|
//---------------------------------------------------------------------
// <copyright file="StaticContext.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
namespace System.Data.Common.EntitySql
{
using System.Collections.Generic;
using System.Data.Common.CommandTrees;
using System.Data.Common.CommandTrees.ExpressionBuilder;
using System.Data.Entity;
using System.Diagnostics;
/// <summary>
/// Represents a scope of key-value pairs.
/// </summary>
internal sealed class Scope : IEnumerable<KeyValuePair<string, ScopeEntry>>
{
private readonly Dictionary<string, ScopeEntry> _scopeEntries;
/// <summary>
/// Initialize using a given key comparer.
/// </summary>
/// <param name="keyComparer"></param>
internal Scope(IEqualityComparer<string> keyComparer)
{
_scopeEntries = new Dictionary<string, ScopeEntry>(keyComparer);
}
/// <summary>
/// Add new key to the scope. If key already exists - throw.
/// </summary>
internal Scope Add(string key, ScopeEntry value)
{
_scopeEntries.Add(key, value);
return this;
}
/// <summary>
/// Remove an entry from the scope.
/// </summary>
internal void Remove(string key)
{
Debug.Assert(Contains(key));
_scopeEntries.Remove(key);
}
internal void Replace(string key, ScopeEntry value)
{
Debug.Assert(Contains(key));
_scopeEntries[key] = value;
}
/// <summary>
/// Returns true if the key belongs to the scope.
/// </summary>
internal bool Contains(string key)
{
return _scopeEntries.ContainsKey(key);
}
/// <summary>
/// Search item by key. Returns true in case of success and false otherwise.
/// </summary>
internal bool TryLookup(string key, out ScopeEntry value)
{
return (_scopeEntries.TryGetValue(key, out value));
}
#region GetEnumerator
public Dictionary<string, ScopeEntry>.Enumerator GetEnumerator()
{
return _scopeEntries.GetEnumerator();
}
System.Collections.Generic.IEnumerator<KeyValuePair<string, ScopeEntry>> System.Collections.Generic.IEnumerable<KeyValuePair<string, ScopeEntry>>.GetEnumerator()
{
return _scopeEntries.GetEnumerator();
}
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
{
return _scopeEntries.GetEnumerator();
}
#endregion
}
internal enum ScopeEntryKind
{
SourceVar,
GroupKeyDefinition,
ProjectionItemDefinition,
FreeVar,
/// <summary>
/// Represents a group input scope entry that should no longer be referenced.
/// </summary>
InvalidGroupInputRef
}
/// <summary>
/// Represents an entry in the scope.
/// </summary>
internal abstract class ScopeEntry
{
private readonly ScopeEntryKind _scopeEntryKind;
internal ScopeEntry(ScopeEntryKind scopeEntryKind)
{
_scopeEntryKind = scopeEntryKind;
}
internal ScopeEntryKind EntryKind
{
get { return _scopeEntryKind; }
}
/// <summary>
/// Returns CQT expression corresponding to the scope entry.
/// </summary>
internal abstract DbExpression GetExpression(string refName, ErrorContext errCtx);
}
internal interface IGroupExpressionExtendedInfo
{
/// <summary>
/// Returns <see cref="DbGroupExpressionBinding.GroupVariable"/> based expression during the <see cref="DbGroupByExpression"/> construction process, otherwise null.
/// </summary>
DbExpression GroupVarBasedExpression { get; }
/// <summary>
/// Returns <see cref="DbGroupAggregate"/> based expression during the <see cref="DbGroupByExpression"/> construction process, otherwise null.
/// </summary>
DbExpression GroupAggBasedExpression { get; }
}
internal interface IGetAlternativeName
{
/// <summary>
/// If current scope entry reperesents an alternative group key name (see SemanticAnalyzer.ProcessGroupByClause(...) for more info)
/// then this property returns the alternative name, otherwise null.
/// </summary>
string[] AlternativeName { get; }
}
/// <summary>
/// Represents simple source var scope entry.
