1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
5 -- G N A T . P E R F E C T _ H A S H _ G E N E R A T O R S --
9 -- Copyright (C) 2002-2007, AdaCore --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
29 -- GNAT was originally developed by the GNAT team at New York University. --
30 -- Extensive contributions were provided by Ada Core Technologies Inc. --
32 ------------------------------------------------------------------------------
34 with Ada.IO_Exceptions; use Ada.IO_Exceptions;
36 with GNAT.Heap_Sort_G;
37 with GNAT.OS_Lib; use GNAT.OS_Lib;
40 package body GNAT.Perfect_Hash_Generators is
42 -- We are using the algorithm of J. Czech as described in Zbigniew J.
43 -- Czech, George Havas, and Bohdan S. Majewski ``An Optimal Algorithm for
44 -- Generating Minimal Perfect Hash Functions'', Information Processing
45 -- Letters, 43(1992) pp.257-264, Oct.1992
47 -- This minimal perfect hash function generator is based on random graphs
48 -- and produces a hash function of the form:
50 -- h (w) = (g (f1 (w)) + g (f2 (w))) mod m
52 -- where f1 and f2 are functions that map strings into integers, and g is a
53 -- function that maps integers into [0, m-1]. h can be order preserving.
54 -- For instance, let W = {w_0, ..., w_i, ...,
55 -- w_m-1}, h can be defined such that h (w_i) = i.
57 -- This algorithm defines two possible constructions of f1 and f2. Method
58 -- b) stores the hash function in less memory space at the expense of
61 -- a) fk (w) = sum (for i in 1 .. length (w)) (Tk (i, w (i))) mod n
63 -- size (Tk) = max (for w in W) (length (w)) * size (used char set)
65 -- b) fk (w) = sum (for i in 1 .. length (w)) (Tk (i) * w (i)) mod n
67 -- size (Tk) = max (for w in W) (length (w)) but the table lookups are
68 -- replaced by multiplications.
70 -- where Tk values are randomly generated. n is defined later on but the
71 -- algorithm recommends to use a value a little bit greater than 2m. Note
72 -- that for large values of m, the main memory space requirements comes
73 -- from the memory space for storing function g (>= 2m entries).
75 -- Random graphs are frequently used to solve difficult problems that do
76 -- not have polynomial solutions. This algorithm is based on a weighted
77 -- undirected graph. It comprises two steps: mapping and assignment.
79 -- In the mapping step, a graph G = (V, E) is constructed, where = {0, 1,
80 -- ..., n-1} and E = {(for w in W) (f1 (w), f2 (w))}. In order for the
81 -- assignment step to be successful, G has to be acyclic. To have a high
82 -- probability of generating an acyclic graph, n >= 2m. If it is not
83 -- acyclic, Tk have to be regenerated.
85 -- In the assignment step, the algorithm builds function g. As is acyclic,
86 -- there is a vertex v1 with only one neighbor v2. Let w_i be the word such
87 -- that v1 = f1 (w_i) and v2 = f2 (w_i). Let g (v1) = 0 by construction and
88 -- g (v2) = (i - g (v1)) mod n (or to be general, (h (i) - g (v1) mod n).
89 -- If word w_j is such that v2 = f1 (w_j) and v3 = f2 (w_j), g (v3) = (j -
90 -- g (v2)) mod (or to be general, (h (j) - g (v2)) mod n). If w_i has no
91 -- neighbor, then another vertex is selected. The algorithm traverses G to
92 -- assign values to all the vertices. It cannot assign a value to an
93 -- already assigned vertex as G is acyclic.
95 subtype Word_Id is Integer;
96 subtype Key_Id is Integer;
97 subtype Vertex_Id is Integer;
98 subtype Edge_Id is Integer;
99 subtype Table_Id is Integer;
101 No_Vertex : constant Vertex_Id := -1;
102 No_Edge : constant Edge_Id := -1;
103 No_Table : constant Table_Id := -1;
105 Max_Word_Length : constant := 32;
106 subtype Word_Type is String (1 .. Max_Word_Length);
107 Null_Word : constant Word_Type := (others => ASCII.NUL);
108 -- Store keyword in a word. Note that the length of word is limited to 32
111 type Key_Type is record
114 -- A key corresponds to an edge in the algorithm graph
116 type Vertex_Type is record
120 -- A vertex can be involved in several edges. First and Last are the bounds
121 -- of an array of edges stored in a global edge table.
