diff --git a/README.md b/README.md
index d574418..76cb3a2 100644
--- a/README.md
+++ b/README.md
@@ -1,73 +1,47 @@
-zsh-syntax-highlighting ![Project status](http://stillmaintained.com/nicoulaj/zsh-syntax-highlighting.png)
-==========================================================================================================
+zsh-syntax-highlighting
+=======================
 
 **[Fish shell](http://www.fishshell.com) like syntax highlighting for [Zsh](http://www.zsh.org).**
 
-*Requirements: zsh 4.3.9 or superior.*
+*Requirements: zsh 4.3.9+.*
 
 
-## Try it
-
-Here is a one-liner to try it without installing or modifying anything:
-
-    wget --no-check-certificate --output-document=/tmp/zsh-syntax-highlighting.zsh https://github.com/nicoulaj/zsh-syntax-highlighting/raw/master/zsh-syntax-highlighting.zsh && . /tmp/zsh-syntax-highlighting.zsh
-
-
-## Install it
-
+How to install
+--------------
 
 ### In your ~/.zshrc
 
 * Download the script or clone this repository:
 
-      git clone git://github.com/nicoulaj/zsh-syntax-highlighting.git
+        git clone git://github.com/nicoulaj/zsh-syntax-highlighting.git
 
 * Source the script **at the end** of `~/.zshrc`:
 
-      source /path/to/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh
+        source /path/to/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh
 
 * Source `~/.zshrc`  to take changes into account:
 
-      source ~/.zshrc
+        source ~/.zshrc
 
 
 ### With oh-my-zsh
 
 * Download the script or clone this repository in [oh-my-zsh](http://github.com/robbyrussell/oh-my-zsh) plugins directory:
 
-      cd ~/.oh-my-zsh/plugins/
-      git clone git://github.com/nicoulaj/zsh-syntax-highlighting.git
+        cd ~/.oh-my-zsh/plugins/
+        git clone git://github.com/nicoulaj/zsh-syntax-highlighting.git
 
 * Activate the plugin in `~/.zshrc` (in **last** position):
 
-      plugins=( [plugins...] zsh-syntax-highlighting)
+        plugins=( [plugins...] zsh-syntax-highlighting)
 
 * Source `~/.zshrc`  to take changes into account:
     
-      source ~/.zshrc
+        source ~/.zshrc
 
 
-## Tweak it
+How to tweak
+------------
 
-Optionally, you can override the default styles used for highlighting. The styles are declared in the `ZSH_HIGHLIGHT_STYLES` array. You can override styles this way:
-
-    # To differentiate aliases from other command types
-    ZSH_HIGHLIGHT_STYLES[alias]='fg=magenta,bold'
-    
-    # To have paths colored instead of underlined
-    ZSH_HIGHLIGHT_STYLES[path]='fg=cyan'
-    
-    # To disable highlighting of globbing expressions
-    ZSH_HIGHLIGHT_STYLES[globbing]='none'
-
-You can tweak the styles used to colorize matching brackets by overriding the `ZSH_HIGHLIGHT_MATCHING_BRACKETS_STYLES`.
-
-    ZSH_HIGHLIGHT_MATCHING_BRACKETS_STYLES=(
-      'fg=blue,bold'    # Style for first level of imbrication
-      'fg=green,bold'   # Style for second level of imbrication
-      'fg=magenta,bold' # etc... Put as many styles as you wish, or leave
-      'fg=yellow,bold'  # empty to disable brackets matching.
-      'fg=cyan,bold'
-    )
-
-This must be done **after** the script is sourced, otherwise your styles will be overwritten. The syntax for declaring styles is [documented here](http://zsh.sourceforge.net/Doc/Release/Zsh-Line-Editor.html#SEC135).
+Syntax highlighting is done by pluggable highlighter scripts, see the [highlighters directory](highlighters)
+for documentation and configuration settings.
diff --git a/highlighters/README.md b/highlighters/README.md
new file mode 100644
index 0000000..bd02395
--- /dev/null
+++ b/highlighters/README.md
@@ -0,0 +1,47 @@
+zsh-syntax-highlighting / highlighters
+======================================
+
+Syntax highlighting is done by pluggable highlighters:
+
+* [***main***](main) - the base highlighter, and the only one active by default.
+* [***brackets***](brackets) - matches brackets and parenthesis.
+* [***pattern***](pattern) - matches user-defined patterns.
+
+
+How to activate highlighters
+----------------------------
+
+To activate an highlighter, add it to the `ZSH_HIGHLIGHT_HIGHLIGHTERS` array in `~/.zshrc`, for example:
+
+    ZSH_HIGHLIGHT_HIGHLIGHTERS=(main brackets pattern)
+
+
+How to tweak highlighters
+-------------------------
+
+Highlighters look up styles from the `ZSH_HIGHLIGHT_STYLES` array. Navigate into each highlighter directory to see what styles it defines and how to configure it.
+
+
+How to implement a new highlighter
+----------------------------------
+
+To create your own ***myhighlighter*** highlighter:
+ 
+* Create your script at **highlighters/*myhighlighter*/*myhighlighter*-highlighter.zsh**.
+* Implement the `_zsh_highlight_myhighlighter_highlighter_predicate` function. This function must return 0 when the highlighter needs to be called, for example:
+
+        _zsh_highlight_myhighlighter_highlighter_predicate() {
+          # Call this highlighter in SVN repositories
+          [[ -d .svn ]]
+        }
+
+* Implement the `_zsh_highlight_myhighlighter_highlighter` function. This function does the actual syntax highlighting, by modifying `region_highlight`, for example:
+
+        _zsh_highlight_myhighlighter_highlighter() {
+          # Colorize the whole buffer with blue background
+          region_highlight+=(0 $#BUFFER bg=blue)
+        }
+
+* Activate your highlighter in `~/.zshrc`:
+
+        ZSH_HIGHLIGHT_HIGHLIGHTERS+=(myhighlighter)
diff --git a/highlighters/brackets/README.md b/highlighters/brackets/README.md
new file mode 100644
index 0000000..813c9b9
--- /dev/null
+++ b/highlighters/brackets/README.md
@@ -0,0 +1,28 @@
+zsh-syntax-highlighting / highlighters / brackets
+=================================================
+
+This is the ***brackets*** highlighter, that highlights brackets, parenthesis and matches them.
+
+
+How to activate it
+------------------
+To activate it, add it to `ZSH_HIGHLIGHT_HIGHLIGHTERS`:
+
+    ZSH_HIGHLIGHT_HIGHLIGHTERS=( [...] brackets)
+
+
+How to tweak it
+---------------
+This highlighter defines the following styles:
+* `bracket-error` - unmatched brackets
+* `bracket-level-N` - brackets with nest level N
+
+To override one of those styles, change its entry in `ZSH_HIGHLIGHT_STYLES`, for example in `~/.zshrc`:
+
+    # To define styles for nested brackets up to level 4
+    ZSH_HIGHLIGHT_STYLES[bracket-level-1]='fg=blue,bold'
+    ZSH_HIGHLIGHT_STYLES[bracket-level-2]='fg=red,bold'
+    ZSH_HIGHLIGHT_STYLES[bracket-level-3]='fg=yellow,bold'
+    ZSH_HIGHLIGHT_STYLES[bracket-level-4]='fg=magenta,bold'
+
+The syntax for declaring styles is [documented here](http://zsh.sourceforge.net/Doc/Release/Zsh-Line-Editor.html#SEC135).
diff --git a/highlighters/brackets.zsh b/highlighters/brackets/brackets-highlighter.zsh
similarity index 78%
rename from highlighters/brackets.zsh
rename to highlighters/brackets/brackets-highlighter.zsh
index 6af9ba2..63aae99 100644
--- a/highlighters/brackets.zsh
+++ b/highlighters/brackets/brackets-highlighter.zsh
@@ -29,29 +29,24 @@
 # -------------------------------------------------------------------------------------------------
 
