Add latched rules.

internal/mappingrules/matching.go

@@ -5,6 +5,10 @@ import (
 	"github.com/holoplot/go-evdev"
 )
 
+func (rule *MappingRuleBase) OutputName() string {
+	return rule.Output.DeviceName
+}
+
 // eventFromTarget creates an outputtable event from a RuleTarget
 func eventFromTarget(output RuleTarget, value int32) *evdev.InputEvent {
 	return &evdev.InputEvent{
@@ -79,10 +83,21 @@ func (rule *ComboMappingRule) MatchEvent(device *evdev.InputDevice, event *evdev
 	return nil
 }
 
-func (rule *SimpleMappingRule) OutputName() string {
-	return rule.Output.DeviceName
-}
+func (rule *LatchedMappingRule) MatchEvent(device *evdev.InputDevice, event *evdev.InputEvent) *evdev.InputEvent {
+	if device != rule.Input.Device ||
+		event.Code != rule.Input.Code ||
+		valueFromTarget(rule.Input, event) == 0 {
+		return nil
+	}
 
-func (rule *ComboMappingRule) OutputName() string {
-	return rule.Output.DeviceName
+	// Input is pressed, so toggle state and emit event
+	var value int32
+	rule.State = !rule.State
+	if rule.State { 
+		value = 1 
+	} else { 
+		value = 0 
+	}
+
+	return eventFromTarget(rule.Output, value)
 }

internal/mappingrules/types.go

@@ -7,21 +7,32 @@ type MappingRule interface {
 	OutputName() string
 }
 
+type MappingRuleBase struct {
+	Output RuleTarget
+}
+
 // A Simple Mapping Rule can map a button to a button or an axis to an axis.
 type SimpleMappingRule struct {
+	MappingRuleBase
 	Input  RuleTarget
-	Output RuleTarget
 	Name   string
 }
 
 // A Combo Mapping Rule can require multiple physical button presses for a single output button
 type ComboMappingRule struct {
+	MappingRuleBase
 	Inputs []RuleTarget
-	Output RuleTarget
 	Name   string
 	State  int
 }
 
+type LatchedMappingRule struct {
+	MappingRuleBase
+	Input  RuleTarget
+	Name   string
+	State  bool
+}
+
 type RuleTarget struct {
 	DeviceName string
 	Device     *evdev.InputDevice