|
| 1 | +iface iterable<A> { |
| 2 | + fn iter(blk: fn(A)); |
| 3 | +} |
| 4 | + |
| 5 | +impl<A> of iterable<A> for fn@(fn(A)) { |
| 6 | + fn iter(blk: fn(A)) { |
| 7 | + self(blk); |
| 8 | + } |
| 9 | +} |
| 10 | + |
| 11 | +// accomodate the fact that int/uint are passed by value by default: |
| 12 | +impl of iterable<int> for fn@(fn(int)) { |
| 13 | + fn iter(blk: fn(&&int)) { |
| 14 | + self {|i| blk(i)} |
| 15 | + } |
| 16 | +} |
| 17 | + |
| 18 | +impl of iterable<uint> for fn@(fn(uint)) { |
| 19 | + fn iter(blk: fn(&&uint)) { |
| 20 | + self {|i| blk(i)} |
| 21 | + } |
| 22 | +} |
| 23 | + |
| 24 | +impl<A> of iterable<A> for [A] { |
| 25 | + fn iter(blk: fn(A)) { |
| 26 | + vec::iter(self, blk) |
| 27 | + } |
| 28 | +} |
| 29 | + |
| 30 | +impl<A> of iterable<A> for option<A> { |
| 31 | + fn iter(blk: fn(A)) { |
| 32 | + option::may(self, blk) |
| 33 | + } |
| 34 | +} |
| 35 | + |
| 36 | +fn enumerate<A,IA:iterable<A>>(self: IA, blk: fn(uint, A)) { |
| 37 | + let i = 0u; |
| 38 | + self.iter {|a| |
| 39 | + blk(i, a); |
| 40 | + i += 1u; |
| 41 | + } |
| 42 | +} |
| 43 | + |
| 44 | +// Here: we have to use fn@ for predicates and map functions, because |
| 45 | +// we will be binding them up into a closure. Disappointing. A true |
| 46 | +// region type system might be able to do better than this. |
| 47 | + |
| 48 | +fn filter<A,IA:iterable<A>>(self: IA, prd: fn@(A) -> bool, blk: fn(A)) { |
| 49 | + self.iter {|a| |
| 50 | + if prd(a) { blk(a) } |
| 51 | + } |
| 52 | +} |
| 53 | + |
| 54 | +fn map<A,B,IA:iterable<A>>(self: IA, cnv: fn@(A) -> B, blk: fn(B)) { |
| 55 | + self.iter {|a| |
| 56 | + let b = cnv(a); |
| 57 | + blk(b); |
| 58 | + } |
| 59 | +} |
| 60 | + |
| 61 | +fn flat_map<A,B,IA:iterable<A>,IB:iterable<B>>( |
| 62 | + self: IA, cnv: fn@(A) -> IB, blk: fn(B)) { |
| 63 | + self.iter {|a| |
| 64 | + cnv(a).iter(blk) |
| 65 | + } |
| 66 | +} |
| 67 | + |
| 68 | +fn foldl<A,B:copy,IA:iterable<A>>(self: IA, b0: B, blk: fn(B, A) -> B) -> B { |
| 69 | + let b = b0; |
| 70 | + self.iter {|a| |
| 71 | + b = blk(b, a); |
| 72 | + } |
| 73 | + ret b; |
| 74 | +} |
| 75 | + |
| 76 | +fn to_list<A:copy,IA:iterable<A>>(self: IA) -> [A] { |
| 77 | + foldl::<A,[A],IA>(self, [], {|r, a| r + [a]}) |
| 78 | +} |
| 79 | + |
| 80 | +fn repeat(times: uint, blk: fn()) { |
| 81 | + let i = 0u; |
| 82 | + while i < times { |
| 83 | + blk(); |
| 84 | + i += 1u; |
| 85 | + } |
| 86 | +} |
| 87 | + |
| 88 | + |
| 89 | +#[test] |
| 90 | +fn test_enumerate() { |
| 91 | + enumerate(["0", "1", "2"]) {|i,j| |
| 92 | + assert #fmt["%u",i] == j; |
| 93 | + } |
| 94 | +} |
| 95 | + |
| 96 | +#[test] |
| 97 | +fn test_map_and_to_list() { |
| 98 | + let a = bind vec::iter([0, 1, 2], _); |
| 99 | + let b = bind map(a, {|i| i*2}, _); |
| 100 | + let c = to_list(b); |
| 101 | + assert c == [0, 2, 4]; |
| 102 | +} |
| 103 | + |
| 104 | +#[test] |
| 105 | +fn test_map_directly_on_vec() { |
| 106 | + let b = bind map([0, 1, 2], {|i| i*2}, _); |
| 107 | + let c = to_list(b); |
| 108 | + assert c == [0, 2, 4]; |
| 109 | +} |
| 110 | + |
| 111 | +#[test] |
| 112 | +fn test_filter_on_int_range() { |
| 113 | + fn is_even(&&i: int) -> bool { |
| 114 | + ret (i % 2) == 0; |
| 115 | + } |
| 116 | + |
| 117 | + let l = to_list(bind filter(bind int::range(0, 10, _), is_even, _)); |
| 118 | + assert l == [0, 2, 4, 6, 8]; |
| 119 | +} |
| 120 | + |
| 121 | +#[test] |
| 122 | +fn test_filter_on_uint_range() { |
| 123 | + fn is_even(&&i: uint) -> bool { |
| 124 | + ret (i % 2u) == 0u; |
| 125 | + } |
| 126 | + |
| 127 | + let l = to_list(bind filter(bind uint::range(0u, 10u, _), is_even, _)); |
| 128 | + assert l == [0u, 2u, 4u, 6u, 8u]; |
| 129 | +} |
| 130 | + |
| 131 | +#[test] |
| 132 | +fn test_flat_map_with_option() { |
| 133 | + fn if_even(&&i: int) -> option<int> { |
| 134 | + if (i % 2) == 0 { some(i) } |
| 135 | + else { none } |
| 136 | + } |
| 137 | + |
| 138 | + let a = bind vec::iter([0, 1, 2], _); |
| 139 | + let b = bind flat_map(a, if_even, _); |
| 140 | + let c = to_list(b); |
| 141 | + assert c == [0, 2]; |
| 142 | +} |
| 143 | + |
| 144 | +#[test] |
| 145 | +fn test_flat_map_with_list() { |
| 146 | + fn repeat(&&i: int) -> [int] { |
| 147 | + let r = []; |
| 148 | + int::range(0, i) {|_j| r += [i]; } |
| 149 | + r |
| 150 | + } |
| 151 | + |
| 152 | + let a = bind vec::iter([0, 1, 2, 3], _); |
| 153 | + let b = bind flat_map(a, repeat, _); |
| 154 | + let c = to_list(b); |
| 155 | + #debug["c = %?", c]; |
| 156 | + assert c == [1, 2, 2, 3, 3, 3]; |
| 157 | +} |
| 158 | + |
| 159 | +#[test] |
| 160 | +fn test_repeat() { |
| 161 | + let c = [], |
| 162 | + i = 0u; |
| 163 | + repeat(5u) {|| |
| 164 | + c += [(i * i)]; |
| 165 | + i += 1u; |
| 166 | + }; |
| 167 | + #debug["c = %?", c]; |
| 168 | + assert c == [0u, 1u, 4u, 9u, 16u]; |
| 169 | +} |
| 170 | + |
| 171 | + |
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