====== Find dependencies ======

=== Continued lines ('\') ===
Some ports' ''%%Makefile%%''s contain line-continuations making it non-trivial to find dependencies etc.
These lines end in a '\' so an ''%%OPT_USE%%'' could be on one line whereas the ''%%mysql%%'' may appear on a different line

To counter this, use

<code>
perl -pe 's/\\\n/ /' {} \;
</code>

to remove line-continuations.

=== Finding in files ===
Finding in (all) files is a lot easier with ''%%textproc/the_silver_searcher%%''. To find all relevant files containing references to mysql as a first filter use

<code>
ag --ignore 'pkg-*' --ignore 'distinfo' --ignore 'patch-*' mysql
</code>

Silver Searcher will perform a case-insensitive search by default

=== Example ===
This example is used to refactor the %%MySQL%% part from ''%%Mk/bsd.databases.mk%%'' to ''%%Mk/Uses/mysql.mk%%''

To find all files requiring %%MySQL%%, you could use something like

<code bash>
for file in `ag --ignore 'pkg-*' --ignore 'distinfo' --ignore 'patch-*' -l mysql` ; do
   perl -pe 's/\\\n/ /' $file \
     | grep -iE '(USE_MYSQL|_USE.*mysql)' \
     | sed -ne "/[Mm][Yy][Ss][Qq][Ll]/s|^|${file}:|p"
done
</code>

Breaking this down
  - Fast finding in files, limits the number of files that we need to process and many forks
  - Concatenate continued lines so we can use grep
  - Depenencies come in two forms that we need to find (USE_MYSQL and OPT_USE are always caps but the latter allows for mixed case values) - USE_MYSQL= boolean:option - OPT_USE= mysql=option
  - We want to know what file this appears in, so add it again using sed

=== More info ===
https://people.freebsd.org/~ak/gettext/

====== Mk/Uses/mysql.mk ======

==== USE_MYSQL ====
193 ports contain USE_MYSQL\\ 
''%%Mk/bsd.databases.mk%%'' defines values as ''%%client/server/embedded%%'' yet only ''%%server%%'' and ''%%embedded%%'' are handled specifically, everything else therefor is ''%%client%%''\\ 
Found in ports: USE_MYSQL=([45]1+|[Yy][Ee][Ss]|client|compat|embedded|server)

| server |  12 |
| embedded |  1 |
| client |  188 |
| **total** |  201 |

=== Transformations ===
''%%USE_MYSQL=\([  ]*\)server%%'' to ''%%USES+=\1mysql:server%%''\\ 
''%%USE_MYSQL=\([  ]*\)embedded%%'' to ''%%USES+=\1mysql:embedded%%''\\ 
''%%USE_MYSQL=\([  ]*\)([45]1+|[Yy][Ee][Ss]|client|compat)%%'' to ''%%USES+=\1mysql%%''

==== OPT_USE= mysql ====

Often shown as ''%%OPT_USE= mysql=yes%%''

There may already be a OPT_USES= line in the Makefile, take that into account

''%%OPT_USE= [Mm][Yy][Ss][Qq][Ll]=([Yy][Ee][Ss]|client|compat|server%%''

There may be multiple OPT_USE= variables\\ 
''%%OPT_USE=       MYSQL=client PHP=mysql,pdo_mysql%%''

There's a USE_OFF awell
''%%MYSQLD_USE_OFF=        MYSQL=client%%''

=== Transformations ===

\([A-Z_]*\)_USE=\([     ]*\)[Mm][Yy][Ss][Qq][Ll]=[Yy][Ee][Ss] to \1_USES=\2mysql

==== Convert git diff ====

git diffs need to be transformed to use in ports.

<code>
--- a/src/openssl-dtls.c
+++ b/openssl-dtls.c
</code>

needs to be transformed into

<code>
--- src/openssl-dtls.c.orig
+++ src/openssl-dtls.c
</code>

This can easily be achieved with sed

<code>
sed -e 's|^--- a/\(.*\)|--- \1.orig|;s|^+++ b/|+++ |' patch-LibreSSL
</code>