wisn / format-preserving-yaml

A Format-Preserving YAML Parser

Format.Preserving.YAML

A format-preserving YAML parser.

Progress Note

We are following the YAML 1.2 Spec in general and use Core Schema as the reference for YAML native data structure in Haskell.

Implementation

YAML Native Data Structure in Haskell

YAML supports multi-document content in one file. Each document could contains Directive and Body (YAML Node).

data YAML = YAML Documents

type Documents = [Document]

data Document = Document Directives Node

Finished Implementation

Directive

• Version Directive
• Tag Directive
• None-reserved YAML Directive

Scalar

• Comment
• Null
• Bool
• Int (base 16, base 10, base 8)
• Float including Inf and NaN
• Node Alias

Sequence

• Empty Sequence
• Single element Sequence
• Many elements Sequence

TODO: Investigate more tricky cases and add more tests.

Ongoing Implementation

Scalar

• Quoted Str (single, double)
• Node Anchor

Sequence

• Nested Sequence

NOTE: Fixing bugs. Implements parser for escaped character.

Miscellaneous

Constructing and researching about algorithm & data structure for block-scoped indentation in YAML. This is the hardest part.

Implementation Validation

I'm reading Learn YAML in Y Minutes to think about the implementation and looked at the YAML 1.2 Spec production grammar for the best outcome. Making sure that the YAML is valid using online YAML Linter and online YAML Parser. However, there are several limitation in those YAML Linter and YAML Parser implementation. Hence, we stick with the YAML 1.2 Spec to the end.

Usage Example

Example will be added later. There are tests instead in test/ directory.

License

Licensed under The BSD3 License.