321 lines
8.6 KiB
Rust
321 lines
8.6 KiB
Rust
/*!
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The iteration traits and common implementation
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*/
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#[forbid(deprecated_mode)];
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#[forbid(deprecated_pattern)];
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use cmp::{Eq, Ord};
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/// A function used to initialize the elements of a sequence
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pub type InitOp<T> = &fn(uint) -> T;
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pub trait BaseIter<A> {
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pure fn each(blk: fn(v: &A) -> bool);
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pure fn size_hint() -> Option<uint>;
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}
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pub trait ExtendedIter<A> {
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pure fn eachi(blk: fn(uint, v: &A) -> bool);
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pure fn all(blk: fn(&A) -> bool) -> bool;
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pure fn any(blk: fn(&A) -> bool) -> bool;
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pure fn foldl<B>(b0: B, blk: fn(&B, &A) -> B) -> B;
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pure fn position(f: fn(&A) -> bool) -> Option<uint>;
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}
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pub trait EqIter<A:Eq> {
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pure fn contains(x: &A) -> bool;
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pure fn count(x: &A) -> uint;
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}
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pub trait Times {
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pure fn times(it: fn() -> bool);
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}
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pub trait CopyableIter<A:Copy> {
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pure fn filter_to_vec(pred: fn(a: A) -> bool) -> ~[A];
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pure fn map_to_vec<B>(op: fn(v: A) -> B) -> ~[B];
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pure fn to_vec() -> ~[A];
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pure fn find(p: fn(a: A) -> bool) -> Option<A>;
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}
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pub trait CopyableOrderedIter<A:Copy Ord> {
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pure fn min() -> A;
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pure fn max() -> A;
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}
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pub trait CopyableNonstrictIter<A:Copy> {
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// Like "each", but copies out the value. If the receiver is mutated while
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// iterating over it, the semantics must not be memory-unsafe but are
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// otherwise undefined.
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pure fn each_val(&const self, f: &fn(A) -> bool);
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}
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// A trait for sequences that can be by imperatively pushing elements
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// onto them.
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pub trait Buildable<A> {
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/**
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* Builds a buildable sequence by calling a provided function with
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* an argument function that pushes an element onto the back of
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* the sequence.
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* This version takes an initial size for the sequence.
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*
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* # Arguments
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*
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* * size - A hint for an initial size of the sequence
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* * builder - A function that will construct the sequence. It recieves
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* as an argument a function that will push an element
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* onto the sequence being constructed.
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*/
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static pure fn build_sized(size: uint,
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builder: fn(push: pure fn(v: A))) -> self;
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}
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pub pure fn eachi<A,IA:BaseIter<A>>(self: &IA,
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blk: fn(uint, v: &A) -> bool) {
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let mut i = 0;
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for self.each |a| {
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if !blk(i, a) { break; }
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i += 1;
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}
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}
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pub pure fn all<A,IA:BaseIter<A>>(self: &IA,
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blk: fn(&A) -> bool) -> bool {
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for self.each |a| {
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if !blk(a) { return false; }
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}
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return true;
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}
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pub pure fn any<A,IA:BaseIter<A>>(self: &IA,
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blk: fn(&A) -> bool) -> bool {
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for self.each |a| {
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if blk(a) { return true; }
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}
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return false;
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}
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pub pure fn filter_to_vec<A:Copy,IA:BaseIter<A>>(
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self: &IA, prd: fn(a: A) -> bool) -> ~[A] {
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do vec::build_sized_opt(self.size_hint()) |push| {
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for self.each |a| {
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if prd(*a) { push(*a); }
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}
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}
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}
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pub pure fn map_to_vec<A:Copy,B,IA:BaseIter<A>>(self: &IA,
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op: fn(v: A) -> B)
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-> ~[B] {
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do vec::build_sized_opt(self.size_hint()) |push| {
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for self.each |a| {
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push(op(*a));
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}
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}
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}
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pub pure fn flat_map_to_vec<A:Copy,B:Copy,IA:BaseIter<A>,IB:BaseIter<B>>(
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self: &IA, op: fn(a: A) -> IB) -> ~[B] {
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do vec::build |push| {
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for self.each |a| {
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for op(*a).each |b| {
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push(*b);
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}
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}
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}
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}
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pub pure fn foldl<A,B,IA:BaseIter<A>>(self: &IA, b0: B,
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blk: fn(&B, &A) -> B)
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-> B {
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let mut b = move b0;
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for self.each |a| {
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b = blk(&b, a);
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}
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move b
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}
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pub pure fn to_vec<A:Copy,IA:BaseIter<A>>(self: &IA) -> ~[A] {
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foldl::<A,~[A],IA>(self, ~[], |r, a| vec::append(copy (*r), ~[*a]))
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}
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pub pure fn contains<A:Eq,IA:BaseIter<A>>(self: &IA, x: &A) -> bool {
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for self.each |a| {
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if *a == *x { return true; }
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}
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return false;
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}
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pub pure fn count<A:Eq,IA:BaseIter<A>>(self: &IA, x: &A) -> uint {
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do foldl(self, 0) |count, value| {
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if *value == *x {
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*count + 1
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} else {
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*count
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}
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}
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}
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pub pure fn position<A,IA:BaseIter<A>>(self: &IA, f: fn(&A) -> bool)
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-> Option<uint>
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{
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let mut i = 0;
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for self.each |a| {
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if f(a) { return Some(i); }
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i += 1;
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}
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return None;
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}
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// note: 'rposition' would only make sense to provide with a bidirectional
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// iter interface, such as would provide "reach" in addition to "each". as is,
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// it would have to be implemented with foldr, which is too inefficient.
