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using System;
using System.Collections.Generic;
namespace System.Data.Linq.SqlClient {
using System.Data.Linq.Mapping;
using System.Data.Linq.Provider;
using System.Diagnostics.CodeAnalysis;
// flatten object expressions into rows
internal class SqlFlattener {
Visitor visitor;
internal SqlFlattener(SqlFactory sql, SqlColumnizer columnizer) {
this.visitor = new Visitor(sql, columnizer);
}
internal SqlNode Flatten(SqlNode node) {
node = this.visitor.Visit(node);
return node;
}
class Visitor : SqlVisitor {
[SuppressMessage("Microsoft.Performance", "CA1823:AvoidUnusedPrivateFields", Justification = "Microsoft: part of our standard visitor pattern")]
SqlFactory sql;
SqlColumnizer columnizer;
bool isTopLevel;
Dictionary<SqlColumn, SqlColumn> map = new Dictionary<SqlColumn,SqlColumn>();
[SuppressMessage("Microsoft.Performance", "CA1805:DoNotInitializeUnnecessarily", Justification="Unknown reason.")]
internal Visitor(SqlFactory sql, SqlColumnizer columnizer) {
this.sql = sql;
this.columnizer = columnizer;
this.isTopLevel = true;
}
internal override SqlExpression VisitColumnRef(SqlColumnRef cref) {
SqlColumn mapped;
if (this.map.TryGetValue(cref.Column, out mapped)) {
return new SqlColumnRef(mapped);
}
return cref;
}
internal override SqlSelect VisitSelectCore(SqlSelect select) {
bool saveIsTopLevel = this.isTopLevel;
this.isTopLevel = false;
try {
return base.VisitSelectCore(select);
}
finally {
this.isTopLevel = saveIsTopLevel;
}
}
internal override SqlSelect VisitSelect(SqlSelect select) {
select = base.VisitSelect(select);
select.Selection = this.FlattenSelection(select.Row, false, select.Selection);
if (select.GroupBy.Count > 0) {
this.FlattenGroupBy(select.GroupBy);
}
if (select.OrderBy.Count > 0) {
this.FlattenOrderBy(select.OrderBy);
}
if (!this.isTopLevel) {
select.Selection = new SqlNop(select.Selection.ClrType, select.Selection.SqlType, select.SourceExpression);
}
return select;
}
internal override SqlStatement VisitInsert(SqlInsert sin) {
base.VisitInsert(sin);
sin.Expression = this.FlattenSelection(sin.Row, true, sin.Expression);
return sin;
}
private SqlExpression FlattenSelection(SqlRow row, bool isInput, SqlExpression selection) {
selection = this.columnizer.ColumnizeSelection(selection);
return new SelectionFlattener(row, this.map, isInput).VisitExpression(selection);
}
class SelectionFlattener : SqlVisitor {
SqlRow row;
Dictionary<SqlColumn, SqlColumn> map;
bool isInput;
bool isNew;
internal SelectionFlattener(SqlRow row, Dictionary<SqlColumn, SqlColumn> map, bool isInput) {
this.row = row;
this.map = map;
this.isInput = isInput;
}
internal override SqlExpression VisitNew(SqlNew sox) {
this.isNew = true;
return base.VisitNew(sox);
}
internal override SqlExpression VisitColumn(SqlColumn col) {
SqlColumn c = this.FindColumn(this.row.Columns, col);
if (c == null && col.Expression != null && !this.isInput && (!this.isNew || (this.isNew && !col.Expression.IsConstantColumn))) {
c = this.FindColumnWithExpression(this.row.Columns, col.Expression);
}
if (c == null) {
this.row.Columns.Add(col);
c = col;
}
else if (c != col) {
// preserve expr-sets when folding expressions together
if (col.Expression.NodeType == SqlNodeType.ExprSet && c.Expression.NodeType != SqlNodeType.ExprSet) {
c.Expression = col.Expression;
}
this.map[col] = c;
}
return new SqlColumnRef(c);
}
internal override SqlExpression VisitColumnRef(SqlColumnRef cref) {
SqlColumn c = this.FindColumn(this.row.Columns, cref.Column);
if (c == null) {
return MakeFlattenedColumn(cref, null);
}
else {
return new SqlColumnRef(c);
}
}
