271 lines
10 KiB
C#
271 lines
10 KiB
C#
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using System;
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using System.Collections.Generic;
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using System.Text;
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using System.Data.Linq;
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using System.Diagnostics.CodeAnalysis;
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namespace System.Data.Linq.SqlClient {
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internal class SqlNamer {
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Visitor visitor;
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internal SqlNamer() {
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this.visitor = new Visitor();
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}
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internal SqlNode AssignNames(SqlNode node) {
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return this.visitor.Visit(node);
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}
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class Visitor : SqlVisitor {
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int aliasCount;
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SqlAlias alias;
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bool makeUnique;
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bool useMappedNames;
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string lastName;
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internal Visitor() {
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this.makeUnique = true;
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this.useMappedNames = false;
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}
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internal string GetNextAlias() {
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return "t" + (aliasCount++);
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}
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internal override SqlAlias VisitAlias(SqlAlias sqlAlias) {
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SqlAlias save = this.alias;
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this.alias = sqlAlias;
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sqlAlias.Node = this.Visit(sqlAlias.Node);
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sqlAlias.Name = this.GetNextAlias();
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this.alias = save;
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return sqlAlias;
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}
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internal override SqlExpression VisitScalarSubSelect(SqlSubSelect ss) {
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base.VisitScalarSubSelect(ss);
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if (ss.Select.Row.Columns.Count > 0) {
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System.Diagnostics.Debug.Assert(ss != null && ss.Select != null && ss.Select.Row != null && ss.Select.Row.Columns.Count == 1);
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// make sure these scalar subselects don't get redundantly named
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ss.Select.Row.Columns[0].Name = "";
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}
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return ss;
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}
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internal override SqlStatement VisitInsert(SqlInsert insert) {
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bool saveMakeUnique = this.makeUnique;
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this.makeUnique = false;
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bool saveUseMappedNames = this.useMappedNames;
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this.useMappedNames = true;
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SqlStatement stmt = base.VisitInsert(insert);
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this.makeUnique = saveMakeUnique;
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this.useMappedNames = saveUseMappedNames;
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return stmt;
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}
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internal override SqlStatement VisitUpdate(SqlUpdate update) {
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bool saveMakeUnique = this.makeUnique;
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this.makeUnique = false;
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bool saveUseMappedNames = this.useMappedNames;
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this.useMappedNames = true;
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SqlStatement stmt = base.VisitUpdate(update);
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this.makeUnique = saveMakeUnique;
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this.useMappedNames = saveUseMappedNames;
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return stmt;
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}
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internal override SqlSelect VisitSelect(SqlSelect select) {
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select = base.VisitSelect(select);
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string[] names = new string[select.Row.Columns.Count];
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for (int i = 0, n = names.Length; i < n; i++) {
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SqlColumn c = select.Row.Columns[i];
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string name = c.Name;
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if (name == null) {
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name = SqlNamer.DiscoverName(c);
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}
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names[i] = name;
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c.Name = null;
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}
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var reservedNames = this.GetColumnNames(select.OrderBy);
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for (int i = 0, n = select.Row.Columns.Count; i < n; i++) {
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SqlColumn c = select.Row.Columns[i];
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string rootName = names[i];
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string name = rootName;
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if (this.makeUnique) {
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int iName = 1;
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while (!this.IsUniqueName(select.Row.Columns, reservedNames, c, name)) {
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iName++;
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name = rootName + iName;
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}
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}
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c.Name = name;
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c.Ordinal = i;
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}
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return select;
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}
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[SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic", Justification="Unknown reason.")]
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private bool IsUniqueName(List<SqlColumn> columns, ICollection<string> reservedNames, SqlColumn c, string name) {
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foreach (SqlColumn sc in columns) {
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if (sc != c && string.Compare(sc.Name, name, StringComparison.OrdinalIgnoreCase) == 0)
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return false;
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}
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if (!IsSimpleColumn(c, name)) {
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return !reservedNames.Contains(name);
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}
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return true;
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}
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/// <summary>
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/// An expression is a simple reprojection if it's a column node whose expression is null, or
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/// whose expression is a column whose name matches the name of the given name or where
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/// where the given name is null or empty.
