color-words: make regex configurable via attributes

Make the --color-words splitting regular expression configurable via
the diff driver's 'wordregex' attribute.  The user can then set the
driver on a file in .gitattributes.  If a regex is given on the
command line, it overrides the driver's setting.

We also provide built-in regexes for the languages that already had
funcname patterns, and add an appropriate diff driver entry for C/++.
(The patterns are designed to run UTF-8 sequences into a single chunk
to make sure they remain readable.)

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/t/t4034-diff-words.sh b/t/t4034-diff-words.sh
index 487348630..744221bef 100755
--- a/t/t4034-diff-words.sh
+++ b/t/t4034-diff-words.sh
@@ -84,6 +84,41 @@ test_expect_success 'word diff with a regular expression' '
 
 '
 
+test_expect_success 'set a diff driver' '
+	git config diff.testdriver.wordregex "[^[:space:]]" &&
+	cat <<EOF > .gitattributes
+pre diff=testdriver
+post diff=testdriver
+EOF
+'
+
+test_expect_success 'option overrides default' '
+
+	word_diff --color-words="[a-z]+"
+
+'
+
+cat > expect <<\EOF
+<WHITE>diff --git a/pre b/post<RESET>
+<WHITE>index 330b04f..5ed8eff 100644<RESET>
+<WHITE>--- a/pre<RESET>
+<WHITE>+++ b/post<RESET>
+<BROWN>@@ -1,3 +1,7 @@<RESET>
+h(4)<GREEN>,hh[44]<RESET>
+<RESET>
+a = b + c<RESET>
+
+<GREEN>aa = a<RESET>
+
+<GREEN>aeff = aeff * ( aaa )<RESET>
+EOF
+
+test_expect_success 'use default supplied by driver' '
+
+	word_diff --color-words
+
+'
+
 echo 'aaa (aaa)' > pre
 echo 'aaa (aaa) aaa' > post
 
@@ -100,6 +135,7 @@ test_expect_success 'test parsing words for newline' '
 
 	word_diff --color-words="a+"
 
+
 '
 
 echo '(:' > pre