package tokenize_test

import (
	"fmt"

	"git.makaay.nl/mauricem/go-parsekit/tokenize"
)

func ExampleTokenAPI_Fork() {
	// This custom TokenHandler checks for input 'a', 'b' or 'c'.
	abcHandler := func(t *tokenize.TokenAPI) bool {
		a := tokenize.A
		for _, r := range []rune{'a', 'b', 'c'} {
			child := t.Fork() // fork, so we won't change parent t
			if a.Rune(r)(child) {
				child.Merge() // accept results into parent t
				return true   // and report a successful match
			}
		}
		// If we get here, then no match was found. Return false to communicate
		// this to the caller.
		return false
	}

	// Note: a custom TokenHandler is normally not what you need.
	// You can make use of the parser/combinator tooling to do things
	// a lot simpler and take care of forking at the appropriate places.
	// The handler from above can be replaced with:
	simpler := tokenize.A.RuneRange('a', 'c')

	result, err := tokenize.NewTokenizer(abcHandler).Execute("another test")
	fmt.Println(result, err)
	result, err = tokenize.NewTokenizer(simpler).Execute("curious")
	fmt.Println(result, err)
	result, err = tokenize.NewTokenizer(abcHandler).Execute("bang on!")
	fmt.Println(result, err)
	result, err = tokenize.NewTokenizer(abcHandler).Execute("not a match")
	fmt.Println(result, err)

	// Output:
	// a <nil>
	// c <nil>
	// b <nil>
	// <nil> mismatch at start of file
}

func ExampleTokenAPI_Merge() {
	tokenHandler := func(t *tokenize.TokenAPI) bool {
		child1 := t.Fork()
		child1.NextRune() // reads 'H'
		child1.Accept()
		child1.NextRune() // reads 'i'
		child1.Accept()

		child2 := child1.Fork()
		child2.NextRune() // reads ' '
		child2.Accept()
		child2.NextRune() // reads 'd'
		child2.Accept()

		child1.Merge() // We merge child1, which has read 'H' and 'i' only.
		return true
	}

	result, _ := tokenize.NewTokenizer(tokenHandler).Execute("Hi mister X!")
	fmt.Println(result)

	// Output:
	// Hi
}