MSpec DSL Support for VSCode

A comprehensive VSCode extension providing rich language support for PLC4X MSpec (Message Specification) protocol definitions.

Features

Core Language Support

✅ Syntax Highlighting - Full syntax highlighting for all MSpec constructs
✅ Auto-Completion - Context-aware completion for keywords, types, fields, and constants
✅ Error Detection - Real-time syntax and semantic validation with detailed error messages
✅ Hover Information - Detailed documentation and type information on hover
✅ Go to Definition - Navigate to type and field definitions with Ctrl+Click
✅ Document Formatting - Automatic code formatting with configurable indentation
✅ Code Snippets - Pre-defined snippets for common MSpec patterns

Packet Decoder

✅ Binary Packet Decoding - Decode binary packets using MSpec type definitions
✅ Tree View Display - Hierarchical tree view of decoded packet structure
✅ Field Overlay - Visual overlay of field values on the MSpec file
✅ Byte Order Support - Automatic handling of BIG_ENDIAN and LITTLE_ENDIAN byte orders
✅ Expression Evaluation - Automatic evaluation of const and implicit field expressions

Supported MSpec Constructs

Type definitions (type, discriminatedType, enum, dataIo)
Field types (simple, array, const, reserved, optional, implicit, etc.)
Data types (bit, byte, int, uint, float, string, etc.)
Expressions and operators with full expression evaluation
Type switching and discriminated unions
Attributes and parameters
Batch sets with custom byte orders

Installation

From VSCode Marketplace

Open VSCode
Go to Extensions (Ctrl+Shift+X / Cmd+Shift+X)
Search for "MSpec DSL Support"
Click Install

From VSIX Package

Download the latest .vsix file from releases
Open Command Palette (Ctrl+Shift+P / Cmd+Shift+P)
Run Extensions: Install from VSIX...
Select the downloaded .vsix file

Quick Start

Creating MSpec Files

Create a new file with .mspec extension
Start typing MSpec definitions
Use Ctrl+Space for auto-completion suggestions
Use snippets for quick scaffolding

Example MSpec File

[type SimpleMessage byteOrder='BIG_ENDIAN'
    [const uint 8 messageType 0x01]
    [simple uint 16 messageId]
    [implicit uint 16 payloadLength 'payload.lengthInBytes']
    [array byte payload count 'payloadLength']
]

[enum uint 8 MessageType
    ['0x01' REQUEST]
    ['0x02' RESPONSE]
]

[discriminatedType ProtocolMessage
    [discriminator uint 8 messageType]
    [typeSwitch messageType
        ['0x01' RequestMessage
            [simple string 32 command]
        ]
        ['0x02' ResponseMessage
            [simple uint 8 status]
        ]
    ]
]

Using the Packet Decoder

Open an MSpec file
Run MSpec: Open Packet Decoder from the Command Palette
Select a binary file or paste hex data
Choose the root type to decode
View the decoded packet structure in the tree view

Configuration

Configure the extension through VSCode settings:

{
  "mspec.validation.enabled": true,
  "mspec.validation.strictMode": false,
  "mspec.completion.enabled": true,
  "mspec.completion.snippets": true,
  "mspec.formatting.enabled": true,
  "mspec.formatting.indentSize": 4,
  "mspec.trace.server": "off"
}

Configuration Options

validation.enabled - Enable/disable real-time validation
validation.strictMode - Enable strict validation mode for additional checks
completion.enabled - Enable/disable auto-completion
completion.snippets - Enable/disable code snippets
formatting.enabled - Enable/disable document formatting
formatting.indentSize - Number of spaces for indentation (default: 4)
trace.server - Trace communication with language server (off, messages, verbose)

Commands

Available Commands

MSpec: Restart Language Server - Restart the language server
MSpec: Show Output - Show language server output channel
MSpec: Go to Definition - Navigate to type/field definition
MSpec: Format Document - Format the current document
MSpec: Open Packet Decoder - Open the packet decoder panel

Keyboard Shortcuts

Ctrl+Space - Trigger auto-completion
Ctrl+Shift+F - Format document
Ctrl+Click - Go to definition
F12 - Go to definition (alternative)

Troubleshooting

Language Server Not Starting

Verify Node.js 18+ is installed
Check the MSpec output channel for error messages
Try restarting VSCode

No Syntax Highlighting

Ensure file has .mspec extension
Restart VSCode after installation

Auto-Completion Not Working

Check if completion is enabled in settings
Verify language server is running
Try restarting the language server with MSpec: Restart Language Server

Packet Decoder Issues

Ensure the MSpec file is valid and has no syntax errors
Verify the binary data format matches the selected type
Check byte order settings in the MSpec type definition

Support

For issues, feature requests, or questions:

License

Licensed under the Apache License 2.0 - see LICENSE file for details.

MSpec DSL Support

Ben Hutcheson