123 type Edge_Type is record
128 -- An edge is a peer of vertices. In the algorithm, a key is associated to
131 package WT is new GNAT.Table (Word_Type, Word_Id, 0, 32, 32);
132 package IT is new GNAT.Table (Integer, Integer, 0, 32, 32);
133 -- The two main tables. IT is used to store several tables of components
134 -- containing only integers.
136 function Image (Int : Integer; W : Natural := 0) return String;
137 function Image (Str : String; W : Natural := 0) return String;
138 -- Return a string which includes string Str or integer Int preceded by
139 -- leading spaces if required by width W.
141 Output : File_Descriptor renames GNAT.OS_Lib.Standout;
144 EOL : constant Character := ASCII.LF;
146 Max : constant := 78;
148 Line : String (1 .. Max);
149 -- Use this line to provide buffered IO
151 procedure Add (C : Character);
152 procedure Add (S : String);
153 -- Add a character or a string in Line and update Last
156 (F : File_Descriptor;
164 -- Write string S into file F as a element of an array of one or two
165 -- dimensions. Fk (resp. Lk and Ck) indicates the first (resp last and
166 -- current) index in the k-th dimension. If F1 = L1 the array is considered
167 -- as a one dimension array. This dimension is described by F2 and L2. This
168 -- routine takes care of all the parenthesis, spaces and commas needed to
169 -- format correctly the array. Moreover, the array is well indented and is
170 -- wrapped to fit in a 80 col line. When the line is full, the routine
171 -- writes it into file F. When the array is completed, the routine adds
172 -- semi-colon and writes the line into file F.
174 procedure New_Line (File : File_Descriptor);
175 -- Simulate Ada.Text_IO.New_Line with GNAT.OS_Lib
177 procedure Put (File : File_Descriptor; Str : String);
178 -- Simulate Ada.Text_IO.Put with GNAT.OS_Lib
180 procedure Put_Used_Char_Set (File : File_Descriptor; Title : String);
181 -- Output a title and a used character set
183 procedure Put_Int_Vector
184 (File : File_Descriptor;
188 -- Output a title and a vector
190 procedure Put_Int_Matrix
191 (File : File_Descriptor;
196 -- Output a title and a matrix. When the matrix has only one non-empty
197 -- dimension (Len_2 = 0), output a vector.
199 procedure Put_Edges (File : File_Descriptor; Title : String);
200 -- Output a title and an edge table
202 procedure Put_Initial_Keys (File : File_Descriptor; Title : String);
203 -- Output a title and a key table
205 procedure Put_Reduced_Keys (File : File_Descriptor; Title : String);
206 -- Output a title and a key table
208 procedure Put_Vertex_Table (File : File_Descriptor; Title : String);
209 -- Output a title and a vertex table
211 ----------------------------------
212 -- Character Position Selection --
213 ----------------------------------
215 -- We reduce the maximum key size by selecting representative positions
216 -- in these keys. We build a matrix with one word per line. We fill the
217 -- remaining space of a line with ASCII.NUL. The heuristic selects the
218 -- position that induces the minimum number of collisions. If there are
219 -- collisions, select another position on the reduced key set responsible
220 -- of the collisions. Apply the heuristic until there is no more collision.
222 procedure Apply_Position_Selection;
223 -- Apply Position selection and build the reduced key table
225 procedure Parse_Position_Selection (Argument : String);
226 -- Parse Argument and compute the position set. Argument is list of
227 -- substrings separated by commas. Each substring represents a position
228 -- or a range of positions (like x-y).
230 procedure Select_Character_Set;
231 -- Define an optimized used character set like Character'Pos in order not
232 -- to allocate tables of 256 entries.
234 procedure Select_Char_Position;
235 -- Find a min char position set in order to reduce the max key length. The
236 -- heuristic selects the position that induces the minimum number of
237 -- collisions. If there are collisions, select another position on the
238 -- reduced key set responsible of the collisions. Apply the heuristic until
239 -- there is no collision.
