protected virtual Expression AnalyzeConstant(Expression expression, BuilderContext builderContext)
{
// we try to find a non-constant operand, and if we do, we won't change this expression
foreach (var operand in expression.GetOperands())
{
if (!(operand is ConstantExpression))
return expression;
}
// now, we just simply return a constant with new value
try
{
var optimizedExpression = Expression.Constant(expression.Evaluate());
// sometimes, optimizing an expression changes its type, and we just can't allow this.
if (optimizedExpression.Type == expression.Type)
return optimizedExpression;
}
// if we fail to evaluate the expression, then just return it
catch (ArgumentException) { }
return expression;
}
protected virtual SqlStatement BuildSelect(Expression select, QueryContext queryContext)
{
var sqlProvider = queryContext.DataContext.Vendor.SqlProvider;
var selectClauses = new List<SqlStatement>();
foreach (var selectExpression in select.GetOperands())
{
var expressionString = BuildExpression(selectExpression, queryContext);
if (selectExpression is SelectExpression)
selectClauses.Add(sqlProvider.GetParenthesis(expressionString));
else
selectClauses.Add(expressionString);
}
SelectExpression selectExp = select as SelectExpression;
if (selectExp != null)
{
if (selectExp.Group.Count == 1 && selectExp.Group[0].GroupedExpression == selectExp.Group[0].KeyExpression)
{
// this is a select DISTINCT expression
// TODO: better handle selected columns on DISTINCT: I suspect this will not work in some cases
if (selectClauses.Count == 0)
{
selectClauses.Add(sqlProvider.GetColumns());
}
return sqlProvider.GetSelectDistinctClause(selectClauses.ToArray());
}
}
return sqlProvider.GetSelectClause(selectClauses.ToArray());
}
/// <summary>
/// The simple part: converts an expression to SQL
/// This is not used for FROM clause
/// </summary>
/// <param name="expression"></param>
/// <param name="queryContext"></param>
/// <returns></returns>
protected virtual SqlStatement BuildExpression(Expression expression, QueryContext queryContext)
{
var sqlProvider = queryContext.DataContext.Vendor.SqlProvider;
var currentPrecedence = ExpressionQualifier.GetPrecedence(expression);
// first convert operands
var operands = expression.GetOperands();
var literalOperands = new List<SqlStatement>();
foreach (var operand in operands)
{
var operandPrecedence = ExpressionQualifier.GetPrecedence(operand);
var literalOperand = BuildExpression(operand, queryContext);
if (operandPrecedence > currentPrecedence)
literalOperand = sqlProvider.GetParenthesis(literalOperand);
literalOperands.Add(literalOperand);
}
// then converts expression
if (expression is SpecialExpression)
return sqlProvider.GetLiteral(((SpecialExpression)expression).SpecialNodeType, literalOperands);
if (expression is EntitySetExpression)
expression = ((EntitySetExpression)expression).TableExpression;
if (expression is TableExpression)
{
var tableExpression = (TableExpression)expression;
if (tableExpression.Alias != null) // if we have an alias, use it
{
return sqlProvider.GetColumn(sqlProvider.GetTableAlias(tableExpression.Alias),
sqlProvider.GetColumns());
}
return sqlProvider.GetColumns();
}
if (expression is ColumnExpression)
{
var columnExpression = (ColumnExpression)expression;
if (columnExpression.Table.Alias != null)
{
return sqlProvider.GetColumn(sqlProvider.GetTableAlias(columnExpression.Table.Alias),
columnExpression.Name);
}
return sqlProvider.GetColumn(columnExpression.Name);
}
if (expression is InputParameterExpression)
{
var inputParameterExpression = (InputParameterExpression)expression;
if (expression.Type.IsArray)
{
int i = 0;
List<SqlStatement> inputParameters = new List<SqlStatement>();
foreach (object p in (Array)inputParameterExpression.GetValue())
{
inputParameters.Add(new SqlStatement(new SqlParameterPart(sqlProvider.GetParameterName(inputParameterExpression.Alias + i.ToString()),
inputParameterExpression.Alias + i.ToString())));
++i;
}
return new SqlStatement(sqlProvider.GetLiteral(inputParameters.ToArray()));
}
return
new SqlStatement(new SqlParameterPart(sqlProvider.GetParameterName(inputParameterExpression.Alias),
inputParameterExpression.Alias));
}
if (expression is SelectExpression)
return Build((SelectExpression)expression, queryContext);
if (expression is ConstantExpression)
return sqlProvider.GetLiteral(((ConstantExpression)expression).Value);
if (expression is GroupExpression)
return BuildExpression(((GroupExpression)expression).GroupedExpression, queryContext);
StartIndexOffsetExpression indexExpression = expression as StartIndexOffsetExpression;
if (indexExpression!=null)
{
if (indexExpression.StartsAtOne)
{
literalOperands.Add(BuildExpression(Expression.Constant(1), queryContext));
return sqlProvider.GetLiteral(ExpressionType.Add, literalOperands);
}
else
return literalOperands.First();
}
if (expression.NodeType == ExpressionType.Convert || expression.NodeType == ExpressionType.ConvertChecked)
{
var unaryExpression = (UnaryExpression)expression;
var firstOperand = literalOperands.First();
if (IsConversionRequired(unaryExpression))
return sqlProvider.GetLiteralConvert(firstOperand, unaryExpression.Type);
return firstOperand;
}
return sqlProvider.GetLiteral(expression.NodeType, literalOperands);
}
/// <summary>
/// Cuts tiers in CLR / SQL.