 
-ZSH_HIGHLIGHT_STYLES+=(
-  bracket-error                 'fg=red,bold'
-)
+# Define default styles.
+: ${ZSH_HIGHLIGHT_STYLES[bracket-error]:=fg=red,bold}
+: ${ZSH_HIGHLIGHT_STYLES[bracket-level-1]:=fg=blue,bold}
+: ${ZSH_HIGHLIGHT_STYLES[bracket-level-2]:=fg=green,bold}
+: ${ZSH_HIGHLIGHT_STYLES[bracket-level-3]:=fg=magenta,bold}
+: ${ZSH_HIGHLIGHT_STYLES[bracket-level-4]:=fg=yellow,bold}
+: ${ZSH_HIGHLIGHT_STYLES[bracket-level-5]:=fg=cyan,bold}
 
-# Colors for bracket levels.
-# Put as many color as you wish.
-# Leave it as an empty array to disable.
-ZSH_HIGHLIGHT_MATCHING_BRACKETS_STYLES=(
-  'fg=blue,bold'
-  'fg=green,bold'
-  'fg=magenta,bold'
-  'fg=yellow,bold'
-  'fg=cyan,bold'
-)
-
-# Whether the bracket match highlighting shound be called or not.
-_zsh_highlight_bracket-match-p() {
-  _zsh_highlight_cursor-moved-p || _zsh_highlight_buffer-modified-p
+# Whether the brackets highlighter should be called or not.
+_zsh_highlight_brackets_highlighter_predicate()
+{
+  _zsh_highlight_cursor_moved || _zsh_highlight_buffer_modified
 }
 
