protected override ColumnAssignment VisitColumnAssignment(ColumnAssignment ca)
{
ca = base.VisitColumnAssignment(ca);
Expression expression = ca.Expression;
NamedValueExpression nv = expression as NamedValueExpression;
if (nv != null)
{
expression = new NamedValueExpression(nv.Name, ca.Column.QueryType, nv.Value);
}
return(this.UpdateColumnAssignment(ca, ca.Column, expression));
}
protected override Expression VisitMemberAccess(MemberExpression m)
{
m = (MemberExpression)base.VisitMemberAccess(m);
NamedValueExpression nv = m.Expression as NamedValueExpression;
if (nv != null)
{
Expression x = Expression.MakeMemberAccess(nv.Value, m.Member);
return(GetNamedValue(x));
}
return(m);
}
private Expression GetNamedValue(Expression e)
{
NamedValueExpression nv;
HashedExpression he = new HashedExpression(e);
if (!this.pmap.TryGetValue(he, out nv))
{
string name = "p" + (iParam++);
nv = new NamedValueExpression(name, this.language.TypeSystem.GetColumnType(e.Type), e);
this.pmap.Add(he, nv);
}
return(nv);
}
protected override Expression VisitColumn(ColumnExpression column)
{
if (column.Alias == this.outerAlias)
{
NamedValueExpression nv;
if (!this.map.TryGetValue(column, out nv))
{
nv = new NamedValueExpression("n" + (iParam++), column.QueryType, column);
this.map.Add(column, nv);
}
return(nv);
}
return(column);
}
protected override Expression VisitConstant(ConstantExpression c)
{
if (c.Value != null && !IsNumeric(c.Value.GetType()))
{
NamedValueExpression nv;
TypeAndValue tv = new TypeAndValue(c.Type, c.Value);
if (!this.map.TryGetValue(tv, out nv)) // re-use same name-value if same type & value
{
string name = "p" + (iParam++);
nv = new NamedValueExpression(name, this.language.TypeSystem.GetColumnType(c.Type), c);
this.map.Add(tv, nv);
}
return(nv);
}
return(c);
}
protected override Expression VisitBinary(BinaryExpression b)
{
Expression left = this.Visit(b.Left);
Expression right = this.Visit(b.Right);
if (left.NodeType == (ExpressionType)DbExpressionType.NamedValue &&
right.NodeType == (ExpressionType)DbExpressionType.Column)
{
NamedValueExpression nv = (NamedValueExpression)left;
ColumnExpression c = (ColumnExpression)right;
left = new NamedValueExpression(nv.Name, c.QueryType, nv.Value);
}
else if (right.NodeType == (ExpressionType)DbExpressionType.NamedValue &&
left.NodeType == (ExpressionType)DbExpressionType.Column)
{
NamedValueExpression nv = (NamedValueExpression)right;
ColumnExpression c = (ColumnExpression)left;
right = new NamedValueExpression(nv.Name, c.QueryType, nv.Value);
}
return(this.UpdateBinary(b, left, right, b.Conversion, b.IsLiftedToNull, b.Method));
}
protected override Expression VisitDeclaration(DeclarationCommand decl)
{
if (decl.Source != null)
{
// make query that returns all these declared values as an object[]
var projection = new ProjectionExpression(
decl.Source,
Expression.NewArrayInit(
typeof(object),
decl.Variables.Select(v => v.Expression.Type.IsValueType
? Expression.Convert(v.Expression, typeof(object))
: v.Expression).ToArray()
),
Aggregator.GetAggregator(typeof(object[]), typeof(IEnumerable <object[]>))
);
// create execution variable to hold the array of declared variables
var vars = Expression.Parameter(typeof(object[]), "vars");
this.variables.Add(vars);
this.initializers.Add(Expression.Constant(null, typeof(object[])));
// create subsitution for each variable (so it will find the variable value in the new vars array)
for (int i = 0, n = decl.Variables.Count; i < n; i++)
{
var v = decl.Variables[i];
NamedValueExpression nv = new NamedValueExpression(
v.Name, v.QueryType,
Expression.Convert(Expression.ArrayIndex(vars, Expression.Constant(i)), v.Expression.Type)
);
this.variableMap.Add(v.Name, nv);
}
// make sure the execution of the select stuffs the results into the new vars array
return(MakeAssign(vars, this.Visit(projection)));
}
// probably bad if we get here since we must not allow mulitple commands
throw new InvalidOperationException("Declaration query not allowed for this langauge");
}
protected override Expression VisitNamedValue(NamedValueExpression value)
{
this.namedValues.Add(value);
return(value);
}