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pub pure fn repeat(times: uint, blk: fn() -> bool) {
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let mut i = 0;
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while i < times {
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if !blk() { break }
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i += 1;
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}
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}
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pub pure fn min<A:Copy Ord,IA:BaseIter<A>>(self: &IA) -> A {
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match do foldl::<A,Option<A>,IA>(self, None) |a, b| {
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match a {
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&Some(ref a_) if *a_ < *b => {
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*(move a)
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}
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_ => Some(*b)
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}
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} {
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Some(move val) => val,
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None => fail ~"min called on empty iterator"
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}
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}
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pub pure fn max<A:Copy Ord,IA:BaseIter<A>>(self: &IA) -> A {
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match do foldl::<A,Option<A>,IA>(self, None) |a, b| {
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match a {
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&Some(ref a_) if *a_ > *b => {
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*(move a)
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}
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_ => Some(*b)
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}
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} {
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Some(move val) => val,
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None => fail ~"max called on empty iterator"
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}
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}
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pub pure fn find<A: Copy,IA:BaseIter<A>>(self: &IA,
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p: fn(a: A) -> bool) -> Option<A> {
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for self.each |i| {
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if p(*i) { return Some(*i) }
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}
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return None;
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}
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// Some functions for just building
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/**
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* Builds a sequence by calling a provided function with an argument
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* function that pushes an element to the back of a sequence.
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*
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* # Arguments
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*
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* * builder - A function that will construct the sequence. It recieves
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* as an argument a function that will push an element
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* onto the sequence being constructed.
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*/
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#[inline(always)]
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pub pure fn build<A,B: Buildable<A>>(builder: fn(push: pure fn(v: A)))
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-> B {
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build_sized(4, builder)
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}
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/**
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* Builds a sequence by calling a provided function with an argument
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* function that pushes an element to the back of a sequence.
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* This version takes an initial size for the sequence.
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*
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* # Arguments
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*
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* * size - An option, maybe containing initial size of the sequence
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* to reserve
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* * builder - A function that will construct the sequence. It recieves
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* as an argument a function that will push an element
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* onto the sequence being constructed.
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*/
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#[inline(always)]
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pub pure fn build_sized_opt<A,B: Buildable<A>>(
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size: Option<uint>,
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builder: fn(push: pure fn(v: A))) -> B {
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build_sized(size.get_default(4), builder)
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}
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// Functions that combine iteration and building
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/// Apply a function to each element of an iterable and return the results
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pub fn map<T,IT: BaseIter<T>,U,BU: Buildable<U>>(v: &IT, f: fn(&T) -> U)
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-> BU {
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do build_sized_opt(v.size_hint()) |push| {
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for v.each() |elem| {
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push(f(elem));
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}
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}
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}
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/**
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* Creates and initializes a generic sequence from a function
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*
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* Creates a generic sequence of size `n_elts` and initializes the elements
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* to the value returned by the function `op`.
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*/
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pub pure fn from_fn<T,BT: Buildable<T>>(n_elts: uint,
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op: InitOp<T>) -> BT {
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do build_sized(n_elts) |push| {
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let mut i: uint = 0u;
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while i < n_elts { push(op(i)); i += 1u; }
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}
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}
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/**
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* Creates and initializes a generic sequence with some element
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*
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* Creates an immutable vector of size `n_elts` and initializes the elements
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* to the value `t`.
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*/
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pub pure fn from_elem<T: Copy,BT: Buildable<T>>(n_elts: uint,
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t: T) -> BT {
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do build_sized(n_elts) |push| {
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let mut i: uint = 0;
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while i < n_elts { push(t); i += 1; }
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}
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}
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/// Appending two generic sequences
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#[inline(always)]
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pub pure fn append<T: Copy,IT: BaseIter<T>,BT: Buildable<T>>(
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lhs: &IT, rhs: &IT) -> BT {
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let size_opt = lhs.size_hint().chain_ref(
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|sz1| rhs.size_hint().map(|sz2| *sz1+*sz2));
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do build_sized_opt(size_opt) |push| {
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for lhs.each |x| { push(*x); }
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for rhs.each |x| { push(*x); }
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}
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}
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/// Copies a generic sequence, possibly converting it to a different
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/// type of sequence.
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#[inline(always)]
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pub pure fn copy_seq<T: Copy,IT: BaseIter<T>,BT: Buildable<T>>(
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v: &IT) -> BT {
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do build_sized_opt(v.size_hint()) |push| {
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for v.each |x| { push(*x); }
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}
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}
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