-# Bracket match highlighting.
-_zsh_highlight_bracket-match() {
-  bracket_color_size=${#ZSH_HIGHLIGHT_MATCHING_BRACKETS_STYLES}
+# Brackets highlighting function.
+_zsh_highlight_brackets_highlighter()
+{
+  bracket_color_size=${#ZSH_HIGHLIGHT_STYLES[(I)bracket-level-*]}
   if ((bracket_color_size > 0)); then
     typeset -A levelpos lastoflevel matching revmatching
     ((level = 0))
@@ -73,7 +68,7 @@ _zsh_highlight_bracket-match() {
       if ((level < 1)); then
         region_highlight+=("$((pos - 1)) $pos "$ZSH_HIGHLIGHT_STYLES[bracket-error])
       else
-        region_highlight+=("$((pos - 1)) $pos "$ZSH_HIGHLIGHT_MATCHING_BRACKETS_STYLES[(( (level - 1) % bracket_color_size + 1 ))])
+        region_highlight+=("$((pos - 1)) $pos "$ZSH_HIGHLIGHT_STYLES[bracket-level-$(( (level - 1) % bracket_color_size + 1 ))])
       fi
     done
     ((c = CURSOR + 1))
@@ -85,5 +80,3 @@ _zsh_highlight_bracket-match() {
     fi
   fi
 }
-
-_zsh_highlight_add-highlighter _zsh_highlight_bracket-match
diff --git a/highlighters/main/README.md b/highlighters/main/README.md
new file mode 100644
index 0000000..a834572
--- /dev/null
+++ b/highlighters/main/README.md
@@ -0,0 +1,55 @@
+zsh-syntax-highlighting / highlighters / main
+=============================================
+
+This is the ***main*** highlighter, that highlights:
+
+* Commands
+* Options
+* Arguments
+* Paths
+* Strings
+
+How to activate it
+------------------
+To activate it, add it to `ZSH_HIGHLIGHT_HIGHLIGHTERS`:
+
+    ZSH_HIGHLIGHT_HIGHLIGHTERS=( [...] main)
+
+This highlighter is active by default.
+
+
+How to tweak it
+---------------
+This highlighter defines the following styles:
+* `unknown-token` - unknown tokens / errors
+* `reserved-word` - shell reserved words
+* `alias` - aliases
+* `builtin` - shell builtin commands
+* `function` - functions
+* `command` - commands
+* `hashed-command` - hashed commands
+* `path` - paths
+* `globbing` - globbing expressions
+* `history-expansion` - history expansion expressions
+* `single-hyphen-option` - single hyphen options
+* `double-hyphen-option` - double hyphen options
+* `back-quoted-argument` - backquoted expressions
+* `single-quoted-argument` - single quoted arguments
+* `double-quoted-argument` - double quoted arguments
+* `dollar-double-quoted-argument` -  dollar double quoted arguments
+* `back-double-quoted-argument` -  back double quoted arguments
+* `assign` - variable assignments
+* `default` - parts of the buffer that do not match anything
+
+To override one of those styles, change its entry in `ZSH_HIGHLIGHT_STYLES`, for example in `~/.zshrc`:
+
+    # To differentiate aliases from other command types
+    ZSH_HIGHLIGHT_STYLES[alias]='fg=magenta,bold'
+    
+    # To have paths colored instead of underlined
+    ZSH_HIGHLIGHT_STYLES[path]='fg=cyan'
+    
+    # To disable highlighting of globbing expressions
+    ZSH_HIGHLIGHT_STYLES[globbing]='none'
+
+The syntax for declaring styles is [documented here](http://zsh.sourceforge.net/Doc/Release/Zsh-Line-Editor.html#SEC135).
diff --git a/highlighters/main/main-highlighter.zsh b/highlighters/main/main-highlighter.zsh
new file mode 100644
index 0000000..3996f87
--- /dev/null
+++ b/highlighters/main/main-highlighter.zsh
@@ -0,0 +1,164 @@
+#!/usr/bin/env zsh
+# -------------------------------------------------------------------------------------------------
+# Copyright (c) 2010-2011 zsh-syntax-highlighting contributors
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without modification, are permitted
+# provided that the following conditions are met:
+#
+#  * Redistributions of source code must retain the above copyright notice, this list of conditions
+#    and the following disclaimer.
+#  * Redistributions in binary form must reproduce the above copyright notice, this list of
+#    conditions and the following disclaimer in the documentation and/or other materials provided
+#    with the distribution.
+#  * Neither the name of the zsh-syntax-highlighting contributors nor the names of its contributors
+#    may be used to endorse or promote products derived from this software without specific prior
+#    written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+# FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
+# IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+# -------------------------------------------------------------------------------------------------
+# -*- mode: zsh; sh-indentation: 2; indent-tabs-mode: nil; sh-basic-offset: 2; -*-
+# vim: ft=zsh sw=2 ts=2 et
+# -------------------------------------------------------------------------------------------------
+
+
+# Define default styles.
+: ${ZSH_HIGHLIGHT_STYLES[default]:=none}
+: ${ZSH_HIGHLIGHT_STYLES[unknown-token]:=fg=red,bold}
+: ${ZSH_HIGHLIGHT_STYLES[reserved-word]:=fg=yellow}
+: ${ZSH_HIGHLIGHT_STYLES[alias]:=fg=green}
+: ${ZSH_HIGHLIGHT_STYLES[builtin]:=fg=green}
+: ${ZSH_HIGHLIGHT_STYLES[function]:=fg=green}
+: ${ZSH_HIGHLIGHT_STYLES[command]:=fg=green}
+: ${ZSH_HIGHLIGHT_STYLES[hashed-command]:=fg=green}
+: ${ZSH_HIGHLIGHT_STYLES[path]:=underline}
+: ${ZSH_HIGHLIGHT_STYLES[globbing]:=fg=blue}
+: ${ZSH_HIGHLIGHT_STYLES[history-expansion]:=fg=blue}
+: ${ZSH_HIGHLIGHT_STYLES[single-hyphen-option]:=none}
+: ${ZSH_HIGHLIGHT_STYLES[double-hyphen-option]:=none}
+: ${ZSH_HIGHLIGHT_STYLES[back-quoted-argument]:=none}
+: ${ZSH_HIGHLIGHT_STYLES[single-quoted-argument]:=fg=yellow}
+: ${ZSH_HIGHLIGHT_STYLES[double-quoted-argument]:=fg=yellow}
+: ${ZSH_HIGHLIGHT_STYLES[dollar-double-quoted-argument]:=fg=cyan}
+: ${ZSH_HIGHLIGHT_STYLES[back-double-quoted-argument]:=fg=cyan}
+: ${ZSH_HIGHLIGHT_STYLES[assign]:=none}
+
+# Tokens that are always immediately followed by a command.
+ZSH_HIGHLIGHT_TOKENS_FOLLOWED_BY_COMMANDS=(
+  '|' '||' ';' '&' '&&' 'noglob' 'nocorrect' 'builtin'
+)
+
+# Whether the highlighter should be called or not.
+_zsh_highlight_main_highlighter_predicate()
+{
+  _zsh_highlight_buffer_modified
+}
+
+# Main syntax highlighting function.
+_zsh_highlight_main_highlighter()
+{
+  setopt localoptions extendedglob bareglobqual
+  local start_pos=0 end_pos highlight_glob=true new_expression=true arg style
+  region_highlight=()
+  for arg in ${(z)BUFFER}; do
+    local substr_color=0
+    [[ $start_pos -eq 0 && $arg = 'noglob' ]] && highlight_glob=false
+    ((start_pos+=${#BUFFER[$start_pos+1,-1]}-${#${BUFFER[$start_pos+1,-1]##[[:space:]]#}}))
+    ((end_pos=$start_pos+${#arg}))
