ZON parsing in std

griush · June 15, 2024, 7:45am

I’ve seen the std.zig.Parse.parseZon function in the std lib, however, I was wondering if there are plans for the future to implement more robust functionality for zon files, like a more high level reading and emitting structs to files.

Thanks.

squeek502 · June 15, 2024, 8:28am

github.com/ziglang/zig

ZON

ziglang:master ← MasonRemaley:zon

opened 01:14AM - 12 Jun 24 UTC

MasonRemaley

+6548 -158

# ZON This PR implements ZON, or Zig Object Format (think JSON, but with Zig sy…ntax instead of Javascript.) In particular, it implements: * Runtime parsing of ZON data * Runtime stringification of ZON data * Compile time importing of ZON data A lot of files are added since I added a lot of test cases, the bulk of the work is in `Module.zig` and `lib/std/zon`. If there's anything I can do to make this easier to review, let me know. Tests cover all new features. ## Runtime The runtime code can be found at `lib/std/zon`. ### Parsing `lib/std/zon/parse.zig` Detailed doc comments are provided in the source. At a high level, this module provides the following functions and some configuration options: * `parseFromSlice` * `parseFromAst` * `parseFromAstNoAlloc` * `parseFromAstNode` * `parseFromAstNodeNoAlloc` * `parseFree` Most people will just want `parseFromSlice` and maybe `parseFree`, but the more fine grained functions are available for those who need them. ### Stringify `lib/std/zon/stringify.zig` Detailed doc comments are provided in the source. At a high level, this module provides the following functions and some configuration options: * `stringify` * `stringifyMaxDepth` * `stringifyArbitraryDepth` * `stringifier` Most users will just need stringify, or one of its variants. However, `stringifier` returns a much more fine grained interface that is used in the implementation of the other functions. It may be used directly if you need to serialize something piece by piece--perhaps to apply different configuration to different parts of the value, or because the value does not actually exist laid out in memory in the same form in which you want to stringify it. ## Compile Time Almost all of the logic for this is in `Module.zig`. This PR also implements importing ZON at compile time: ```zig const Foo = @import("foo.zon"); ``` ## Things that will probably change... ### `&` In ZON syntax Right now, ZON slices need to be prefixed with `&` to distinguish them from tuples. This is necessary because we don't know the result type when importing. In the future I think ZON should not distinguish between tuples and slices, it should just coerce to whatever the destination type is. * [ ] After this PR is merged I'll file an issue to track this. ### Untagged nonexhaustive enum values not yet supported Zig does not currently have a way to represent an untagged enum value as a literal, and as such there's no way to represent one in ZON. We could resolve this by adding a syntax for untagged enum literals to Zig, or by allowing ZON to coerce integers to untagged enum literals (provided the destination type is known.) Personally I prefer the former solution. * [ ] After this PR is merged I'll file an issue to track this if still relevant. ### Divergences from Zig Zig has no NaN or inf literals right now. Zon does, since otherwise it would have no way to represent these values. IMO we should add the same literals to Zig. * [ ] After this PR is merged I'll file an issue to track this. ### See Also * #15552 * #17731 * #14531 * #14532 * #14534 * #5039 * #14532 * [ ] #20275 (fixed, can probably parse directly as dest types now) * #20277