mirror of
https://github.com/golang/go
synced 2024-11-12 10:00:25 -07:00
94 lines
1.6 KiB
Go
94 lines
1.6 KiB
Go
// $G $D/$F.go && $L $F.$A && ./$A.out
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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// test range over channels
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func gen(c chan int, lo, hi int) {
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for i := lo; i <= hi; i++ {
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c <- i;
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}
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close(c);
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}
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func seq(lo, hi int) chan int {
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c := make(chan int);
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go gen(c, lo, hi);
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return c;
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}
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func testchan() {
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s := "";
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for i := range seq('a', 'z') {
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s += string(i);
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}
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if s != "abcdefghijklmnopqrstuvwxyz" {
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panicln("Wanted lowercase alphabet; got", s);
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}
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}
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// test that range over array only evaluates
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// the expression after "range" once.
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var nmake = 0;
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func makearray() []int {
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nmake++;
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return []int{1,2,3,4,5};
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}
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func testarray() {
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s := 0;
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for _, v := range makearray() {
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s += v;
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}
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if nmake != 1 {
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panicln("range called makearray", nmake, "times");
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}
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if s != 15 {
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panicln("wrong sum ranging over makearray");
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}
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}
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// test that range evaluates the index and value expressions
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// exactly once per iteration.
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var ncalls = 0
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func getvar(p *int) *int {
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ncalls++
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return p
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}
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func testcalls() {
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var i, v int
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si := 0
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sv := 0
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for *getvar(&i), *getvar(&v) = range [2]int{1, 2} {
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si += i
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sv += v
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}
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if ncalls != 4 {
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panicln("wrong number of calls:", ncalls, "!= 4")
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}
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if si != 1 || sv != 3 {
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panicln("wrong sum in testcalls", si, sv)
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}
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ncalls = 0
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for *getvar(&i), *getvar(&v) = range [0]int{} {
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panicln("loop ran on empty array")
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}
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if ncalls != 0 {
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panicln("wrong number of calls:", ncalls, "!= 0")
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}
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}
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func main() {
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testchan();
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testarray();
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testcalls();
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}
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