Phase 2: Transpilation

Phase 2 converts source code from the detected language into Rust using external transpiler tools. It dispatches each file to the appropriate transpiler based on the language map produced by Phase 1.

Transpiler Dispatch

The TranspilationStage reads the primary_language from PipelineContext and selects the matching tool from the ToolRegistry:

The ToolRegistry::get_transpiler_for_language() method performs the lookup:

#![allow(unused)]
fn main() {
pub fn get_transpiler_for_language(&self, lang: &Language) -> Option<&ToolInfo> {
    match lang {
        Language::C | Language::Cpp => self.decy.as_ref(),
        Language::Python => self.depyler.as_ref(),
        Language::Shell => self.bashrs.as_ref(),
        _ => None,
    }
}
}

Pipeline Context Flow

Phase 2 receives the context from Phase 1 and adds file mappings:

PipelineContext {
    primary_language: Some(Python),    // <-- from Phase 1
    file_mappings: [                   // <-- populated by Phase 2
        ("src/main.py", "src/main.rs"),
        ("src/utils.py", "src/utils.rs"),
    ],
}

These mappings are consumed by Phase 4 (Validation) for equivalence checking.

Parallel File Processing

For multi-file projects, transpilation processes files independently. Each file is dispatched to its language-specific transpiler in parallel, with results collected and merged into the pipeline context.

Jidoka Stop-on-Error

If any file fails to transpile, the ValidationStrategy::StopOnError setting halts the pipeline. The error includes the specific file and transpiler output:

Error: Stage 'Transpilation' failed
  Caused by: depyler exited with code 1
  File "complex_class.py", line 42
    Unsupported Python feature: metaclass with __prepare__

The workflow state records the failure, and Phase 3 refuses to start until the issue is resolved.

Sub-Topics

• Tool Selection – how transpilers are detected and validated
• Incremental Compilation – only retranspile changed files
• Caching Strategy – cross-run persistence of transpilation results
• Error Handling – Jidoka error patterns

CLI Usage

# Transpile the entire project
batuta transpile --incremental --cache

# Transpile specific modules
batuta transpile --modules auth,api

# Force retranspilation of all files
batuta transpile --force

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