105 lines
2.6 KiB
Go
105 lines
2.6 KiB
Go
package scripting
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import (
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"errors"
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"git.kirsle.net/go/render/event"
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"github.com/robertkrimen/otto"
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)
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// Event name constants.
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const (
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CollideEvent = "OnCollide" // another doodad collides with us
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EnterEvent = "OnEnter" // a doodad is fully inside us
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LeaveEvent = "OnLeave" // a doodad no longer collides with us
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// Controllable (player character) doodad events
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KeypressEvent = "OnKeypress" // i.e. arrow keys
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)
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// Event return errors.
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var (
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ErrReturnFalse = errors.New("JS callback function returned false")
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)
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// Events API for Doodad scripts.
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type Events struct {
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registry map[string][]otto.Value
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}
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// NewEvents initializes the Events API.
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func NewEvents() *Events {
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return &Events{
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registry: map[string][]otto.Value{},
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}
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}
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// OnCollide fires when another actor collides with yours.
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func (e *Events) OnCollide(call otto.FunctionCall) otto.Value {
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return e.register(CollideEvent, call.Argument(0))
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}
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// RunCollide invokes the OnCollide handler function.
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func (e *Events) RunCollide(v interface{}) error {
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return e.run(CollideEvent, v)
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}
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// OnLeave fires when another actor stops colliding with yours.
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func (e *Events) OnLeave(call otto.FunctionCall) otto.Value {
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return e.register(LeaveEvent, call.Argument(0))
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}
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// RunLeave invokes the OnLeave handler function.
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func (e *Events) RunLeave(v interface{}) error {
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return e.run(LeaveEvent, v)
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}
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// OnKeypress fires when another actor collides with yours.
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func (e *Events) OnKeypress(call otto.FunctionCall) otto.Value {
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return e.register(KeypressEvent, call.Argument(0))
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}
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// RunKeypress invokes the OnCollide handler function.
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func (e *Events) RunKeypress(ev *event.State) error {
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return e.run(KeypressEvent, ev)
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}
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// register a named event.
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func (e *Events) register(name string, callback otto.Value) otto.Value {
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if !callback.IsFunction() {
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return otto.Value{} // TODO
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}
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if _, ok := e.registry[name]; !ok {
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e.registry[name] = []otto.Value{}
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}
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e.registry[name] = append(e.registry[name], callback)
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return otto.Value{}
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}
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// Run an event handler. Returns an error only if there was a JavaScript error
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// inside the function. If there are no event handlers, just returns nil.
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func (e *Events) run(name string, args ...interface{}) error {
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if _, ok := e.registry[name]; !ok {
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return nil
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}
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for _, callback := range e.registry[name] {
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value, err := callback.Call(otto.Value{}, args...)
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if err != nil {
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return err
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}
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// If the event handler returned a boolean false, stop all other
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// callbacks and return the boolean.
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if value.IsBoolean() {
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if b, err := value.ToBoolean(); err == nil && b == false {
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return ErrReturnFalse
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}
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}
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}
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return nil
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}
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