Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data.Linq/SqlClient/Query/ContainsRowNumberChecker.cs

@@ -0,0 +1,75 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace System.Data.Linq.SqlClient {
+    internal class SqlRowNumberChecker {
+        Visitor rowNumberVisitor;
+
+        internal SqlRowNumberChecker() {
+            this.rowNumberVisitor = new Visitor();
+        }
+
+        internal bool HasRowNumber(SqlNode node) {
+            this.rowNumberVisitor.Visit(node);
+            return rowNumberVisitor.HasRowNumber;
+        }
+
+        internal bool HasRowNumber(SqlRow row) {
+            foreach (SqlColumn column in row.Columns) {
+                if (this.HasRowNumber(column)) {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        internal SqlColumn RowNumberColumn {
+            get {
+                return rowNumberVisitor.HasRowNumber ? rowNumberVisitor.CurrentColumn : null;
+            }
+        }
+
+        private class Visitor: SqlVisitor {
+            bool hasRowNumber = false;
+
+            public bool HasRowNumber {
+                get { return hasRowNumber; }
+            }
+
+            public SqlColumn CurrentColumn { private set; get; }
+
+            internal override SqlRowNumber VisitRowNumber(SqlRowNumber rowNumber) {
+                this.hasRowNumber = true;
+                return rowNumber;
+            }
+
+            // shortcuts
+            internal override SqlExpression VisitScalarSubSelect(SqlSubSelect ss) {
+                return ss;
+            }
+
+            internal override SqlExpression VisitSubSelect(SqlSubSelect ss) {
+                return ss;
+            }
+
+            internal override SqlRow VisitRow(SqlRow row)
+            {
+                for (int i = 0, n = row.Columns.Count; i < n; i++) {
+                    row.Columns[i].Expression = this.VisitExpression(row.Columns[i].Expression);
+                    if (this.hasRowNumber) {
+                        this.CurrentColumn = row.Columns[i];
+                        break;
+                    }
+                }
+                return row;
+            }
+            internal override SqlSelect VisitSelect(SqlSelect select) {
+                this.Visit(select.Row);
+                this.Visit(select.Where);
+
+                return select;
+            }
+        }
+    }
+}