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//---------------------------------------------------------------------
// <copyright file="AliasedSlot.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
using System.Linq;
using System.Data.Mapping.ViewGeneration.Structures;
using System.Text;
using System.Diagnostics;
using System.Data.Common.CommandTrees;
using System.Data.Common.CommandTrees.ExpressionBuilder;
using System.Data.Common.Utils;
using System.Collections.Generic;
namespace System.Data.Mapping.ViewGeneration.CqlGeneration
{
/// <summary>
/// Encapsulates a slot in a particular cql block.
/// </summary>
internal sealed class QualifiedSlot : ProjectedSlot
{
#region Constructor
/// <summary>
/// Creates a qualified slot "block_alias.slot_alias"
/// </summary>
internal QualifiedSlot(CqlBlock block, ProjectedSlot slot)
{
Debug.Assert(block != null && slot != null, "Null input to QualifiedSlot constructor");
m_block = block;
m_slot = slot; // Note: slot can be another qualified slot.
}
#endregion
#region Fields
private readonly CqlBlock m_block;
private readonly ProjectedSlot m_slot;
#endregion
#region Methods
/// <summary>
/// Creates new <see cref="ProjectedSlot"/> that is qualified with <paramref name="block"/>.CqlAlias.
/// If current slot is composite (such as <see cref="CaseStatementProjectedSlot"/>, then this method recursively qualifies all parts
/// and returns a new deeply qualified slot (as opposed to <see cref="CqlBlock.QualifySlotWithBlockAlias"/>).
/// </summary>
internal override ProjectedSlot DeepQualify(CqlBlock block)
{
// We take the slot inside this and change the block
QualifiedSlot result = new QualifiedSlot(block, m_slot);
return result;
}
/// <summary>
/// Delegates alias generation to the leaf slot in the qualified chain.
/// </summary>
internal override string GetCqlFieldAlias(MemberPath outputMember)
{
// Keep looking inside the chain of qualified slots till we find a non-qualified slot and then get the alias name for it.
string result = GetOriginalSlot().GetCqlFieldAlias(outputMember);
return result;
}
/// <summary>
/// Walks the chain of <see cref="QualifiedSlot"/>s starting from the current one and returns the original slot.
/// </summary>
internal ProjectedSlot GetOriginalSlot()
{
ProjectedSlot slot = m_slot;
while (true)
{
QualifiedSlot qualifiedSlot = slot as QualifiedSlot;
if (qualifiedSlot == null)
{
break;
}
slot = qualifiedSlot.m_slot;
}
return slot;
}
internal string GetQualifiedCqlName(MemberPath outputMember)
{
return CqlWriter.GetQualifiedName(m_block.CqlAlias, GetCqlFieldAlias(outputMember));
}
internal override StringBuilder AsEsql(StringBuilder builder, MemberPath outputMember, string blockAlias, int indentLevel)
{
Debug.Assert(blockAlias == null || m_block.CqlAlias == blockAlias, "QualifiedSlot: blockAlias mismatch");
builder.Append(GetQualifiedCqlName(outputMember));
return builder;
}
internal override DbExpression AsCqt(DbExpression row, MemberPath outputMember)
{
return m_block.GetInput(row).Property(GetCqlFieldAlias(outputMember));
}
internal override void ToCompactString(StringBuilder builder)
{
StringUtil.FormatStringBuilder(builder, "{0} ", m_block.CqlAlias);
m_slot.ToCompactString(builder);
}
#endregion
}
}
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