From 4fcfb15913a20c955d5b22299f715be06f4c79db Mon Sep 17 00:00:00 2001
From: Daniel Shahaf <d.s@daniel.shahaf.name>
Date: Tue, 17 Nov 2015 01:33:30 +0000
Subject: [PATCH] Highlight parameter expansions that are a command word.

Fixes zsh-users/zsh-syntax-highlighting#101.
---
 highlighters/main/main-highlighter.zsh        | 14 ++++++++
 .../main/test-data/commmand-parameter.zsh     | 36 +++++++++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100644 highlighters/main/test-data/commmand-parameter.zsh

diff --git a/highlighters/main/main-highlighter.zsh b/highlighters/main/main-highlighter.zsh
index d12d9bf..9e8f650 100644
--- a/highlighters/main/main-highlighter.zsh
+++ b/highlighters/main/main-highlighter.zsh
@@ -267,6 +267,20 @@ _zsh_highlight_main_highlighter()
       _zsh_highlight_main_highlighter_expand_path $arg
       local expanded_arg="$REPLY"
       local res="$(_zsh_highlight_main__type ${expanded_arg})"
+      () {
+        # Special-case: command word is '$foo', like that, without braces or anything.
+        #
+        # That's not entirely correct --- if the parameter's value happens to be a reserved
+        # word, the parameter expansion will be highlighted as a reserved word --- but that
+        # incorrectness is outweighed by the usability improvement of permitting the use of
+        # parameters that refer to commands, functions, and builtins.
+        local -a match mbegin mend
+        local MATCH; integer MBEGIN MEND
+        if [[ $res == *': none' ]] && (( ${+parameters} )) &&
+           [[ ${arg[1]} == \$ ]] && [[ ${arg:1} =~ ^([A-Za-z_][A-Za-z0-9_]*|[0-9]+)$ ]]; then
+          res="$(_zsh_highlight_main__type ${(P)MATCH})"
+        fi
+      }
       case $res in
         *': reserved')  style=$ZSH_HIGHLIGHT_STYLES[reserved-word];;
         *': suffix alias')
diff --git a/highlighters/main/test-data/commmand-parameter.zsh b/highlighters/main/test-data/commmand-parameter.zsh
new file mode 100644
index 0000000..a2b756c
--- /dev/null
+++ b/highlighters/main/test-data/commmand-parameter.zsh
@@ -0,0 +1,36 @@
+# -------------------------------------------------------------------------------------------------
+# Copyright (c) 2015 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
+# -------------------------------------------------------------------------------------------------
+
+x=/usr/bin/env
+BUFFER='$x "argument"'
+
+expected_region_highlight=(
+  "1 2 $ZSH_HIGHLIGHT_STYLES[command]" # $x
+  "4 13 $ZSH_HIGHLIGHT_STYLES[double-quoted-argument]" # "argument"
+)