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
ParameterExpression vars = Expression.Parameter(typeof(object[]), "vars");
variables.Add(vars);
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++)
{
VariableDeclaration v = decl.Variables[i];
var nv = new NamedValueExpression(v.Name, v.QueryType, Expression.Convert(Expression.ArrayIndex(vars, Expression.Constant(i)), v.Expression.Type));
variableMap.Add(v.Name, nv);
}
// make sure the execution of the select stuffs the results into the new vars array
return(MakeAssign(vars, 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 ColumnAssignment VisitColumnAssignment(ColumnAssignment ca)
{
ca = base.VisitColumnAssignment(ca);
Expression expression = ca.Expression;
var nv = expression as NamedValueExpression;
if (nv != null)
{
expression = new NamedValueExpression(nv.Name, ca.Column.QueryType, nv.Value);
}
return(UpdateColumnAssignment(ca, ca.Column, expression));
}
private Expression GetNamedValue(Expression e)
{
NamedValueExpression nv;
var he = new HashedExpression(e);
if (!pmap.TryGetValue(he, out nv))
{
string name = "p" + (iParam++);
nv = new NamedValueExpression(name, language.TypeSystem.GetColumnType(e.Type), e);
pmap.Add(he, nv);
}
return(nv);
}
protected override Expression VisitColumn(ColumnExpression column)
{
if (column.Alias == outerAlias)
{
NamedValueExpression nv;
if (!map.TryGetValue(column, out nv))
{
nv = new NamedValueExpression("n" + (iParam++), column.QueryType, column);
map.Add(column, nv);
}
return(nv);
}
return(column);
}
protected override Expression VisitConstant(ConstantExpression c)
{
if (c.Value != null && !IsNumeric(c.Value.GetType()))
{
NamedValueExpression nv;
var tv = new TypeAndValue(c.Type, c.Value);
if (!map.TryGetValue(tv, out nv))
{
// re-use same name-value if same type & value
string name = "p" + (iParam++);
nv = new NamedValueExpression(name, language.TypeSystem.GetColumnType(c.Type), c);
map.Add(tv, nv);
}
return(nv);
}
return(c);
}
protected override Expression VisitBinary(BinaryExpression b)
{
Expression left = Visit(b.Left);
Expression right = Visit(b.Right);
if (left.NodeType == (ExpressionType)DbExpressionType.NamedValue && right.NodeType == (ExpressionType)DbExpressionType.Column)
{
var nv = (NamedValueExpression)left;
var c = (ColumnExpression)right;
left = new NamedValueExpression(nv.Name, c.QueryType, nv.Value);
}
else if (b.Right.NodeType == (ExpressionType)DbExpressionType.NamedValue && b.Left.NodeType == (ExpressionType)DbExpressionType.Column)
{
var nv = (NamedValueExpression)right;
var c = (ColumnExpression)left;
right = new NamedValueExpression(nv.Name, c.QueryType, nv.Value);
}
return(UpdateBinary(b, left, right, b.Conversion, b.IsLiftedToNull, b.Method));
}
protected virtual bool CompareNamedValue(NamedValueExpression a, NamedValueExpression b)
{
return(a.Name == b.Name && Compare(a.Value, b.Value));
}
protected virtual Expression VisitNamedValue(NamedValueExpression value)
{
return(value);
}
protected override Expression VisitNamedValue(NamedValueExpression value)
{
namedValues.Add(value);
return(value);
}
protected override Expression VisitNamedValue(NamedValueExpression value)
{
WriteParameterName(value.Name);
return(value);
}