public ComparisonExpression(ComparisonParamExpression param, ComparisonValueExpression value, string @operator)
{
Require.NotNull(param, "param");
Require.NotNull(value, "value");
Require.NotNullOrEmpty(@operator, "operator");
Param = param;
Value = value;
Operator = @operator;
}
public ComparisonExpression(ComparisonParamExpression param, ComparisonValueExpression value, string @operator)
{
Require.NotNull(param, "param");
Require.NotNull(value, "value");
Require.NotNullOrEmpty(@operator, "operator");
Param = param;
Value = value;
Operator = @operator;
}
protected virtual void Visit(ComparisonParamExpression exp)
{
}
void IExpressionVisitor.Visit(ComparisonParamExpression exp)
{
Visit(exp);
}
void IExpressionVisitor.Visit(ComparisonParamExpression exp)
{
Visit(exp);
}
protected virtual void Visit(ComparisonParamExpression exp)
{
}
// comparison : identifier comparison_op param_value
private Expression Comparison()
{
using (var lookahead = _tokenzier.BeginLookahead())
{
var sourceLocation = _tokenzier.CurrentLocation;
var paramName = _tokenzier.NextToken();
if (paramName == null)
{
return null;
}
if (paramName.Kind != TokenKind.Identifier)
{
_context.AddError("Expected identifier.", sourceLocation);
return null;
}
sourceLocation = _tokenzier.CurrentLocation;
var op = _tokenzier.NextToken();
if (op == null || (op.Kind != TokenKind.ComparisonOperator && op.Kind != TokenKind.Identifier) || !_context.RegisteredComparisonOperators.Contains(op.Value))
{
_context.AddError("Missing comparison operator after the parameter name.", sourceLocation);
return null;
}
sourceLocation = _tokenzier.CurrentLocation;
var value = ComparisonValue();
if (value == null)
{
_context.AddError("Missing parameter value.", sourceLocation);
return null;
}
lookahead.Accept();
var param = new ComparisonParamExpression(paramName.Value);
return new ComparisonExpression(param, value, op.Value);
}
}