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//------------------------------------------------------------------------------
// <copyright file="ConstraintEnumerator.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">[....]</owner>
// <owner current="true" primary="false">[....]</owner>
// <owner current="false" primary="false">[....]</owner>
//------------------------------------------------------------------------------
namespace System.Data {
using System;
using System.Diagnostics;
using System.Collections;
using System.ComponentModel;
/// <devdoc>
/// ConstraintEnumerator is an object for enumerating all constraints in a DataSet
/// </devdoc>
internal class ConstraintEnumerator {
System.Collections.IEnumerator tables;
System.Collections.IEnumerator constraints;
Constraint currentObject;
public ConstraintEnumerator(DataSet dataSet) {
tables = (dataSet != null) ? dataSet.Tables.GetEnumerator() : null;
currentObject = null;
}
public bool GetNext() {
Constraint candidate;
currentObject = null;
while (tables != null) {
if (constraints == null) {
if (!tables.MoveNext()) {
tables = null;
return false;
}
constraints = ((DataTable)tables.Current).Constraints.GetEnumerator();
}
if (!constraints.MoveNext()) {
constraints = null;
continue;
}
Debug.Assert(constraints.Current is Constraint, "ConstraintEnumerator, contains object which is not constraint");
candidate = (Constraint)constraints.Current;
if (IsValidCandidate(candidate)) {
currentObject = candidate;
return true;
}
}
return false;
}
public Constraint GetConstraint() {
// If currentObject is null we are before first GetNext or after last GetNext--consumer is bad
Debug.Assert (currentObject != null, "GetObject should never be called w/ null currentObject.");
return currentObject;
}
protected virtual bool IsValidCandidate(Constraint constraint) {
return true;
}
protected Constraint CurrentObject {
get {
return currentObject;
}
}
}
internal class ForeignKeyConstraintEnumerator : ConstraintEnumerator {
public ForeignKeyConstraintEnumerator(DataSet dataSet) : base(dataSet) {
}
protected override bool IsValidCandidate(Constraint constraint) {
return(constraint is ForeignKeyConstraint);
}
public ForeignKeyConstraint GetForeignKeyConstraint() {
// If CurrentObject is null we are before first GetNext or after last GetNext--consumer is bad
Debug.Assert (CurrentObject != null, "GetObject should never be called w/ null currentObject.");
return(ForeignKeyConstraint)CurrentObject;
}
}
internal sealed class ChildForeignKeyConstraintEnumerator : ForeignKeyConstraintEnumerator {
// this is the table to do comparisons against
DataTable table;
public ChildForeignKeyConstraintEnumerator(DataSet dataSet, DataTable inTable) : base(dataSet) {
this.table = inTable;
}
protected override bool IsValidCandidate(Constraint constraint) {
return((constraint is ForeignKeyConstraint) && (((ForeignKeyConstraint)constraint).Table == table));
}
}
internal sealed class ParentForeignKeyConstraintEnumerator : ForeignKeyConstraintEnumerator {
// this is the table to do comparisons against
DataTable table;
public ParentForeignKeyConstraintEnumerator(DataSet dataSet, DataTable inTable) : base(dataSet) {
this.table = inTable;
}
protected override bool IsValidCandidate(Constraint constraint) {
return((constraint is ForeignKeyConstraint) && (((ForeignKeyConstraint)constraint).RelatedTable == table));
}
}
}
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