241 -----------------------------
242 -- Random Graph Generation --
243 -----------------------------
245 procedure Random (Seed : in out Natural);
246 -- Simulate Ada.Discrete_Numerics.Random
248 procedure Generate_Mapping_Table
252 Seed : in out Natural);
253 -- Random generation of the tables below. T is already allocated
255 procedure Generate_Mapping_Tables
257 Seed : in out Natural);
258 -- Generate the mapping tables T1 and T2. They are used to define fk (w) =
259 -- sum (for i in 1 .. length (w)) (Tk (i, w (i))) mod n. Keys, NK and Chars
260 -- are used to compute the matrix size.
262 ---------------------------
263 -- Algorithm Computation --
264 ---------------------------
266 procedure Compute_Edges_And_Vertices (Opt : Optimization);
267 -- Compute the edge and vertex tables. These are empty when a self loop is
268 -- detected (f1 (w) = f2 (w)). The edge table is sorted by X value and then
269 -- Y value. Keys is the key table and NK the number of keys. Chars is the
270 -- set of characters really used in Keys. NV is the number of vertices
271 -- recommended by the algorithm. T1 and T2 are the mapping tables needed to
272 -- compute f1 (w) and f2 (w).
274 function Acyclic return Boolean;
275 -- Return True when the graph is acyclic. Vertices is the current vertex
276 -- table and Edges the current edge table.
278 procedure Assign_Values_To_Vertices;
279 -- Execute the assignment step of the algorithm. Keys is the current key
280 -- table. Vertices and Edges represent the random graph. G is the result of
281 -- the assignment step such that:
282 -- h (w) = (g (f1 (w)) + g (f2 (w))) mod m
287 Opt : Optimization) return Natural;
288 -- For an optimization of CPU_Time return
289 -- fk (w) = sum (for i in 1 .. length (w)) (Tk (i, w (i))) mod n
290 -- For an optimization of Memory_Space return
291 -- fk (w) = sum (for i in 1 .. length (w)) (Tk (i) * w (i)) mod n
294 -------------------------------
295 -- Internal Table Management --
296 -------------------------------
298 function Allocate (N : Natural; S : Natural := 1) return Table_Id;
299 -- Allocate N * S ints from IT table
301 procedure Free_Tmp_Tables;
302 -- Deallocate the tables used by the algorithm (but not the keys table)
308 Keys : Table_Id := No_Table;
310 -- NK : Number of Keys
312 function Initial (K : Key_Id) return Word_Id;
313 pragma Inline (Initial);
315 function Reduced (K : Key_Id) return Word_Id;
316 pragma Inline (Reduced);
318 function Get_Key (N : Key_Id) return Key_Type;
319 procedure Set_Key (N : Key_Id; Item : Key_Type);
320 -- Get or Set Nth element of Keys table
326 Char_Pos_Set : Table_Id := No_Table;
327 Char_Pos_Set_Len : Natural;
328 -- Character Selected Position Set
330 function Get_Char_Pos (P : Natural) return Natural;
331 procedure Set_Char_Pos (P : Natural; Item : Natural);
332 -- Get or Set the string position of the Pth selected character
338 Used_Char_Set : Table_Id := No_Table;
339 Used_Char_Set_Len : Natural;
340 -- Used Character Set : Define a new character mapping. When all the
341 -- characters are not present in the keys, in order to reduce the size
342 -- of some tables, we redefine the character mapping.
344 function Get_Used_Char (C : Character) return Natural;
345 procedure Set_Used_Char (C : Character; Item : Natural);
351 T1 : Table_Id := No_Table;
352 T2 : Table_Id := No_Table;
355 -- T1 : Values table to compute F1
356 -- T2 : Values table to compute F2
358 function Get_Table (T : Integer; X, Y : Natural) return Natural;
359 procedure Set_Table (T : Integer; X, Y : Natural; Item : Natural);
365 G : Table_Id := No_Table;
367 -- Values table to compute G
369 NT : Natural := Default_Tries;
370 -- Number of tries running the algorithm before raising an error
372 function Get_Graph (N : Natural) return Integer;
373 procedure Set_Graph (N : Natural; Item : Integer);
374 -- Get or Set Nth element of graph
380 Edge_Size : constant := 3;
381 Edges : Table_Id := No_Table;
383 -- Edges : Edge table of the random graph G
385 function Get_Edges (F : Natural) return Edge_Type;
386 procedure Set_Edges (F : Natural; Item : Edge_Type);
392 Vertex_Size : constant := 2;
394 Vertices : Table_Id := No_Table;
395 -- Vertex table of the random graph G
398 -- Number of Vertices
400 function Get_Vertices (F : Natural) return Vertex_Type;
401 procedure Set_Vertices (F : Natural; Item : Vertex_Type);
402 -- Comments needed ???
