diff-highlight: split code into module
The diff-so-fancy project is also written in perl, and most of its users pipe diffs through both diff-highlight and diff-so-fancy. It would be nice if this could be done in a single script. So let's pull most of diff-highlight's code into its own module which can be used by diff-so-fancy. In addition, we'll abstract a few basic items like reading from stdio so that a script using the module can do more processing before or after diff-highlight handles the lines. See the README update for more details. One small downside is that the diff-highlight script must now be built using the Makefile. There are ways around this, but it quickly gets into perl arcana. Let's go with the simple solution. As a bonus, our Makefile now respects the PERL_PATH variable if it is set. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Jeff King committed
Jun 15, 2017 at 12:30 UTC
0c977dbc8180892af42d7ab9235fd3e51d6c4078
5 files changed
+82
-19
contrib/diff-highlight/.gitignore
new
+2
@@ -0,0 +1,2 @@
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+shebang.perl
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+diff-highlight
contrib/diff-highlight/DiffHighlight.pm
renamed
+24
-16
@@ -1,4 +1,4 @@
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-#!/usr/bin/perl
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+package DiffHighlight;
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use 5.008;
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use warnings FATAL => 'all';
@@ -29,13 +29,14 @@ my @removed;
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my @added;
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my $in_hunk;
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-# Some scripts may not realize that SIGPIPE is being ignored when launching the
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-# pager--for instance scripts written in Python.
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-$SIG{PIPE} = 'DEFAULT';
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+our $line_cb = sub { print @_ };
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+our $flush_cb = sub { local $| = 1 };
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+
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+sub handle_line {
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+ local $_ = shift;
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-while (<>) {
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if (!$in_hunk) {
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- print;
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+ $line_cb->($_);
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$in_hunk = /^$GRAPH*$COLOR*\@\@ /;
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}
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elsif (/^$GRAPH*$COLOR*-/) {
@@ -49,7 +50,7 @@ while (<>) {
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@removed = ();
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@added = ();
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- print;
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+ $line_cb->($_);
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$in_hunk = /^$GRAPH*$COLOR*[\@ ]/;
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}
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@@ -62,15 +63,22 @@ while (<>) {
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# place to flush. Flushing on a blank line is a heuristic that
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# happens to match git-log output.
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if (!length) {
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- local $| = 1;
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+ $flush_cb->();
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}
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}
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-# Flush any queued hunk (this can happen when there is no trailing context in
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-# the final diff of the input).
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-show_hunk(\@removed, \@added);
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+sub flush {
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+ # Flush any queued hunk (this can happen when there is no trailing
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+ # context in the final diff of the input).
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+ show_hunk(\@removed, \@added);
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+}
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-exit 0;
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+sub highlight_stdin {
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+ while (<STDIN>) {
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+ handle_line($_);
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+ }
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+ flush();
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+}
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# Ideally we would feed the default as a human-readable color to
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# git-config as the fallback value. But diff-highlight does
@@ -88,7 +96,7 @@ sub show_hunk {
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# If one side is empty, then there is nothing to compare or highlight.
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if (!@$a || !@$b) {
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- print @$a, @$b;
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+ $line_cb->(@$a, @$b);
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return;
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}
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@@ -97,17 +105,17 @@ sub show_hunk {
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# stupid, and only handle multi-line hunks that remove and add the same
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# number of lines.
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if (@$a != @$b) {
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- print @$a, @$b;
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+ $line_cb->(@$a, @$b);
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return;
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}
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my @queue;
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for (my $i = 0; $i < @$a; $i++) {
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my ($rm, $add) = highlight_pair($a->[$i], $b->[$i]);
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- print $rm;
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+ $line_cb->($rm);
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push @queue, $add;
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}
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- print @queue;
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+ $line_cb->(@queue);
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}
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sub highlight_pair {
contrib/diff-highlight/Makefile
+18
-3
@@ -1,5 +1,20 @@
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-# nothing to build
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-all:
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+all: diff-highlight
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-test:
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+PERL_PATH = /usr/bin/perl
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+-include ../../config.mak
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+
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+PERL_PATH_SQ = $(subst ','\'',$(PERL_PATH))
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+
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+diff-highlight: shebang.perl DiffHighlight.pm diff-highlight.perl
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+ cat $^ >$@+
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+ chmod +x $@+
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+ mv $@+ $@
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+
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+shebang.perl: FORCE
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+ @echo '#!$(PERL_PATH_SQ)' >$@+
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+ @cmp $@+ $@ >/dev/null 2>/dev/null || mv $@+ $@
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+
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+test: all
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$(MAKE) -C t
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+
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+.PHONY: FORCE
contrib/diff-highlight/README
+30
@@ -99,6 +99,36 @@ newHighlight = "black #aaffaa"
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---------------------------------------------
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+Using diff-highlight as a module
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+--------------------------------
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+
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+If you want to pre- or post- process the highlighted lines as part of
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+another perl script, you can use the DiffHighlight module. You can
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+either "require" it or just cat the module together with your script (to
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+avoid run-time dependencies).
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+
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+Your script may set up one or more of the following variables:
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+
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+ - $DiffHighlight::line_cb - this should point to a function which is
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+ called whenever DiffHighlight has lines (which may contain
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+ highlights) to output. The default function prints each line to
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+ stdout. Note that the function may be called with multiple lines.
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+
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+ - $DiffHighlight::flush_cb - this should point to a function which
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+ flushes the output (because DiffHighlight believes it has completed
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+ processing a logical chunk of input). The default function flushes
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+ stdout.
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+
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+The script may then feed lines, one at a time, to DiffHighlight::handle_line().
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+When lines are done processing, they will be fed to $line_cb. Note that
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+DiffHighlight may queue up many input lines (to analyze a whole hunk)
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+before calling $line_cb. After providing all lines, call
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+DiffHighlight::flush() to flush any unprocessed lines.
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+
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+If you just want to process stdin, DiffHighlight::highlight_stdin()
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+is a convenience helper which will loop and flush for you.
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+
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+
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Bugs
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----
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contrib/diff-highlight/diff-highlight.perl
new
+8
@@ -0,0 +1,8 @@
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+package main;
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+
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+# Some scripts may not realize that SIGPIPE is being ignored when launching the
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+# pager--for instance scripts written in Python.
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+$SIG{PIPE} = 'DEFAULT';
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+
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+DiffHighlight::highlight_stdin();
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+exit 0;