Velocity Language Service

This extension aims to implement a complete language service for the Apache Velocity template language.

Functionality

This Language Server works with .vm or .vt extension files. It has the following language features:

• Syntax highlighting
• Completions for variables, directives and methods
• Code folding
• Parsing diagnostics
• Snippets

Release Notes

1.0.4

• Adds support for dictionarys and alternate values for references, making it compatible with Velocity 2.1 version.
• Adds support for symbol renaming
• Adds support for symbol reference finding within the template
• Folding is now done in the language server for cycles, conditions and macro definitions

1.0.3

• Adds syntax highlighting for block escapes
• Fixes some edge cases in the lexer causing some false diagnostics

1.0.2

• Added support for most of the advanced language syntax
• Basic autocomplete for inline macros and defines
• Added lots of unit tests to the parser
• Added lexing errors to the diagnostics output

1.0.1

• first version

Limitations

This is an early version of the extension. In the future hopefully some, or all, of these limitations will be addressed:

• Only single files are supported now. Workspace scanning or global symbols are not available.
• Only syntax error checking is available. No semantic checks are implemented yet.
• Velocity does not type its variables, making method inference hard. Method autocomplete currently uses a global list of symbols.

Development

• Run npm install in this folder. This installs all necessary npm modules in both the client and server folder
• Open VS Code on this folder.
• Press Ctrl+Shift+B to compile the client and server.
• Switch to the Debug viewlet.
• Select Launch Client from the drop down.
• Run the launch config.
• If you want to debug the server as well use the launch configuration Attach to Server
• In the [Extension Development Host] instance of VSCode, open a document with '.vm' extension to activate Velocity language mode.

If you make changes to the grammar, the generated parsers will not update automatically so you will need to run the npm run compile task manually.

To test, change the launch target to Language Server E2E Test in the debug tab of vscode, then run. The debug console should present the test results.

To publish, ensure you have the publishing tool installed with npm install -g vsce, then you can run vsce package to create a .vsix plugin.

Project structure

.
├── client // Language Client
│   ├── src
│   │   ├── test // End to End tests for Language Client / Server
│   │   └── extension.ts // Language Client entry point
├── package.json // The extension manifest.
├── server // Language Server
│   └── src
│       └── server.ts // Language Server entry point
├── syntaxes //grammar definitions
└── snippets

Credits

The syntax highlighting was based on the grammar from project sodatea/vscode-velocity. It was translated to a tmGrammar.json format and indented to facilitate readability. A few bugs were fixed and a few simplifications were made.

Project structure followed the microsoft sample for the language server extension.

Parsing was implemented in Antlr4, using the antlr4ts target for Typescript.

License

This project is provided under the MIT license. Please see license file for more details.

Copyright 2020 Quidgest