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using System;
using System.Collections.Generic;
using System.Data.Linq;
using System.Diagnostics.CodeAnalysis;
namespace System.Data.Linq.SqlClient {
/// <summary>
/// Compare two trees for value equality. Implemented as a parallel visitor.
/// </summary>
internal class SqlComparer {
internal SqlComparer() {
}
[SuppressMessage("Microsoft.Performance", "CA1800:DoNotCastUnnecessarily", Justification = "Microsoft: Cast is dependent on node type and casts do not happen unecessarily in a single code path.")]
[SuppressMessage("Microsoft.Maintainability", "CA1506:AvoidExcessiveClassCoupling", Justification = "These issues are related to our use of if-then and case statements for node types, which adds to the complexity count however when reviewed they are easy to navigate and understand.")]
[SuppressMessage("Microsoft.Maintainability", "CA1505:AvoidUnmaintainableCode", Justification = "These issues are related to our use of if-then and case statements for node types, which adds to the complexity count however when reviewed they are easy to navigate and understand.")]
[SuppressMessage("Microsoft.Maintainability", "CA1502:AvoidExcessiveComplexity", Justification = "These issues are related to our use of if-then and case statements for node types, which adds to the complexity count however when reviewed they are easy to navigate and understand.")]
internal static bool AreEqual(SqlNode node1, SqlNode node2) {
if (node1 == node2)
return true;
if (node1 == null || node2 == null)
return false;
if (node1.NodeType == SqlNodeType.SimpleCase)
node1 = UnwrapTrivialCaseExpression((SqlSimpleCase)node1);
if (node2.NodeType == SqlNodeType.SimpleCase)
node2 = UnwrapTrivialCaseExpression((SqlSimpleCase)node2);
if (node1.NodeType != node2.NodeType) {
// allow expression sets to compare against single expressions
if (node1.NodeType == SqlNodeType.ExprSet) {
SqlExprSet eset = (SqlExprSet)node1;
for (int i = 0, n = eset.Expressions.Count; i < n; i++) {
if (AreEqual(eset.Expressions[i], node2))
return true;
}
}
else if (node2.NodeType == SqlNodeType.ExprSet) {
SqlExprSet eset = (SqlExprSet)node2;
for (int i = 0, n = eset.Expressions.Count; i < n; i++) {
if (AreEqual(node1, eset.Expressions[i]))
return true;
}
}
return false;
}
if (node1.Equals(node2))
return true;
switch (node1.NodeType) {
case SqlNodeType.Not:
case SqlNodeType.Not2V:
case SqlNodeType.Negate:
case SqlNodeType.BitNot:
case SqlNodeType.IsNull:
case SqlNodeType.IsNotNull:
case SqlNodeType.Count:
case SqlNodeType.Max:
case SqlNodeType.Min:
case SqlNodeType.Sum:
case SqlNodeType.Avg:
case SqlNodeType.Stddev:
case SqlNodeType.ValueOf:
case SqlNodeType.OuterJoinedValue:
case SqlNodeType.ClrLength:
return AreEqual(((SqlUnary)node1).Operand, ((SqlUnary)node2).Operand);
case SqlNodeType.Add:
case SqlNodeType.Sub:
case SqlNodeType.Mul:
case SqlNodeType.Div:
case SqlNodeType.Mod:
case SqlNodeType.BitAnd:
case SqlNodeType.BitOr:
case SqlNodeType.BitXor:
case SqlNodeType.And:
case SqlNodeType.Or:
case SqlNodeType.GE:
case SqlNodeType.GT:
case SqlNodeType.LE:
case SqlNodeType.LT:
case SqlNodeType.EQ:
case SqlNodeType.NE:
case SqlNodeType.EQ2V:
case SqlNodeType.NE2V:
case SqlNodeType.Concat:
SqlBinary firstNode = (SqlBinary)node1;
SqlBinary secondNode = (SqlBinary)node2;
return AreEqual(firstNode.Left, secondNode.Left)
&& AreEqual(firstNode.Right, secondNode.Right);
case SqlNodeType.Convert:
case SqlNodeType.Treat: {
SqlUnary sun1 = (SqlUnary)node1;
SqlUnary sun2 = (SqlUnary)node2;
return sun1.ClrType == sun2.ClrType && sun1.SqlType == sun2.SqlType && AreEqual(sun1.Operand, sun2.Operand);
}
case SqlNodeType.Between: {
SqlBetween b1 = (SqlBetween)node1;
SqlBetween b2 = (SqlBetween)node1;
return AreEqual(b1.Expression, b2.Expression) &&
AreEqual(b1.Start, b2.Start) &&
AreEqual(b1.End, b2.End);
}
case SqlNodeType.Parameter:
return node1 == node2;
case SqlNodeType.Alias:
return AreEqual(((SqlAlias)node1).Node, ((SqlAlias)node2).Node);
case SqlNodeType.AliasRef:
return AreEqual(((SqlAliasRef)node1).Alias, ((SqlAliasRef)node2).Alias);
case SqlNodeType.Column:
SqlColumn col1 = (SqlColumn)node1;
SqlColumn col2 = (SqlColumn)node2;
return col1 == col2 || (col1.Expression != null && col2.Expression != null && AreEqual(col1.Expression, col2.Expression));
case SqlNodeType.Table:
return ((SqlTable)node1).MetaTable == ((SqlTable)node2).MetaTable;
case SqlNodeType.Member:
return (((SqlMember)node1).Member == ((SqlMember)node2).Member) &&
AreEqual(((SqlMember)node1).Expression, ((SqlMember)node2).Expression);
case SqlNodeType.ColumnRef:
SqlColumnRef cref1 = (SqlColumnRef)node1;
SqlColumnRef cref2 = (SqlColumnRef)node2;
return GetBaseColumn(cref1) == GetBaseColumn(cref2);
case SqlNodeType.Value:
return Object.Equals(((SqlValue)node1).Value, ((SqlValue)node2).Value);
case SqlNodeType.TypeCase: {
SqlTypeCase c1 = (SqlTypeCase)node1;
SqlTypeCase c2 = (SqlTypeCase)node2;
if (!AreEqual(c1.Discriminator, c2.Discriminator)) {
return false;
}
if (c1.Whens.Count != c2.Whens.Count) {
return false;
}
for (int i = 0, c = c1.Whens.Count; i < c; ++i) {
if (!AreEqual(c1.Whens[i].Match, c2.Whens[i].Match)) {
return false;
}
if (!AreEqual(c1.Whens[i].TypeBinding, c2.Whens[i].TypeBinding)) {
return false;
}
}
return true;
}
case SqlNodeType.SearchedCase: {
SqlSearchedCase c1 = (SqlSearchedCase)node1;
SqlSearchedCase c2 = (SqlSearchedCase)node2;
if (c1.Whens.Count != c2.Whens.Count)
return false;
for (int i = 0, n = c1.Whens.Count; i < n; i++) {
if (!AreEqual(c1.Whens[i].Match, c2.Whens[i].Match) ||
!AreEqual(c1.Whens[i].Value, c2.Whens[i].Value))
return false;
}
return AreEqual(c1.Else, c2.Else);
}
case SqlNodeType.ClientCase: {
SqlClientCase c1 = (SqlClientCase)node1;
SqlClientCase c2 = (SqlClientCase)node2;
if (c1.Whens.Count != c2.Whens.Count)
return false;
for (int i = 0, n = c1.Whens.Count; i < n; i++) {
if (!AreEqual(c1.Whens[i].Match, c2.Whens[i].Match) ||
!AreEqual(c1.Whens[i].Value, c2.Whens[i].Value))
return false;
}
return true;
}
case SqlNodeType.DiscriminatedType: {
SqlDiscriminatedType dt1 = (SqlDiscriminatedType)node1;
SqlDiscriminatedType dt2 = (SqlDiscriminatedType)node2;
return AreEqual(dt1.Discriminator, dt2.Discriminator);
}
case SqlNodeType.SimpleCase: {
SqlSimpleCase c1 = (SqlSimpleCase)node1;
SqlSimpleCase c2 = (SqlSimpleCase)node2;
if (c1.Whens.Count != c2.Whens.Count)
return false;