/// The search for cut is top-down
/// </summary>
/// <param name="expression"></param>
/// <param name="dataRecordParameter"></param>
/// <param name="mappingContextParameter"></param>
/// <param name="builderContext"></param>
/// <returns></returns>
protected virtual Expression CutOutOperands(Expression expression,
ParameterExpression dataRecordParameter, ParameterExpression mappingContextParameter,
BuilderContext builderContext)
{
// two options: we cut and return
if (GetCutOutOperand(expression, builderContext))
{
// "cutting out" means we replace the current expression by a SQL result reader
// before cutting out, we check that we're not cutting a table
// in this case, we convert it into its declared columns
if (expression is TableExpression)
{
return GetOutputTableReader((TableExpression)expression, dataRecordParameter,
mappingContextParameter, builderContext);
}
// for EntitySets, we have a special EntitySet builder
if (expression is EntitySetExpression)
{
return GetEntitySetBuilder((EntitySetExpression) expression, dataRecordParameter,
mappingContextParameter, builderContext);
// TODO record EntitySet information, so we can initalize it with owner
}
// then, the result is registered
return GetOutputValueReader(expression, dataRecordParameter, mappingContextParameter, builderContext);
}
// or we dig down
var operands = new List<Expression>();
foreach (var operand in expression.GetOperands())
{
operands.Add(operand == null
? null
: CutOutOperands(operand, dataRecordParameter, mappingContextParameter, builderContext));
}
return expression.ChangeOperands(operands);
}
protected virtual Expression AnalyzeNull(Expression expression, BuilderContext builderContext)
{
// this first test only to speed up things a little
if (expression.NodeType == ExpressionType.Equal || expression.NodeType == ExpressionType.NotEqual)
{
var operands = expression.GetOperands().ToList();
var nullComparison = GetNullComparison(expression.NodeType, operands[0], operands[1]);
if (nullComparison == null)
nullComparison = GetNullComparison(expression.NodeType, operands[1], operands[0]);
if (nullComparison != null)
return nullComparison;
return expression;
}
return expression;
}
protected virtual Expression AnalyzeConstant(Expression expression, BuilderContext builderContext)
{
// we try to find a non-constant operand, and if we do, we won't change this expression
foreach (var operand in expression.GetOperands())
{
if (!(operand is ConstantExpression))
return expression;
}
if (expression.NodeType == ExpressionType.Parameter)
return expression;
if (expression.NodeType == (ExpressionType)SpecialExpressionType.Like)
return expression;
// SETuse
// If the value of the first SpecialExpressionType change this 999 should change too
if ((short)expression.NodeType > 999)
return expression;
// now, we just simply return a constant with new value
try
{
var optimizedExpression = Expression.Constant(expression.Evaluate());
// sometimes, optimizing an expression changes its type, and we just can't allow this.
