# meta-language
A Rust foundation for a universal, self-describing meta language backed by a
links network. The initial crate focuses on the common structural substrate:
links, references, source spans, parse status metadata, configurable trivia
attachment, self-description roots, and verification that a parsed region is
clean.
## What Is Implemented
- A mutable `LinkNetwork` where every item is a link.
- Self-referential point links, so a point is represented without introducing a
separate primitive.
- Relation links as ordinary links with ordered references to other links.
- Field labels as explicit links instead of side-table metadata.
- Source metadata: link type, named/anonymous flag, byte range, row/column
points, and `is_error`, `has_error`, `is_missing`, `is_extra` flags.
- `verify_full_match()` for reporting error and missing links in a selected
source region.
- `parse()` as the default lossless parse entry point; the explicit
`parse_lossless_text()` boundary remains available.
- `reconstruct_text()` for byte-for-byte reconstruction from non-missing token
links ordered by source span.
- `projected_links()` for viewing the same lossless network as concrete syntax,
abstract syntax, or semantic-only data by stripping lower-level preservation
links from the view.
- `NetworkSnapshot` and `MutableNetworkSnapshot` for immutable versioned
snapshots, editable forks, provenance, and forward commits.
- `ParseConfiguration` with containment-link, token-link, or combined trivia
attachment policies.
- Mixed-region links for Markdown fenced code and HTML regions, plus HTML
script, style, and style-attribute regions, with `txt` fallback for prose
regions that content sniffing cannot classify.
- `LinkQuery` for structural matching by link type, term, language, and named
flag.
- `SubstitutionRule` / `apply_substitution()` for the link-cli-style
match-and-substitute operation.
- Concept-to-language syntax mappings for cross-language reconstruction.
- Object-identity links and many-valued `TruthValue` semantics.
- A testable parity registry and `PARITY_FIXTURES` for executable competitor
and ecosystem feature gates.
- `LANGUAGE_FIXTURES` with lossless parse/reconstruction samples for every
required markup, programming-language, and natural-language target.
- Coverage targets for full `txt`, Markdown, and HTML support, mixed grammar
embedding, ten programming-language parser targets, and ten natural-language
parser targets.
- Self-description roots for `link`, `reference`, `relation link`, `language`,
`grammar`, `type`, `concept`, `point`, `field`, `trivia`, `region`, and
`object`.
- A lossless text parser boundary that preserves tokens, trivia, recovery
markers, and mixed-region metadata behind the same representation.
## Usage
```rust
use meta_language::{LinkNetwork, ParseConfiguration};
let network = LinkNetwork::parse("alpha beta", "plain-text", ParseConfiguration::default());
let report = network.verify_full_match(None);
assert!(report.is_clean());
assert_eq!(network.reconstruct_text(), "alpha beta");
```
The default parse path is lossless. Callers that need a narrower view can use a
projection without mutating the original network:
```rust
use meta_language::{LinkNetwork, NetworkProjection, ParseConfiguration};
let network = LinkNetwork::parse("alpha beta", "plain-text", ParseConfiguration::default());
let abstract_links = network
.projected_links(NetworkProjection::AbstractSyntax)
.count();
assert!(abstract_links < network.len());
```
## CLI
```bash
cargo run -- describe
cargo run -- verify --language plain-text --text "alpha beta"
```
`describe` prints the built-in self-description roots. `verify` parses the text
with the lossless text boundary and exits successfully when the resulting region
has no error or missing links.
## Parity Implementation
The crate exposes `PARITY_TARGETS`, `MARKUP_LANGUAGE_TARGETS`,
`PROGRAMMING_LANGUAGE_TARGETS`, `NATURAL_LANGUAGE_TARGETS`, and
`GRAMMAR_EMBEDDING_TARGETS` so comparison scope is part of the tested Rust API.
It also exposes `PARITY_FIXTURES`, with executable fixtures covering every
advertised target capability, and `LANGUAGE_FIXTURES`, with a lossless fixture
for every requested language target.
The current registry tracks tree-sitter, LibCST, Recast, jscodeshift, Rowan,
cstree, Roslyn, links-notation, link-cli, lino-objects-codec,
relative-meta-logic, formal-ai, and meta-expression.
See [docs/parity-roadmap.md](docs/parity-roadmap.md) for the feature matrix,
executable fixture gates, and language coverage targets.
## Development
```bash
cargo fmt --check
cargo clippy --all-targets --all-features
cargo test --all-features
rust-script scripts/check-no-src-tests.rs
```
This repository uses changelog fragments in `changelog.d/`; code changes should
include a fragment with the intended semantic-version bump.