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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.CodeDom;
using System.Collections;
using System.Globalization;
using System.Reflection;
namespace System.ComponentModel.Design.Serialization;
/// <summary>
/// This serializer serializes collections. This can either create statements or expressions.
/// It will create an expression and assign it to the statement in the current context stack if the object is an array.
/// If it is a collection with an add range or similar method, it will create a statement calling the method.
/// </summary>
public class CollectionCodeDomSerializer : CodeDomSerializer
{
private static CollectionCodeDomSerializer? s_defaultSerializer;
/// <summary>
/// Retrieves a default static instance of this serializer.
/// </summary>
internal static new CollectionCodeDomSerializer Default => s_defaultSerializer ??= new CollectionCodeDomSerializer();
/// <summary>
/// Computes the delta between an existing collection and a modified one.
/// This is for the case of inherited items that have collection properties so we only
/// generate Add/AddRange calls for the items that have been added.
/// It works by Hashing up the items in the original collection and then walking the modified collection
/// and only returning those items which do not exist in the base collection.
/// </summary>
[return: NotNullIfNotNull(nameof(modified))]
private static ICollection? GetCollectionDelta(ICollection? original, ICollection? modified)
{
if (original is null || modified is null || original.Count == 0)
{
return modified;
}
IEnumerator modifiedEnum = modified.GetEnumerator();
if (modifiedEnum is null)
{
Debug.Fail($"Collection of type {modified.GetType().FullName} doesn't return an enumerator");
return modified;
}
// first hash up the values so we can quickly decide if it's a new one or not
Dictionary<object, int> originalValues = [];
foreach (object originalValue in original)
{
// the array could contain multiple copies of the same value (think of a string collection), so we need to be sensitive of that.
if (originalValues.TryGetValue(originalValue, out int count))
{
originalValues[originalValue] = count + 1;
}
else
{
originalValues.Add(originalValue, 1);
}
}
// now walk through and delete existing values
List<object>? result = null;
// now compute the delta.
for (int i = 0; i < modified.Count && modifiedEnum.MoveNext(); i++)
{
object value = modifiedEnum.Current!;
if (originalValues.TryGetValue(value, out int count))
{
// we've got one we need to remove, so create our array list, and push all the values we've passed into it.
if (result is null)
{
result = [];
modifiedEnum.Reset();
for (int n = 0; n < i && modifiedEnum.MoveNext(); n++)
{
result.Add(modifiedEnum.Current!);
}
// and finally skip the one we're on
modifiedEnum.MoveNext();
}
// decrement the count if we've got more than one...
if (--count == 0)
{
originalValues.Remove(value);
}
else
{
originalValues[value] = count;
}
}
else // this one isn't in the old list, so add it to our result list.
{
result?.Add(value);
}
// this item isn't in the list and we haven't yet created our array list so just keep on going.
}
return result ?? modified;
}
/// <summary>
/// Checks the attributes on this method to see if they support serialization.
/// </summary>
protected bool MethodSupportsSerialization(MethodInfo method)
{
ArgumentNullException.ThrowIfNull(method);
object[] attributes = method.GetCustomAttributes(typeof(DesignerSerializationVisibilityAttribute), true);
if (attributes.Length > 0)
{
DesignerSerializationVisibilityAttribute visibility = (DesignerSerializationVisibilityAttribute)attributes[0];
if (visibility is { Visibility: DesignerSerializationVisibility.Hidden })
{
return false;
}
}
return true;
}
/// <summary>
/// Serializes the given object into a CodeDom object.
/// </summary>
public override object? Serialize(IDesignerSerializationManager manager, object value)
{
ArgumentNullException.ThrowIfNull(manager);
ArgumentNullException.ThrowIfNull(value);
object? result = null;
// We serialize collections as follows:
// If the collection is an array, we write out the array.
// If the collection has a method called AddRange, we will call that, providing an array.
// If the collection has an Add method, we will call it repeatedly.
// If the collection is an IList, we will cast to IList and add to it.
// If the collection has no add method, but is marked with PersistContents,
// we will enumerate the collection and serialize each element.
// Check to see if there is a CodePropertyReferenceExpression on the stack.
// If there is, we can use it as a guide for serialization.
