/usr/share/source-highlight/zsh.lang is in libsource-highlight-common 3.1.8-1.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50  | preproc = "import"
#number = '(?<=-)([[:digit:]]+)'
include "number.lang"
normal = '\\"'
normal = '\\\''
#include "c_string.lang"
string delim "\"" "\"" escape "\\"
string delim "'" "'" escape "\\"
function = 'function[[:blank:]]+([[:alpha:]]|_)[[:word:]]*[[:blank:]]*(\(\))?'
function = '([[:alpha:]]|_)[[:word:]]*[[:blank:]]*\(\)'
# avoids, in things such as --bind, that words are highlighted as keywords
normal = '([[:alpha:]]*[-/]+[[:alpha:]]+)+'
keyword = "alias|always|autoload|bg|bindkey|break|builtin",
          "bye|cap|case|cd|chdir|clone|command|comparguments",
          "compcall|compctl|compdescribe|compfiles|compgroups",
          "compquote|comptags|comptry|compvalues|continue",
          "declare|dirs|disable|disown|do|echo|echotc|echoti",
          "elif|else|emulate|enable|esac|eval|exec|exec|exit",
          "export|false|fc|fg|fi|float|for|foreach|function",
          "functions|getcap|getln|getopts|hash|history|if|in",
          "integer|jobs|kill|let|limit|local|log|logout",
          "nocorrect|noglob|none|popd|print|printf|pushd",
          "pushln|pwd|r|read|readonly|rehash|repeat|return",
          "sched|select|set|setcap|setopt|shift|source|stat",
          "suspend|test|then|time|times|trap|true|ttyctl|type",
          "typeset|ulimit|umask|unalias|unfunction|unhash",
          "unlimit|unset|unsetopt|until|vared|wait|whence",
          "where|which|while|zcompile|zformat|zftp|zle",
          "zmodload|zparseopts|zprof|zpty|zregexparse",
          "zsocket|zstyle|ztcp|"
variable = '\$\{([^[:blank:]]+)\}'
variable = '\$\(([^[:blank:]]+)\)'
variable = '\$([[:alpha:]]|_)[[:word:]]*'
variable = '\$([^[:blank:]]{1})'
# notice that - is not a symbol since it can be used in command line parameters
symbol = "~","!","%","^","*","(",")","+","=","[",
        "]","\\",":",";",",",".","/","?","&","<",">","\|","%%"
symbol = '(##){2}(?!#)'
include "script_comment.lang"
 |