I'm attempting to construct a “heatmap” from a multi-year history stored in a git repository where the unit of granularity is individual functions. Functions should grow hotter as they change more times, more frequently, and with more non-blank lines changed.
As a start, I examined the output of
git log --patch -M --find-renames --find-copies-harder --function-context -- *.c
I looked at using Language.C from Hackage, but it seems to want a complete translation unit—expanded headers and all—rather being able to cope with a source fragment.
The --function-context option is new since version 1.7.8. The foundation of the implementation in v1.7.9.4 is a regex:
PATTERNS("cpp",
/* Jump targets or access declarations */
"!^[ \t]*[A-Za-z_][A-Za-z_0-9]*:.*$\n"
/* C/++ functions/methods at top level */
"^([A-Za-z_][A-Za-z_0-9]*([ \t*]+[A-Za-z_][A-Za-z_0-9]*([ \t]*::[ \t]*[^[:space:]]+)?){1,}[ \t]*\\([^;]*)$\n"
/* compound type at top level */
"^((struct|class|enum)[^;]*)$",
/* -- */
"[a-zA-Z_][a-zA-Z0-9_]*"
"|[-+0-9.e]+[fFlL]?|0[xXbB]?[0-9a-fA-F]+[lL]?"
"|[-+*/<>%&^|=!]=|--|\\+\\+|<<=?|>>=?|&&|\\|\\||::|->"),
This seems to recognize boundaries reasonably well but doesn’t always leave the function as the first line of the diff hunk, e.g., with #include directives at the top or with a hunk that contains multiple function definitions. An option to tell diff to emit separate hunks for each function changed would be really useful.
This isn’t safety-critical, so I can tolerate some misses. Does that mean I