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// $G $D/$F.go && $L $F.$A && ./$A.out
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
// test range over channels
func gen(c chan int, lo, hi int) {
for i := lo; i <= hi; i++ {
c <- i
}
close(c)
}
func seq(lo, hi int) chan int {
c := make(chan int)
go gen(c, lo, hi)
return c
}
func testchan() {
s := ""
for i := range seq('a', 'z') {
s += string(i)
}
if s != "abcdefghijklmnopqrstuvwxyz" {
println("Wanted lowercase alphabet; got", s)
panic("fail")
}
}
// test that range over array only evaluates
// the expression after "range" once.
var nmake = 0
func makearray() []int {
nmake++
return []int{1, 2, 3, 4, 5}
}
func testarray() {
s := 0
for _, v := range makearray() {
s += v
}
if nmake != 1 {
println("range called makearray", nmake, "times")
panic("fail")
}
if s != 15 {
println("wrong sum ranging over makearray")
panic("fail")
}
}
// test that range evaluates the index and value expressions
// exactly once per iteration.
var ncalls = 0
func getvar(p *int) *int {
ncalls++
return p
}
func testcalls() {
var i, v int
si := 0
sv := 0
for *getvar(&i), *getvar(&v) = range [2]int{1, 2} {
si += i
sv += v
}
if ncalls != 4 {
println("wrong number of calls:", ncalls, "!= 4")
panic("fail")
}
if si != 1 || sv != 3 {
println("wrong sum in testcalls", si, sv)
panic("fail")
}
ncalls = 0
for *getvar(&i), *getvar(&v) = range [0]int{} {
println("loop ran on empty array")
panic("fail")
}
if ncalls != 0 {
println("wrong number of calls:", ncalls, "!= 0")
panic("fail")
}
}
func main() {
testchan()
testarray()
testcalls()
}
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