WIP implementing a historywords suggestion strategy

src/strategies/historywords.zsh

@@ -0,0 +1,28 @@
+
+#--------------------------------------------------------------------#
+# History Words Suggestion Strategy                                  #
+#--------------------------------------------------------------------#
+# Suggests the most recent history word that matches the given
+# prefix.
+#
+
+_zsh_autosuggest_strategy_historywords() {
+	# Reset options to defaults and enable LOCAL_OPTIONS
+	emulate -L zsh
+
+	# Enable globbing flags so that we can use (#m)
+	setopt EXTENDED_GLOB
+
+	local last_word="${${=1}[-1]}"
+
+	# Escape backslashes and all of the glob operators so we can use
+	# this string as a pattern to search the $history associative array.
+	# - (#m) globbing flag enables setting references for match data
+	# TODO: Use (b) flag when we can drop support for zsh older than v5.0.8
+	local prefix="${last_word//(#m)[\\*?[\]<>()|^~#]/\\$MATCH}"
+
+	# Get the first history word that matches. Concatenate it together with the
+	# prefix to form the full suggestion.
+	# - (r) subscript flag makes the pattern match on values
+	typeset -g suggestion="${1:0:-$#last_word}${historywords[(r)${prefix}?*]}"
+}

zsh-autosuggestions.zsh

@@ -611,6 +611,34 @@ _zsh_autosuggest_strategy_completion() {
 	}
 }
 
+#--------------------------------------------------------------------#
+# History Words Suggestion Strategy                                  #
+#--------------------------------------------------------------------#
+# Suggests the most recent history word that matches the given
+# prefix.
+#
+
+_zsh_autosuggest_strategy_historywords() {
+	# Reset options to defaults and enable LOCAL_OPTIONS
+	emulate -L zsh
+
+	# Enable globbing flags so that we can use (#m)
+	setopt EXTENDED_GLOB
+
+	local last_word="${${=1}[-1]}"
+
+	# Escape backslashes and all of the glob operators so we can use
+	# this string as a pattern to search the $history associative array.
+	# - (#m) globbing flag enables setting references for match data
+	# TODO: Use (b) flag when we can drop support for zsh older than v5.0.8
+	local prefix="${last_word//(#m)[\\*?[\]<>()|^~#]/\\$MATCH}"
+
+	# Get the first history word that matches. Concatenate it together with the
+	# prefix to form the full suggestion.
+	# - (r) subscript flag makes the pattern match on values
+	typeset -g suggestion="${1:0:-$#last_word}${historywords[(r)${prefix}?*]}"
+}
+
 #--------------------------------------------------------------------#
 # History Suggestion Strategy                                        #
 #--------------------------------------------------------------------#