Accept ints as doubles in Bson inputs

[pulewicz]

Just a draft, I'm not sure it's a good approach.

Ready for review now.

[ghik]

Hi,

I'm fine with reading INT32 as Double since every Int value fits into a Double. This is not the case with INT64 though - reading it as Double is not safe.

There are two approaches we can take here:

• only allow DOUBLE and INT32 BSON types in readDouble()
• allow other types like INT64 and DECIMAL128 but validate whether the value is a valid Double, throw exception otherwise

However, in each approach we need to look at other readX() methods and change them accordingly in order to make the behaviour of these Inputs consistent. For example, if we're accepting INT32 when reading Double, we should probably also accept INT32 and INT64 when reading BigDecimal.

If sufficient, the first approach would be preferable by me because it's much simpler to implement. Taking the second approach, i.e. making the Input implementation as lenient as possible while keeping it as safe as possible would be nice but also probably complex to implement due to the necessity of thorough validation of runtime values.

Thanks,
Roman

[pulewicz]

I'm also fine with the first approach. I updated the code to disallow Int64, I also added a test for BsonBinaryReader.