EM4 Script
Language support for Emergency 4 and 911: First Responders .script files in Visual Studio Code.
EM4 Script combines reliable syntax highlighting with a dedicated Language Server Protocol implementation, providing completion, navigation, documentation, diagnostics, formatting, and symbol tools for Emergency 4 mod development.
Project repository: https://github.com/gustavo-bozzano/em4-vscode
Features
Syntax highlighting
- Automatic recognition of
.script files as EM4 Script
- Highlighting for types, declarations, functions, members, constants, numbers, operators, comments, strings, and preprocessor directives
- Correct highlighting for multiple variables declared on the same line
- Recovery after incomplete strings, comments, and enum declarations, preventing the rest of the file from losing its colors
bool mStartCutScene, mBusExtinguished, mExplosion, mTooManyVictims;
Intelligent completion
- Suggestions for language keywords, local symbols, and SDK symbols
- Type-aware member completion after
->, ., and ::
- Contextual suggestions for classes such as
Vehicle, Person, and other SDK types
- Support for inherited SDK members
Navigation and documentation
- Go to Definition for local declarations, SDK symbols, and contextual members
- Hover information with signatures and documentation
- Documentation extracted from comments placed directly above SDK or source declarations
- Document symbol navigation for classes, functions, variables, enums, and other declarations
Diagnostics
The language server detects common editing mistakes, including:
- Unbalanced parentheses, brackets, and braces
- Unterminated strings and block comments
- Undeclared base identifiers in member access expressions
- Members that do not exist on an inferred type or namespace
Diagnostics are designed to provide fast feedback while editing. They do not replace validation by the Emergency 4 game engine.
- Document formatting with spaces or tabs
- Preservation of the file's existing line endings
- Scope-aware rename for symbols declared in the current document
- Automatic refresh when
.script files change
Getting started
- Install EM4 Script from the Visual Studio Code Marketplace.
- Open your Emergency 4 mod or script folder in Visual Studio Code.
- Open any file ending in
.script.
The extension activates automatically. If a file is not detected, click the language indicator in the lower-right corner of Visual Studio Code and select EM4 Script.
SDK support
The extension includes a bundled Emergency 4 SDK, so completion, hover information, definitions, and validation work immediately after installation.
You can add project-specific declarations by creating an EM4 sdk folder at the root of your workspace:
my-em4-mod/
├── EM4 sdk/
│ ├── custom-types.script
│ └── custom-commands.script
└── Scripts/
└── Command/
└── MyCommand.script
All .script files inside EM4 sdk are loaded together with the bundled SDK. Changes to script files are detected without restarting Visual Studio Code.
To provide useful hover documentation, place // comments or block comments directly above a declaration:
// Starts the custom vehicle command.
object StartVehicleCommand : CommandScript
{
StartVehicleCommand();
};
Development
Clone the repository and install the dependencies:
git clone https://github.com/gustavo-bozzano/em4-vscode.git
cd em4-vscode
npm ci
npm test
Open the repository in Visual Studio Code and press F5 to launch an Extension Development Host.
Feedback and contributions
Bug reports, feature requests, and contributions are welcome.
When reporting a highlighting or language-server issue, include a small .script example that reproduces the problem.
License
This project is distributed under the GNU General Public License v3.0.