for (int i = 0, n = c1.Whens.Count; i < n; i++) {
if (!AreEqual(c1.Whens[i].Match, c2.Whens[i].Match) ||
!AreEqual(c1.Whens[i].Value, c2.Whens[i].Value))
return false;
}
return true;
}
case SqlNodeType.Like: {
SqlLike like1 = (SqlLike)node1;
SqlLike like2 = (SqlLike)node2;
return AreEqual(like1.Expression, like2.Expression) &&
AreEqual(like1.Pattern, like2.Pattern) &&
AreEqual(like1.Escape, like2.Escape);
}
case SqlNodeType.Variable: {
SqlVariable v1 = (SqlVariable)node1;
SqlVariable v2 = (SqlVariable)node2;
return v1.Name == v2.Name;
}
case SqlNodeType.FunctionCall: {
SqlFunctionCall f1 = (SqlFunctionCall)node1;
SqlFunctionCall f2 = (SqlFunctionCall)node2;
if (f1.Name != f2.Name)
return false;
if (f1.Arguments.Count != f2.Arguments.Count)
return false;
for (int i = 0, n = f1.Arguments.Count; i < n; i++) {
if (!AreEqual(f1.Arguments[i], f2.Arguments[i]))
return false;
}
return true;
}
case SqlNodeType.Link: {
SqlLink l1 = (SqlLink)node1;
SqlLink l2 = (SqlLink)node2;
if (!MetaPosition.AreSameMember(l1.Member.Member, l2.Member.Member)) {
return false;
}
if (!AreEqual(l1.Expansion, l2.Expansion)) {
return false;
}
if (l1.KeyExpressions.Count != l2.KeyExpressions.Count) {
return false;
}
for (int i = 0, c = l1.KeyExpressions.Count; i < c; ++i) {
if (!AreEqual(l1.KeyExpressions[i], l2.KeyExpressions[i])) {
return false;
}
}
return true;
}
case SqlNodeType.ExprSet:
SqlExprSet es1 = (SqlExprSet)node1;
SqlExprSet es2 = (SqlExprSet)node2;
if (es1.Expressions.Count != es2.Expressions.Count)
return false;
for(int i = 0, n = es1.Expressions.Count; i < n; i++) {
if (!AreEqual(es1.Expressions[i], es2.Expressions[i]))
return false;
}
return true;
case SqlNodeType.OptionalValue:
SqlOptionalValue ov1 = (SqlOptionalValue)node1;
SqlOptionalValue ov2 = (SqlOptionalValue)node2;
return AreEqual(ov1.Value, ov2.Value);
case SqlNodeType.Row:
case SqlNodeType.UserQuery:
case SqlNodeType.StoredProcedureCall:
case SqlNodeType.UserRow:
case SqlNodeType.UserColumn:
case SqlNodeType.Multiset:
case SqlNodeType.ScalarSubSelect:
case SqlNodeType.Element:
case SqlNodeType.Exists:
case SqlNodeType.Join:
case SqlNodeType.Select:
case SqlNodeType.New:
case SqlNodeType.ClientQuery:
case SqlNodeType.ClientArray:
case SqlNodeType.Insert:
case SqlNodeType.Update:
case SqlNodeType.Delete:
case SqlNodeType.MemberAssign:
case SqlNodeType.Assign:
case SqlNodeType.Block:
case SqlNodeType.Union:
case SqlNodeType.DoNotVisit:
case SqlNodeType.MethodCall:
case SqlNodeType.Nop:
default:
return false;
}
}
private static SqlColumn GetBaseColumn(SqlColumnRef cref) {
while (cref != null && cref.Column.Expression != null) {
SqlColumnRef cr = cref.Column.Expression as SqlColumnRef;
if (cr != null) {
cref = cr;
continue;
}
else {
break;
}
}
return cref.Column;
}
private static SqlExpression UnwrapTrivialCaseExpression(SqlSimpleCase sc) {
if (sc.Whens.Count != 1) {
return sc;
}
if (!SqlComparer.AreEqual(sc.Expression, sc.Whens[0].Match)) {
return sc;
}
SqlExpression result = sc.Whens[0].Value;
if (result.NodeType == SqlNodeType.SimpleCase) {
return UnwrapTrivialCaseExpression((SqlSimpleCase)result);
}
return result;
}
}
}
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