193 lines
3.3 KiB
Rust
193 lines
3.3 KiB
Rust
/*
|
|
Module: list
|
|
|
|
A standard linked list
|
|
*/
|
|
|
|
import core::option;
|
|
import option::*;
|
|
import option::{some, none};
|
|
|
|
/* Section: Types */
|
|
|
|
/*
|
|
Tag: list
|
|
*/
|
|
tag list<T> {
|
|
/* Variant: cons */
|
|
cons(T, @list<T>);
|
|
/* Variant: nil */
|
|
nil;
|
|
}
|
|
|
|
/*Section: Operations */
|
|
|
|
/*
|
|
Function: from_vec
|
|
|
|
Create a list from a vector
|
|
*/
|
|
fn from_vec<T: copy>(v: [const T]) -> list<T> {
|
|
*vec::foldr(v, @nil::<T>, { |h, t| @cons(h, t) })
|
|
}
|
|
|
|
/*
|
|
Function: foldl
|
|
|
|
Left fold
|
|
|
|
Applies `f` to `u` and the first element in the list, then applies
|
|
`f` to the result of the previous call and the second element,
|
|
and so on, returning the accumulated result.
|
|
|
|
Parameters:
|
|
|
|
ls - The list to fold
|
|
z - The initial value
|
|
f - The function to apply
|
|
*/
|
|
fn foldl<T: copy, U>(ls: list<U>, z: T, f: block(T, U) -> T) -> T {
|
|
let accum: T = z;
|
|
iter(ls) {|elt| accum = f(accum, elt);}
|
|
accum
|
|
}
|
|
|
|
/*
|
|
Function: find
|
|
|
|
Search for an element that matches a given predicate
|
|
|
|
Apply function `f` to each element of `v`, starting from the first.
|
|
When function `f` returns true then an option containing the element
|
|
is returned. If `f` matches no elements then none is returned.
|
|
*/
|
|
fn find<T: copy, U: copy>(ls: list<T>, f: block(T) -> option::t<U>)
|
|
-> option::t<U> {
|
|
let ls = ls;
|
|
while true {
|
|
alt ls {
|
|
cons(hd, tl) {
|
|
alt f(hd) { none. { ls = *tl; } some(rs) { ret some(rs); } }
|
|
}
|
|
nil. { break; }
|
|
}
|
|
}
|
|
ret none;
|
|
}
|
|
|
|
/*
|
|
Function: has
|
|
|
|
Returns true if a list contains an element with the given value
|
|
*/
|
|
fn has<T: copy>(ls: list<T>, elt: T) -> bool {
|
|
let ls = ls;
|
|
while true {
|
|
alt ls {
|
|
cons(hd, tl) { if elt == hd { ret true; } else { ls = *tl; } }
|
|
nil. { break; }
|
|
}
|
|
}
|
|
ret false;
|
|
}
|
|
|
|
/*
|
|
Function: is_empty
|
|
|
|
Returns true if the list is empty.
|
|
*/
|
|
pure fn is_empty<T: copy>(ls: list<T>) -> bool {
|
|
alt ls {
|
|
nil. { true }
|
|
_ { false }
|
|
}
|
|
}
|
|
|
|
/*
|
|
Function: is_not_empty
|
|
|
|
Returns true if the list is not empty.
|
|
*/
|
|
pure fn is_not_empty<T: copy>(ls: list<T>) -> bool {
|
|
ret !is_empty(ls);
|
|
}
|
|
|
|
/*
|
|
Function: len
|
|
|
|
Returns the length of a list
|
|
*/
|
|
fn len<T>(ls: list<T>) -> uint {
|
|
let count = 0u;
|
|
iter(ls) {|_e| count += 1u;}
|
|
count
|
|
}
|
|
|
|
/*
|
|
Function: tail
|
|
|
|
Returns all but the first element of a list
|
|
*/
|
|
pure fn tail<T: copy>(ls: list<T>) : is_not_empty(ls) -> list<T> {
|
|
alt ls {
|
|
cons(_, tl) { ret *tl; }
|
|
nil. { fail "list empty" }
|
|
}
|
|
}
|
|
|
|
/*
|
|
Function: head
|
|
|
|
Returns the first element of a list
|
|
*/
|
|
pure fn head<T: copy>(ls: list<T>) : is_not_empty(ls) -> T {
|
|
alt ls {
|
|
cons(hd, _) { ret hd; }
|
|
nil. { fail "list empty" }
|
|
}
|
|
}
|
|
|
|
/*
|
|
Function: append
|
|
|
|
Appends one list to another
|
|
*/
|
|
pure fn append<T: copy>(l: list<T>, m: list<T>) -> list<T> {
|
|
alt l {
|
|
nil. { ret m; }
|
|
cons(x, xs) { let rest = append(*xs, m); ret cons(x, @rest); }
|
|
}
|
|
}
|
|
|
|
/*
|
|
Function: iter
|
|
|
|
Iterate over a list
|
|
*/
|
|
fn iter<T>(l: list<T>, f: block(T)) {
|
|
alt l {
|
|
cons(hd, tl) {
|
|
f(hd);
|
|
let cur = tl;
|
|
while true {
|
|
alt *cur {
|
|
cons(hd, tl) {
|
|
f(hd);
|
|
cur = tl;
|
|
}
|
|
nil. { break; }
|
|
}
|
|
}
|
|
}
|
|
nil. {}
|
|
}
|
|
}
|
|
|
|
// Local Variables:
|
|
// mode: rust;
|
|
// fill-column: 78;
|
|
// indent-tabs-mode: nil
|
|
// c-basic-offset: 4
|
|
// buffer-file-coding-system: utf-8-unix
|
|
// End:
|