68 lines
2 KiB
Go
68 lines
2 KiB
Go
// Package component holds the main abstraction for components.
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package component
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import (
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"reflect"
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"github.com/FAU-CDI/wisski-distillery/pkg/lazy"
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)
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// Component represents a logical subsystem of the distillery.
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// Every component must embed [ComponentBase] and should be initialized using [Initialize].
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//
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// By convention these are defined within their corresponding subpackage.
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// This subpackage also contains all required resources.
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// Furthermore, a component is typically instantiated using a call on the ["distillery.Distillery"] struct.
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//
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// For example, the web.Web component lives in the web package and can be created like:
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//
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// var dis Distillery
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// web := dis.Web()
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type Component interface {
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// Name returns the name of this component.
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// It should correspond to the appropriate subpackage.
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Name() string
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// getBase returns the embedded ComponentBase struct.
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getBase() *ComponentBase
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}
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// ComponentBase should be embedded into every component
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type ComponentBase struct {
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Core // the core of the associated distillery
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}
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func (cb *ComponentBase) getBase() *ComponentBase {
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return cb
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}
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// Initialize makes or returns a component based on a lazy.
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//
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// C is the type of component to initialize. It must be backed by a pointer, or Initialize will panic.
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//
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// dis is the distillery to initialize components for
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// field is a pointer to the appropriate struct field within the distillery components
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// init is called with a new non-nil component to initialize it. It may be nil, to indicate no initialization is required.
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//
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// makeComponent returns the new or existing component instance
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func Initialize[C Component](core Core, field *lazy.Lazy[C], init func(C)) C {
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// get the typeof C and make sure that it is a pointer type!
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typC := reflect.TypeOf((*C)(nil)).Elem()
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if typC.Kind() != reflect.Pointer {
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panic("Initialize: C must be backed by a pointer")
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}
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// return the field
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return field.Get(func() (c C) {
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c = reflect.New(typC.Elem()).Interface().(C)
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if init != nil {
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init(c)
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}
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base := c.getBase()
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base.Core = core
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return
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})
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}
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