/// </summary>
internal sealed class SourceScopeEntry : ScopeEntry, IGroupExpressionExtendedInfo, IGetAlternativeName
{
private readonly string[] _alternativeName;
private List<string> _propRefs;
private DbExpression _varBasedExpression;
private DbExpression _groupVarBasedExpression;
private DbExpression _groupAggBasedExpression;
private bool _joinClauseLeftExpr = false;
internal SourceScopeEntry(DbVariableReferenceExpression varRef) : this(varRef, null) { }
internal SourceScopeEntry(DbVariableReferenceExpression varRef, string[] alternativeName)
: base(ScopeEntryKind.SourceVar)
{
_varBasedExpression = varRef;
_alternativeName = alternativeName;
}
internal override DbExpression GetExpression(string refName, ErrorContext errCtx)
{
return _varBasedExpression;
}
DbExpression IGroupExpressionExtendedInfo.GroupVarBasedExpression
{
get { return _groupVarBasedExpression; }
}
DbExpression IGroupExpressionExtendedInfo.GroupAggBasedExpression
{
get { return _groupAggBasedExpression; }
}
internal bool IsJoinClauseLeftExpr
{
get { return _joinClauseLeftExpr; }
set { _joinClauseLeftExpr = value; }
}
string[] IGetAlternativeName.AlternativeName
{
get { return _alternativeName; }
}
/// <summary>
/// Prepend <paramref name="parentVarRef"/> to the property chain.
/// </summary>
internal SourceScopeEntry AddParentVar(DbVariableReferenceExpression parentVarRef)
{
//
// No parent var adjustment is allowed while adjusted to group var (see AdjustToGroupVar(...) for more info).
//
Debug.Assert(_groupVarBasedExpression == null, "_groupVarBasedExpression == null");
Debug.Assert(_groupAggBasedExpression == null, "_groupAggBasedExpression == null");
if (_propRefs == null)
{
Debug.Assert(_varBasedExpression is DbVariableReferenceExpression, "_varBasedExpression is DbVariableReferenceExpression");
_propRefs = new List<string>(2);
_propRefs.Add(((DbVariableReferenceExpression)_varBasedExpression).VariableName);
}
_varBasedExpression = parentVarRef;
for (int i = _propRefs.Count - 1; i >= 0; --i)
{
_varBasedExpression = _varBasedExpression.Property(_propRefs[i]);
}
_propRefs.Add(parentVarRef.VariableName);
return this;
}
/// <summary>
/// Replace existing var at the head of the property chain with the new <paramref name="parentVarRef"/>.
/// </summary>
internal void ReplaceParentVar(DbVariableReferenceExpression parentVarRef)
{
//
// No parent var adjustment is allowed while adjusted to group var (see AdjustToGroupVar(...) for more info).
//
Debug.Assert(_groupVarBasedExpression == null, "_groupVarBasedExpression == null");
Debug.Assert(_groupAggBasedExpression == null, "_groupAggBasedExpression == null");
if (_propRefs == null)
{
Debug.Assert(_varBasedExpression is DbVariableReferenceExpression, "_varBasedExpression is DbVariableReferenceExpression");
_varBasedExpression = parentVarRef;
}
else
{
Debug.Assert(_propRefs.Count > 0, "_propRefs.Count > 0");
_propRefs.RemoveAt(_propRefs.Count - 1);
AddParentVar(parentVarRef);
}
}
/// <summary>
/// Rebuild the current scope entry expression as the property chain off the <paramref name="parentVarRef"/> expression.
/// Also build
/// - <see cref="IGroupExpressionExtendedInfo.GroupVarBasedExpression"/> off the <paramref name="parentGroupVarRef"/> expression;
/// - <see cref="IGroupExpressionExtendedInfo.GroupAggBasedExpression"/> off the <paramref name="groupAggRef"/> expression.
/// This adjustment is reversable by <see cref="RollbackAdjustmentToGroupVar"/>(...).
/// </summary>
internal void AdjustToGroupVar(DbVariableReferenceExpression parentVarRef, DbVariableReferenceExpression parentGroupVarRef, DbVariableReferenceExpression groupAggRef)
{
// Adjustment is not reentrant.
