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