+    if $new_expression; then
+      new_expression=false
+      res=$(LC_ALL=C builtin type -w $arg 2>/dev/null)
+      case $res in
+        *': reserved')  style=$ZSH_HIGHLIGHT_STYLES[reserved-word];;
+        *': alias')     style=$ZSH_HIGHLIGHT_STYLES[alias]
+                        local aliased_command="${"$(alias $arg)"#*=}"
+                        [[ -n ${(M)ZSH_HIGHLIGHT_TOKENS_FOLLOWED_BY_COMMANDS:#"$aliased_command"} && -z ${(M)ZSH_HIGHLIGHT_TOKENS_FOLLOWED_BY_COMMANDS:#"$arg"} ]] && ZSH_HIGHLIGHT_TOKENS_FOLLOWED_BY_COMMANDS+=($arg)
+                        ;;
+        *': builtin')   style=$ZSH_HIGHLIGHT_STYLES[builtin];;
+        *': function')  style=$ZSH_HIGHLIGHT_STYLES[function];;
+        *': command')   style=$ZSH_HIGHLIGHT_STYLES[command];;
+        *': hashed')    style=$ZSH_HIGHLIGHT_STYLES[hashed-command];;
+        *)              if _zsh_highlight_main_highlighter_check_assign; then
+                          style=$ZSH_HIGHLIGHT_STYLES[assign]
+                          new_expression=true
+                        elif _zsh_highlight_main_highlighter_check_path; then
+                          style=$ZSH_HIGHLIGHT_STYLES[path]
+                        elif [[ $arg[0,1] = $histchars[0,1] ]]; then
+                          style=$ZSH_HIGHLIGHT_STYLES[history-expansion]
+                        else
+                          style=$ZSH_HIGHLIGHT_STYLES[unknown-token]
+                        fi
+                        ;;
+      esac
+    else
+      case $arg in
+        '--'*)   style=$ZSH_HIGHLIGHT_STYLES[double-hyphen-option];;
+        '-'*)    style=$ZSH_HIGHLIGHT_STYLES[single-hyphen-option];;
+        "'"*"'") style=$ZSH_HIGHLIGHT_STYLES[single-quoted-argument];;
+        '"'*'"') style=$ZSH_HIGHLIGHT_STYLES[double-quoted-argument]
+                 region_highlight+=("$start_pos $end_pos $style")
+                 _zsh_highlight_main_highlighter_highlight_string
+                 substr_color=1
+                 ;;
+        '`'*'`') style=$ZSH_HIGHLIGHT_STYLES[back-quoted-argument];;
+        *"*"*)   $highlight_glob && style=$ZSH_HIGHLIGHT_STYLES[globbing] || style=$ZSH_HIGHLIGHT_STYLES[default];;
+        *)       if _zsh_highlight_main_highlighter_check_path; then
+                   style=$ZSH_HIGHLIGHT_STYLES[path]
+                 elif [[ $arg[0,1] = $histchars[0,1] ]]; then
+                   style=$ZSH_HIGHLIGHT_STYLES[history-expansion]
+                 else
+                   style=$ZSH_HIGHLIGHT_STYLES[default]
+                 fi
+                 ;;
+      esac
+    fi
+    [[ $substr_color = 0 ]] && region_highlight+=("$start_pos $end_pos $style")
+    [[ -n ${(M)ZSH_HIGHLIGHT_TOKENS_FOLLOWED_BY_COMMANDS:#"$arg"} ]] && new_expression=true
+    start_pos=$end_pos
+  done
+}
+
+# Check if the argument is variable assignment
+_zsh_highlight_main_highlighter_check_assign()
+{
+    setopt localoptions extended_glob
+    [[ ${(Q)arg} == [[:alpha:]_]([[:alnum:]_])#=* ]]
+}
+
+# Check if the argument is a path.
+_zsh_highlight_main_highlighter_check_path()
+{
+  [[ -z ${(Q)arg} ]] && return 1
+  [[ -e ${(Q)arg} ]] && return 0
+  [[ ! -e ${(Q)arg:h} ]] && return 1
+  [[ ${#BUFFER} == $end_pos && -n $(print ${(Q)arg}*(N)) ]] && return 0
+  return 1
+}
+
+# Highlight special chars inside double-quoted strings
+_zsh_highlight_main_highlighter_highlight_string()
+{
+  setopt localoptions noksharrays
+  local i j k style
+  # Starting quote is at 1, so start parsing at offset 2 in the string.
+  for (( i = 2 ; i < end_pos - start_pos ; i += 1 )) ; do
+    (( j = i + start_pos - 1 ))
+    (( k = j + 1 ))
+    case "$arg[$i]" in
+      '$')  style=$ZSH_HIGHLIGHT_STYLES[dollar-double-quoted-argument];;
+      "\\") style=$ZSH_HIGHLIGHT_STYLES[back-double-quoted-argument]
+            (( k += 1 )) # Color following char too.
+            (( i += 1 )) # Skip parsing the escaped char.
+            ;;
+      *)    continue;;
+    esac
+    region_highlight+=("$j $k $style")
+  done
+}
diff --git a/tests/data/multiple-redirections.zsh b/highlighters/main/test-data/multiple-redirections.zsh
similarity index 100%
rename from tests/data/multiple-redirections.zsh
rename to highlighters/main/test-data/multiple-redirections.zsh
diff --git a/tests/data/nested-parentheses.zsh b/highlighters/main/test-data/nested-parentheses.zsh
similarity index 100%
rename from tests/data/nested-parentheses.zsh
rename to highlighters/main/test-data/nested-parentheses.zsh
diff --git a/tests/data/simple-command.zsh b/highlighters/main/test-data/simple-command.zsh
similarity index 100%
rename from tests/data/simple-command.zsh
rename to highlighters/main/test-data/simple-command.zsh
diff --git a/tests/data/simple-redirection.zsh b/highlighters/main/test-data/simple-redirection.zsh
similarity index 100%
rename from tests/data/simple-redirection.zsh
rename to highlighters/main/test-data/simple-redirection.zsh
diff --git a/tests/data/unknown-command.zsh b/highlighters/main/test-data/unknown-command.zsh
similarity index 100%
rename from tests/data/unknown-command.zsh
rename to highlighters/main/test-data/unknown-command.zsh
diff --git a/highlighters/pattern/README.md b/highlighters/pattern/README.md
new file mode 100644
index 0000000..82a7c65
--- /dev/null
+++ b/highlighters/pattern/README.md
@@ -0,0 +1,21 @@
+zsh-syntax-highlighting / highlighters / pattern
+================================================
+
+This is the ***pattern*** highlighter, that highlights user defined patterns.
+
+
+How to activate it
+------------------
+To activate it, add it to `ZSH_HIGHLIGHT_HIGHLIGHTERS`:
+
+    ZSH_HIGHLIGHT_HIGHLIGHTERS=( [...] pattern)
+
+
+How to tweak it
+---------------
+To use this highlighter, associate patterns with styles in the `ZSH_HIGHLIGHT_PATTERNS` array, for example in `~/.zshrc`:
+
+    # To have commands starting with `rm -rf` in red:
+    ZSH_HIGHLIGHT_PATTERNS+=('rm -rf *' 'fg=white,bold,bg=red')
+
+The syntax for declaring styles is [documented here](http://zsh.sourceforge.net/Doc/Release/Zsh-Line-Editor.html#SEC135).
diff --git a/highlighters/keyword.zsh b/highlighters/pattern/pattern-highlighter.zsh
similarity index 75%
rename from highlighters/keyword.zsh
rename to highlighters/pattern/pattern-highlighter.zsh
index 7302d15..93041a3 100644
--- a/highlighters/keyword.zsh
+++ b/highlighters/pattern/pattern-highlighter.zsh
@@ -29,35 +29,31 @@
 # -------------------------------------------------------------------------------------------------
 
