Parsnip for VS Code

Syntax highlighting, IntelliSense, formatting, and syntax checking for Parsnip snips — Trident's rule/expression DSL (src/Abbey/Common/Parsnip.Core).

MAP(
    FILTER(
        @all_products,
        AND(
            @val['globalKey'] != 'GAP',
            @val['globalKey'] != 'VSC',
            @val['globalKey'] != 'maintenance'
        )
    ),
    @val['name']
)

Features

Language: files ending in .snip or .parsnip open as Parsnip. Bracket matching, auto-closing quotes and brackets.
Highlighting: functions, @variables, strings, numbers, booleans, operators. Bare identifiers that the real lexer would silently drop (EQ(@a, GAP)) are highlighted as invalid.
IntelliSense: start typing a name and every Parsnip function drops down with its signature, description and examples; accepting one inserts placeholders for its parameters. Type @ for variables already used in the file, plus @val / @acc inside FILTER, MAP, REDUCE and friends.
Signature help: parameter hints while typing inside a call. Hover a function for its docs.
Format Document / Format Selection (Shift+Alt+F): reflows a snip to the configured width.
Parsnip: Format Selection as Snip: command that formats the selected text as a snip in any file type, for snips embedded in C#, JSON or SQL.
Diagnostics: syntax errors are underlined as you type. A file that does not parse is never reformatted.

Formatting rules

A call or array prints on one line if it fits within parsnip.format.printWidth; otherwise one argument per line with the closing bracket on its own line.
Operator chains that do not fit break one operand per line with the operator leading (&& @apr >= 0.0).
A single-operator expression keeps the operator on the closing line when only one side needs to break: COUNT(\n ...\n) > 0.
Function names and TRUE/FALSE are uppercased (they are case-insensitive in Parsnip). Variable names are case-sensitive and never changed.
Numbers and strings are copied verbatim: 5 is a long, 5.0 is a decimal, and strings have no escapes.
Explicit parentheses are always kept.
Whitespace is the only thing that changes: the formatted output lexes to exactly the same tokens as the input.
A file may hold several snips, each starting on its own line; they are separated by one blank line.

Indentation follows the editor's tabSize / insertSpaces for the file.

Settings

Setting	Default	Description
`parsnip.format.printWidth`	`80`	Line width to fit a call or expression into before breaking it.

Development

npm install
npm run compile
npm run test:unit   # fast, pure formatter tests
npm test            # extension-host tests (downloads VS Code on first run)

Press F5 to launch an Extension Development Host with the extension loaded.

To package: npx @vscode/vsce package. To publish: npx @vscode/vsce publish (needs a Marketplace PAT for the timscriv publisher; run npx @vscode/vsce login timscriv once).