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// Copyright 2020 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 ld
import (
"cmd/link/internal/loader"
"testing"
)
func TestHeap(t *testing.T) {
tests := [][]loader.Sym{
{10, 20, 30, 40, 50, 60, 70, 80, 90, 100},
{100, 90, 80, 70, 60, 50, 40, 30, 20, 10},
{30, 50, 80, 20, 60, 70, 10, 100, 90, 40},
}
for _, s := range tests {
h := heap{}
for _, i := range s {
h.push(i)
if !verify(&h, 0) {
t.Errorf("heap invariant violated: %v", h)
}
}
for j := 0; j < len(s); j++ {
x := h.pop()
if !verify(&h, 0) {
t.Errorf("heap invariant violated: %v", h)
}
// pop should return elements in ascending order.
if want := loader.Sym((j + 1) * 10); x != want {
t.Errorf("pop returns wrong element: want %d, got %d", want, x)
}
}
if !h.empty() {
t.Errorf("heap is not empty after all pops")
}
}
// Also check that mixed pushes and pops work correctly.
for _, s := range tests {
h := heap{}
for i := 0; i < len(s)/2; i++ {
// two pushes, one pop
h.push(s[2*i])
if !verify(&h, 0) {
t.Errorf("heap invariant violated: %v", h)
}
h.push(s[2*i+1])
if !verify(&h, 0) {
t.Errorf("heap invariant violated: %v", h)
}
h.pop()
if !verify(&h, 0) {
t.Errorf("heap invariant violated: %v", h)
}
}
for !h.empty() { // pop remaining elements
h.pop()
if !verify(&h, 0) {
t.Errorf("heap invariant violated: %v", h)
}
}
}
}
// recursively verify heap-ness, starting at element i.
func verify(h *heap, i int) bool {
n := len(*h)
c1 := 2*i + 1 // left child
c2 := 2*i + 2 // right child
if c1 < n {
if (*h)[c1] < (*h)[i] {
return false
}
if !verify(h, c1) {
return false
}
}
if c2 < n {
if (*h)[c2] < (*h)[i] {
return false
}
if !verify(h, c2) {
return false
}
}
return true
}
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