Add object functions

[ziflex]

• KEYS(object, sort) → strArray
• HAS(object, keyName) → isPresent
  LENGTH(object) → count (Implemented here)
• MERGE(object1, object2, ... objectN) → newMergedObject
• MERGE_RECURSIVE(object1, object2, ... objectN) → newMergedObject
• VALUES(document, removeInternal) → anyArray
• ZIP(keys, values) → newObj
• KEEP(object, key1, key2, ... key) → newObj

[3timeslazy]

I wanted to work on this issue. If there is any useful additional information - I will be glad to know it.

[ziflex]

@3timeslazy great!

1. Read the documentation
2. Do not implement those methods that are related to ArangoDB Collections like IS_SAME_COLLECTION, PARSE_IDENTIFIER and etc.
3. Do not mutate values itself - return only new instances.
4. Here is an example how to create function. I will merge my work on Array functions, that will be even better reference.

Let's do the work in small chunks. 1 PR per function. It will be easier to review and track progress.

[3timeslazy]

I understand correctly that function KEYS the same with ATTRIBUTES function from the doc?
https://docs.arangodb.com/3.4/AQL/Functions/Document.html#attributes
First of all, Im interesting in the sort argument. Does it have the same purpose?

[ziflex]

@3timeslazy you are right. Pretty much the same. Go maps also do not guarantee consistent order, so the sort argument makes sense here.

[3timeslazy]

link inside #10 (comment) is no longer valid.

[ziflex]

@3timeslazy updated.

[3timeslazy]

Question about the MERGE function. The documentation supports 2 function signatures:

1. MERGE(object1, object2, ... objectN) → mergedObject
2. MERGE(objArray) → mergedObject

In this case need to implement only one (1th signature) or both?

[ziflex]

@3timeslazy let's implement both.
Just do a check for a type when you deal with an array.
Which means if any of an array elements is not an object - return None.

Here is ArangoDB's behavior.

[3timeslazy]

@ziflex OK no problem :)

[3timeslazy]

Question about VALUES function. There is optional parameter removeInternal into the doc that responsible for the internal keys (they start with _, such as _id, _key etc.). It is necessary to implement it or not?

[ziflex]

Nope, our objects do not have these properties. They are ArangoDB collections related.

[3timeslazy]

How AQL works?
1th query

2th query

3th query

[ziflex]

Looks good. Ferret has some differences in how it works.
And one of them is that RETURN statement in FQL returns expression result as it is.
Contrary to that,RETURN statement in AQL returns an expression result in array.

Maybe it was not a good decision to change the behavior but that’s how it is now.