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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" {
panicln("Wanted lowercase alphabet; got", s);
}
}
// 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 {
panicln("range called makearray", nmake, "times");
}
if s != 15 {
panicln("wrong sum ranging over makearray");
}
}
// 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 {
panicln("wrong number of calls:", ncalls, "!= 4")
}
if si != 1 || sv != 3 {
panicln("wrong sum in testcalls", si, sv)
}
ncalls = 0
for *getvar(&i), *getvar(&v) = range [0]int{} {
panicln("loop ran on empty array")
}
if ncalls != 0 {
panicln("wrong number of calls:", ncalls, "!= 0")
}
}
func main() {
testchan();
testarray();
testcalls();
}
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