package libzipperposition

  1. Overview
  2. Docs
package libzipperposition
Legend:
Page
Library
Module
Module type
Parameter
Class
Class type
Source

Source file MyHeap.ml

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
224
(* This code is extracted from Msat ( https://github.com/Gbury/mSAT ).
   As such it is under the Apache 2 License.
*)

module type RANKED = CCMutHeap_intf.RANKED

module type S = CCMutHeap_intf.S

module Make(Elt : RANKED) = struct
  module Vec = CCVector
  type elt = Elt.t

  type t = {
    heap : elt Vec.vector;
  } [@@unboxed]

  let _absent_index = -1

  let create () =
    { heap = Vec.create(); }

  let[@inline] left i = (i lsl 1) + 1 (* i*2 + 1 *)
  let[@inline] right i = (i + 1) lsl 1 (* (i+1)*2 *)
  let[@inline] parent i = (i - 1) asr 1 (* (i-1) / 2 *)

  (*
  let rec heap_property ({heap=heap} as s) i =
    i >= (Vec.size heap)  ||
      ((i = 0 || not(cmp (Vec.get heap i) (Vec.get heap (parent i))))
       && heap_property s (left i) && heap_property s (right i))

  let heap_property s = heap_property s 1
  *)

  (* [elt] is above or at its expected position. Move it up the heap
     (towards high indices) to restore the heap property *)
  let percolate_up {heap} (elt:Elt.t) : unit =
    let pi = ref (parent (Elt.idx elt)) in
    let i = ref (Elt.idx elt) in
    while !i <> 0 && Elt.lt elt (Vec.get heap !pi) do
      Vec.set heap !i (Vec.get heap !pi);
      Elt.set_idx (Vec.get heap !i) !i;
      i  := !pi;
      pi := parent !i
    done;
    Vec.set heap !i elt;
    Elt.set_idx elt !i

  let percolate_down {heap} (elt:Elt.t): unit =
    let sz = Vec.size heap in
    let li = ref (left (Elt.idx elt)) in
    let ri = ref (right (Elt.idx elt)) in
    let i = ref (Elt.idx elt) in
    begin
      try
        while !li < sz do
          let child =
            if !ri < sz && Elt.lt (Vec.get heap !ri) (Vec.get heap !li)
            then !ri
            else !li
          in
          if not (Elt.lt (Vec.get heap child) elt) then raise Exit;
          Vec.set heap !i (Vec.get heap child);
          Elt.set_idx (Vec.get heap !i) !i;
          i  := child;
          li := left !i;
          ri := right !i
        done;
      with Exit -> ()
    end;
    Vec.set heap !i elt;
    Elt.set_idx elt !i

  let[@inline] in_heap x = Elt.idx x >= 0

  let[@inline] decrease s x = assert (in_heap x); percolate_up s x

  let[@inline] increase s x = assert (in_heap x); percolate_down s x

  let filter s filt =
    let j = ref 0 in
    let lim = Vec.size s.heap in
    for i = 0 to lim - 1 do
      if filt (Vec.get s.heap i) then (
        Vec.set s.heap !j (Vec.get s.heap i);
        Elt.set_idx (Vec.get s.heap i) !j;
        incr j;
      ) else (
        Elt.set_idx (Vec.get s.heap i) _absent_index;
      );
    done;
    Vec.truncate s.heap !j;
    if not (Vec.is_empty s.heap) then 
        (for i = (!j / 2) downto 0 do
            percolate_down s (Vec.get s.heap i)
        done)

  let size s = Vec.size s.heap

  let is_empty s = Vec.is_empty s.heap

  let iter s f = Vec.iter f s.heap

  let clear {heap} =
    Vec.iter (fun e -> Elt.set_idx e _absent_index) heap;
    Vec.clear heap;
    ()

  let insert s elt =
    if not (in_heap elt) then (
      Elt.set_idx elt (Vec.size s.heap);
      Vec.push s.heap elt;
      percolate_up s elt;
    )

  (*
  let update cmp s n =
    assert (heap_property cmp s);
    begin
      if in_heap s n then
        begin
          percolate_up cmp s (Vec.get s.indices n);
          percolate_down cmp s (Vec.get s.indices n)
        end
      else insert cmp s n
    end;
    assert (heap_property cmp s)
  *)

  let remove_min ({heap} as s) =
    match Vec.size heap with
    | 0 -> raise Not_found
    | 1 ->
      let x = Vec.pop_exn heap in
      Elt.set_idx x _absent_index;
      x
    | _ ->
      let x = Vec.get heap 0 in
      let new_hd = Vec.pop_exn heap in (* heap.last() *)
      Vec.set heap 0 new_hd;
      Elt.set_idx x _absent_index;
      Elt.set_idx new_hd 0;
      (* enforce heap property again *)
      if Vec.size heap > 1 then (
        percolate_down s new_hd;
      );
      x

end [@@inline]

(*$inject
  type elt = {
    x: string;
    mutable rank: int;
    mutable idx: int;
  }
  module Elt = struct
    type t = elt
    let idx x = x.idx
    let set_idx x i = x.idx <- i
    let lt a b =
      if a.rank = b.rank then a.x < b.x else a.rank < b.rank
  end
  module H = CCMutHeap.Make(Elt)
*)

(*$R
  let h = H.create() in
  let x1 = {x="a"; rank=10; idx= -1} in
  let x2 = {x="b"; rank=10; idx= -1} in
  let x3 = {x="c"; rank=10; idx= -1} in
  H.insert h x1;
  assert (H.in_heap x1);
  assert (not (H.in_heap x2));
  assert (not (H.in_heap x3));
  H.insert h x2;
  H.insert h x3;

  assert (Elt.lt x1 x2);
  assert (Elt.lt x2 x3);

  let x = H.remove_min h in
  assert (x == x1);

  let x = H.remove_min h in
  assert (x == x2);

  let x = H.remove_min h in
  assert (x == x3);

  assert (try ignore (H.remove_min h); false with Not_found -> true);

  *)

(*$R
  let h = H.create() in
  let x1 = {x="a"; rank=10; idx= -1} in
  let x2 = {x="b"; rank=10; idx= -1} in
  let x3 = {x="c"; rank=10; idx= -1} in
  H.insert h x1;
  H.insert h x2;
  H.insert h x3;

  x3.rank <- 2;
  H.decrease h x3;

  assert (Elt.lt x3 x1);
  assert (Elt.lt x3 x2);

  let x = H.remove_min h in
  assert (x == x3);

  x1.rank <- 20;
  H.increase h x1;

  let x = H.remove_min h in
  assert (x == x2);

  let x = H.remove_min h in
  assert (x == x1);

  assert (try ignore (H.remove_min h); false with Not_found -> true);

  *)
OCaml

Innovation. Community. Security.

GitHub Discord Twitter Peertube RSS
About
Changelog Releases Industrial Users Academic Users Why OCaml
Ecosystem
Packages Community Events OCaml Planet Jobs
Resources
Install OCaml Get Started Platform Tools Language Manual Standard Library API Books Exercises Papers OCaml Playground Logo
Policies
Carbon Footprint Governance Privacy Code of Conduct