Allow configuring to ignore history entries matching a pattern

Set ZSH_AUTOSUGGEST_HISTORY_IGNORE to a glob pattern to have the history
and match_prev_cmd suggestion strategies never make suggestions matching
that pattern.

For example, set to "cd *" to never suggest any `cd` commands from
history (see issues #340 and #425). Or set to "?(#c50,)" to never
suggest anything 50 characters or longer (see issue #429).

README.md

@@ -86,6 +86,12 @@ As of `v0.4.0`, suggestions can be fetched asynchronously. To enable this behavi
 
 Set `ZSH_AUTOSUGGEST_MANUAL_REBIND` (it can be set to anything) to disable automatic widget re-binding on each precmd. This can be a big boost to performance, but you'll need to handle re-binding yourself if any of the widget lists change or if you or another plugin wrap any of the autosuggest widgets. To re-bind widgets, run `_zsh_autosuggest_bind_widgets`.
 
+### Ignoring history suggestions that match a pattern
+
+Set `ZSH_AUTOSUGGEST_HISTORY_IGNORE` to a glob pattern to prevent offering suggestions for history entries that match the pattern. For example, set it to `"cd *"` to never suggest any `cd` commands from history. Or set to `"?(#c50,)"` to never suggest anything 50 characters or longer.
+
+**Note:** This only affects the `history` and `match_prev_cmd` suggestion strategies.
+
 
 ### Key Bindings
 

spec/strategies/history_spec.rb

@@ -8,5 +8,16 @@ describe 'the `history` suggestion strategy' do
     end
   end
 
+  context 'when ZSH_AUTOSUGGEST_HISTORY_IGNORE is set to a pattern' do
+    let(:options) { ['ZSH_AUTOSUGGEST_HISTORY_IGNORE="* bar"'] }
+
+    it 'does not make suggestions that match the pattern' do
+      with_history('ls foo', 'ls bar', 'echo baz') do
+        session.send_string('ls')
+        wait_for { session.content }.to eq('ls foo')
+      end
+    end
+  end
+
   include_examples 'special characters'
 end

spec/strategies/match_prev_cmd_spec.rb

@@ -3,19 +3,32 @@ require 'strategies/special_characters_helper'
 describe 'the `match_prev_cmd` strategy' do
   let(:options) { ['ZSH_AUTOSUGGEST_STRATEGY=match_prev_cmd'] }
 
-  it 'suggests the last matching history entry after the previous command' do
-    with_history(
+  let(:history) { [
     'echo what',
     'ls foo',
     'echo what',
     'ls bar',
     'ls baz',
     'echo what'
-    ) do
+  ] }
+
+  it 'suggests the last matching history entry after the previous command' do
+    with_history(*history) do
       session.send_string('ls')
       wait_for { session.content }.to eq('ls bar')
     end
   end
 
+  context 'when ZSH_AUTOSUGGEST_HISTORY_IGNORE is set to a pattern' do
+    let(:options) { ['ZSH_AUTOSUGGEST_STRATEGY=match_prev_cmd', 'ZSH_AUTOSUGGEST_HISTORY_IGNORE="* bar"'] }
+
+    it 'does not make suggestions that match the pattern' do
+      with_history(*history) do
+        session.send_string('ls')
+        wait_for { session.content }.to eq('ls foo')
+      end
+    end
+  end
+
   include_examples 'special characters'
 end

src/strategies/history.zsh

@@ -10,7 +10,7 @@ _zsh_autosuggest_strategy_history() {
 	# Reset options to defaults and enable LOCAL_OPTIONS
 	emulate -L zsh
 
-	# Enable globbing flags so that we can use (#m)
+	# Enable globbing flags so that we can use (#m) and (x~y) glob operator
 	setopt EXTENDED_GLOB
 
 	# Escape backslashes and all of the glob operators so we can use
@@ -19,7 +19,14 @@ _zsh_autosuggest_strategy_history() {
 	# TODO: Use (b) flag when we can drop support for zsh older than v5.0.8
 	local prefix="${1//(#m)[\\*?[\]<>()|^~#]/\\$MATCH}"
 
