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//---------------------------------------------------------------------
// <copyright file="SlotInfo.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
using System.Data.Common.CommandTrees;
using System.Data.Common.CommandTrees.ExpressionBuilder;
using System.Data.Common.Utils;
using System.Data.Mapping.ViewGeneration.Structures;
using System.Text;
using System.Diagnostics;
namespace System.Data.Mapping.ViewGeneration.CqlGeneration
{
/// <summary>
/// A class that keeps track of slot information in a <see cref="CqlBlock"/>.
/// </summary>
internal sealed class SlotInfo : InternalBase
{
#region Constructor
/// <summary>
/// Creates a <see cref="SlotInfo"/> for a <see cref="CqlBlock"/> X with information about whether this slot is needed by X's parent
/// (<paramref name="isRequiredByParent"/>), whether X projects it (<paramref name="isProjected"/>) along with the slot value (<paramref name="slotValue"/>) and
/// the output member path (<paramref name="outputMember"/> (for regular/non-boolean slots) for the slot.
/// </summary>
internal SlotInfo(bool isRequiredByParent, bool isProjected, ProjectedSlot slotValue, MemberPath outputMember)
: this(isRequiredByParent, isProjected, slotValue, outputMember, false /* enforceNotNull */)
{ }
/// <summary>
/// Creates a <see cref="SlotInfo"/> for a <see cref="CqlBlock"/> X with information about whether this slot is needed by X's parent
/// (<paramref name="isRequiredByParent"/>), whether X projects it (<paramref name="isProjected"/>) along with the slot value (<paramref name="slotValue"/>) and
/// the output member path (<paramref name="outputMember"/> (for regular/non-boolean slots) for the slot.
/// </summary>
/// <param name="enforceNotNull">We need to ensure that _from variables are never null since view generation uses 2-valued boolean logic.
/// If <paramref name="enforceNotNull"/>=true, the generated Cql adds a condition (AND <paramref name="slotValue"/> NOT NULL).
/// This flag is used only for boolean slots.</param>
internal SlotInfo(bool isRequiredByParent, bool isProjected, ProjectedSlot slotValue, MemberPath outputMember, bool enforceNotNull)
{
m_isRequiredByParent = isRequiredByParent;
m_isProjected = isProjected;
m_slotValue = slotValue;
m_outputMember = outputMember;
m_enforceNotNull = enforceNotNull;
Debug.Assert(false == m_isRequiredByParent || m_slotValue != null, "Required slots cannot be null");
Debug.Assert(m_slotValue is QualifiedSlot ||
(m_slotValue == null && m_outputMember == null) || // unused boolean slot
(m_slotValue is BooleanProjectedSlot) == (m_outputMember == null),
"If slot is boolean slot, there is no member path for it and vice-versa");
}
#endregion
#region Fields
/// <summary>
/// If slot is required by the parent. Can be reset to false in <see cref="ResetIsRequiredByParent"/> method.
/// </summary>
private bool m_isRequiredByParent;
/// <summary>
/// If the node is capable of projecting this slot.
/// </summary>
private readonly bool m_isProjected;
/// <summary>
/// The slot represented by this <see cref="SlotInfo"/>.
/// </summary>
private readonly ProjectedSlot m_slotValue;
/// <summary>
/// The output member path of this slot.
/// </summary>
private readonly MemberPath m_outputMember;
/// <summary>
/// Whether to add AND NOT NULL to Cql.
/// </summary>
private readonly bool m_enforceNotNull;
#endregion
#region Properties
/// <summary>
/// Returns true iff this slot is required by the <see cref="CqlBlock"/>'s parent.
/// Can be reset to false by calling <see cref="ResetIsRequiredByParent"/> method.
/// </summary>
internal bool IsRequiredByParent
{
get { return m_isRequiredByParent; }
}
/// <summary>
/// Returns true iff this slot is projected by this <see cref="CqlBlock"/>.
/// </summary>
internal bool IsProjected
{
get { return m_isProjected; }
}
/// <summary>
/// Returns the output memberpath of this slot
/// </summary>
internal MemberPath OutputMember
{
get { return m_outputMember; }
}
/// <summary>
/// Returns the slot value corresponfing to this object.
/// </summary>
internal ProjectedSlot SlotValue
{
get { return m_slotValue; }
}
/// <summary>
/// Returns the Cql alias for this slot, e.g., "CPerson1_Pid", "_from0", etc
/// </summary>
internal string CqlFieldAlias
{
get
{
return m_slotValue != null ? m_slotValue.GetCqlFieldAlias(m_outputMember) : null;
}
}
/// <summary>
/// Returns true if Cql generated for the slot needs to have an extra AND IS NOT NULL condition.
/// </summary>
internal bool IsEnforcedNotNull
{
get { return m_enforceNotNull; }
}
#endregion
#region Methods
/// <summary>
/// Sets the <see cref="IsRequiredByParent"/> to false.
/// Note we don't have a setter because we don't want people to set this field to true after the object has been created.
/// </summary>
internal void ResetIsRequiredByParent()
{
m_isRequiredByParent = false;
}
/// <summary>
/// Generates eSQL representation of the slot. For different slots, the result is different, e.g., "_from0", "CPerson1.pid", "TREAT(....)".
/// </summary>
internal StringBuilder AsEsql(StringBuilder builder, string blockAlias, int indentLevel)
{
if (m_enforceNotNull)
{
builder.Append('(');
m_slotValue.AsEsql(builder, m_outputMember, blockAlias, indentLevel);
builder.Append(" AND ");
m_slotValue.AsEsql(builder, m_outputMember, blockAlias, indentLevel);
builder.Append(" IS NOT NULL)");
}
else
{
m_slotValue.AsEsql(builder, m_outputMember, blockAlias, indentLevel);
}
return builder;
}
/// <summary>
/// Generates CQT representation of the slot.
/// </summary>
internal DbExpression AsCqt(DbExpression row)
{
DbExpression cqt = m_slotValue.AsCqt(row, m_outputMember);
if (m_enforceNotNull)
{
cqt = cqt.And(cqt.IsNull().Not());
}
return cqt;
}
internal override void ToCompactString(StringBuilder builder)
{
if (m_slotValue != null)
{
builder.Append(CqlFieldAlias);
}
}
#endregion
}
}
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