gohan/context.go

package gohan

import "log"

type Context struct {
	Entity Entity

	s int // System index.
	c []ComponentID
	w *World
}

// Component gets a Component of the currently handled Entity.
func (ctx *Context) Component(componentID ComponentID) interface{} {
	var found bool
	for _, id := range ctx.c {
		if id == componentID {
			found = true
			break
		}
	}
	if !found {
		log.Panicf("illegal component access: component %d is not queried by system %d", componentID, ctx.s)
	}
	return ctx.w.Component(ctx.Entity, componentID)
}

// RemoveEntity removes the currently handled Entity's components, causing it
// to no longer be handled by any system.  Because Gohan reuses removed EntityIDs,
// applications must also remove any internal references to the removed Entity.
func (ctx *Context) RemoveEntity() {
	ctx.w.RemoveEntity(ctx.Entity)
}