293 lines
12 KiB
C#
293 lines
12 KiB
C#
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Reflection;
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namespace System.Data.Linq.SqlClient {
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using System.Data.Linq.Mapping;
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using System.Data.Linq.Provider;
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using System.Diagnostics.CodeAnalysis;
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using System.Linq.Expressions;
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// moves order-by clauses from sub-queries to outer-most or top selects
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// removes ordering in correlated sub-queries
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internal class SqlReorderer {
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TypeSystemProvider typeProvider;
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SqlFactory sql;
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internal SqlReorderer(TypeSystemProvider typeProvider, SqlFactory sqlFactory) {
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this.typeProvider = typeProvider;
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this.sql = sqlFactory;
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}
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internal SqlNode Reorder(SqlNode node) {
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return new Visitor(this.typeProvider, this.sql).Visit(node);
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}
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class Visitor : SqlVisitor {
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TypeSystemProvider typeProvider;
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bool topSelect = true;
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bool addPrimaryKeys;
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List<SqlOrderExpression> orders;
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List<SqlOrderExpression> rowNumberOrders;
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SqlSelect currentSelect;
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SqlFactory sql;
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SqlAggregateChecker aggregateChecker;
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internal Visitor(TypeSystemProvider typeProvider, SqlFactory sqlFactory) {
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this.orders = new List<SqlOrderExpression>();
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this.typeProvider = typeProvider;
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this.sql = sqlFactory;
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this.aggregateChecker = new SqlAggregateChecker();
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}
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internal override SqlExpression VisitSubSelect(SqlSubSelect ss) {
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List<SqlOrderExpression> save = this.orders;
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this.orders = new List<SqlOrderExpression>();
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base.VisitSubSelect(ss);
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this.orders = save;
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return ss;
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}
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private void PrependOrderExpressions(IEnumerable<SqlOrderExpression> exprs) {
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if (exprs != null) {
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this.Orders.InsertRange(0, exprs);
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}
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}
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private List<SqlOrderExpression> Orders {
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get {
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if (this.orders == null) {
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this.orders = new List<SqlOrderExpression>();
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}
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return this.orders;
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}
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}
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internal override SqlSource VisitJoin(SqlJoin join) {
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this.Visit(join.Left);
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List<SqlOrderExpression> leftOrders = this.orders;
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this.orders = null;
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this.Visit(join.Right);
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this.PrependOrderExpressions(leftOrders);
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return join;
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}
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internal override SqlNode VisitUnion(SqlUnion su) {
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// ordering does not carry through a union
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this.orders = null;
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su.Left = this.Visit(su.Left);
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this.orders = null;
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su.Right = this.Visit(su.Right);
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this.orders = null;
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return su;
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}
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internal override SqlAlias VisitAlias(SqlAlias a) {
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SqlTable tab = a.Node as SqlTable;
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SqlTableValuedFunctionCall tvf = a.Node as SqlTableValuedFunctionCall;
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if (this.addPrimaryKeys && (tab != null || tvf != null)) {
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List<SqlOrderExpression> list = new List<SqlOrderExpression>();
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bool isTable = tab != null;
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MetaType rowType = isTable ? tab.RowType : tvf.RowType;
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foreach (MetaDataMember mm in rowType.IdentityMembers) {
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string name = mm.MappedName;
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SqlColumn col;
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Expression sourceExpression;
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List<SqlColumn> columns;
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if (isTable) {
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col = tab.Find(name);
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sourceExpression = tab.SourceExpression;
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columns = tab.Columns;
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}
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else {
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col = tvf.Find(name);
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sourceExpression = tvf.SourceExpression;
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columns = tvf.Columns;
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}
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if (col == null) {
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col = new SqlColumn(mm.MemberAccessor.Type, typeProvider.From(mm.MemberAccessor.Type), name, mm, null, sourceExpression);
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col.Alias = a;
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columns.Add(col);
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}
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list.Add(new SqlOrderExpression(SqlOrderType.Ascending, new SqlColumnRef(col)));
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}
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this.PrependOrderExpressions(list);
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return a;
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}
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else {
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return base.VisitAlias(a);
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}
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}
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internal override SqlSelect VisitSelect(SqlSelect select) {
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bool saveTop = this.topSelect;
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bool savePK = this.addPrimaryKeys;
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SqlSelect saveSelect = this.currentSelect;
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this.currentSelect = select;
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if (select.OrderingType == SqlOrderingType.Always) {
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this.addPrimaryKeys = true;
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}
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this.topSelect = false;
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// can't forward ordering information through a group-by
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if (select.GroupBy.Count > 0) {
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this.Visit(select.From);
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this.orders = null;
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}
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else {
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this.Visit(select.From);
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}
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if (select.OrderBy.Count > 0) {
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this.PrependOrderExpressions(select.OrderBy);
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}
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List<SqlOrderExpression> save = this.orders;
