private AqlExpression VisitUnary(UnaryExpression node)
{
AqlExpression operand = Visit(node.Operand);
switch (node.NodeType)
{
case ExpressionType.Convert:
case ExpressionType.ConvertChecked:
// ignore the cast, because AQL does not support casts
return(operand);
case ExpressionType.UnaryPlus:
return(new AqlUnaryOperator(
operand,
AqlExpressionType.UnaryPlus
));
case ExpressionType.Negate:
case ExpressionType.NegateChecked:
return(new AqlUnaryOperator(
operand,
AqlExpressionType.UnaryMinus
));
case ExpressionType.Not:
return(new AqlUnaryOperator(
operand,
AqlExpressionType.Not
));
}
throw new AqlParsingException(
$"Cannot parse node {node.NodeType} - not implemented"
);
}
public AqlBinaryOperator(
AqlExpression left,
AqlExpression right,
AqlExpressionType type
)
{
if (
type != AqlExpressionType.Add &&
type != AqlExpressionType.Subtract &&
type != AqlExpressionType.Multiply &&
type != AqlExpressionType.Divide &&
type != AqlExpressionType.Modulo &&
type != AqlExpressionType.Equal &&
type != AqlExpressionType.NotEqual &&
type != AqlExpressionType.GreaterThan &&
type != AqlExpressionType.GreaterThanOrEqual &&
type != AqlExpressionType.LessThan &&
type != AqlExpressionType.LessThanOrEqual &&
type != AqlExpressionType.And &&
type != AqlExpressionType.Or
)
{
throw new ArgumentException(
$"Provided expression type {type} is not a binary operation"
);
}
ExpressionType = type;
Left = left;
Right = right;
Parameters = new ReadOnlyCollection <string>(
left.Parameters.Union(right.Parameters).ToList()
);
}
/// <summary>
/// Parse an expression tree directly, without the lambda wrapper
/// </summary>
public AqlExpression ParseExpression(Expression expression)
{
// simplify parts that have no parameters
Expression demungified = demungifier.Demungify(expression);
// convert to AQL expression
AqlExpression converted = converter.Convert(demungified);
return(converted);
}
public AqlJsonObjectExpression Add(string key, AqlExpression expression)
{
if (expression.Parameters.Count > 0)
{
parameters = new ReadOnlyCollection <string>(
parameters.Union(expression.Parameters).ToList()
);
}
Items.Add(key, expression);
return(this);
}
public AqlMemberAccessExpression(
AqlExpression subject,
AqlExpression member
)
{
Subject = subject;
Member = member;
Parameters = new ReadOnlyCollection <string>(
Subject.Parameters.Union(Member.Parameters).ToList()
);
}
public AqlUnaryOperator(AqlExpression operand, AqlExpressionType type)
{
if (
type != AqlExpressionType.UnaryPlus &&
type != AqlExpressionType.UnaryMinus &&
type != AqlExpressionType.Not
)
{
throw new ArgumentException(
$"Provided expression type {type} is not an unary operation"
);
}
ExpressionType = type;
Operand = operand;
}
private AqlExpression VisitCall(MethodCallExpression node)
{
AqlExpression instance = Visit(node.Object);
List <AqlExpression> args = node.Arguments
.Select(Visit)
.ToList();
// === handle arango functions ===
ArangoFunctionAttribute attribute = node.Method
.GetCustomAttribute <ArangoFunctionAttribute>();
if (attribute != null)
{
return(new AqlFunctionExpression(attribute, args));
}
// === intercept indexing on JSON objects and arrays ===
if (possibleIndexerMethods.Contains(node.Method) &&
args.Count == 1)
{
return(new AqlMemberAccessExpression(
instance,
args[0]
));
}
// === handle JSON object construction ===
// if we call .Add on a JsonObject instance
if (node.Object?.Type == typeof(JsonObject) &&
node.Method.Name == "Add")
{
// start construction
if (instance is AqlConstantExpression constant)
{
instance = new AqlJsonObjectExpression(constant.Value);
}
// continue construction
if (instance is AqlJsonObjectExpression obj)
{
return(obj.CallAddViaArgs(args));
}
}
// === handle JSON array construction ===
// if we call .Add on a JsonArray instance
if (node.Object?.Type == typeof(JsonArray) &&
node.Method.Name == "Add")
{
// start construction
if (instance is AqlConstantExpression constant)
{
instance = new AqlJsonArrayExpression(constant.Value);
}
// continue construction
if (instance is AqlJsonArrayExpression arr)
{
return(arr.CallAddViaArgs(args));
}
}
// === expression is invalid ===
throw new AqlParsingException(
$"Expression uses parameters in method '{node.Method}'" +
", but this method cannot be translated to AQL"
);
}
private AqlExpression VisitBinary(BinaryExpression node)
{
AqlExpression left = Visit(node.Left);
AqlExpression right = Visit(node.Right);
switch (node.NodeType)
{
case ExpressionType.Add:
case ExpressionType.AddChecked:
if (node.Left.Type == typeof(string) ||
node.Right.Type == typeof(string))
{
return(new AqlFunctionExpression(
"CONCAT", left, right
));
}
return(new AqlBinaryOperator(
left, right, AqlExpressionType.Add
));
case ExpressionType.Subtract:
case ExpressionType.SubtractChecked:
return(new AqlBinaryOperator(
left, right, AqlExpressionType.Subtract
));
case ExpressionType.Multiply:
case ExpressionType.MultiplyChecked:
return(new AqlBinaryOperator(
left, right, AqlExpressionType.Multiply
));
case ExpressionType.Divide:
return(new AqlBinaryOperator(
left, right, AqlExpressionType.Divide
));
case ExpressionType.Modulo:
return(new AqlBinaryOperator(
left, right, AqlExpressionType.Modulo
));
case ExpressionType.Equal:
return(new AqlBinaryOperator(
left, right, AqlExpressionType.Equal
));
case ExpressionType.NotEqual:
return(new AqlBinaryOperator(
left, right, AqlExpressionType.NotEqual
));
case ExpressionType.GreaterThan:
return(new AqlBinaryOperator(
left, right, AqlExpressionType.GreaterThan
));
case ExpressionType.GreaterThanOrEqual:
return(new AqlBinaryOperator(
left, right,
AqlExpressionType.GreaterThanOrEqual
));
case ExpressionType.LessThan:
return(new AqlBinaryOperator(
left, right, AqlExpressionType.LessThan
));
case ExpressionType.LessThanOrEqual:
return(new AqlBinaryOperator(
left, right,
AqlExpressionType.LessThanOrEqual
));
case ExpressionType.And:
case ExpressionType.AndAlso:
return(new AqlBinaryOperator(
left, right, AqlExpressionType.And
));
case ExpressionType.Or:
case ExpressionType.OrElse:
return(new AqlBinaryOperator(
left, right, AqlExpressionType.Or
));
}
throw new AqlParsingException(
$"Cannot convert node {node.NodeType} - not implemented"
);
}