Debug.Assert(_groupVarBasedExpression == null, "_groupVarBasedExpression == null");
Debug.Assert(_groupAggBasedExpression == null, "_groupAggBasedExpression == null");
//
// Let's assume this entry represents variable "x" in the following query:
// select x, y, z from {1, 2} as x join {2, 3} as y on x = y join {3, 4} as z on y = z
// In this case _propRefs contains x._##join0._##join1 and the corresponding input expression looks like this:
// |_Input : '_##join1'
// | |_InnerJoin
// | |_Left : '_##join0'
// | | |_InnerJoin
// | | |_Left : 'x'
// | | |_Right : 'y'
// | |_Right : 'z'
// When we start processing a group by, like in this query:
// select k1, k2, k3 from {1, 2} as x join {2, 3} as y on x = y join {3, 4} as z on y = z group by x as k1, y as k2, z as k3
// we are switching to the following input expression:
// |_Input : '_##geb2', '_##group3'
// | |_InnerJoin
// | |_Left : '_##join0'
// | | |_InnerJoin
// | | |_Left : 'x'
// | | |_Right : 'y'
// | |_Right : 'z'
// where _##join1 is replaced by _##geb2 for the regular expression and by _##group3 for the group var based expression.
// So the switch, or the adjustment, is done by
// a. replacing _##join1 with _##geb2 in _propRefs and rebuilding the regular expression accordingly to get
// the following property chain: _##geb2._##join1.x
// b. building a group var based expression using _##group3 instead of _##geb2 to get
// the following property chain: _##group3._##join1.x
//
//
// Rebuild ScopeEntry.Expression using the new parent var.
//
ReplaceParentVar(parentVarRef);
//
// Build the GroupVarBasedExpression and GroupAggBasedExpression,
// take into account that parentVarRef has already been added to the _propRefs in the AdjustToParentVar(...) call, so ignore it.
//
_groupVarBasedExpression = parentGroupVarRef;
_groupAggBasedExpression = groupAggRef;
if (_propRefs != null)
{
for (int i = _propRefs.Count - 2/*ignore the parentVarRef*/; i >= 0; --i)
{
_groupVarBasedExpression = _groupVarBasedExpression.Property(_propRefs[i]);
_groupAggBasedExpression = _groupAggBasedExpression.Property(_propRefs[i]);
}
}
}
/// <summary>
/// Rolls back the <see cref="AdjustToGroupVar"/>(...) adjustment, clears the <see cref="IGroupExpressionExtendedInfo.GroupVarBasedExpression"/>.
/// </summary>
internal void RollbackAdjustmentToGroupVar(DbVariableReferenceExpression pregroupParentVarRef)
{
Debug.Assert(_groupVarBasedExpression != null, "_groupVarBasedExpression != null");
_groupVarBasedExpression = null;
_groupAggBasedExpression = null;
ReplaceParentVar(pregroupParentVarRef);
}
}
/// <summary>
/// Represents a group input scope entry that should no longer be referenced.
/// </summary>
internal sealed class InvalidGroupInputRefScopeEntry : ScopeEntry
{
internal InvalidGroupInputRefScopeEntry()
: base(ScopeEntryKind.InvalidGroupInputRef) { }
internal override DbExpression GetExpression(string refName, ErrorContext errCtx)
{
throw EntityUtil.EntitySqlError(errCtx, Strings.InvalidGroupIdentifierReference(refName));
}
}
/// <summary>
/// Represents group key during GROUP BY clause processing phase, used during group aggregate search mode.
/// This entry will be replaced by the <see cref="SourceScopeEntry"/> when GROUP BY processing is complete.
/// </summary>
internal sealed class GroupKeyDefinitionScopeEntry : ScopeEntry, IGroupExpressionExtendedInfo, IGetAlternativeName
{
private readonly DbExpression _varBasedExpression;
private readonly DbExpression _groupVarBasedExpression;
private readonly DbExpression _groupAggBasedExpression;
private readonly string[] _alternativeName;
internal GroupKeyDefinitionScopeEntry(
DbExpression varBasedExpression,
DbExpression groupVarBasedExpression, DbExpression
groupAggBasedExpression,
string[] alternativeName) : base(ScopeEntryKind.GroupKeyDefinition)
{
_varBasedExpression = varBasedExpression;
_groupVarBasedExpression = groupVarBasedExpression;
_groupAggBasedExpression = groupAggBasedExpression;
_alternativeName = alternativeName;
}
internal override DbExpression GetExpression(string refName, ErrorContext errCtx)
{
return _varBasedExpression;
}
DbExpression IGroupExpressionExtendedInfo.GroupVarBasedExpression
{
get
{
return _groupVarBasedExpression;
}
}
DbExpression IGroupExpressionExtendedInfo.GroupAggBasedExpression
{
get { return _groupAggBasedExpression; }
}
string[] IGetAlternativeName.AlternativeName
{
get { return _alternativeName; }
}
}
/// <summary>
/// Represents a projection item definition scope entry.