if (optimizedExpression.Type == expression.Type)
return optimizedExpression;
}
// if we fail to evaluate the expression, then just return it
catch (ArgumentException)
{
return expression;
}
return expression;
}
protected virtual string BuildSelect(Expression select, QueryContext queryContext)
{
var sqlProvider = queryContext.DataContext.Vendor.SqlProvider;
var selectClauses = new List<string>();
foreach (var selectExpression in select.GetOperands())
{
selectClauses.Add(BuildExpression(selectExpression, queryContext));
}
return sqlProvider.GetSelectClause(selectClauses.ToArray());
}
/// <summary>
/// The simple part: converts an expression to SQL
/// This is not used for FROM clause
/// </summary>
/// <param name="expression"></param>
/// <param name="queryContext"></param>
/// <returns></returns>
protected virtual string BuildExpression(Expression expression, QueryContext queryContext)
{
var sqlProvider = queryContext.DataContext.Vendor.SqlProvider;
var currentPrecedence = ExpressionQualifier.GetPrecedence(expression);
// first convert operands
var operands = expression.GetOperands();
var literalOperands = new List<string>();
foreach (var operand in operands)
{
var operandPrecedence = ExpressionQualifier.GetPrecedence(operand);
string literalOperand = BuildExpression(operand, queryContext);
if (operandPrecedence > currentPrecedence)
literalOperand = sqlProvider.GetParenthesis(literalOperand);
literalOperands.Add(literalOperand);
}
// then converts expression
if (expression is SpecialExpression)
return sqlProvider.GetLiteral(((SpecialExpression)expression).SpecialNodeType, literalOperands);
if (expression is TableExpression)
{
var tableExpression = (TableExpression)expression;
if (tableExpression.Alias != null) // if we have an alias, use it
{
return sqlProvider.GetColumn(sqlProvider.GetTableAlias(tableExpression.Alias),
sqlProvider.GetColumns());
}
return sqlProvider.GetColumns();
}
if (expression is ColumnExpression)
{
var columnExpression = (ColumnExpression)expression;
if (columnExpression.Table.Alias != null)
{
return sqlProvider.GetColumn(sqlProvider.GetTableAlias(columnExpression.Table.Alias),
columnExpression.Name);
}
return sqlProvider.GetColumn(columnExpression.Name);
}
if (expression is InputParameterExpression)
return sqlProvider.GetParameterName(((InputParameterExpression)expression).Alias);
if (expression is SelectExpression)
return Build((SelectExpression)expression, queryContext);
if (expression is ConstantExpression)
return sqlProvider.GetLiteral(((ConstantExpression)expression).Value);
if (expression is GroupExpression)
return BuildExpression(((GroupExpression)expression).GroupedExpression, queryContext);
if (expression.NodeType == ExpressionType.Convert || expression.NodeType == ExpressionType.ConvertChecked)
return sqlProvider.GetLiteralConvert(literalOperands.First(), (expression as UnaryExpression).Type);
return sqlProvider.GetLiteral(expression.NodeType, literalOperands);
}
protected virtual Expression AnalyzeOperands(Expression expression, TranslationContext context)
{
var operands = expression.GetOperands().ToList();
var newOperands = new List<Expression>();
for (int operandIndex = 0; operandIndex < operands.Count; operandIndex++)
{
var op = operands[operandIndex];
var newOp = Analyze(op, context);
newOperands.Add(newOp);
}
return expression.ChangeOperands(newOperands, operands);
}
// TODO: (RI:) should be removed most likely
protected Expression AnalyzeTimeSpanMemberAccess(Expression objectExpression, MemberInfo memberInfo)
{
//A timespan expression can be only generated in a c# query as a DateTime difference, as a function call return or as a paramter
//this case is for the DateTime difference operation
if (!(objectExpression is BinaryExpression))
throw new NotSupportedException();
var operands = objectExpression.GetOperands();
bool absoluteSpam = memberInfo.Name.StartsWith("Total");
string operationKey = absoluteSpam ? memberInfo.Name.Substring(5) : memberInfo.Name;
Expression currentExpression;
switch (operationKey)
{
case "Milliseconds":
currentExpression = Expression.Convert(CreateSqlFunction(SqlFunctionType.DateDiffInMilliseconds, operands.First(), operands.ElementAt(1)), typeof(double));
break;
case "Seconds":
currentExpression = Expression.Divide(
Expression.Convert(CreateSqlFunction(SqlFunctionType.DateDiffInMilliseconds, operands.First(), operands.ElementAt(1)), typeof(double)),