405 -- Ratio between Keys and Vertices (parameter of Czech's algorithm)
408 -- Optimization mode (memory vs CPU)
410 Max_Key_Len : Natural := 0;
411 Min_Key_Len : Natural := Max_Word_Length;
412 -- Maximum and minimum of all the word length
417 function Type_Size (L : Natural) return Natural;
418 -- Given the last L of an unsigned integer type T, return its size
424 function Acyclic return Boolean is
425 Marks : array (0 .. NV - 1) of Vertex_Id := (others => No_Vertex);
427 function Traverse (Edge : Edge_Id; Mark : Vertex_Id) return Boolean;
428 -- Propagate Mark from X to Y. X is already marked. Mark Y and propagate
429 -- it to the edges of Y except the one representing the same key. Return
430 -- False when Y is marked with Mark.
436 function Traverse (Edge : Edge_Id; Mark : Vertex_Id) return Boolean is
437 E : constant Edge_Type := Get_Edges (Edge);
438 K : constant Key_Id := E.Key;
439 Y : constant Vertex_Id := E.Y;
440 M : constant Vertex_Id := Marks (E.Y);
447 elsif M = No_Vertex then
449 V := Get_Vertices (Y);
451 for J in V.First .. V.Last loop
453 -- Do not propagate to the edge representing the same key
455 if Get_Edges (J).Key /= K
456 and then not Traverse (J, Mark)
468 -- Start of processing for Acyclic
471 -- Edges valid range is
473 for J in 1 .. Edges_Len - 1 loop
475 Edge := Get_Edges (J);
477 -- Mark X of E when it has not been already done
479 if Marks (Edge.X) = No_Vertex then
480 Marks (Edge.X) := Edge.X;
483 -- Traverse E when this has not already been done
485 if Marks (Edge.Y) = No_Vertex
486 and then not Traverse (J, Edge.X)
499 procedure Add (C : Character) is
501 Line (Last + 1) := C;
509 procedure Add (S : String) is
510 Len : constant Natural := S'Length;
512 Line (Last + 1 .. Last + Len) := S;
520 function Allocate (N : Natural; S : Natural := 1) return Table_Id is
521 L : constant Integer := IT.Last;
523 IT.Set_Last (L + N * S);
527 ------------------------------
528 -- Apply_Position_Selection --
529 ------------------------------
531 procedure Apply_Position_Selection is
533 WT.Set_Last (2 * NK);
534 for J in 0 .. NK - 1 loop
536 I_Word : constant Word_Type := WT.Table (Initial (J));
537 R_Word : Word_Type := Null_Word;
538 Index : Natural := I_Word'First - 1;
541 -- Select the characters of Word included in the position
544 for C in 0 .. Char_Pos_Set_Len - 1 loop
545 exit when I_Word (Get_Char_Pos (C)) = ASCII.NUL;
547 R_Word (Index) := I_Word (Get_Char_Pos (C));
550 -- Build the new table with the reduced word
552 WT.Table (Reduced (J)) := R_Word;
553 Set_Key (J, (Edge => No_Edge));
556 end Apply_Position_Selection;
558 -------------------------------
559 -- Assign_Values_To_Vertices --
560 -------------------------------
562 procedure Assign_Values_To_Vertices is
565 procedure Assign (X : Vertex_Id);
566 -- Execute assignment on X's neighbors except the vertex that we are
567 -- coming from which is already assigned.
573 procedure Assign (X : Vertex_Id) is
575 V : constant Vertex_Type := Get_Vertices (X);
578 for J in V.First .. V.Last loop
581 if Get_Graph (E.Y) = -1 then
582 Set_Graph (E.Y, (E.Key - Get_Graph (X)) mod NK);
588 -- Start of processing for Assign_Values_To_Vertices
591 -- Value -1 denotes an uninitialized value as it is supposed to
592 -- be in the range 0 .. NK.