 
-# A simple keyword highlighting extension for zsh-syntax-highlighting.
-
-# To use this, please do the following steps.
-# 1) Source this file after zsh-syntax-highlighting.zsh
-# % source zsh-syntax-highlighting.zsh
-# % source contrib/keyword.zsh
-# 2) Add keyword and color pairs to `ZSH_HIGHLIGHT_KEYWORD_KEYWORDS`.
-# % ZSH_HIGHLIGHT_KEYWORD_KEYWORDS+=('rm -rf *' 'fg=white,bold,bg=red')
-# 3) Please see the effect.
-# % ;# rm -rf /tmp/doesnotexist
-
 # List of keyword and color pairs.
-typeset -gA ZSH_HIGHLIGHT_KEYWORD_KEYWORDS
+typeset -gA ZSH_HIGHLIGHT_PATTERNS
 
-_zsh_highlight-keyword() {
+# Whether the pattern highlighter should be called or not.
+_zsh_highlight_pattern_highlighter_predicate()
+{
+  _zsh_highlight_buffer_modified
+}
+
+# Pattern syntax highlighting function.
+_zsh_highlight_pattern_highlighter()
+{
   setopt localoptions extendedglob
-  for pattern in ${(k)ZSH_HIGHLIGHT_KEYWORD_KEYWORDS}; do
-    _zsh_highlight-keyword-loop "$BUFFER" "$pattern"
+  for pattern in ${(k)ZSH_HIGHLIGHT_PATTERNS}; do
+    _zsh_highlight_pattern_highlighter_loop "$BUFFER" "$pattern"
   done
 }
 
-_zsh_highlight-keyword-loop() {
+_zsh_highlight_pattern_highlighter_loop()
+{
   # This does *not* do its job syntactically, sorry.
   local buf="$1" pat="$2"
   local -a match mbegin mend
   if [[ "$buf" == (#b)(*)(${~pat})* ]]; then
-    region_highlight+=("$((mbegin[2] - 1)) $mend[2] $ZSH_HIGHLIGHT_KEYWORD_KEYWORDS[$pat]")
+    region_highlight+=("$((mbegin[2] - 1)) $mend[2] $ZSH_HIGHLIGHT_PATTERNS[$pat]")
     "$0" "$match[1]" "$pat"; return $?
   fi
 }
-
-_zsh_highlight_add-highlighter _zsh_highlight-keyword _zsh_highlight_buffer-modified-p
diff --git a/tests/README.md b/tests/README.md
new file mode 100644
index 0000000..ed3cd85
--- /dev/null
+++ b/tests/README.md
@@ -0,0 +1,20 @@
+zsh-syntax-highlighting / tests
+===============================
+
+Utility scripts for testing zsh-syntax-highlighting highlighters.
+
+The tests expect the highlighter directory to contain a `test-data` directory with test data files. See the [main highlighter](../highlighters/main/test-data) for examples.
+
+
+highlighting test
+-----------------
+[`test-highlighting.zsh`](test-highlighting.zsh) tests the correctness of the highlighting. Usage:
+
+    zsh test-highlighting.zsh <HIGHLIGHTER NAME>
+
+
+performance test
+----------------
+[`test-perfs.zsh`](test-highlighting.zsh) measures the time spent doing the highlighting. Usage:
+
+    zsh test-perfs.zsh <HIGHLIGHTER NAME>
diff --git a/tests/test-highlighting.zsh b/tests/test-highlighting.zsh
index 7166eae..2e72b2b 100755
--- a/tests/test-highlighting.zsh
+++ b/tests/test-highlighting.zsh
@@ -29,14 +29,35 @@
 # -------------------------------------------------------------------------------------------------
 
 
+# Check an highlighter was given as argument.
+[[ -n "$1" ]] || {
+  echo "You must provide the name of a valid highlighter as argument." >&2
+  exit 1
+}
+
+# Check the highlighter is valid.
+[[ -f ${0:h:h}/highlighters/$1/$1-highlighter.zsh ]] || {
+  echo "Could not find highlighter '$1'." >&2
+  exit 1
+}
+
+# Check the highlighter has test data.
+[[ -d ${0:h:h}/highlighters/$1/test-data ]] || {
+  echo "Highlighter '$1' has no test data." >&2
+  exit 1
+}
+
 local -a errors highlight_zone
 local -A observed_result
 
 # Load the main script.
-. $(dirname $0)/../zsh-syntax-highlighting.zsh
+. ${0:h:h}/zsh-syntax-highlighting.zsh
 
-# Process each test data file in data/.
-for data_file in $(dirname $0)/data/*.zsh; do
+# Activate the highlighter.
+ZSH_HIGHLIGHT_HIGHLIGHTERS=($1)
+
+# Process each test data file in test data directory.
+for data_file in ${0:h:h}/highlighters/$1/test-data/*; do
 
   # Load the data and prepare checking it.
   BUFFER= ; expected_region_highlight=(); errors=()
@@ -55,7 +76,7 @@ for data_file in $(dirname $0)/data/*.zsh; do
 
       # Process the data.
       region_highlight=()
-      _zsh_highlight-zle-buffer
+      _zsh_highlight
 
       # Overlapping regions can be declared in region_highlight, so we first build an array of the
       # observed highlighting.
diff --git a/tests/test-perfs.zsh b/tests/test-perfs.zsh
index 570bce6..0d4adc3 100755
--- a/tests/test-perfs.zsh
+++ b/tests/test-perfs.zsh
@@ -29,11 +29,32 @@
 # -------------------------------------------------------------------------------------------------
 
 
-# Load the main script.
-. $(dirname $0)/../zsh-syntax-highlighting.zsh
+# Check an highlighter was given as argument.
+[[ -n "$1" ]] || {
+  echo "You must provide the name of a valid highlighter as argument." >&2
+  exit 1
+}
 
-# Process each test data file in data/.
-for data_file in $(dirname $0)/data/*.zsh; do
+# Check the highlighter is valid.
+[[ -f ${0:h:h}/highlighters/$1/$1-highlighter.zsh ]] || {
+  echo "Could not find highlighter '$1'." >&2
+  exit 1
+}
+
+# Check the highlighter has test data.
+[[ -d ${0:h:h}/highlighters/$1/test-data ]] || {
+  echo "Highlighter '$1' has no test data." >&2
+  exit 1
+}
+
+# Load the main script.
+. ${0:h:h}/zsh-syntax-highlighting.zsh
+
+# Activate the highlighter.
+ZSH_HIGHLIGHT_HIGHLIGHTERS=($1)
+
+# Process each test data file in test data directory.
+for data_file in ${0:h:h}/highlighters/$1/test-data/*; do
 