Expression.Constant(1000.0));
break;
case "Minutes":
currentExpression = Expression.Divide(
Expression.Convert(CreateSqlFunction(SqlFunctionType.DateDiffInMilliseconds, operands.First(), operands.ElementAt(1)), typeof(double)),
Expression.Constant(60000.0));
break;
case "Hours":
currentExpression = Expression.Divide(
Expression.Convert(CreateSqlFunction(SqlFunctionType.DateDiffInMilliseconds, operands.First(), operands.ElementAt(1)), typeof(double)),
Expression.Constant(3600000.0));
break;
case "Days":
currentExpression = Expression.Divide(
Expression.Convert(CreateSqlFunction(SqlFunctionType.DateDiffInMilliseconds, operands.First(), operands.ElementAt(1)), typeof(double)),
Expression.Constant(86400000.0));
break;
default:
throw new NotSupportedException(string.Format("The operation {0} over the TimeSpan isn't currently supported", memberInfo.Name));
}
if (!absoluteSpam)
{
switch (memberInfo.Name)
{
case "Milliseconds":
currentExpression = Expression.Convert(Expression.Modulo(Expression.Convert(currentExpression, typeof(long)), Expression.Constant(1000L)), typeof(int));
break;
case "Seconds":
currentExpression = Expression.Convert(Expression.Modulo(Expression.Convert(currentExpression, typeof(long)),
Expression.Constant(60L)), typeof(int));
break;
case "Minutes":
currentExpression = Expression.Convert(Expression.Modulo(Expression.Convert(currentExpression, typeof(long)),
Expression.Constant(60L)), typeof(int));
break;
case "Hours":
currentExpression = Expression.Convert(Expression.Modulo(Expression.Convert(
currentExpression, typeof(long)),
Expression.Constant(24L)), typeof(int));
break;
case "Days":
currentExpression = Expression.Convert(currentExpression, typeof(int));
break;
}
}
return currentExpression;
}
protected virtual Expression CutOutSqlTier(Expression expression,
ParameterExpression dataRecordParameter, ParameterExpression sessionParameter,
Type expectedType,
TranslationContext context)
{
expectedType = expectedType ?? expression.Type;
// two options: we cut and return
if (IsSqlTier(expression, context))
{
// "cutting out" means we replace the current expression by a SQL result reader
// before cutting out, we check that we're not cutting a table in this case, we convert it into its declared columns
if (expression is TableExpression)
// RI: entity reader comes here
return GetOutputTableReader((TableExpression)expression, dataRecordParameter,
sessionParameter, context);
// RI: single-value result goes here
return GetOutputValueReader(expression, expectedType, dataRecordParameter, sessionParameter, context);
}
// RI: Anon types, custom types go here
var newOperands = new List<Expression>();
var operands = expression.GetOperands();
var argTypes = expression.GetArgumentTypes();
for(int i = 0; i < operands.Count; i++ ) {
var op = operands[i];
var newOp = op == null ? null : CutOutSqlTier(op, dataRecordParameter, sessionParameter, argTypes[i], context);
newOperands.Add(newOp);
}
Expression newExpr;
if (expression is MetaTableExpression)
//Joins go here
newExpr = ((MetaTableExpression)expression).ConvertToNew(newOperands);
else
newExpr = expression.ChangeOperands(newOperands, operands);
return newExpr;
}
protected virtual SqlStatement BuildExpression(Expression expression)
{
if (expression is ConstantExpression)
return _sqlProvider.GetLiteral(((ConstantExpression)expression).Value);
var currentPrecedence = ExpressionUtil.GetPrecedence(expression);
// first convert operands
var operands = expression.GetOperands();
var literalOperands = new List<SqlStatement>();
foreach (var operand in operands)
{
var operandPrecedence = ExpressionUtil.GetPrecedence(operand);
var literalOperand = BuildExpression(operand);
if (operandPrecedence > currentPrecedence)
literalOperand = _sqlProvider.GetParenthesis(literalOperand);
literalOperands.Add(literalOperand);
}
if (expression is AliasedExpression) {
var aliasExpr = (AliasedExpression) expression;
return BuildExpression(aliasExpr.Expression); //Alias will be added later
}
// then converts expression
if (expression is SqlFunctionExpression) {
var specExpr = (SqlFunctionExpression)expression;
//RI: Special case for multiple "*" operands
if (specExpr.FunctionType == SqlFunctionType.Count && literalOperands.Count > 0) {
literalOperands.Clear();
literalOperands.Add("*");
}
