From 95fd43668a72d29f66cbc499a49c1772ed9a388c Mon Sep 17 00:00:00 2001
From: William Melody <hi@williammelody.com>
Date: Sat, 12 Sep 2015 16:09:49 -0700
Subject: [PATCH] Assign `remove` regular expressions to variables.

Since the regular expressions are essentially repeated, with the only
difference being the capturing groups that have no impact on the delete
operations, assign them to a set of descriptive variables. This makes
things more organized and additionally provides some explanation for
what each regular expression is matching against.
---
 hosts | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/hosts b/hosts
index 6dfe065..cd34db1 100755
--- a/hosts
+++ b/hosts
@@ -935,9 +935,9 @@ EOM
 remove() {
   _verify_write_permissions
   local is_search_pair=0
-  local search_ip
-  local search_hostname
-  local search_string
+  local search_ip=""
+  local search_hostname=""
+  local search_string=""
 
   _debug printf "remove() \$1: %s\n" "${1:-}"
   _debug printf "remove() \$2: %s\n" "${2:-}"
@@ -957,6 +957,14 @@ remove() {
     _debug printf "remove() \$search_string: %s\n" "$search_string"
   fi
 
+  # IP / Hostname pair regular expressions:
+  local target_regex_ip_hostname_commented="^\(${search_ip}[${_TAB_SPACE_}]*${search_hostname}[${_TAB_SPACE_}]..*\)$"
+  local target_regex_ip_hostname="^\(${search_ip}[${_TAB_SPACE_}]*${search_hostname}\)$"
+  # Search string regular expressions:
+  local target_regex_ip="^\(${search_string}[${_TAB_SPACE_}]..*\)$"
+  local target_regex_commented_hostname="^\(..*[${_TAB_SPACE_}]${search_string}[${_TAB_SPACE_}]..*\)$"
+  local target_regex_hostname="^\(..*[${_TAB_SPACE_}]${search_string}\)$"
+
   # Regular Expression Notes
   #
   # - Note double periods in regular expression in order to emulate /.+/,
@@ -967,16 +975,16 @@ remove() {
   then
     target_records=$(
       sed -n \
-        -e "s/^\(${search_ip}[${_TAB_SPACE_}]*${search_hostname}[${_TAB_SPACE_}]..*\)$/\1/p" \
-        -e "s/^\(${search_ip}[${_TAB_SPACE_}]*${search_hostname}\)$/\1/p" \
+        -e "s/${target_regex_ip_hostname_commented}/\1/p" \
+        -e "s/${target_regex_ip_hostname}/\1/p" \
         "${HOSTS_PATH}"
     )
   else
     target_records=$(
       sed -n \
-        -e "s/^\(${search_string}[${_TAB_SPACE_}]..*\)$/\1/p" \
-        -e "s/^\(..*[${_TAB_SPACE_}]${search_string}[${_TAB_SPACE_}]..*\)$/\1/p" \
-        -e "s/^\(..*[${_TAB_SPACE_}]${search_string}\)$/\1/p" \
+        -e "s/${target_regex_ip}/\1/p" \
+        -e "s/${target_regex_commented_hostname}/\1/p" \
+        -e "s/${target_regex_hostname}/\1/p" \
         "${HOSTS_PATH}"
     )
   fi
@@ -1016,14 +1024,14 @@ remove() {
   if ((is_search_pair))
   then
     sed -i '' \
-      -e "s/^${search_ip}[${_TAB_SPACE_}]${search_hostname}[${_TAB_SPACE_}]..*$/d" \
-      -e "s/^${search_ip}[${_TAB_SPACE_}]${search_hostname}$/d" \
+      -e "/${target_regex_ip_hostname_commented}/d" \
+      -e "/${target_regex_ip_hostname}/d" \
       "${HOSTS_PATH}"
   else
     sed -i '' \
-      -e "/^${search_string}[${_TAB_SPACE_}]..*$/d" \
-      -e "/^..*[${_TAB_SPACE_}]${search_string}[${_TAB_SPACE_}]..*$/d" \
-      -e "/^..*[${_TAB_SPACE_}]${search_string}$/d" \
+      -e "/${target_regex_ip}/d" \
+      -e "/${target_regex_commented_hostname}/d" \
+      -e "/${target_regex_hostname}/d" \
       "${HOSTS_PATH}"
   fi
   printf "Removed:\n%s\n" "${target_records}"