Parsing

svugy-parse turns Markdown, d2 and JSON into a Model, one module per language, so no other crate parses source text and every language reports problems the same way.

Components

diagnostic is the reporting harness every language implements.

• SourceLanguage::import(text) returns an Import: the model’s admission, the language’s errors (message + byte span, as miette diagnostics) and its warnings (d2 only).
• Import::admitted_model returns the model only if neither the language nor admission reported an error.
• Every stage records its problems and continues, so one run reports all of them, sorted by source offset.

prose writes name lists in messages as `a`, `b` and `c`.

markdown reads and prints the Markdown format.

• comrak splits the file into frontmatter, ## sections, list-item nesting and verbatim item lines; any other block is an error. The frontmatter is YAML (serde-saphyr).
• logos and chumsky parse each item line into a component, an edge or a legend row, recovering at each broken entry.
• Lowering builds the model through ModelBuilder. Named styles expand into each properties list, left to right, then its key=value entries apply over them; the model receives only the result.
• A reference (edge endpoint, link, legend target) resolves to the path it spells, else to the one path it is a dotted suffix of. Unknown references get a suggestion; ambiguous ones list their matches.
• MarkdownPrinter::print writes any model back, behind svugy import my.d2 -o my.md. Whatever Markdown cannot express, such as a stroke-dash other than 5 or 2, is reported, never rounded. Print then parse returns the same model.

Other properties map to the field of the same name.

d2 imports d2 v0.9.0.

• d2 has no Rust parser, so svugy has its own: logos for tokens, chumsky with recovery for statements.
• Constructs outside svugy’s subset (classes, imports, globs, sql_table, …) are dropped with a warning.
• Lowering follows d2’s compiler: keys are case-folded, repeated keys merge with the last write winning, an edge to an undeclared key declares it.
• What d2 cannot say (subtitle, legend, caption, shape, height, position, badge) comes from vars: { svugy: { … } }, which d2 compiles and ignores, so the files stay valid d2. CI compiles every committed .d2 fixture with d2 v0.9.0.

json saves and loads a model without loss.

• JsonPrinter::print writes elements keyed by path and edges as {from, to, ordinal, …} records.
• Loading keeps the saved ordinals and goes straight to admission, skipping ModelBuilder, which would renumber them.
• Duplicate keys are errors; serde_json alone would keep the last one.

examples/svugy/svugy.md, examples/svugy/svugy.d2 and examples/svugy/svugy.json must yield the same model, spans aside (examples/tests/twins.rs).