Function prettify_js::generate_source_map

pub fn generate_source_map(
    from_name: String, 
    from_content: String, 
    mappings: Vec<SourceMapping>
) -> String

Generate a source-map as a string, given the original source file name, file data, and a list of mappings from the original source to the generated source.

from_name is the name of the "original source code" file. from_content is the content of that file. We always insert the content inline into the source map. Currently we only support mappings where a single source file is mapped to a single generated file.