switch to saner defaults

Change default new prefix to "", update documentation.
Get git-remap-data in line with diff-remap-data

3 files changed, 13 insertions, 11 deletions

diff --git a/git-remap-data b/git-remap-data
index e7a887d..7c85700 100755
--- a/git-remap-data
+++ b/git-remap-data
@@ -1,2 +1,2 @@
 #!/bin/sh
-GIT_DIFF_OPTS="-u 0" git diff -M "$@"
+GIT_DIFF_OPTS="-u 0" git diff -M "$@"|remap-log
diff --git a/remap-log.c b/remap-log.c
index e8dacf0..c8c2691 100644
--- a/remap-log.c
+++ b/remap-log.c
@@ -30,7 +30,7 @@
 #include <limits.h>
 
 char *prefix1 = "a/", *prefix2 = "b/";
-char *from_prefix = "", *old_prefix = "O:", *new_prefix = "N:";
+char *from_prefix = "", *old_prefix = "O:", *new_prefix = "";
 size_t from_len = 0;
 
 char *line;
diff --git a/what-it-does b/what-it-does
index f0030d5..f6d29f7 100644
--- a/what-it-does
+++ b/what-it-does
@@ -9,19 +9,16 @@ will look at the lines in stdin that have form
 <filename>:<number>:<text>
 If the indicated line from old tree had survived into the new one, we will
 get
-N:<new-filename>:<new-number>:<text>
+<new-filename>:<new-number>:<text>
 on the output.  If it hadn't, we get
 O:<filename>:<number>:<text>
 Lines that do not have such form are passed unchanged.
 
 Even that is already very useful for log comparison.  E.g. if old-log is
 from the old tree and new-log is from the new one, we can do
-	remap-log map <old-log >foo
-	remap-log /dev/null <new-log >bar
-	diff -u foo bar
-and have the noise due to line number changes excluded (empty map means
-identity mapping, so the second line will simply slap N: on all lines of
-form <filename>:<number>:<text> in new-log).
+	remap-log map <old-log >remapped-log
+	diff -u remapped-log new-log
+and have the noise due to line number changes excluded.
 
 Note that it's not just for build logs; the thing is useful for sparse logs,
 grep -n output, etc., etc. 
@@ -33,12 +30,12 @@ and replace them with
 <prefix_for_new><new-filename>:<new-number>:<text>
 or
 <prefix_for_old><filename>:<number>:<text>
-Defaults are "", "N:" and "O:" resp.; what it gives us is the ability to
+Defaults are "", "" and "O:" resp.; what it gives us is the ability to
 do multiple remappings.  IOW, we can say
 
 diff-remap-data old-tree newer-tree > map1
 diff-remap-data newer-tree current-tree > map2
-remap-log -o old: map1 <old-log | remap-log -p N: -o newer: -N current: map2>foo
+remap-log -o old: map1 <old-log | remap-log -o newer: -n current: map2>foo
 
 and get lines that didn't make it into the newer tree marked with old: and
 otherwise be unchanged, ones that made it to newer, but not the current to
@@ -50,3 +47,8 @@ That's quite useful when you want to carry logs for a while, basically using
 them as annotated TODO ("logs" here can very well be results of grep -n with
 annotations added to them).  You can have all still relevant bits stay with
 the locations in text and see what had fallen out.
+
+Note on relation to git: only git-remap-data needs it.  Aside of working on
+revisions in git repository instead of a couple of directory trees, it
+generates slightly better map than diff-remap-data does.  I.e. it manages
+to remap more lines - it does notice renames.