116 lines
3.3 KiB
Rust
116 lines
3.3 KiB
Rust
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/**
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* A deque, for fun. Untested as of yet. Likely buggy.
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*/
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type t[T] =
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obj {
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fn size() -> uint ;
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fn add_front(&T) ;
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fn add_back(&T) ;
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fn pop_front() -> T ;
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fn pop_back() -> T ;
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fn peek_front() -> T ;
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fn peek_back() -> T ;
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fn get(int) -> T ;
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};
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fn create[@T]() -> t[T] {
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type cell[T] = option::t[T];
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let initial_capacity: uint = 32u; // 2^5
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/**
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* Grow is only called on full elts, so nelts is also len(elts), unlike
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* elsewhere.
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*/
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fn grow[@T](nelts: uint, lo: uint, elts: &(cell[T])[mutable ]) ->
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(cell[T])[mutable ] {
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assert (nelts == ivec::len(elts));
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let rv = ~[mutable ];
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let i = 0u;
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let nalloc = uint::next_power_of_two(nelts + 1u);
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while i < nalloc {
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if i < nelts {
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rv += ~[mutable elts.((lo + i) % nelts)];
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} else { rv += ~[mutable option::none]; }
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i += 1u;
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}
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ret rv;
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}
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fn get[@T](elts: &(cell[T])[mutable ], i: uint) -> T {
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ret alt elts.(i) { option::some(t) { t } _ { fail } };
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}
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obj deque[@T](mutable nelts: uint,
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mutable lo: uint,
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mutable hi: uint,
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mutable elts: (cell[T])[mutable ]) {
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fn size() -> uint { ret nelts; }
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fn add_front(t: &T) {
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let oldlo: uint = lo;
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if lo == 0u {
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lo = ivec::len[cell[T]](elts) - 1u;
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} else { lo -= 1u; }
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if lo == hi {
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elts = grow[T](nelts, oldlo, elts);
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lo = ivec::len[cell[T]](elts) - 1u;
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hi = nelts;
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}
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elts.(lo) = option::some[T](t);
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nelts += 1u;
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}
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fn add_back(t: &T) {
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if lo == hi && nelts != 0u {
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elts = grow[T](nelts, lo, elts);
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lo = 0u;
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hi = nelts;
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}
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elts.(hi) = option::some[T](t);
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hi = (hi + 1u) % ivec::len[cell[T]](elts);
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nelts += 1u;
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}
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/**
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* We actually release (turn to none()) the T we're popping so
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* that we don't keep anyone's refcount up unexpectedly.
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*/
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fn pop_front() -> T {
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let t: T = get[T](elts, lo);
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elts.(lo) = option::none[T];
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lo = (lo + 1u) % ivec::len[cell[T]](elts);
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nelts -= 1u;
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ret t;
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}
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fn pop_back() -> T {
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if hi == 0u {
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hi = ivec::len[cell[T]](elts) - 1u;
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} else { hi -= 1u; }
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let t: T = get[T](elts, hi);
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elts.(hi) = option::none[T];
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nelts -= 1u;
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ret t;
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}
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fn peek_front() -> T { ret get[T](elts, lo); }
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fn peek_back() -> T { ret get[T](elts, hi - 1u); }
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fn get(i: int) -> T {
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let idx: uint = (lo + (i as uint)) % ivec::len[cell[T]](elts);
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ret get[T](elts, idx);
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}
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}
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let v: (cell[T])[mutable ] =
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ivec::init_elt_mut(option::none, initial_capacity);
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ret deque[T](0u, 0u, 0u, v);
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}
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// Local Variables:
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// mode: rust;
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// fill-column: 78;
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// indent-tabs-mode: nil
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// c-basic-offset: 4
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// buffer-file-coding-system: utf-8-unix
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// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
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// End:
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