Self-Referential Substitutions don't work about cpp-hocon

[MikaelSmith]

The implementation is incomplete. I would appreciate any help finishing it for those cases.

[troizky]

Even the simplest testcase does not work:

  "a": {
    "b": 27
  },
  "obj": ${a}
  "val": ${obj.b}

Maybe this one is easier to fix?

[MikaelSmith]

That is likely HC-73. I'll take a quick look to see if I can figure out what's wrong, but don't have a ton of time to spend on it before I'm on vacation for 2 weeks.

[MikaelSmith]

This library was implemented to closely mirror the structure of https://github.com/lightbend/config. So tracing the exception I get with your simple test case back to https://github.com/puppetlabs/cpp-hocon/blob/master/lib/src/values/config_reference.cc#L75 and comparing to https://github.com/lightbend/config/blob/master/config/src/main/java/com/typesafe/config/impl/ConfigReference.java#L70, it looks like the fallback code at https://github.com/puppetlabs/cpp-hocon/blob/master/lib/src/values/config_reference.cc#L61 wasn't implemented. I'll try that out.

[MikaelSmith]

It looks like this might have actually been fixed recently in config v1.3.2. So there's some work to incorporate the fixes added. Update: I might be jumping to conclusions here; but this is the area where a fix will probably be needed. If it's not a fix in config 1.3.2, then the lookup_subst is failing somehow.

[troizky]

I've found bug in https://github.com/puppetlabs/cpp-hocon/blob/master/lib/src/values/simple_config_object.cc#L32, must be checking for non-empty.
Corresponding line in Java project: https://github.com/lightbend/config/blob/master/config/src/main/java/com/typesafe/config/impl/SimpleConfigObject.java#L364
Unfortunately 2 test cases are failing now...

[troizky]

Also found that method config_delayed_merge_object::resolve_substitutions was not implemented like here: https://github.com/lightbend/config/blob/master/config/src/main/java/com/typesafe/config/impl/ConfigDelayedMergeObject.java#L53

After fixing that I'm getting an exception 'should not be reached (merging non-simple_config_object)' in simple_config_object::merged_with_object on parsing following config:

    a = {aa = mama, bb = mia}
    b = ${a}
    b.aa = mea
    # below is failing
    b.bb = culpa

[troizky]

One more bug in https://github.com/puppetlabs/cpp-hocon/blob/master/lib/inc/internal/values/config_delayed_merge_object.hpp#L10, class config_delayed_merge_object did not inherit from class unmergeable like here: https://github.com/lightbend/config/blob/master/config/src/main/java/com/typesafe/config/impl/ConfigDelayedMergeObject.java#L21

[troizky]

Here is my suggested patch:
cpp-hocon.patch.gz

[troizky]

Open Merge Request #106

[MikaelSmith]

Thanks for digging into this! I'll work on reviewing the PRs.