596 G := Allocate (G_Len, 1);
599 for J in 0 .. G_Len - 1 loop
603 for K in 0 .. NK - 1 loop
604 X := Get_Edges (Get_Key (K).Edge).X;
606 if Get_Graph (X) = -1 then
612 for J in 0 .. G_Len - 1 loop
613 if Get_Graph (J) = -1 then
619 Put_Int_Vector (Output, "Assign Values To Vertices", G, G_Len);
621 end Assign_Values_To_Vertices;
627 procedure Compute (Position : String := Default_Position) is
628 Success : Boolean := False;
631 NV := Natural (K2V * Float (NK));
633 Keys := Allocate (NK);
636 Put_Initial_Keys (Output, "Initial Key Table");
639 if Position'Length /= 0 then
640 Parse_Position_Selection (Position);
642 Select_Char_Position;
647 (Output, "Char Position Set", Char_Pos_Set, Char_Pos_Set_Len);
650 Apply_Position_Selection;
653 Put_Reduced_Keys (Output, "Reduced Keys Table");
656 Select_Character_Set;
659 Put_Used_Char_Set (Output, "Character Position Table");
662 -- Perform Czech's algorithm
664 for J in 1 .. NT loop
665 Generate_Mapping_Tables (Opt, S);
666 Compute_Edges_And_Vertices (Opt);
668 -- When graph is not empty (no self-loop from previous operation) and
671 if 0 < Edges_Len and then Acyclic then
678 raise Too_Many_Tries;
681 Assign_Values_To_Vertices;
684 --------------------------------
685 -- Compute_Edges_And_Vertices --
686 --------------------------------
688 procedure Compute_Edges_And_Vertices (Opt : Optimization) is
693 Vertex : Vertex_Type;
694 Not_Acyclic : Boolean := False;
696 procedure Move (From : Natural; To : Natural);
697 function Lt (L, R : Natural) return Boolean;
698 -- Subprograms needed for GNAT.Heap_Sort_G
704 function Lt (L, R : Natural) return Boolean is
705 EL : constant Edge_Type := Get_Edges (L);
706 ER : constant Edge_Type := Get_Edges (R);
708 return EL.X < ER.X or else (EL.X = ER.X and then EL.Y < ER.Y);
715 procedure Move (From : Natural; To : Natural) is
717 Set_Edges (To, Get_Edges (From));
720 package Sorting is new GNAT.Heap_Sort_G (Move, Lt);
722 -- Start of processing for Compute_Edges_And_Vertices
725 -- We store edges from 1 to 2 * NK and leave zero alone in order to use
728 Edges_Len := 2 * NK + 1;
730 if Edges = No_Table then
731 Edges := Allocate (Edges_Len, Edge_Size);
734 if Vertices = No_Table then
735 Vertices := Allocate (NV, Vertex_Size);
738 for J in 0 .. NV - 1 loop
739 Set_Vertices (J, (No_Vertex, No_Vertex - 1));
742 -- For each w, X = f1 (w) and Y = f2 (w)
744 for J in 0 .. NK - 1 loop
749 X := Sum (WT.Table (Reduced (J)), T1, Opt);
750 Y := Sum (WT.Table (Reduced (J)), T2, Opt);
752 -- Discard T1 and T2 as soon as we discover a self loop
759 -- We store (X, Y) and (Y, X) to ease assignment step
761 Set_Edges (2 * J + 1, (X, Y, J));
762 Set_Edges (2 * J + 2, (Y, X, J));
765 -- Return an empty graph when self loop detected
772 Put_Edges (Output, "Unsorted Edge Table");
773 Put_Int_Matrix (Output, "Function Table 1", T1,
775 Put_Int_Matrix (Output, "Function Table 2", T2,
779 -- Enforce consistency between edges and keys. Construct Vertices and
780 -- compute the list of neighbors of a vertex First .. Last as Edges
781 -- is sorted by X and then Y. To compute the neighbor list, sort the
784 Sorting.Sort (Edges_Len - 1);
787 Put_Edges (Output, "Sorted Edge Table");
788 Put_Int_Matrix (Output, "Function Table 1", T1,
790 Put_Int_Matrix (Output, "Function Table 2", T2,
794 -- Edges valid range is 1 .. 2 * NK
796 for E in 1 .. Edges_Len - 1 loop
797 Edge := Get_Edges (E);
798 Key := Get_Key (Edge.Key);
800 if Key.Edge = No_Edge then
802 Set_Key (Edge.Key, Key);
805 Vertex := Get_Vertices (Edge.X);
807 if Vertex.First = No_Edge then
812 Set_Vertices (Edge.X, Vertex);
816 Put_Reduced_Keys (Output, "Key Table");
817 Put_Edges (Output, "Edge Table");
818 Put_Vertex_Table (Output, "Vertex Table");
821 end Compute_Edges_And_Vertices;
829 Item_Size : out Natural;
830 Length_1 : out Natural;
831 Length_2 : out Natural)
835 when Character_Position =>
837 Length_1 := Char_Pos_Set_Len;
840 when Used_Character_Set =>
845 when Function_Table_1
846 | Function_Table_2 =>
