LPC Language Support (LDMUD/LP-245)

Syntax highlighting, editor support, and a formatter for LPC as implemented by the LDMUD driver, tuned for the LP-245 mudlib.

Author: Andreas Bogataj (andreas@bogga.se)

Using it with .c and .h files

The extension only claims .lpc files, so ordinary C projects are not affected. Mudlibs usually keep LPC in .c and .h files; to treat them as LPC in a workspace, run LPC: Treat .c/.h Files as LPC in This Workspace from the Command Palette, or add this to the workspace's .vscode/settings.json:

{
    "files.associations": { "*.c": "lpc", "*.h": "lpc" }
}

Features

Highlighting for LDMUD keywords, types (including lwobject, coroutine, union types), modifiers, efuns and applies (when called), closures (#'name, (: :), lambda), arrays, mappings, multisets, struct literals, and preprocessor directives.

Editor support: comment toggling and continuation, auto-closing of ({, ([, (< and /*, and folding for #if/#ifdef/#ifndef … #endif and #region.

Formatting with Format Document, Format Selection, or LPC: Format LPC Code:

Indents nested blocks, brace-less if/else/loop bodies (including dangling else), continuation lines, and multi-line arrays, mappings, multisets, and closures.
Indents case labels at the level of their switch (LDMUD -cli0 style).
Keeps brace placement, brace-less bodies, one-line statements, trailing commas, comments, strings, and \-continued strings and macros as written.
Keeps the indentation context across comments, blank lines, and #if branches.
Uses C-style spacing, since LPC has no style guide of its own:
- one space around binary and assignment operators (a == b, x <<= 1, a ? b : c);
- none after unary operators (-x, !ok, &ref) or around ->, ., and ::;
- one space after commas and for semicolons; "key": value in mappings and struct literals; case 1:; foreach (x : items); if (…), while (…);
- LPC syntax stays as written: int|string, <int|string>*, arr[<1..<2], #'>, (<Foo>.
Puts functions with one simple statement on one line, such as int query_level() { return level; } (can be turned off).

Settings

Setting	Default	Description
`lpc.formatting.enabled`	`true`	Enable the formatter.
`lpc.formatting.indentSize`	`4`	Spaces per indentation level. Takes precedence over the editor's tab size; with tabs, each level is one tab.
`lpc.formatting.insertFinalNewline`	`true`	End formatted documents with a newline.
`lpc.formatting.compactSingleStatementFunctions`	`true`	Put functions with a single simple statement on one line.

All settings can be set per user, workspace, or folder.

Development

Requires Node.js 24.11 or newer.

npm install
npm test            # compile, type-check, unit tests in Node, then tests in VS Code
npm run test:unit   # formatter fixtures only, without VS Code
npm run package     # build the .vsix

Formatter cases are input/expected pairs in src/test/fixtures/formatter/; each must match exactly and stay unchanged by a second pass. npm test -- "name" runs matching VS Code tests, and VSCODE_TEST_VERSION=1.74.0 tests an older VS Code. Press F5 to launch an Extension Development Host.

The only dependencies are typescript, @types/node, and @types/vscode. Packaging (scripts/package-vsix.mjs) and the VS Code test host (src/test/vscodeTestHost.ts) are part of the repository instead of vsce and @vscode/test-electron.

Releases: after CI is green on main, push a vX.Y.Z tag matching package.json and run the Release workflow, which tests, packages, and publishes the GitHub release. Upload its .vsix to the Marketplace manually.

Links

MIT License.