Module LanguageFeature 

LanguageFeature (Command)

RESPONSIBILITIES:

• Defines Tauri command handlers for language feature requests from Sky frontend
• Bridges Monaco Editor language requests to LanguageFeatureProviderRegistry
• Provides type-safe parameter handling and validation for LSP features
• Implements hover, code actions, document highlights, completions, definition, references
• Uses generic InvokeProvider helper to reduce boilerplate

ARCHITECTURAL ROLE:

• Command layer that exposes language features via Tauri IPC (#[command])
• Delegates to Environment’s LanguageFeatureProvider via DI with Require() trait
• Translates between frontend JSON parameters and Rust DTO types
• Error strings returned directly to frontend for display

COMMAND REFERENCE (Tauri IPC):

• MountainProvideHover: Show hover information at cursor position
• MountainProvideCodeActions: Get quick fixes and refactorings for a code range
• MountainProvideDocumentHighlights: Find symbol occurrences in document
• MountainProvideCompletions: Get code completion suggestions with context
• MountainProvideDefinition: Jump to symbol definition location
• MountainProvideReferences: Find all references to a symbol

ERROR HANDLING:

• Returns Result<Value, String> where errors sent directly to frontend
• Validates URI non-empty and position format (line/character numbers)
• JSON serialization errors converted to strings
• Provider errors (CommonError) converted to strings via map_err(|Error| Error.to_string())

PERFORMANCE:

• Each command is async and non-blocking
• Provider lookup is O(1) via Require() from DI container
• URI parsing and DTO deserialization adds minimal overhead

VS CODE REFERENCE:

• vs/workbench/api/common/extHostLanguageFeatures.ts - ext host language features API
• vs/workbench/services/languageFeatures/common/languageFeaturesService.ts
  • service layer
• vs/workbench/contrib/hover/browser/hover.ts - hover implementation
• vs/workbench/contrib/completion/browser/completion.ts - completion widget
• vs/workbench/contrib/definition/browser/definition.ts - go to definition
• vs/workbench/contrib/references/browser/references.ts - find references

TODO:

• Implement more language features: document symbols, formatting, rename, signature help
• Add cancellation token support for long-running operations
• Implement request deduplication for identical concurrent requests
• Add request caching for repeated symbol lookups
• Support workspace symbol search
• Add semantic tokens for syntax highlighting
• Implement code lens provider
• Add inlay hints support
• Support linked editing range
• Add call hierarchy and type hierarchy
• Implement document color and color presentation
• Add folding range provider
• Support selection range provider

MODULE STRUCTURE:

• validation.rs - request validation helper
• invoke_provider.rs - generic provider invoker
• Individual command modules for each language feature (containing impls only)

Modules

code_actions 🔒

LanguageFeature - Code Actions

completions 🔒

LanguageFeature - Completions

definition 🔒

LanguageFeature - Definition

highlights 🔒

LanguageFeature - Document Highlights

hover 🔒

LanguageFeature - Hover

invoke_provider 🔒

LanguageFeature - Invoke Provider Helper

references 🔒

LanguageFeature - References

validation 🔒

LanguageFeature - Validation

Functions

MountainProvideCodeActions

Provides code actions (quick fixes and refactorings) for a code range

MountainProvideCompletions

Provides code completion suggestions

MountainProvideDefinition

Provides go-to-definition functionality

MountainProvideDocumentHighlights

Finds symbol occurrences (document highlights) in a document

MountainProvideHover

Provides hover information at cursor position

MountainProvideReferences

Finds all references to a symbol