847 Item_Size := Type_Size (NV);
852 Item_Size := Type_Size (NK);
862 procedure Finalize is
871 Min_Key_Len := Max_Word_Length;
874 ---------------------
875 -- Free_Tmp_Tables --
876 ---------------------
878 procedure Free_Tmp_Tables is
884 Char_Pos_Set := No_Table;
885 Char_Pos_Set_Len := 0;
887 Used_Char_Set := No_Table;
888 Used_Char_Set_Len := 0;
902 Vertices := No_Table;
906 ----------------------------
907 -- Generate_Mapping_Table --
908 ----------------------------
910 procedure Generate_Mapping_Table
914 Seed : in out Natural)
917 for J in 0 .. L1 - 1 loop
918 for K in 0 .. L2 - 1 loop
920 Set_Table (Tab, J, K, Seed mod NV);
923 end Generate_Mapping_Table;
925 -----------------------------
926 -- Generate_Mapping_Tables --
927 -----------------------------
929 procedure Generate_Mapping_Tables
931 Seed : in out Natural)
934 -- If T1 and T2 are already allocated no need to do it twice. Reuse them
935 -- as their size has not changed.
937 if T1 = No_Table and then T2 = No_Table then
939 Used_Char_Last : Natural := 0;
943 if Opt = CPU_Time then
944 for P in reverse Character'Range loop
945 Used_Char := Get_Used_Char (P);
946 if Used_Char /= 0 then
947 Used_Char_Last := Used_Char;
953 T1_Len := Char_Pos_Set_Len;
954 T2_Len := Used_Char_Last + 1;
955 T1 := Allocate (T1_Len * T2_Len);
956 T2 := Allocate (T1_Len * T2_Len);
960 Generate_Mapping_Table (T1, T1_Len, T2_Len, Seed);
961 Generate_Mapping_Table (T2, T1_Len, T2_Len, Seed);
964 Put_Used_Char_Set (Output, "Used Character Set");
965 Put_Int_Matrix (Output, "Function Table 1", T1,
967 Put_Int_Matrix (Output, "Function Table 2", T2,
970 end Generate_Mapping_Tables;
976 function Get_Char_Pos (P : Natural) return Natural is
977 N : constant Natural := Char_Pos_Set + P;
986 function Get_Edges (F : Natural) return Edge_Type is
987 N : constant Natural := Edges + (F * Edge_Size);
991 E.Y := IT.Table (N + 1);
992 E.Key := IT.Table (N + 2);
1000 function Get_Graph (N : Natural) return Integer is
1002 return IT.Table (G + N);
1009 function Get_Key (N : Key_Id) return Key_Type is
1012 K.Edge := IT.Table (Keys + N);
1020 function Get_Table (T : Integer; X, Y : Natural) return Natural is
1021 N : constant Natural := T + (Y * T1_Len) + X;
1023 return IT.Table (N);
1030 function Get_Used_Char (C : Character) return Natural is
1031 N : constant Natural := Used_Char_Set + Character'Pos (C);
1033 return IT.Table (N);
1040 function Get_Vertices (F : Natural) return Vertex_Type is
1041 N : constant Natural := Vertices + (F * Vertex_Size);
1044 V.First := IT.Table (N);
1045 V.Last := IT.Table (N + 1);
1053 function Image (Int : Integer; W : Natural := 0) return String is
1054 B : String (1 .. 32);
1057 procedure Img (V : Natural);
1058 -- Compute image of V into B, starting at B (L), incrementing L
1064 procedure Img (V : Natural) is
1071 B (L) := Character'Val ((V mod 10) + Character'Pos ('0'));
1074 -- Start of processing for Image
1085 return Image (B (1 .. L), W);
1092 function Image (Str : String; W : Natural := 0) return String is
1093 Len : constant Natural := Str'Length;
1094 Max : Natural := Len;
1102 Buf : String (1 .. Max) := (1 .. Max => ' ');
1105 for J in 0 .. Len - 1 loop
1106 Buf (Max - Len + 1 + J) := Str (Str'First + J);
1117 function Initial (K : Key_Id) return Word_Id is
1126 procedure Initialize
1128 K_To_V : Float := Default_K_To_V;
1129 Optim : Optimization := CPU_Time;
1130 Tries : Positive := Default_Tries)
1133 -- Free previous tables (the settings may have changed between two runs)
1137 if K_To_V <= 2.0 then
1138 Put (Output, "K to V ratio cannot be lower than 2.0");
1140 raise Program_Error;
1153 procedure Insert (Value : String) is
1154 Word : Word_Type := Null_Word;
1155 Len : constant Natural := Value'Length;
1158 Word (1 .. Len) := Value (Value'First .. Value'First + Len - 1);
1160 WT.Table (NK) := Word;
1162 NV := Natural (Float (NK) * K2V);
1164 -- Do not accept a value of K2V too close to 2.0 such that once rounded
1165 -- up, NV = 2 * NK because the algorithm would not converge.
