• Thomas Rast's avatar
    Implement line-history search (git log -L) · 12da1d1f
    Thomas Rast authored
    This is a rewrite of much of Bo's work, mainly in an effort to split
    it into smaller, easier to understand routines.
    
    The algorithm is built around the struct range_set, which encodes a
    series of line ranges as intervals [a,b).  This is used in two
    contexts:
    
    * A set of lines we are tracking (which will change as we dig through
      history).
    * To encode diffs, as pairs of ranges.
    
    The main routine is range_set_map_across_diff().  It processes the
    diff between a commit C and some parent P.  It determines which diff
    hunks are relevant to the ranges tracked in C, and computes the new
    ranges for P.
    
    The algorithm is then simply to process history in topological order
    from newest to oldest, computing ranges and (partial) diffs.  At
    branch points, we need to merge the ranges we are watching.  We will
    find that many commits do not affect the chosen ranges, and mark them
    TREESAME (in addition to those already filtered by pathspec limiting).
    Another pass of history simplification then gets rid of such commits.
    
    This is wired as an extra filtering pass in the log machinery.  This
    currently only reduces code duplication, but should allow for other
    simplifications and options to be used.
    
    Finally, we hook a diff printer into the output chain.  Ideally we
    would wire directly into the diff logic, to optionally use features
    like word diff.  However, that will require some major reworking of
    the diff chain, so we completely replace the output with our own diff
    for now.
    
    As this was a GSoC project, and has quite some history by now, many
    people have helped.  In no particular order, thanks go to
    
      Jakub Narebski <[email protected].com>
      Jens Lehmann <[email protected]>
      Jonathan Nieder <[email protected]>
      Junio C Hamano <[email protected]>
      Ramsay Jones <[email protected]>
      Will Palmer <[email protected]>
    
    Apologies to everyone I forgot.
    Signed-off-by: default avatarBo Yang <[email protected]>
    Signed-off-by: default avatarThomas Rast <[email protected]>
    Signed-off-by: default avatarJunio C Hamano <[email protected]>
    12da1d1f
log.c 42.3 KB