   # Load the data and prepare checking it.
   BUFFER=
@@ -45,9 +66,9 @@ for data_file in $(dirname $0)/data/*.zsh; do
     echo "KO\n   - 'BUFFER' is not declared or blank."
   else
 
-    # Measure the time taken by _zsh_highlight-zle-buffer.
+    # Measure the time taken by _zsh_highlight.
     TIMEFMT="%*Es"
-    time ( BUFFER="$BUFFER" && _zsh_highlight-zle-buffer)
+    time ( BUFFER="$BUFFER" && _zsh_highlight)
 
   fi
 
diff --git a/zsh-syntax-highlighting.zsh b/zsh-syntax-highlighting.zsh
index 87ae5d8..a180e44 100644
--- a/zsh-syntax-highlighting.zsh
+++ b/zsh-syntax-highlighting.zsh
@@ -33,255 +33,81 @@
 # Core highlighting update system
 # -------------------------------------------------------------------------------------------------
 
-# Array used by highlighters to declare overridable styles.
-typeset -gA ZSH_HIGHLIGHT_STYLES
+# Array declaring active highlighters names.
+typeset -ga ZSH_HIGHLIGHT_HIGHLIGHTERS
 
-# An `object' implemented by below 3 arrays' elements could be called a
-# `highlighter', registered by `_zsh_highlight_add-highlighter`. In other words, these
-# arrays are indexed and tied by their own functionality. If they have been
-# arranged inconsistently, things goes wrong.
-# Please see `_zsh_highlight-zle-buffer` and `_zsh_highlight_add-highlighter`.
-
-# Actual recolorize functions to be called.
-typeset -a zsh_highlight_functions; zsh_highlight_functions=()
-
-# Predicate functions whether its recolorize function should be called or not.
-typeset -a zsh_highlight_predicates; zsh_highlight_predicates=()
-
-# Highlight storages for each recolorize functions.
-typeset -a zsh_highlight_caches; zsh_highlight_caches=()
-
-_zsh_highlight-zle-buffer() {
+# Update ZLE buffer syntax highlighting.
+#
+# Invokes each highlighter that needs updating.
+# This function is supposed to be called whenever the ZLE state changes.
+_zsh_highlight()
+{
+  # Store the previous command return code to restore it whatever happens.
   local ret=$?
+
+  # Do not highlight if there are pending inputs (copy/paste).
+  [[ $PENDING -gt 0 ]] && return $ret
+
   {
-    local -a funinds
-    local -i rh_size=$#region_highlight
-    for i in {1..${#zsh_highlight_functions}}; do
-      local pred=${zsh_highlight_predicates[i]} cache_place=${zsh_highlight_caches[i]}
-      if _zsh_highlight-zle-buffer-p "$rh_size" "$pred"; then
-        if ((${#${(P)cache_place}} > 0)); then
-          region_highlight=(${region_highlight:#(${(P~j.|.)cache_place})})
-          local -a empty; empty=(); : ${(PA)cache_place::=$empty}
-        fi
-        funinds+=$i
+    local -a selected_highlighters
+    local cache_place
+
+    # Select which highlighters in ZSH_HIGHLIGHT_HIGHLIGHTERS need to be invoked.
+    local highlighter; for highlighter in $ZSH_HIGHLIGHT_HIGHLIGHTERS; do
+
+      # If highlighter needs to be invoked
+      if "_zsh_highlight_${highlighter}_highlighter_predicate"; then
+
+        # Mark the highlighter as selected for update.
+        selected_highlighters+=($highlighter)
+
+        # Remove what was stored in its cache from region_highlight.
+        cache_place="_zsh_highlight_${highlighter}_highlighter_cache"
+        [[ ${#${(P)cache_place}} -gt 0 ]] && region_highlight=(${region_highlight:#(${(P~j.|.)cache_place})})
       fi
     done
-    for i in $funinds; do
-      local func=${zsh_highlight_functions[i]} cache_place=${zsh_highlight_caches[i]}
-      local -a rh; rh=($region_highlight)
+
+    # Invoke each selected highlighter and store the result in its cache.
+    local -a region_highlight_copy
+    for highlighter in $selected_highlighters; do
+      cache_place="_zsh_highlight_${highlighter}_highlighter_cache"
+      region_highlight_copy=($region_highlight)
       {
-        "$func"
+        "_zsh_highlight_${highlighter}_highlighter"
       } always  {
-        : ${(PA)cache_place::=${region_highlight:#(${(~j.|.)rh})}}
+        : ${(PA)cache_place::=${region_highlight:#(${(~j.|.)region_highlight_copy})}}
       }
     done
+
   } always {
-    ZSH_PRIOR_CURSOR=$CURSOR
-    ZSH_PRIOR_HIGHLIGHTED_BUFFER=$BUFFER
+    _ZSH_HIGHLIGHT_PRIOR_BUFFER=$BUFFER
+    _ZSH_HIGHLIGHT_PRIOR_CURSOR=$CURSOR
     return $ret
   }
 }
 
-# Whether supplied highlight_predicate satisfies or not.
-_zsh_highlight-zle-buffer-p() {
-  local region_highlight_size="$1" highlight_predicate="$2"
-  # If any highlightings are not taken into account, asume it is needed.
-  # This holds for some up/down-history commands, for example.
-  ((region_highlight_size == 0)) || "$highlight_predicate"
-}
-
-# Whether the command line buffer is modified or not.
-_zsh_highlight_buffer-modified-p() {
-  [[ ${ZSH_PRIOR_HIGHLIGHTED_BUFFER:-} != $BUFFER ]]
-}
-
-# Whether the cursor is moved or not.
-_zsh_highlight_cursor-moved-p() {
-  ((ZSH_PRIOR_CURSOR != $CURSOR))
-}
-
-# Register an highlighter.
-_zsh_highlight_add-highlighter() {
-  zsh_highlight_functions+="$1"
-  zsh_highlight_predicates+="${2-${1}-p}"
-  zsh_highlight_caches+="${3-${1//-/_}}"
-}
-
 
