1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/*! Composable internal iterators
Internal iterators are functions implementing the protocol used by the `for` loop.
An internal iterator takes `fn(...) -> bool` as a parameter, with returning `false` used to signal
breaking out of iteration. The adaptors in the module work with any such iterator, not just ones
tied to specific traits. For example:
~~~~
println(iter::to_vec(|f| uint::range(0, 20, f)).to_str());
~~~~
An external iterator object implementing the interface in the `iterator` module can be used as an
internal iterator by calling the `advance` method. For example:
~~~~
use core::iterator::*;
let xs = [0u, 1, 2, 3, 4, 5];
let ys = [30, 40, 50, 60];
let mut it = xs.iter().chain(ys.iter());
for it.advance |&x: &uint| {
println(x.to_str());
}
~~~~
Internal iterators provide a subset of the functionality of an external iterator. It's not possible
to interleave them to implement algorithms like `zip`, `union` and `merge`. However, they're often
much easier to implement.
*/
use cmp::Ord;
use option::{Option, Some, None};
pub trait Times {
fn times(&self, it: &fn() -> bool);
}
/**
* Transform an internal iterator into an owned vector.
*
* # Example:
*
* ~~~
* let xs = ~[1, 2, 3];
* let ys = do iter::to_vec |f| { xs.each(|x| f(*x)) };
* assert_eq!(xs, ys);
* ~~~
*/
#[inline(always)]
pub fn to_vec<T>(iter: &fn(f: &fn(T) -> bool)) -> ~[T] {
let mut v = ~[];
for iter |x| { v.push(x) }
v
}
/**
* Return true if `predicate` is true for any values yielded by an internal iterator.
*
* Example:
*
* ~~~~
* let xs = ~[1u, 2, 3, 4, 5];
* assert!(any(|&x: &uint| x > 2, |f| xs.each(f)));
* assert!(!any(|&x: &uint| x > 5, |f| xs.each(f)));
* ~~~~
*/
#[inline(always)]
pub fn any<T>(predicate: &fn(T) -> bool, iter: &fn(f: &fn(T) -> bool)) -> bool {
for iter |x| {
if predicate(x) {
return true
}
}
false
}
/**
* Return true if `predicate` is true for all values yielded by an internal iterator.
*
* # Example:
*
* ~~~~
* assert!(all(|&x: &uint| x < 6, |f| uint::range(1, 6, f)));
* assert!(!all(|&x: &uint| x < 5, |f| uint::range(1, 6, f)));
* ~~~~
*/
#[inline(always)]
pub fn all<T>(predicate: &fn(T) -> bool, iter: &fn(f: &fn(T) -> bool)) -> bool {
for iter |x| {
if !predicate(x) {
return false
}
}
true
}
/**
* Return the first element where `predicate` returns `true`. Return `None` if no element is found.
*
* # Example:
*
* ~~~~
* let xs = ~[1u, 2, 3, 4, 5, 6];
* assert_eq!(*find(|& &x: & &uint| x > 3, |f| xs.each(f)).unwrap(), 4);
* ~~~~
*/
#[inline(always)]
pub fn find<T>(predicate: &fn(&T) -> bool, iter: &fn(f: &fn(T) -> bool)) -> Option<T> {
for iter |x| {
if predicate(&x) {
return Some(x);
}
}
None
}
/**
* Return the largest item yielded by an iterator. Return `None` if the iterator is empty.
*
* # Example:
*
* ~~~~
* let xs = ~[8, 2, 3, 1, -5, 9, 11, 15];
* assert_eq!(max(|f| xs.each(f)).unwrap(), &15);
* ~~~~
*/
#[inline]
pub fn max<T: Ord>(iter: &fn(f: &fn(T) -> bool)) -> Option<T> {
let mut result = None;
for iter |x| {
match result {
Some(ref mut y) => {
if x > *y {
*y = x;
}
}
None => result = Some(x)
}
}
result
}
/**
* Return the smallest item yielded by an iterator. Return `None` if the iterator is empty.
*
* # Example:
*
* ~~~~
* let xs = ~[8, 2, 3, 1, -5, 9, 11, 15];
* assert_eq!(max(|f| xs.each(f)).unwrap(), &-5);
* ~~~~
*/
#[inline]
pub fn min<T: Ord>(iter: &fn(f: &fn(T) -> bool)) -> Option<T> {
let mut result = None;
for iter |x| {
match result {
Some(ref mut y) => {
if x < *y {
*y = x;
}
}
None => result = Some(x)
}
}
result
}
#[cfg(test)]
mod tests {
use super::*;
use prelude::*;
#[test]
fn test_to_vec() {
let xs = ~[1, 2, 3];
let ys = do to_vec |f| { xs.each(|x| f(*x)) };
assert_eq!(xs, ys);
}
#[test]
fn test_any() {
let xs = ~[1u, 2, 3, 4, 5];
assert!(any(|&x: &uint| x > 2, |f| xs.each(f)));
assert!(!any(|&x: &uint| x > 5, |f| xs.each(f)));
}
#[test]
fn test_all() {
assert!(all(|x: uint| x < 6, |f| uint::range(1, 6, f)));
assert!(!all(|x: uint| x < 5, |f| uint::range(1, 6, f)));
}
#[test]
fn test_find() {
let xs = ~[1u, 2, 3, 4, 5, 6];
assert_eq!(*find(|& &x: & &uint| x > 3, |f| xs.each(f)).unwrap(), 4);
}
#[test]
fn test_max() {
let xs = ~[8, 2, 3, 1, -5, 9, 11, 15];
assert_eq!(max(|f| xs.each(f)).unwrap(), &15);
}
#[test]
fn test_min() {
let xs = ~[8, 2, 3, 1, -5, 9, 11, 15];
assert_eq!(min(|f| xs.each(f)).unwrap(), &-5);
}
}
|
