Awesome

json5_nodes

This Rust library parses JSON5 into JsonNode structures that contain both the JSON value and the location of the data in the original string. This allows you to use JSON5 as a configuration format and refer back to the location of semantic errors in the original JSON5 as opposed to just reporting syntactic errors when reading the file.

See the stampver-rs tool for an example of how to use the library.

Implementation

We use IndexHashMap instead of a plain HashMap because JavaScript mostly preserves the order of insertion into objects. This libraries JSON5 parser currently only allows string based keys, so the rules are simplified.

All JSON breaks down into nodes of different types, JsonNode::Null, JsonNode::String, JsonNode::Bool, JsonNode::Integer, JsonNode::Float, JsonNode::Array and JsonNode::Object. We define and parse two types of numbers because it's more important in statically typed languages to specifically pick one or the other.

To Do

This library is a work in progress. The following are some things that still need to be done:

• Get closer to 100% code coverage with the unit tests.
• Rewrite the hex conversions to avoid the pathological Err cases; the values are already parsed to be valid input.
• Maybe ensure that what's read by parse can be written back out in stringify with full fidelity. In particular escape codes are not handled at all and hex numbers don't round-trip.
• A better README!