveTypes[0];
                        return true;
                    }
 
                    Debug.Assert(facetDescriptions.Length > 0);
                    facets = CacheForPrimitiveTypes.CreateInitialFacets(facetDescriptions);
                }
 
                Debug.Assert(type == null, "type must be null here");
                bool isMaxLengthSentinel = false;
 
                // Create a dictionary of facets for easy lookup
                foreach (Facet facet in facets)
                {
                    if ((primitiveTypeKind == PrimitiveTypeKind.String ||
                         primitiveTypeKind == PrimitiveTypeKind.Binary) &&
                        facet.Value != null &&
                        facet.Name == EdmProviderManifest.MaxLengthFacetName &&
                        Helper.IsUnboundedFacetValue(facet))
                    {
                        // MaxLength has the sentinel value. So this facet need not be added.
                        isMaxLengthSentinel = true;
                        continue;
                    }
                }
 
                int maxLength = 0;
                // Find a primitive type with the matching constraint
                foreach (PrimitiveType primitiveType in primitiveTypes)
                {
                    if (isMaxLengthSentinel)
                    {
                        if (type == null)
                        {
                            type = primitiveType;
                            maxLength = Helper.GetFacet(primitiveType.FacetDescriptions, EdmProviderManifest.MaxLengthFacetName).MaxValue.Value;
                        }
                        else
                        {
                            int newMaxLength = Helper.GetFacet(primitiveType.FacetDescriptions, EdmProviderManifest.MaxLengthFacetName).MaxValue.Value;
                            if (newMaxLength > maxLength)
                            {
                                type = primitiveType;
                                maxLength = newMaxLength;
                            }
                        }
                    }
                    else
                    {
                        type = primitiveType;
                        break;
                    }
                }
 
                Debug.Assert(type != null);
                return true;
            }
 
            return false;
        }
 
        private static Facet[] CreateInitialFacets(FacetDescription[] facetDescriptions)
        {
            Debug.Assert(facetDescriptions != null && facetDescriptions.Length > 0);
 
            Facet[] facets = new Facet[facetDescriptions.Length];
 
            for (int i = 0; i < facetDescriptions.Length; ++i)
            {
                switch (facetDescriptions[i].FacetName)
                {
                    case DbProviderManifest.MaxLengthFacetName:
                        facets[i] = Facet.Create(facetDescriptions[i], TypeUsage.DefaultMaxLengthFacetValue);
                        break;
 
                    case DbProviderManifest.UnicodeFacetName:
                        facets[i] = Facet.Create(facetDescriptions[i], TypeUsage.DefaultUnicodeFacetValue);
                        break;
 
                    case DbProviderManifest.FixedLengthFacetName:
                        facets[i] = Facet.Create(facetDescriptions[i], TypeUsage.DefaultFixedLengthFacetValue);
                        break;
 
                    case DbProviderManifest.PrecisionFacetName:
                        facets[i] = Facet.Create(facetDescriptions[i], TypeUsage.DefaultPrecisionFacetValue);
                        break;
 
                    case DbProviderManifest.ScaleFacetName:
                        facets[i] = Facet.Create(facetDescriptions[i], TypeUsage.DefaultScaleFacetValue);
                        break;
 
                    default:
                        Debug.Assert(false, "Unexpected facet");
                        break;
                }
            }
 
            return facets;
        }
 
        /// <summary>
        /// Get the list of the primitive types for the given dataspace
        /// </summary>
        /// <returns></returns>
        internal System.Collections.ObjectModel.ReadOnlyCollection<PrimitiveType> GetTypes()
        {
            List<PrimitiveType> primitiveTypes = new List<PrimitiveType>();
            foreach (List<PrimitiveType> types in _primitiveTypeMap)
            {
                if (null != types)
                {
                    primitiveTypes.AddRange(types);
                }
            }
            return primitiveTypes.AsReadOnly();
        }
        #endregion
    }
}