Rust Call Graph
Visualize function call relationships using LSP call hierarchy.
Usage
/rust-call-graph <function_name> [--depth N] [--direction in|out|both]
Options:
--depth N: How many levels to traverse (default: 3)--direction:in(callers),out(callees),both
Examples:
/rust-call-graph process_request- Show both callers and callees/rust-call-graph handle_error --direction in- Show only callers/rust-call-graph main --direction out --depth 5- Deep callee analysis
LSP Operations
1. Prepare Call Hierarchy
Get the call hierarchy item for a function.
LSP(
operation: "prepareCallHierarchy",
filePath: "src/handler.rs",
line: 45,
character: 8
)
2. Incoming Calls (Who calls this?)
LSP(
operation: "incomingCalls",
filePath: "src/handler.rs",
line: 45,
character: 8
)
3. Outgoing Calls (What does this call?)
LSP(
operation: "outgoingCalls",
filePath: "src/handler.rs",
line: 45,
character: 8
)
Workflow
User: "Show call graph for process_request"
│
▼
[1] Find function location
LSP(workspaceSymbol) or Grep
│
▼
[2] Prepare call hierarchy
LSP(prepareCallHierarchy)
│
▼
[3] Get incoming calls (callers)
LSP(incomingCalls)
│
▼
[4] Get outgoing calls (callees)
LSP(outgoingCalls)
│
▼
[5] Recursively expand to depth N
│
▼
[6] Generate ASCII visualization
Output Format
Incoming Calls (Who calls this?)
## Callers of `process_request`
main
└── run_server
└── handle_connection
└── process_request ◄── YOU ARE HERE
Outgoing Calls (What does this call?)
## Callees of `process_request`
process_request ◄── YOU ARE HERE
├── parse_headers
│ └── validate_header
├── authenticate
│ ├── check_token
│ └── load_user
├── execute_handler
│ └── [dynamic dispatch]
└── send_response
└── serialize_body
Bidirectional (Both)
## Call Graph for `process_request`
┌─────────────────┐
│ main │
└────────┬────────┘
│
┌────────▼────────┐
│ run_server │
└────────┬────────┘
│
┌────────▼────────┐
│handle_connection│
└────────┬────────┘
│
┌────────────────────┼────────────────────┐
│ │ │
┌───────▼───────┐ ┌───────▼───────┐ ┌───────▼───────┐
│ parse_headers │ │ authenticate │ │send_response │
└───────────────┘ └───────┬───────┘ └───────────────┘
│
┌───────┴───────┐
│ │
┌──────▼──────┐ ┌──────▼──────┐
│ check_token │ │ load_user │
└─────────────┘ └─────────────┘
Analysis Insights
After generating the call graph, provide insights:
## Analysis
**Entry Points:** main, test_process_request
**Leaf Functions:** validate_header, serialize_body
**Hot Path:** main → run_server → handle_connection → process_request
**Complexity:** 12 functions, 3 levels deep
**Potential Issues:**
- `authenticate` has high fan-out (4 callees)
- `process_request` is called from 3 places (consider if this is intentional)
Common Patterns
| User Says | Direction | Use Case | |-----------|-----------|----------| | "Who calls X?" | incoming | Impact analysis | | "What does X call?" | outgoing | Understanding implementation | | "Show call graph" | both | Full picture | | "Trace from main to X" | outgoing | Execution path |
Visualization Options
| Style | Best For | |-------|----------| | Tree (default) | Simple hierarchies | | Box diagram | Complex relationships | | Flat list | Many connections | | Mermaid | Export to docs |
Mermaid Export
graph TD
main --> run_server
run_server --> handle_connection
handle_connection --> process_request
process_request --> parse_headers
process_request --> authenticate
process_request --> send_response
Related Skills
| When | See | |------|-----| | Find definition | rust-code-navigator | | Project structure | rust-symbol-analyzer | | Trait implementations | rust-trait-explorer | | Safe refactoring | rust-refactor-helper |