return _sqlProvider.GetSqlFunction(specExpr.FunctionType, specExpr.ForceIgnoreCase, literalOperands);
}
if (expression is TableExpression)
{
var tableExpression = (TableExpression)expression;
if (tableExpression.Alias != null) // if we have an alias, use it
{
return _sqlProvider.GetColumn(_sqlProvider.GetTableAlias(tableExpression.Alias),
_sqlProvider.GetColumns());
}
return _sqlProvider.GetColumns();
}
//RI: We might have NewExpression here! Query: (from b in books select new {b.Title}).Count();
// in this case the NewExpression is 'hidden' inside subquery and it is not visible to CutOutOperands
// We just return list of arguments (columns) of New expression
if (expression is NewExpression)
return new SqlStatement(literalOperands);
//RI: adding this
if (expression is MetaTableExpression) {
var metaTable = (MetaTableExpression)expression;
return _sqlProvider.GetColumns();
}
if (expression is ColumnExpression)
{
var columnExpression = (ColumnExpression)expression;
if(columnExpression.Table.Alias != null)
{
return _sqlProvider.GetColumn(_sqlProvider.GetTableAlias(columnExpression.Table.Alias),
columnExpression.Name);
}
//RI: changed this to keep output type
var sqlPart = new SqlLiteralPart(_sqlProvider.GetColumn(columnExpression.Name), expression.Type);
return new SqlStatement(sqlPart);
//return _sqlProvider.GetColumn(columnExpression.Name);
}
if (expression is ExternalValueExpression) {
var extValue = (ExternalValueExpression)expression;
switch(extValue.SqlUse) {
case ExternalValueSqlUse.Literal:
var sql = _sqlProvider.GetLiteral(extValue.LiteralValue);
return sql;
case ExternalValueSqlUse.Parameter:
// In SQL templates the first 2 args are reserved for { and } symbols
return _sqlProvider.GetParameter(extValue);
default:
// we should never get here
Util.Throw("LINQ engine error: encountered ExternalValueExpression with invalid Usage type: {0}, Expression: {1}",
extValue.SqlUse, extValue.SourceExpression);
return null; //never happens
}
}
if (expression is SelectExpression)
return BuildSelectSql((SelectExpression)expression);
if (expression is GroupExpression)
return BuildExpression(((GroupExpression)expression).GroupedExpression);
StartIndexOffsetExpression indexExpression = expression as StartIndexOffsetExpression;
if (indexExpression!=null)
{
if (indexExpression.StartsAtOne)
{
literalOperands.Add(BuildExpression(Expression.Constant(1)));
return _sqlProvider.GetLiteral(ExpressionType.Add, literalOperands);
}
else
return literalOperands.First();
}
if (expression.NodeType == ExpressionType.Convert || expression.NodeType == ExpressionType.ConvertChecked)
{
var unaryExpression = (UnaryExpression)expression;
var firstOperand = literalOperands.First();
if (IsConversionRequired(unaryExpression))
return _sqlProvider.GetLiteralConvert(firstOperand, unaryExpression.Type);
return firstOperand;
}
if (expression is BinaryExpression || expression is UnaryExpression)
return _sqlProvider.GetLiteral(expression.NodeType, literalOperands);
if (expression is TableFilterExpression)
return _sqlProvider.GetTableFilter((TableFilterExpression)expression);
return _sqlProvider.GetLiteral(expression.NodeType, literalOperands);
}
protected virtual SqlStatement BuildSelectClause(Expression select)
{
var selectClauses = new List<SqlStatement>();
var ops = select.GetOperands().ToList();
foreach(var outputExpr in ops) {
var exprString = BuildOutputExpression(outputExpr);
selectClauses.Add(exprString);
}
SelectExpression selectExp = select as SelectExpression;
if(selectExp != null) {
if(selectExp.Group.Count == 1 && selectExp.Group[0].IsDistinct) {
//RI: changed code
var g = selectExp.Group[0];
var outCols = new List<SqlStatement>();
foreach(var col in g.Columns) {
var sqlCol = col.Table.Alias == null ?
_sqlProvider.GetColumn(col.Name) :
_sqlProvider.GetColumn(_sqlProvider.GetTableAlias(col.Table.Alias), col.Name);
if(!string.IsNullOrEmpty(col.Alias))
sqlCol += " AS " + col.Alias;
outCols.Add(sqlCol);
}
return _sqlProvider.GetSelectDistinctClause(outCols.ToArray());
/*
// this is a select DISTINCT expression
// TODO: better handle selected columns on DISTINCT: I suspect this will not work in some cases
if (selectClauses.Count == 0)
{
selectClauses.Add(_sqlProvider.GetColumns());
}
return _sqlProvider.GetSelectDistinctClause(selectClauses.ToArray());
*/
}
}
return _sqlProvider.GetSelectClause(selectClauses.ToArray());
}
