gohan/context.go

39 lines
1.1 KiB
Go

package gohan
import "log"
// Context represents the current iteration of a System's matching entities. It
// provides methods for retrieving components for the currently matched Entity,
// and removing the currently matched Entity.
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{} {
if debug != 0 {
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 %s", componentID, ctx.w.systemName(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 Entity
// IDs, applications must also remove any other references to the removed Entity.
func (ctx *Context) RemoveEntity() bool {
return ctx.w.RemoveEntity(ctx.Entity)
}