binarytrees_quit.go

     1  // Copyright 2015 The Go Authors.  All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build ignore
     6  
     7  package main
     8  
     9  import (
    10  	"fmt"
    11  
    12  	"golang.org/x/tour/tree"
    13  )
    14  
    15  func walkImpl(t *tree.Tree, ch, quit chan int) {
    16  	if t == nil {
    17  		return
    18  	}
    19  	walkImpl(t.Left, ch, quit)
    20  	select {
    21  	case ch <- t.Value:
    22  		// Value successfully sent.
    23  	case <-quit:
    24  		return
    25  	}
    26  	walkImpl(t.Right, ch, quit)
    27  }
    28  
    29  // Walk walks the tree t sending all values
    30  // from the tree to the channel ch.
    31  func Walk(t *tree.Tree, ch, quit chan int) {
    32  	walkImpl(t, ch, quit)
    33  	close(ch)
    34  }
    35  
    36  // Same determines whether the trees
    37  // t1 and t2 contain the same values.
    38  func Same(t1, t2 *tree.Tree) bool {
    39  	w1, w2 := make(chan int), make(chan int)
    40  	quit := make(chan int)
    41  	defer close(quit)
    42  
    43  	go Walk(t1, w1, quit)
    44  	go Walk(t2, w2, quit)
    45  
    46  	for {
    47  		v1, ok1 := <-w1
    48  		v2, ok2 := <-w2
    49  		if !ok1 || !ok2 {
    50  			return ok1 == ok2
    51  		}
    52  		if v1 != v2 {
    53  			return false
    54  		}
    55  	}
    56  }
    57  
    58  func main() {
    59  	fmt.Print("tree.New(1) == tree.New(1): ")
    60  	if Same(tree.New(1), tree.New(1)) {
    61  		fmt.Println("PASSED")
    62  	} else {
    63  		fmt.Println("FAILED")
    64  	}
    65  
    66  	fmt.Print("tree.New(1) != tree.New(2): ")
    67  	if !Same(tree.New(1), tree.New(2)) {
    68  		fmt.Println("PASSED")
    69  	} else {
    70  		fmt.Println("FAILED")
    71  	}
    72  }
    73
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