Fragment Implementation

[shalarewicz]

Summary

• Adds support for fragments and inline fragments on interfaces and unions.
• Refactor AST functions to allow fragment complexities to be stored in closure.
• Refactors fieldNode function to improve error handling
• Refactors buildTypeWeights process and object to better hanlde union types. Shared field types are now added to both the parent Union type and the child types. Matches are determined by field name and resolved type. There is a task to make the test suite for union types more robust and better handle cases when lists and non-null operators are involved.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Issues

• closes Complexity algorithm should work with fragments #44
• closes Undefined fieldWeight throws an error during complexity anlaysis #59

Evidence

• Inline fragments on interfaces and union tests are passing
• Fragment Definition tests are passing

[shalarewicz]

• Rename ASTnodefunctions to ASTParser. I held off on this to maintain readability of the file diffs.

[evanmcneely]

This is all really good. I think it would be good for future contributors if the comments were more clear. Right now the comments don't help me understand the code any better.

[evanmcneely]

This is good and a big step in functionality.