File mapping

The instrumentation pass creates the file .discopop/FileMapping.txt (more precisely $DOT_DISCOPOP/FileMapping.txt, DOT_DISCOPOP defaults to .discopop, see Environment variables). It assigns an id to every source file the pass encounters. All other files refer to source files by these ids, for example the node ids 1:7 (<file id>:<node id>) and the line ids 1:20 (<file id>:<line>).

Each line has the format <file id><TAB><absolute file path>:

1	/home/user/dp_example/example.cpp

• ids start at 1
• the id 0 stands for code outside of the project root directory (DP_PROJECT_ROOT_DIR, default /); such code gets no file id
• every compiled module appends the files it encounters, so the ids are the same in all translation units of a project; a file that is already listed keeps its id

Remove .discopop before you instrument a project again, otherwise stale entries remain.

Usage

Use the file to map the file ids in Data.xml, dynamic_dependencies.txt, patterns.json and other files to source files. In Python, load_file_mapping(fmap_path) -> Dict[int, Path] in library/discopop_library/PathManagement/PathManagement.py reads the file; it warns about listed files that do not exist.

line_mapping.json

.discopop/line_mapping.json is created when the explorer sets up the .discopop directory. It tracks how lines of the source files move when patches insert pragmas. The format is {"<file id>": {"<original line>": <current line>}}; initially every line maps to itself:

{"1": {"1": 1, "2": 2, "3": 3, "...": "..."}}

The patch applicator and the other patch tools update it.