Refactor default field resolver

[murtukov]

Q	A
Bug fix?	no
New feature?	no
BC breaks?	no
Deprecations?	yes
Tests pass?	yes
License	MIT

Made changes to the default field resolver:

• 1. Replace self with static for a better extensibility

• 2. Add checking of getters that start with has prefix (like in PropertyAccess)

• 3. Reduce function calls (micro-optimisation):

  This call:

  str_replace(' ', '', ucwords(str_replace('_', ' ', $fieldName)))

  is equal to this:

  str_replace('_', '', ucwords($fieldName, '_'))

  Additionally, PHP method names are case-insensitive, which means it is not required to call ucwords. In other words these 2 calls are equal: $object->getMyParentPosts() and $object->getmyparentposts(). So it can be reduced to a single function call:

  str_replace('_', '', $fieldName)

  ---

  Also successive calls to guessObjectMethod were replaced with a foreach loop, which is faster.

Result

As a result it saves unnecessary function calls (on each type's field):

• str_replace
• uswords
• guessObjectMethod (1 to 3 times, depending on prefix)

If user requests a collection of 200 objects with 10 fields each:

• best case (only get prefixes): 200 objects x 10 fields x 3 functions = 6000 calls saved
• worst case (only '' prefixes): 200 objects x 10 fields x 5 functions = 10000 calls saved