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// 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 array
type (
Element interface {};
Array struct {
a []Element
}
)
func copy(dst, src []Element) {
for i := 0; i < len(src); i++ {
dst[i] = src[i]
}
}
// Insert n elements at position i.
func expand(a []Element, i, n int) []Element {
// make sure we have enough space
len0 := len(a);
len1 := len0 + n;
if len1 < cap(a) {
// enough space - just expand
a = a[0 : len1]
} else {
// not enough space - double capacity
capb := cap(a)*2;
if capb < len1 {
// still not enough - use required length
capb = len1
}
// capb >= len1
b := make([]Element, len1, capb);
copy(b, a);
a = b
}
// make a hole
for j := len0-1; j >= i ; j-- {
a[j+n] = a[j]
}
return a
}
func (p *Array) Init(initial_len int) *Array {
a := p.a;
if cap(a) == 0 || cap(a) < initial_len {
n := 8; // initial capacity
if initial_len > n {
n = initial_len
}
a = make([]Element, n);
} else {
// nil out entries
for j := len(a) - 1; j >= 0; j-- {
a[j] = nil
}
}
p.a = a[0 : initial_len];
return p
}
func New(len int) *Array {
return new(Array).Init(len)
}
func (p *Array) Len() int {
return len(p.a)
}
func (p *Array) At(i int) Element {
return p.a[i]
}
func (p *Array) Set(i int, x Element) {
p.a[i] = x
}
func (p *Array) Last() Element {
return p.a[len(p.a) - 1]
}
func (p *Array) Insert(i int, x Element) {
p.a = expand(p.a, i, 1);
p.a[i] = x;
}
func (p *Array) Delete(i int) Element {
a := p.a;
n := len(a);
x := a[i];
copy(a[i : n-1], a[i+1 : n]);
a[n-1] = nil; // support GC, nil out entry
p.a = a[0 : n-1];
return x
}
func (p *Array) InsertArray(i int, x *Array) {
p.a = expand(p.a, i, len(x.a));
copy(p.a[i : i + len(x.a)], x.a);
}
func (p *Array) Cut(i, j int) {
a := p.a;
n := len(a);
m := n - (j - i);
copy(a[i : m], a[j : n]);
for k := m; k < n; k++ {
a[k] = nil // support GC, nil out entries
}
p.a = a[0 : m];
}
func (p *Array) Slice(i, j int) *Array {
s := New(j - i); // will fail in Init() if j < j
copy(s.a, p.a[i : j]);
return s;
}
func (p *Array) Do(f func(elem Element)) {
for i := 0; i < len(p.a); i++ {
f(p.a[i]) // not too safe if f changes the Array
}
}
// Convenience wrappers
func (p *Array) Push(x Element) {
p.Insert(len(p.a), x)
}
func (p *Array) Pop() Element {
return p.Delete(len(p.a) - 1)
}
func (p *Array) AppendArray(x *Array) {
p.InsertArray(len(p.a), x);
}
// Partial SortInterface support
type LessInterface interface {
Less(y Element) bool
}
func (p *Array) Less(i, j int) bool {
return p.a[i].(LessInterface).Less(p.a[j])
}
func (p *Array) Swap(i, j int) {
a := p.a;
a[i], a[j] = a[j], a[i]
}
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