Support the arithmetic for loop

highlighters/main/main-highlighter.zsh

@@ -452,6 +452,7 @@ _zsh_highlight_main_highlighter_highlight_list()
   # "D" for do/done
   # "$" for 'end' (matches 'foreach' always; also used with cshjunkiequotes in repeat/while)
   # "?" for 'if'/'fi'; also checked by 'elif'/'else'
+  # "4" for the arithmetic 'for'
   # ":" for 'then'
   local braces_stack=$2
 
@@ -472,6 +473,8 @@ _zsh_highlight_main_highlighter_highlight_list()
   # - :regular:    "Not a command word", and command delimiters are permitted.
   #                Mainly used to detect premature termination of commands.
   # - :always:     The word 'always' in the «{ foo } always { bar }» syntax.
+  # - :arithmetic_for:
+  #                The double opening parenthesis of an arithmetic 'for' loop.
   #
   # When the kind of a word is not yet known, $this_word / $next_word may contain
   # multiple states.  For example, after "sudo -i", the next word may be either
@@ -812,6 +815,8 @@ _zsh_highlight_main_highlighter_highlight_list()
         style=commandseparator
       elif [[ $this_word == *':start:'* ]] && [[ $arg == $'\n' ]]; then
         style=commandseparator
+      elif [[ $braces_stack == '4'* ]]; then
+        style=commandseparator
       else
         # This highlights empty commands (semicolon follows nothing) as an error.
         # Zsh accepts them, though.
@@ -840,6 +845,8 @@ _zsh_highlight_main_highlighter_highlight_list()
       highlight_glob=true
       saw_assignment=false
       next_word=':start::start_of_pipeline:' # only left brace is allowed, apparently
+    elif [[ $arg == $'\x29\x29' ]] && _zsh_highlight_main__stack_pop '4' reserved-word; then
+      next_word+=':start:'
     elif ! (( in_redirection)) && [[ $this_word == *':start:'* ]]; then # $arg is the command word
       if (( ${+precommand_options[$arg]} )) && _zsh_highlight_main__is_runnable $arg; then
         style=precommand
@@ -908,6 +915,9 @@ _zsh_highlight_main_highlighter_highlight_list()
                           ('fi')
                             _zsh_highlight_main__stack_pop '?'
                             ;;
+                          ('for')
+                            next_word+=':arithmetic_for:'
+                            ;;
                           ('foreach')
                             braces_stack='$'"$braces_stack"
                             ;;
@@ -1033,6 +1043,9 @@ _zsh_highlight_main_highlighter_highlight_list()
       fi
     elif _zsh_highlight_main__type "$arg"; [[ $REPLY == 'global alias' ]]; then # $arg is a global alias that isn't in command position
       style=global-alias
+    elif [[ $this_word == *':arithmetic_for:'* && $arg == $'\x28\x28' ]]; then # arithmetic for loop
+      braces_stack='4'"$braces_stack"
+      style=reserved-word
     else # $arg is a non-command word
       case $arg in
         ($'\x29')

highlighters/main/test-data/arithfor1.zsh

@@ -0,0 +1,44 @@
+#!/usr/bin/env zsh
+# -------------------------------------------------------------------------------------------------
+# Copyright (c) 2020 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
+# -------------------------------------------------------------------------------------------------
+
+BUFFER=$'for (( i = 0; i < 3; ++i )) do pwd; done'
+
+expected_region_highlight=(
+  '1 3 reserved-word' # for
+  '5 6 reserved-word' # ((
+  '8 13 default' # i = 0;
+  '15 20 default' # i < 3;
+  '22 25 default' # ++i 
+  '26 27 reserved-word' # ))
+  '29 30 reserved-word' # do
+  '32 34 builtin' # pwd
+  '35 35 commandseparator' # ;
+  '37 40 reserved-word' # done
+)

highlighters/main/test-data/arithfor2-empty-exprs.zsh

@@ -0,0 +1,43 @@
+#!/usr/bin/env zsh
+# -------------------------------------------------------------------------------------------------
+# Copyright (c) 2020 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
+# -------------------------------------------------------------------------------------------------
+
+BUFFER=$'for (( ; ; )) do pwd; done'
+
+expected_region_highlight=(
+  '1 3 reserved-word' # for
+  '5 6 reserved-word' # ((
+  '8 8 commandseparator' # ;
+  '10 10 commandseparator' # ;
+  '12 13 reserved-word' # ))
+  '15 16 reserved-word' # do
+  '18 20 builtin' # pwd
+  '21 21 commandseparator' # ;
+  '23 26 reserved-word' # done
+)