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/// </summary>
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/// <param name="c"></param>
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/// <returns></returns>
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private static bool IsSimpleColumn(SqlColumn c, string name) {
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if (c.Expression != null) {
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switch (c.Expression.NodeType) {
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case SqlNodeType.ColumnRef:
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var colRef = c.Expression as SqlColumnRef;
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return String.IsNullOrEmpty(name) || string.Compare(name, colRef.Column.Name, StringComparison.OrdinalIgnoreCase) == 0;
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default:
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return false;
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}
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}
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return true;
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}
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internal override SqlExpression VisitExpression(SqlExpression expr) {
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string saveLastName = this.lastName;
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this.lastName = null;
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try {
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return (SqlExpression)this.Visit(expr);
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}
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finally {
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this.lastName = saveLastName;
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}
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}
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private SqlExpression VisitNamedExpression(SqlExpression expr, string name) {
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string saveLastName = this.lastName;
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this.lastName = name;
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try {
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return (SqlExpression)this.Visit(expr);
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}
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finally {
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this.lastName = saveLastName;
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}
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}
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internal override SqlExpression VisitColumnRef(SqlColumnRef cref) {
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if (cref.Column.Name == null && this.lastName != null) {
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cref.Column.Name = this.lastName;
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}
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return cref;
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}
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internal override SqlExpression VisitNew(SqlNew sox) {
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if (sox.Constructor != null) {
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System.Reflection.ParameterInfo[] pis = sox.Constructor.GetParameters();
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for (int i = 0, n = sox.Args.Count; i < n; i++) {
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sox.Args[i] = this.VisitNamedExpression(sox.Args[i], pis[i].Name);
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}
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}
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else {
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for (int i = 0, n = sox.Args.Count; i < n; i++) {
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sox.Args[i] = this.VisitExpression(sox.Args[i]);
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}
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}
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foreach (SqlMemberAssign ma in sox.Members) {
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string n = ma.Member.Name;
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if (this.useMappedNames) {
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n = sox.MetaType.GetDataMember(ma.Member).MappedName;
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}
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ma.Expression = this.VisitNamedExpression(ma.Expression, n);
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}
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return sox;
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}
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internal override SqlExpression VisitGrouping(SqlGrouping g) {
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g.Key = this.VisitNamedExpression(g.Key, "Key");
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g.Group = this.VisitNamedExpression(g.Group, "Group");
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return g;
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}
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internal override SqlExpression VisitOptionalValue(SqlOptionalValue sov) {
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sov.HasValue = this.VisitNamedExpression(sov.HasValue, "test");
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sov.Value = this.VisitExpression(sov.Value);
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return sov;
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}
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internal override SqlExpression VisitMethodCall(SqlMethodCall mc) {
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mc.Object = this.VisitExpression(mc.Object);
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System.Reflection.ParameterInfo[] pis = mc.Method.GetParameters();
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for (int i = 0, n = mc.Arguments.Count; i < n; i++) {
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mc.Arguments[i] = this.VisitNamedExpression(mc.Arguments[i], pis[i].Name);
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}
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return mc;
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}
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ICollection<string> GetColumnNames(IEnumerable<SqlOrderExpression> orderList)
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{
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var visitor = new ColumnNameGatherer();
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foreach (var expr in orderList) {
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visitor.Visit(expr.Expression);
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}
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return visitor.Names;
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}
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}
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internal static string DiscoverName(SqlExpression e) {
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if (e != null) {
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switch (e.NodeType) {
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case SqlNodeType.Column:
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return DiscoverName(((SqlColumn)e).Expression);
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case SqlNodeType.ColumnRef:
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SqlColumnRef cref = (SqlColumnRef)e;
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if (cref.Column.Name != null) return cref.Column.Name;
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return DiscoverName(cref.Column);
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case SqlNodeType.ExprSet:
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SqlExprSet eset = (SqlExprSet)e;
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return DiscoverName(eset.Expressions[0]);
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}
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}
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return "value";
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}
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class ColumnNameGatherer : SqlVisitor {
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public HashSet<string> Names { get; set; }
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public ColumnNameGatherer()
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: base() {
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this.Names = new HashSet<string>();
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}
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internal override SqlExpression VisitColumn(SqlColumn col) {
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if (!String.IsNullOrEmpty(col.Name)) {
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this.Names.Add(col.Name);
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}
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return base.VisitColumn(col);
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}
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internal override SqlExpression VisitColumnRef(SqlColumnRef cref) {
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Visit(cref.Column);
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return base.VisitColumnRef(cref);
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}
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}
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}
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}
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