/// </summary>
internal sealed class ProjectionItemDefinitionScopeEntry : ScopeEntry
{
private readonly DbExpression _expression;
internal ProjectionItemDefinitionScopeEntry(DbExpression expression)
: base(ScopeEntryKind.ProjectionItemDefinition)
{
_expression = expression;
}
internal override DbExpression GetExpression(string refName, ErrorContext errCtx)
{
return _expression;
}
}
/// <summary>
/// Represents a free variable scope entry.
/// Example: parameters of an inline function definition are free variables in the scope of the function definition.
/// </summary>
internal sealed class FreeVariableScopeEntry : ScopeEntry
{
private readonly DbVariableReferenceExpression _varRef;
internal FreeVariableScopeEntry(DbVariableReferenceExpression varRef)
: base(ScopeEntryKind.FreeVar)
{
_varRef = varRef;
}
internal override DbExpression GetExpression(string refName, ErrorContext errCtx)
{
return _varRef;
}
}
/// <summary>
/// Represents a generic list of scopes.
/// </summary>
internal sealed class ScopeManager
{
private readonly IEqualityComparer<string> _keyComparer;
private readonly List<Scope> _scopes = new List<Scope>();
/// <summary>
/// Initialize scope manager using given key-string comparer.
/// </summary>
internal ScopeManager(IEqualityComparer<string> keyComparer)
{
_keyComparer = keyComparer;
}
/// <summary>
/// Enter a new scope.
/// </summary>
internal void EnterScope()
{
_scopes.Add(new Scope(_keyComparer));
}
/// <summary>
/// Leave the current scope.
/// </summary>
internal void LeaveScope()
{
Debug.Assert(CurrentScopeIndex >= 0);
_scopes.RemoveAt(CurrentScopeIndex);
}
/// <summary>
/// Return current scope index.
/// Outer scopes have smaller index values than inner scopes.
/// </summary>
internal int CurrentScopeIndex
{
get
{
return _scopes.Count - 1;
}
}
/// <summary>
/// Return current scope.
/// </summary>
internal Scope CurrentScope
{
get
{
return _scopes[CurrentScopeIndex];
}
}
/// <summary>
/// Get a scope by the index.
/// </summary>
internal Scope GetScopeByIndex(int scopeIndex)
{
Debug.Assert(scopeIndex >= 0, "scopeIndex >= 0");
Debug.Assert(scopeIndex <= CurrentScopeIndex, "scopeIndex <= CurrentScopeIndex");
if (0 > scopeIndex || scopeIndex > CurrentScopeIndex)
{
throw EntityUtil.EntitySqlError(Strings.InvalidScopeIndex);
}
return _scopes[scopeIndex];
}
/// <summary>
/// Rollback all scopes to the scope at the index.
/// </summary>
internal void RollbackToScope(int scopeIndex)
{
//
// assert preconditions
//
Debug.Assert(scopeIndex >= 0, "[PRE] savePoint.ScopeIndex >= 0");
Debug.Assert(scopeIndex <= CurrentScopeIndex, "[PRE] savePoint.ScopeIndex <= CurrentScopeIndex");
Debug.Assert(CurrentScopeIndex >= 0, "[PRE] CurrentScopeIndex >= 0");
if (scopeIndex > CurrentScopeIndex || scopeIndex < 0 || CurrentScopeIndex < 0)
{
throw EntityUtil.EntitySqlError(Strings.InvalidSavePoint);
}
int delta = CurrentScopeIndex - scopeIndex;
if (delta > 0)
{
_scopes.RemoveRange(scopeIndex + 1, CurrentScopeIndex - scopeIndex);
}
//
// make sure invariants are preserved
//
Debug.Assert(scopeIndex == CurrentScopeIndex, "[POST] savePoint.ScopeIndex == CurrentScopeIndex");
Debug.Assert(CurrentScopeIndex >= 0, "[POST] CurrentScopeIndex >= 0");
}
/// <summary>
/// True if key exists in current scope.
/// </summary>
internal bool IsInCurrentScope(string key)
{
return CurrentScope.Contains(key);
}
}
}
|