-	# Get the history items that match
+	# Get the history items that match the prefix, excluding those that match
+	# the ignore pattern
+	local pattern="$prefix*"
+	if [[ -n $ZSH_AUTOSUGGEST_HISTORY_IGNORE ]]; then
+		pattern="($pattern)~($ZSH_AUTOSUGGEST_HISTORY_IGNORE)"
+	fi
+
+	# Give the first history item matching the pattern as the suggestion
 	# - (r) subscript flag makes the pattern match on values
-	typeset -g suggestion="${history[(r)${prefix}*]}"
+	typeset -g suggestion="${history[(r)$pattern]}"
 }

src/strategies/match_prev_cmd.zsh

@@ -24,16 +24,23 @@ _zsh_autosuggest_strategy_match_prev_cmd() {
 	# Reset options to defaults and enable LOCAL_OPTIONS
 	emulate -L zsh
 
-	# Enable globbing flags so that we can use (#m)
+	# Enable globbing flags so that we can use (#m) and (x~y) glob operator
 	setopt EXTENDED_GLOB
 
 	# TODO: Use (b) flag when we can drop support for zsh older than v5.0.8
 	local prefix="${1//(#m)[\\*?[\]<>()|^~#]/\\$MATCH}"
 
+	# Get the history items that match the prefix, excluding those that match
+	# the ignore pattern
+	local pattern="$prefix*"
+	if [[ -n $ZSH_AUTOSUGGEST_HISTORY_IGNORE ]]; then
+		pattern="($pattern)~($ZSH_AUTOSUGGEST_HISTORY_IGNORE)"
+	fi
+
 	# Get all history event numbers that correspond to history
-	# entries that match pattern $prefix*
+	# entries that match the pattern
 	local history_match_keys
-	history_match_keys=(${(k)history[(R)$prefix*]})
+	history_match_keys=(${(k)history[(R)$~pattern]})
 
 	# By default we use the first history number (most recent history entry)
 	local histkey="${history_match_keys[1]}"

zsh-autosuggestions.zsh

@@ -626,7 +626,7 @@ _zsh_autosuggest_strategy_history() {
 	# Reset options to defaults and enable LOCAL_OPTIONS
 	emulate -L zsh
 
-	# Enable globbing flags so that we can use (#m)
+	# Enable globbing flags so that we can use (#m) and (x~y) glob operator
 	setopt EXTENDED_GLOB
 
 	# Escape backslashes and all of the glob operators so we can use
@@ -635,9 +635,16 @@ _zsh_autosuggest_strategy_history() {
 	# TODO: Use (b) flag when we can drop support for zsh older than v5.0.8
 	local prefix="${1//(#m)[\\*?[\]<>()|^~#]/\\$MATCH}"
 
-	# Get the history items that match
+	# Get the history items that match the prefix, excluding those that match
+	# the ignore pattern
+	local pattern="$prefix*"
+	if [[ -n $ZSH_AUTOSUGGEST_HISTORY_IGNORE ]]; then
+		pattern="($pattern)~($ZSH_AUTOSUGGEST_HISTORY_IGNORE)"
+	fi
+
+	# Give the first history item matching the pattern as the suggestion
 	# - (r) subscript flag makes the pattern match on values
-	typeset -g suggestion="${history[(r)${prefix}*]}"
+	typeset -g suggestion="${history[(r)$pattern]}"
 }
 
 #--------------------------------------------------------------------#
@@ -665,16 +672,23 @@ _zsh_autosuggest_strategy_match_prev_cmd() {
 	# Reset options to defaults and enable LOCAL_OPTIONS
 	emulate -L zsh
 
-	# Enable globbing flags so that we can use (#m)
+	# Enable globbing flags so that we can use (#m) and (x~y) glob operator
 	setopt EXTENDED_GLOB
 
 	# TODO: Use (b) flag when we can drop support for zsh older than v5.0.8
 	local prefix="${1//(#m)[\\*?[\]<>()|^~#]/\\$MATCH}"
 
+	# Get the history items that match the prefix, excluding those that match
+	# the ignore pattern
+	local pattern="$prefix*"
+	if [[ -n $ZSH_AUTOSUGGEST_HISTORY_IGNORE ]]; then
+		pattern="($pattern)~($ZSH_AUTOSUGGEST_HISTORY_IGNORE)"
+	fi
+
 	# Get all history event numbers that correspond to history
-	# entries that match pattern $prefix*
+	# entries that match the pattern
 	local history_match_keys
-	history_match_keys=(${(k)history[(R)$prefix*]})
+	history_match_keys=(${(k)history[(R)$~pattern]})
 
 	# By default we use the first history number (most recent history entry)
 	local histkey="${history_match_keys[1]}"