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this.orders = null;
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this.rowNumberOrders = save; // lest orders be null when we need info
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/* do all the lower level stuff */
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select.Where = this.VisitExpression(select.Where);
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for (int i = 0, n = select.GroupBy.Count; i < n; i++) {
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select.GroupBy[i] = this.VisitExpression(select.GroupBy[i]);
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}
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select.Having = this.VisitExpression(select.Having);
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for (int i = 0, n = select.OrderBy.Count; i < n; i++) {
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select.OrderBy[i].Expression = this.VisitExpression(select.OrderBy[i].Expression);
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}
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select.Top = this.VisitExpression(select.Top);
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select.Selection = this.VisitExpression(select.Selection);
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select.Row = (SqlRow)this.Visit(select.Row);
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this.topSelect = saveTop;
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this.addPrimaryKeys = savePK;
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this.orders = save;
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// all ordering is blocked for this layer and above
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if (select.OrderingType == SqlOrderingType.Blocked) {
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this.orders = null;
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}
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// rebuild orderby expressions, provided this select doesn't contain a SqlRowNumber
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// otherwise, replace the orderby with a reference to that column
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select.OrderBy.Clear();
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var rowNumberChecker = new SqlRowNumberChecker();
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if (rowNumberChecker.HasRowNumber(select) && rowNumberChecker.RowNumberColumn != null) {
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select.Row.Columns.Remove(rowNumberChecker.RowNumberColumn);
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this.PushDown(rowNumberChecker.RowNumberColumn);
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this.Orders.Add(new SqlOrderExpression(SqlOrderType.Ascending, new SqlColumnRef(rowNumberChecker.RowNumberColumn)));
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}
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if ((this.topSelect || select.Top != null) && select.OrderingType != SqlOrderingType.Never && this.orders != null) {
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this.orders = new HashSet<SqlOrderExpression>(this.orders).ToList();
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SqlDuplicator dup = new SqlDuplicator(true);
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foreach (SqlOrderExpression sox in this.orders) {
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select.OrderBy.Add(new SqlOrderExpression(sox.OrderType, (SqlExpression)dup.Duplicate(sox.Expression)));
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}
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}
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this.currentSelect = saveSelect;
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return select;
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}
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internal override SqlRowNumber VisitRowNumber(SqlRowNumber rowNumber) {
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if (rowNumber.OrderBy.Count > 0) return rowNumber;
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SqlDuplicator dup = new SqlDuplicator(true);
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List<SqlOrderExpression> orderBy = new List<SqlOrderExpression>();
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List<SqlOrderExpression> existingOrders = new List<SqlOrderExpression>();
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if (this.rowNumberOrders != null && this.rowNumberOrders.Count != 0) {
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existingOrders = new List<SqlOrderExpression>(this.rowNumberOrders);
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}
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else if (this.orders != null) {
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existingOrders = new List<SqlOrderExpression>(this.orders);
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}
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foreach (SqlOrderExpression expr in existingOrders) {
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if (!expr.Expression.IsConstantColumn) {
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orderBy.Add(expr);
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if (this.rowNumberOrders != null) {
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this.rowNumberOrders.Remove(expr);
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}
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if (this.orders != null) {
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this.orders.Remove(expr);
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}
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}
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}
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rowNumber.OrderBy.Clear();
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if (orderBy.Count == 0) {
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List<SqlColumn> columns = SqlGatherColumnsProduced.GatherColumns(this.currentSelect.From);
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foreach (SqlColumn col in columns) {
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if (col.Expression.SqlType.IsOrderable) {
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orderBy.Add(new SqlOrderExpression(SqlOrderType.Ascending, new SqlColumnRef(col)));
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}
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}
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if (orderBy.Count == 0) {
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// insert simple column
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SqlColumn col =
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new SqlColumn(
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"rowNumberOrder",
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sql.Value(typeof(int), this.typeProvider.From(typeof(int)), 1, false, rowNumber.SourceExpression)
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);
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this.PushDown(col);
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orderBy.Add(new SqlOrderExpression(SqlOrderType.Ascending, new SqlColumnRef(col)));
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}
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}
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foreach (SqlOrderExpression sox in orderBy) {
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rowNumber.OrderBy.Add(new SqlOrderExpression(sox.OrderType, (SqlExpression)dup.Duplicate(sox.Expression)));
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}
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return rowNumber;
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}
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private void PushDown(SqlColumn column) {
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SqlSelect select = new SqlSelect(new SqlNop(column.ClrType, column.SqlType, column.SourceExpression), this.currentSelect.From, this.currentSelect.SourceExpression);
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this.currentSelect.From = new SqlAlias(select);
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select.Row.Columns.Add(column);
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}
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}
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internal class SqlGatherColumnsProduced {
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static internal List<SqlColumn> GatherColumns(SqlSource source) {
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List<SqlColumn> columns = new List<SqlColumn>();
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new Visitor(columns).Visit(source);
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return columns;
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}
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class Visitor : SqlVisitor {
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List<SqlColumn> columns;
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internal Visitor(List<SqlColumn> columns) {
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this.columns = columns;
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}
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internal override SqlSelect VisitSelect(SqlSelect select) {
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foreach (SqlColumn c in select.Row.Columns) {
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this.columns.Add(c);
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}
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return select;
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}
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internal override SqlNode VisitUnion(SqlUnion su) {
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return su;
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}
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}
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}
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}
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}
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