static Expression Equal(Expression left, Expression right)
{
List <Expression> exps = new List <Expression>();
// Variable
var l = Expression.Variable(left.Type);
var r = Expression.Variable(right.Type);
var succeeded = Expression.Variable(typeof(bool));
exps.Add(Expression.Assign(l, left));
exps.Add(Expression.Assign(r, right));
// Left -> Right
var leftToRight = TjsConvertBinder.TryConvertExpression(l, right.Type, succeeded);
if (leftToRight != null)
{
var res = Expression.Variable(right.Type);
// ((res = Convert(right, leftType, out succeeded)), succeeded && res == r)
leftToRight = Expression.Block(new[] { res },
Expression.Assign(res, leftToRight),
Expression.AndAlso(succeeded, Expression.Equal(res, r))
);
}
// Right -> Left
var rightToLeft = TjsConvertBinder.TryConvertExpression(r, left.Type, succeeded);
if (rightToLeft != null)
{
var res = Expression.Variable(left.Type);
// ((res = Convert(left, rightType, out succeeded)), succeeded && l == res)
rightToLeft = Expression.Block(new[] { res },
Expression.Assign(res, rightToLeft),
Expression.AndAlso(succeeded, Expression.Equal(l, res))
);
}
if (leftToRight == null && rightToLeft == null)
{
return(Expression.Constant(false));
}
else if (leftToRight == null)
{
exps.Add(rightToLeft);
}
else if (rightToLeft == null)
{
exps.Add(leftToRight);
}
else
{
exps.Add(Expression.OrElse(leftToRight, rightToLeft));
}
return(Expression.Block(new[] { l, r, succeeded }, exps));
}
public override Expression ConvertExpression(Expression expr, Type toType, ConversionResultKind kind, OverloadResolverFactory resolverFactory)
{
return(TjsConvertBinder.TryConvertExpression(expr, toType, null) ?? base.ConvertExpression(expr, toType, kind, resolverFactory));
}