// ignore subquery in selection
internal override SqlExpression VisitSubSelect(SqlSubSelect ss) {
return ss;
}
internal override SqlExpression VisitClientQuery(SqlClientQuery cq) {
return cq;
}
private SqlColumnRef MakeFlattenedColumn(SqlExpression expr, string name) {
SqlColumn c = (!this.isInput) ? this.FindColumnWithExpression(this.row.Columns, expr) : null;
if (c == null) {
c = new SqlColumn(expr.ClrType, expr.SqlType, name, null, expr, expr.SourceExpression);
this.row.Columns.Add(c);
}
return new SqlColumnRef(c);
}
private SqlColumn FindColumn(IEnumerable<SqlColumn> columns, SqlColumn col) {
foreach (SqlColumn c in columns) {
if (this.RefersToColumn(c, col)) {
return c;
}
}
return null;
}
private SqlColumn FindColumnWithExpression(IEnumerable<SqlColumn> columns, SqlExpression expr) {
foreach (SqlColumn c in columns) {
if (c == expr) {
return c;
}
if (SqlComparer.AreEqual(c.Expression, expr)) {
return c;
}
}
return null;
}
}
private void FlattenGroupBy(List<SqlExpression> exprs) {
List<SqlExpression> list = new List<SqlExpression>(exprs.Count);
foreach (SqlExpression gex in exprs) {
if (TypeSystem.IsSequenceType(gex.ClrType)) {
throw Error.InvalidGroupByExpressionType(gex.ClrType.Name);
}
this.FlattenGroupByExpression(list, gex);
}
exprs.Clear();
exprs.AddRange(list);
}
private void FlattenGroupByExpression(List<SqlExpression> exprs, SqlExpression expr) {
SqlNew sn = expr as SqlNew;
if (sn != null) {
foreach (SqlMemberAssign ma in sn.Members) {
this.FlattenGroupByExpression(exprs, ma.Expression);
}
foreach (SqlExpression arg in sn.Args) {
this.FlattenGroupByExpression(exprs, arg);
}
}
else if (expr.NodeType == SqlNodeType.TypeCase) {
SqlTypeCase tc = (SqlTypeCase)expr;
this.FlattenGroupByExpression(exprs, tc.Discriminator);
foreach (SqlTypeCaseWhen when in tc.Whens) {
this.FlattenGroupByExpression(exprs, when.TypeBinding);
}
}
else if (expr.NodeType == SqlNodeType.Link) {
SqlLink link = (SqlLink)expr;
if (link.Expansion != null) {
this.FlattenGroupByExpression(exprs, link.Expansion);
}
else {
foreach (SqlExpression key in link.KeyExpressions) {
this.FlattenGroupByExpression(exprs, key);
}
}
}
else if (expr.NodeType == SqlNodeType.OptionalValue) {
SqlOptionalValue sop = (SqlOptionalValue)expr;
this.FlattenGroupByExpression(exprs, sop.HasValue);
this.FlattenGroupByExpression(exprs, sop.Value);
}
else if (expr.NodeType == SqlNodeType.OuterJoinedValue) {
this.FlattenGroupByExpression(exprs, ((SqlUnary)expr).Operand);
}
else if (expr.NodeType == SqlNodeType.DiscriminatedType) {
SqlDiscriminatedType dt = (SqlDiscriminatedType)expr;
this.FlattenGroupByExpression(exprs, dt.Discriminator);
}
else {
// this expression should have been 'pushed-down' in SqlBinder, so we
// should only find column-references & expr-sets unless the expression could not
// be columnized (in which case it was a bad group-by expression.)
if (expr.NodeType != SqlNodeType.ColumnRef &&
expr.NodeType != SqlNodeType.ExprSet) {
if (!expr.SqlType.CanBeColumn) {
throw Error.InvalidGroupByExpressionType(expr.SqlType.ToQueryString());
}
throw Error.InvalidGroupByExpression();
}
exprs.Add(expr);
}
}
[SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic", Justification="Unknown reason.")]
private void FlattenOrderBy(List<SqlOrderExpression> exprs) {
foreach (SqlOrderExpression obex in exprs) {
if (!obex.Expression.SqlType.IsOrderable) {
if (obex.Expression.SqlType.CanBeColumn) {
throw Error.InvalidOrderByExpression(obex.Expression.SqlType.ToQueryString());
}
else {
throw Error.InvalidOrderByExpression(obex.Expression.ClrType.Name);
}
}
}
}
}
}
}
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