CodeExpression? target;
if (manager.TryGetContext(out ExpressionContext? context) && context.PresetValue == value &&
manager.TryGetContext(out PropertyDescriptor? property) && property.PropertyType == context.ExpressionType)
{
// We only want to give out an expression target if this is our context
// (we find this out by comparing types above) and if the context type is not an array. If it is an array,
// we will just return the array create expression.
target = context.Expression;
}
else
{
// This context is either the wrong context or doesn't match the property descriptor we found.
target = null;
context = null;
property = null;
}
// If we have a target expression see if we can create a delta for the collection. We want to do this only if the
// property the collection is associated with is inherited, and if the collection is not an array.
if (value is ICollection collection)
{
ICollection subset = collection;
Type collectionType = context?.ExpressionType ?? collection.GetType();
bool isArray = typeof(Array).IsAssignableFrom(collectionType);
// If we don't have a target expression and this isn't an array, let's try to create one.
if (target is null && !isArray)
{
target = SerializeCreationExpression(manager, collection, out bool isComplete);
if (isComplete)
{
return target;
}
}
if (target is not null || isArray)
{
if (property is InheritedPropertyDescriptor inheritedDesc && !isArray)
{
subset = GetCollectionDelta(inheritedDesc.OriginalValue as ICollection, collection);
}
result = SerializeCollection(manager, target, collectionType, collection, subset);
// See if we should emit a clear for this collection.
if (target is not null && ShouldClearCollection(manager, collection))
{
CodeStatementCollection? resultCollection = result as CodeStatementCollection;
// If non empty collection is being serialized, but no statements were generated, there is no need to clear.
if (collection.Count > 0 && (result is null || (resultCollection is not null && resultCollection.Count == 0)))
{
return null;
}
if (resultCollection is null)
{
resultCollection = [];
if (result is CodeStatement resultStatement)
{
resultCollection.Add(resultStatement);
}
result = resultCollection;
}
CodeMethodInvokeExpression clearMethod = new(target, "Clear");
CodeExpressionStatement clearStatement = new(clearMethod);
resultCollection.Insert(0, clearStatement);
}
}
}
else
{
Debug.Fail($"Collection serializer invoked for non-collection: {(value is null ? "(null)" : value.GetType().Name)}");
}
return result;
}
/// <summary>
/// Given a set of methods and objects, determines the method with the correct of parameter type for all objects.
/// </summary>
private static MethodInfo? ChooseMethodByType(TypeDescriptionProvider provider, List<MethodInfo> methods, ICollection values)
{
// Note that this method uses reflection types which may not be compatible with runtime types. objType must be
// obtained from the same provider as the methods were to ensure that the reflection types all belong to the
// same type universe.
MethodInfo? final = null;
Type? finalType = null;
foreach (object obj in values)
{
Type objType = provider.GetReflectionType(obj);
MethodInfo? candidate = null;
Type? candidateType = null;
if (final is null || (finalType is not null && !finalType.IsAssignableFrom(objType)))
{
foreach (MethodInfo method in methods)
{
ParameterInfo parameter = method.GetParameters()[0];
if (parameter is not null)
{
Type type = parameter.ParameterType;
if (type.IsArray)
{
type = type.GetElementType()!;
}
if (type.IsAssignableFrom(objType))
{
if (final is not null)
{
if (type.IsAssignableFrom(finalType))
{
final = method;
finalType = type;
break;
}
}
else if (candidate is null)
{
candidate = method;
candidateType = type;
}
else
{
// we found another method. Pick the one that uses the most derived type.
Debug.Assert(candidateType!.IsAssignableFrom(type) || type.IsAssignableFrom(candidateType), "These two types are not related. how were they chosen based on the base type");
bool assignable = candidateType.IsAssignableFrom(type);
candidate = assignable ? method : candidate;
candidateType = assignable ? type : candidateType;
}
}
}
}
}
if (final is null)
{
final = candidate;
finalType = candidateType;
}
}
return final;
}
/// <summary>
/// Serializes the given collection. targetExpression will refer to the expression used
/// to refer to the collection, but it can be null.
/// </summary>
protected virtual object? SerializeCollection(IDesignerSerializationManager manager, CodeExpression? targetExpression, Type targetType, ICollection originalCollection, ICollection valuesToSerialize)
{
ArgumentNullException.ThrowIfNull(manager);
ArgumentNullException.ThrowIfNull(targetType);
ArgumentNullException.ThrowIfNull(originalCollection);
ArgumentNullException.ThrowIfNull(valuesToSerialize);
object? result = null;
bool serialized = false;
if (typeof(Array).IsAssignableFrom(targetType))
{
CodeArrayCreateExpression? arrayCreate = SerializeArray(manager, targetType, (Array)originalCollection, valuesToSerialize);
if (arrayCreate is not null)
{
if (targetExpression is not null)
{
result = new CodeAssignStatement(targetExpression, arrayCreate);
}
else
{
result = arrayCreate;
}
}
}
else if (valuesToSerialize.Count > 0)
{
// Use the TargetFrameworkProviderService to create a provider, or use the default for the collection if the
// service is not available. Since TargetFrameworkProvider reflection types are not compatible with RuntimeTypes,
// they can only be used with other reflection types from the same provider.
