stream.go

// Package stream provides WDTE functions for manipulating streams of
// data.
package stream

import (
	"github.com/DeedleFake/wdte"
	"github.com/DeedleFake/wdte/std"
)

// A Stream is a type of function that can yield successive values.
type Stream interface {
	wdte.Func

	// Next returns the next value and true, or an undefined value and
	// false if the stream is empty.
	Next(frame wdte.Frame) (wdte.Func, bool)
}

// A NextFunc wraps a Go function, making it possible to use it as a
// Stream. When called as a WDTE function, the function simply returns
// itself.
type NextFunc func(frame wdte.Frame) (wdte.Func, bool)

func (n NextFunc) Call(frame wdte.Frame, args ...wdte.Func) wdte.Func { // nolint
	return n
}

func (n NextFunc) Next(frame wdte.Frame) (wdte.Func, bool) { // nolint
	return n(frame)
}

func (NextFunc) String() string { // nolint
	return "<stream>"
}

// Scope is a scope containing the functions in this package.
var Scope = wdte.S().Map(map[wdte.ID]wdte.Func{
	"new":    wdte.GoFunc(New),
	"range":  wdte.GoFunc(Range),
	"concat": wdte.GoFunc(Concat),

	"map":       wdte.GoFunc(Map),
	"filter":    wdte.GoFunc(Filter),
	"flatMap":   wdte.GoFunc(FlatMap),
	"enumerate": wdte.GoFunc(Enumerate),

	"collect": wdte.GoFunc(Collect),
	"drain":   wdte.GoFunc(Drain),
	"reduce":  wdte.GoFunc(Reduce),
	//"chain":   wdte.GoFunc(Chain),
	"any": wdte.GoFunc(Any),
	"all": wdte.GoFunc(All),
})

func init() {
	std.Register("stream", Scope)
}