Transpilation Pipeline

The transpiler (transpiler.mist in mist_api) orchestrates the full pipeline.

Pipeline

1. Read Mist.toml configuration
2. Build a Module tree from the filesystem (discovering package.mist files)
3. For each module: a. Parse Mist source b. Run semantic checks c. Generate Rust code and position mapping d. Write .rs file and .map.json file
4. Recursively transpile included crates

Module Tree

The Module struct represents the file-to-module mapping:

pub class Module
{
    pub String name;
    pub PathBuf path;
    pub Vec<Module> children;

    pub constructor(PathBuf mist_path, MistConfig& config) { ... }
    pub bool is_package(&self) { ... }
    pub PathBuf output_dir(&self, PathBuf& parent_dir) { ... }
    pub PathBuf output_path(&self, PathBuf& parent_dir, ...) { ... }
}

Transpilation Mapping Rules

A package.mist file generates mod.rs in the output directory and contains pub mod <child>; declarations for its children.

Caching

The transpiler implements basic caching via file modification times:

fn is_source_newer(source: &Path, output: &Path) -> io::Result<bool> {
    if !output.exists() { return Ok(true); }
    let source_time = fs::metadata(source)?.modified()?;
    let output_time = fs::metadata(output)?.modified()?;
    Ok(source_time > output_time)
}

If a source file has not changed since the last transpilation, the .rs file is not regenerated.