 # -------------------------------------------------------------------------------------------------
-# Main highlighter
+# API/utility functions for highlighters
 # -------------------------------------------------------------------------------------------------
 
-ZSH_HIGHLIGHT_STYLES+=(
-  default                       'none'
-  unknown-token                 'fg=red,bold'
-  reserved-word                 'fg=yellow'
-  alias                         'fg=green'
-  builtin                       'fg=green'
-  function                      'fg=green'
-  command                       'fg=green'
-  hashed-command                'fg=green'
-  path                          'underline'
-  globbing                      'fg=blue'
-  history-expansion             'fg=blue'
-  single-hyphen-option          'none'
-  double-hyphen-option          'none'
-  back-quoted-argument          'none'
-  single-quoted-argument        'fg=yellow'
-  double-quoted-argument        'fg=yellow'
-  dollar-double-quoted-argument 'fg=cyan'
-  back-double-quoted-argument   'fg=cyan'
-  assign                        'none'
-)
+# Array used by highlighters to declare user overridable styles.
+typeset -gA ZSH_HIGHLIGHT_STYLES
 
-# Tokens that are always immediately followed by a command.
-ZSH_HIGHLIGHT_TOKENS_FOLLOWED_BY_COMMANDS=(
-  '|' '||' ';' '&' '&&' 'noglob' 'nocorrect' 'builtin'
-)
-
-# Check if the argument is variable assignment
-_zsh_highlight_check-assign() {
-    setopt localoptions extended_glob
-    [[ ${(Q)arg} == [[:alpha:]_]([[:alnum:]_])#=* ]]
+# Whether the command line buffer has been modified or not.
+#
+# Returns 0 if the buffer has changed since _zsh_highlight was last called.
+_zsh_highlight_buffer_modified()
+{
+  [[ ${_ZSH_HIGHLIGHT_PRIOR_BUFFER:-} != $BUFFER ]]
 }
 
-# Check if the argument is a path.
-_zsh_highlight_check-path() {
-  [[ -z ${(Q)arg} ]] && return 1
-  [[ -e ${(Q)arg} ]] && return 0
-  [[ ! -e ${(Q)arg:h} ]] && return 1
-  [[ ${#BUFFER} == $end_pos && -n $(print ${(Q)arg}*(N)) ]] && return 0
-  return 1
-}
-
-# Highlight special chars inside double-quoted strings
-_zsh_highlight_highlight_string() {
-  setopt localoptions noksharrays
-  local i j k style
-  # Starting quote is at 1, so start parsing at offset 2 in the string.
-  for (( i = 2 ; i < end_pos - start_pos ; i += 1 )) ; do
-    (( j = i + start_pos - 1 ))
-    (( k = j + 1 ))
-    case "$arg[$i]" in
-      '$')  style=$ZSH_HIGHLIGHT_STYLES[dollar-double-quoted-argument];;
-      "\\") style=$ZSH_HIGHLIGHT_STYLES[back-double-quoted-argument]
-            (( k += 1 )) # Color following char too.
-            (( i += 1 )) # Skip parsing the escaped char.
-            ;;
-      *)    continue;;
-    esac
-    region_highlight+=("$j $k $style")
-  done
-}
-
-# Core syntax highlighting.
-_zsh_main-highlight() {
-  setopt localoptions extendedglob bareglobqual
-  local start_pos=0 end_pos highlight_glob=true new_expression=true arg style
-  region_highlight=()
-  for arg in ${(z)BUFFER}; do
-    local substr_color=0
-    [[ $start_pos -eq 0 && $arg = 'noglob' ]] && highlight_glob=false
-    ((start_pos+=${#BUFFER[$start_pos+1,-1]}-${#${BUFFER[$start_pos+1,-1]##[[:space:]]#}}))
-    ((end_pos=$start_pos+${#arg}))
-    if $new_expression; then
-      new_expression=false
-      res=$(LC_ALL=C builtin type -w $arg 2>/dev/null)
-      case $res in
-        *': reserved')  style=$ZSH_HIGHLIGHT_STYLES[reserved-word];;
-        *': alias')     style=$ZSH_HIGHLIGHT_STYLES[alias]
-                        local aliased_command="${"$(alias $arg)"#*=}"
-                        [[ -n ${(M)ZSH_HIGHLIGHT_TOKENS_FOLLOWED_BY_COMMANDS:#"$aliased_command"} && -z ${(M)ZSH_HIGHLIGHT_TOKENS_FOLLOWED_BY_COMMANDS:#"$arg"} ]] && ZSH_HIGHLIGHT_TOKENS_FOLLOWED_BY_COMMANDS+=($arg)
-                        ;;
-        *': builtin')   style=$ZSH_HIGHLIGHT_STYLES[builtin];;
-        *': function')  style=$ZSH_HIGHLIGHT_STYLES[function];;
-        *': command')   style=$ZSH_HIGHLIGHT_STYLES[command];;
-        *': hashed')    style=$ZSH_HIGHLIGHT_STYLES[hashed-command];;
-        *)              if _zsh_highlight_check-assign; then
-                          style=$ZSH_HIGHLIGHT_STYLES[assign]
-                          new_expression=true
-                        elif _zsh_highlight_check-path; then
-                          style=$ZSH_HIGHLIGHT_STYLES[path]
-                        elif [[ $arg[0,1] = $histchars[0,1] ]]; then
-                          style=$ZSH_HIGHLIGHT_STYLES[history-expansion]
-                        else
-                          style=$ZSH_HIGHLIGHT_STYLES[unknown-token]
-                        fi
-                        ;;
-      esac
-    else
-      case $arg in
-        '--'*)   style=$ZSH_HIGHLIGHT_STYLES[double-hyphen-option];;
-        '-'*)    style=$ZSH_HIGHLIGHT_STYLES[single-hyphen-option];;
-        "'"*"'") style=$ZSH_HIGHLIGHT_STYLES[single-quoted-argument];;
-        '"'*'"') style=$ZSH_HIGHLIGHT_STYLES[double-quoted-argument]
-                 region_highlight+=("$start_pos $end_pos $style")
-                 _zsh_highlight_highlight_string
-                 substr_color=1
-                 ;;
-        '`'*'`') style=$ZSH_HIGHLIGHT_STYLES[back-quoted-argument];;
-        *"*"*)   $highlight_glob && style=$ZSH_HIGHLIGHT_STYLES[globbing] || style=$ZSH_HIGHLIGHT_STYLES[default];;
-        *)       if _zsh_highlight_check-path; then
-                   style=$ZSH_HIGHLIGHT_STYLES[path]
-                 elif [[ $arg[0,1] = $histchars[0,1] ]]; then
-                   style=$ZSH_HIGHLIGHT_STYLES[history-expansion]
-                 else
-                   style=$ZSH_HIGHLIGHT_STYLES[default]
-                 fi
-                 ;;
-      esac
-    fi
-    [[ $substr_color = 0 ]] && region_highlight+=("$start_pos $end_pos $style")
-    [[ -n ${(M)ZSH_HIGHLIGHT_TOKENS_FOLLOWED_BY_COMMANDS:#"$arg"} ]] && new_expression=true
-    start_pos=$end_pos
-  done
-}
-
-
-# -------------------------------------------------------------------------------------------------
-# Setup functions
-# -------------------------------------------------------------------------------------------------
-
-# Intercept specified ZLE events to have highlighting triggered.
-_zsh_highlight_bind-events() {
-
-  # Resolve event names what have to be bound to.
-  zmodload zsh/zleparameter 2>/dev/null || {
-    echo 'zsh-syntax-highlighting:zmodload error. exiting.' >&2
-    return -1
-  }
-  local -a events; : ${(A)events::=${@:#(_*|orig-*|.run-help|.which-command)}}
-
-  # Bind the events to _zsh_highlight-zle-buffer.
-  local clean_event
-  for event in $events; do
-    if [[ "$widgets[$event]" == completion:* ]]; then
-      eval "zle -C orig-$event ${${${widgets[$event]}#*:}/:/ } ; $event() { builtin zle orig-$event && _zsh_highlight-zle-buffer } ; zle -N $event"
-    else
-      case $event in
-        accept-and-menu-complete)
-          eval "$event() { builtin zle .$event && _zsh_highlight-zle-buffer } ; zle -N $event"
-          ;;
-        .*)
-          clean_event=$event[2,${#event}] # Remove the leading dot in the event name
-          case ${widgets[$clean_event]-} in
-            (completion|user):*)
-              ;;
-            *)
-              eval "$clean_event() { builtin zle $event && _zsh_highlight-zle-buffer } ; zle -N $clean_event"
-              ;;
-          esac
-          ;;
-        *)
-          ;;
-      esac
-    fi
-  done
-}
-
-# Load highlighters from specified directory if it exists.
-_zsh_highlight_load-highlighters() {
-  [[ -d $1 ]] && for highlighter_def ($1/*.zsh) . $highlighter_def
+# Whether the cursor has moved or not.
+#
+# Returns 0 if the cursor has moved since _zsh_highlight was last called.
+_zsh_highlight_cursor_moved()
+{
+  ((_ZSH_HIGHLIGHT_PRIOR_CURSOR != $CURSOR))
 }
 
