We used to treat dummy paths like <stdin>, <std>, <extvar> as
real import locations, which causes obvious problem for importers.
After this change we consistently pass "" (an empty string) as location
for non-imported paths.
We exposed new functions to properly handle all paths.
The first function family, EvaluateFile* which allow evaluating
a Jsonnet program at a specified importable path. It should
be used in most cases.
The second function family, EvaluateAnonymousSnippet* allows evaluating
a snippet without an importable path. It should be used for situations
like the code passed as a commandline argument, stdin, etc.
The old function family, EvaluateSnippet* is now deprecated, but
works the same as before, i.e. the passed filenames are treated
as imported paths.
Changes are required to custom importers to make sure they satisfy
the refined contract.
Fixes#329.
There is no reason for external users to directly depend
on parser. It had a few random things exported as well,
namely errors and "children" functions (helpers for AST
traversal).
It was easy to extract the errors package, but I needed to leave
children in parser for now. The errors package was also
made internal, but it's a candidate for making it public
again potentially (if someone wants to display error messages
just like us). For now it's probably too incomplete anyway.
This change has a potential of breaking the existing users
since we technically remove public APIs. These were not needed
or even helpful for actually running Jsonnet code, but perhaps
someone used them anyway.