TypeDescriptionProvider? provider = GetTargetFrameworkProvider(manager, originalCollection);
provider ??= TypeDescriptor.GetProvider(originalCollection);
MethodInfo[] methods = provider.GetReflectionType(originalCollection).GetMethods(BindingFlags.Public | BindingFlags.Instance);
List<MethodInfo> addRangeMethods = [];
List<MethodInfo> addMethods = [];
foreach (MethodInfo method in methods)
{
switch (method.Name)
{
case "AddRange":
ParameterInfo[] parameters = method.GetParameters();
if (parameters is [{ ParameterType.IsArray: true }] && MethodSupportsSerialization(method))
{
addRangeMethods.Add(method);
}
break;
case "Add":
if (method.GetParameters().Length == 1 && MethodSupportsSerialization(method))
{
addMethods.Add(method);
}
break;
}
}
MethodInfo? addRangeMethodToUse = ChooseMethodByType(provider, addRangeMethods, valuesToSerialize);
if (addRangeMethodToUse is not null)
{
Type elementType = provider.GetRuntimeType(addRangeMethodToUse.GetParameters()[0].ParameterType.GetElementType()!);
result = SerializeViaAddRange(manager, targetExpression, elementType, valuesToSerialize);
serialized = true;
}
else
{
MethodInfo? addMethodToUse = ChooseMethodByType(provider, addMethods, valuesToSerialize);
if (addMethodToUse is not null)
{
Type elementType = provider.GetRuntimeType(addMethodToUse.GetParameters()[0].ParameterType);
result = SerializeViaAdd(manager, targetExpression, elementType, valuesToSerialize);
serialized = true;
}
}
#pragma warning disable SYSLIB0050 // Type or member is obsolete
if (!serialized && originalCollection.GetType().IsSerializable)
{
result = SerializeToResourceExpression(manager, originalCollection, false);
}
#pragma warning restore SYSLIB0050
}
return result;
}
/// <summary>
/// Serializes the given array.
/// </summary>
private CodeArrayCreateExpression? SerializeArray(IDesignerSerializationManager manager, Type targetType, Array array, ICollection valuesToSerialize)
{
CodeArrayCreateExpression? result = null;
if (array.Rank != 1)
{
manager.ReportError(string.Format(SR.SerializerInvalidArrayRank, array.Rank.ToString(CultureInfo.InvariantCulture)));
}
else
{
// For an array, we need an array create expression. First, get the array type
Type elementType = targetType.GetElementType()!;
CodeTypeReference elementTypeRef = new(elementType);
// Now create an ArrayCreateExpression, and fill its initializers.
CodeArrayCreateExpression arrayCreate = new CodeArrayCreateExpression
{
CreateType = elementTypeRef
};
bool arrayOk = true;
foreach (object o in valuesToSerialize)
{
// If this object is being privately inherited, it cannot be inside this collection.
// Since we're writing an entire array here, we cannot write any of it.
if (o is IComponent && TypeDescriptor.GetAttributes(o).Contains(InheritanceAttribute.InheritedReadOnly))
{
arrayOk = false;
break;
}
CodeExpression? expression = null;
// If there is an expression context on the stack at this point, we need to fix up the ExpressionType
// on it to be the array element type.
ExpressionContext? newContext = null;
if (manager.TryGetContext(out ExpressionContext? context))
{
newContext = new ExpressionContext(context.Expression, elementType, context.Owner);
manager.Context.Push(newContext);
}
try
{
expression = SerializeToExpression(manager, o);
}
finally
{
if (newContext is not null)
{
Debug.Assert(manager.Context.Current == newContext, "Context stack corrupted.");
manager.Context.Pop();
}
}
if (expression is not null)
{
if (o is not null && o.GetType() != elementType)
{
expression = new CodeCastExpression(elementType, expression);
}
arrayCreate.Initializers.Add(expression);
}
else
{
arrayOk = false;
break;
}
}
if (arrayOk)
{
result = arrayCreate;
}
}
return result;
}
/// <summary>
/// Serializes the given collection by creating multiple calls to an Add method.
/// </summary>
private CodeStatementCollection SerializeViaAdd(
IDesignerSerializationManager manager,
CodeExpression? targetExpression,
Type elementType,
ICollection valuesToSerialize)
{
CodeStatementCollection statements = [];
// Here we need to invoke Add once for each and every item in the collection. We can re-use the property
// reference and method reference, but we will need to recreate the invoke statement each time.
CodeMethodReferenceExpression methodRef = new(targetExpression!, "Add");
if (valuesToSerialize.Count == 0)
{
return statements;
}
foreach (object o in valuesToSerialize)
{
// If this object is being privately inherited, it cannot be inside this collection.
bool genCode = o is not IComponent;
if (!genCode)
{
if (TypeDescriptorHelper.TryGetAttribute(o, out InheritanceAttribute? ia))
{
genCode = ia.InheritanceLevel != InheritanceLevel.InheritedReadOnly;
}
else
{
genCode = true;
}
}
Debug.Assert(genCode, "Why didn't GetCollectionDelta calculate the same thing?");
if (genCode)
{
CodeMethodInvokeExpression statement = new CodeMethodInvokeExpression
{
Method = methodRef
};
CodeExpression? serializedObject = null;
// If there is an expression context on the stack at this point,
// we need to fix up the ExpressionType on it to be the element type.
