34 lines
1.0 KiB
C#
34 lines
1.0 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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namespace System.Data.Linq.SqlClient {
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/// <summary>
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/// Walk a tree and return the set of unique aliases it consumes.
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/// </summary>
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class SqlGatherConsumedAliases {
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internal static HashSet<SqlAlias> Gather(SqlNode node) {
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Gatherer g = new Gatherer();
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g.Visit(node);
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return g.Consumed;
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}
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private class Gatherer : SqlVisitor {
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internal HashSet<SqlAlias> Consumed = new HashSet<SqlAlias>();
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internal void VisitAliasConsumed(SqlAlias a) {
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Consumed.Add(a);
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}
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internal override SqlExpression VisitColumn(SqlColumn col) {
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VisitAliasConsumed(col.Alias);
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VisitExpression(col.Expression);
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return col;
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}
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internal override SqlExpression VisitColumnRef(SqlColumnRef cref) {
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VisitAliasConsumed(cref.Column.Alias);
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return cref;
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}
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}
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}
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}
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