 
@@ -289,11 +115,57 @@ _zsh_highlight_load-highlighters() {
 # Setup
 # -------------------------------------------------------------------------------------------------
 
-# Bind highlighting to all known events.
-_zsh_highlight_bind-events "${(@f)"$(zle -la)"}"
+# Load ZSH module zsh/zleparameter, needed to override user defined widgets.
+zmodload zsh/zleparameter 2>/dev/null || {
+  echo 'zsh-syntax-highlighting: failed loading zsh/zleparameter, exiting.' >&2
+  return -1
+}
 
-# Register the main highlighter.
-_zsh_highlight_add-highlighter _zsh_main-highlight _zsh_highlight_buffer-modified-p
+# Resolve highlighters directory location.
+highlighters_dir="${ZSH_HIGHLIGHT_HIGHLIGHTERS_DIR:-${${(%):-%N}:A:h}/highlighters}"
+[[ -d $highlighters_dir ]] || {
+  echo "zsh-syntax-highlighting: highlighters directory '$highlighters_dir' not found, exiting." >&2
+  return -1
+}
 
-# Load additional highlighters if available.
-_zsh_highlight_load-highlighters "${${(%):-%N}:h}/highlighters"
+# Override ZLE widgets to make them invoke _zsh_highlight.
+for event in ${${(f)"$(zle -la)"}:#(_*|orig-*|.run-help|.which-command)}; do
+  if [[ "$widgets[$event]" == completion:* ]]; then
+    eval "zle -C orig-$event ${${${widgets[$event]}#*:}/:/ } ; $event() { builtin zle orig-$event && _zsh_highlight } ; zle -N $event"
+  else
+    case $event in
+      accept-and-menu-complete)
+        eval "$event() { builtin zle .$event && _zsh_highlight } ; zle -N $event"
+        ;;
+      .*)
+        clean_event=$event[2,${#event}] # Remove the leading dot in the event name
+        case ${widgets[$clean_event]-} in
+          (completion|user):*)
+            ;;
+          *)
+            eval "$clean_event() { builtin zle $event && _zsh_highlight } ; zle -N $clean_event"
+            ;;
+        esac
+        ;;
+      *)
+        ;;
+    esac
+  fi
+done
+unset event clean_event
+
+# Load highlighters from highlighters directory and check they define required functions.
+for highlighter_dir ($highlighters_dir/*/); do
+  highlighter="${highlighter_dir:t}"
+  [[ -f "$highlighter_dir/${highlighter}-highlighter.zsh" ]] && {
+    . "$highlighter_dir/${highlighter}-highlighter.zsh"
+    type "_zsh_highlight_${highlighter}_highlighter" &> /dev/null &&
+    type "_zsh_highlight_${highlighter}_highlighter_predicate" &> /dev/null || {
+      echo "zsh-syntax-highlighting: '${highlighter}' highlighter should define both required functions '_zsh_highlight_${highlighter}_highlighter' and '_zsh_highlight_${highlighter}_highlighter_predicate' in '${highlighter_dir}/${highlighter}-highlighter.zsh'." >&2
+    }
+  }
+done
+unset highlighter highlighter_dir highlighters_dir
+
+# Initialize the array of active highlighters if needed.
+[[ $#ZSH_HIGHLIGHT_HIGHLIGHTERS -eq 0 ]] && ZSH_HIGHLIGHT_HIGHLIGHTERS=(main)