ExpressionContext? newCtx = null;
if (manager.TryGetContext(out ExpressionContext? ctx))
{
newCtx = new ExpressionContext(ctx.Expression, elementType, ctx.Owner);
manager.Context.Push(newCtx);
}
try
{
serializedObject = SerializeToExpression(manager, o);
}
finally
{
if (newCtx is not null)
{
Debug.Assert(manager.Context.Current == newCtx, "Context stack corrupted.");
manager.Context.Pop();
}
}
if (o is not null && !elementType.IsAssignableFrom(o.GetType()) && o.GetType().IsPrimitive)
{
serializedObject = new CodeCastExpression(elementType, serializedObject!);
}
if (serializedObject is not null)
{
statement.Parameters.Add(serializedObject);
statements.Add(statement);
}
}
}
return statements;
}
/// <summary>
/// Serializes the given collection by creating an array and passing it to the AddRange method.
/// </summary>
private CodeStatementCollection SerializeViaAddRange(
IDesignerSerializationManager manager,
CodeExpression? targetExpression,
Type elementType,
ICollection valuesToSerialize)
{
CodeStatementCollection statements = [];
if (valuesToSerialize.Count == 0)
{
return statements;
}
List<CodeExpression> arrayList = new(valuesToSerialize.Count);
foreach (object o in valuesToSerialize)
{
// If this object is being privately inherited, it cannot be inside this collection.
bool genCode = o is not IComponent;
if (!genCode)
{
if (TypeDescriptorHelper.TryGetAttribute(o, out InheritanceAttribute? ia))
{
genCode = ia.InheritanceLevel != InheritanceLevel.InheritedReadOnly;
}
else
{
genCode = true;
}
}
Debug.Assert(genCode, "Why didn't GetCollectionDelta calculate the same thing?");
if (genCode)
{
CodeExpression? expression = null;
// If there is an expression context on the stack at this point, we need to fix up the ExpressionType
// on it to be the element type.
ExpressionContext? newContext = null;
if (manager.TryGetContext(out ExpressionContext? ctx))
{
newContext = new ExpressionContext(ctx.Expression, elementType, ctx.Owner);
manager.Context.Push(newContext);
}
try
{
expression = SerializeToExpression(manager, o);
}
finally
{
if (newContext is not null)
{
Debug.Assert(manager.Context.Current == newContext, "Context stack corrupted.");
manager.Context.Pop();
}
}
if (expression is not null)
{
// Check to see if we need a cast
if (o is not null && !elementType.IsAssignableFrom(o.GetType()))
{
expression = new CodeCastExpression(elementType, expression);
}
arrayList.Add(expression);
}
}
}
if (arrayList.Count > 0)
{
// Now convert the array list into an array create expression.
CodeTypeReference elementTypeRef = new(elementType);
// Now create an ArrayCreateExpression, and fill its initializers.
CodeArrayCreateExpression arrayCreate = new CodeArrayCreateExpression
{
CreateType = elementTypeRef
};
foreach (CodeExpression expression in arrayList)
{
arrayCreate.Initializers.Add(expression);
}
CodeMethodReferenceExpression methodRef = new(targetExpression!, "AddRange");
CodeMethodInvokeExpression methodInvoke = new CodeMethodInvokeExpression
{
Method = methodRef
};
methodInvoke.Parameters.Add(arrayCreate);
statements.Add(new CodeExpressionStatement(methodInvoke));
}
return statements;
}
/// <summary>
/// Returns true if we should clear the collection contents.
/// </summary>
private bool ShouldClearCollection(IDesignerSerializationManager manager, ICollection collection)
{
bool shouldClear = false;
PropertyDescriptor? clearProperty = manager.Properties["ClearCollections"];
if (clearProperty is not null && clearProperty.TryGetValue(manager, out bool b) && b)
{
shouldClear = true;
}
if (!shouldClear)
{
PropertyDescriptor? property = manager.GetContext<PropertyDescriptor>();
if (manager.TryGetContext(out SerializeAbsoluteContext? absolute) && absolute.ShouldSerialize(property))
{
shouldClear = true;
}
}
if (shouldClear)
{
MethodInfo? clearMethod = TypeDescriptor.GetReflectionType(collection).GetMethod("Clear", BindingFlags.Public | BindingFlags.Instance, null, [], null);
if (clearMethod is null || !MethodSupportsSerialization(clearMethod))
{
shouldClear = false;
}
}
return shouldClear;
}
}
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