AXS Language
Language support for AXS, a
human-friendly, indentation-based configuration and serialization format.
- Syntax highlighting for block headers, keys, list items, strings, escapes,
numbers, booleans,
null, empty collections, and comments
- Live diagnostics while you type, with stable error codes (
AXS001–AXS009)
and exact locations, including lines with emoji and other non-ASCII text
- Format Document that produces the same canonical output as
axs fmt
- Smart Enter that continues lists and indents blocks the way AXS expects
- Works out of the box: the AXS Rust core ships inside the extension as
WebAssembly, so you don't need Rust, Cargo, or the
axs CLI
Example
# Application settings
server:
host = localhost
port = 3000
enabled = true
skills:
- Rust
- TypeScript
categories:
- UI:
- MUI
- Tailwind
weight = 2
A duplicate key such as a second port = 3001 under server: is underlined
immediately:
AXS005 Duplicate key 'port' settings.axs [Ln 5, Col 3]
Format Document (Shift+Alt+F, or
Shift+Option+F on macOS) rewrites the file in
canonical AXS. It sorts keys, uses two-space indentation and colon block headers,
and applies minimal quoting.
Formatting removes comments and changes key order. It keeps every value
and type: 1.0 stays a float and large integers keep every digit. The output
is identical to axs fmt, except that the document keeps its own line endings
(LF or CRLF).
Invalid documents are not formatted. The error stays visible as a diagnostic.
Smart Enter
Enter continues the structure the current line started:
| Line before Enter |
New line |
skills: |
indented by 2, ready for a field or a - item |
skills: above existing - items |
- (matches the existing items) |
- Rust |
- at the same indent |
- (empty item) |
removes the dash and moves out one level, which ends the list |
- UI: |
indented 4 below the dash, as Grammar v2 requires |
- (bare dash) |
indented by 2 for a nested collection |
- name = Oleh |
indented by 2 for the next field of that object |
key = value |
same indent |
A key: header can introduce an object or an array, so Enter doesn't add a dash
unless the block already contains list items. Comments, multiple cursors,
selections, and Enter in the middle of a line keep VS Code's normal behavior.
For .axs files the extension defaults to two-space indentation with spaces,
since AXS doesn't allow tabs.
Details
- Diagnostics update 400 ms after you stop typing and immediately when a file
opens. They are removed when the file closes or switches to another language.
- The core reports the first error in a document.
- The AXS limits apply: 8 MiB per document, 262,144 tokens, and 128 nesting
levels. Validating a document near 8 MiB takes tens of milliseconds.
- The extension supports untrusted and virtual workspaces, since it never runs
external programs or reads other files.
- Requires VS Code 1.90 or newer.
License
Apache-2.0