1167 if NV <= 2 * NK then
1171 if Max_Key_Len < Len then
1175 if Len < Min_Key_Len then
1184 procedure New_Line (File : File_Descriptor) is
1186 if Write (File, EOL'Address, 1) /= 1 then
1187 raise Program_Error;
1191 ------------------------------
1192 -- Parse_Position_Selection --
1193 ------------------------------
1195 procedure Parse_Position_Selection (Argument : String) is
1196 N : Natural := Argument'First;
1197 L : constant Natural := Argument'Last;
1198 M : constant Natural := Max_Key_Len;
1200 T : array (1 .. M) of Boolean := (others => False);
1202 function Parse_Index return Natural;
1203 -- Parse argument starting at index N to find an index
1209 function Parse_Index return Natural is
1210 C : Character := Argument (N);
1219 if C not in '0' .. '9' then
1220 raise Program_Error with "cannot read position argument";
1223 while C in '0' .. '9' loop
1224 V := V * 10 + (Character'Pos (C) - Character'Pos ('0'));
1233 -- Start of processing for Parse_Position_Selection
1236 -- Empty specification means all the positions
1239 Char_Pos_Set_Len := M;
1240 Char_Pos_Set := Allocate (Char_Pos_Set_Len);
1242 for C in 0 .. Char_Pos_Set_Len - 1 loop
1243 Set_Char_Pos (C, C + 1);
1249 First, Last : Natural;
1252 First := Parse_Index;
1257 if N <= L and then Argument (N) = '-' then
1259 Last := Parse_Index;
1262 -- Include the positions in the selection
1264 for J in First .. Last loop
1271 if Argument (N) /= ',' then
1272 raise Program_Error with "cannot read position argument";
1278 -- Compute position selection length
1281 for J in T'Range loop
1287 -- Fill position selection
1289 Char_Pos_Set_Len := N;
1290 Char_Pos_Set := Allocate (Char_Pos_Set_Len);
1293 for J in T'Range loop
1295 Set_Char_Pos (N, J);
1300 end Parse_Position_Selection;
1306 procedure Produce (Pkg_Name : String := Default_Pkg_Name) is
1307 File : File_Descriptor;
1310 -- For call to Close
1312 function Array_Img (N, T, R1 : String; R2 : String := "") return String;
1313 -- Return string "N : constant array (R1[, R2]) of T;"
1315 function Range_Img (F, L : Natural; T : String := "") return String;
1316 -- Return string "[T range ]F .. L"
1318 function Type_Img (L : Natural) return String;
1319 -- Return the larger unsigned type T such that T'Last < L
1327 R2 : String := "") return String
1333 Add (" : constant array (");
1344 return Line (1 .. Last);
1351 function Range_Img (F, L : Natural; T : String := "") return String is
1352 FI : constant String := Image (F);
1353 FL : constant Natural := FI'Length;
1354 LI : constant String := Image (L);
1355 LL : constant Natural := LI'Length;
1356 TL : constant Natural := T'Length;
1357 RI : String (1 .. TL + 7 + FL + 4 + LL);
1362 RI (Len + 1 .. Len + TL) := T;
1364 RI (Len + 1 .. Len + 7) := " range ";
1368 RI (Len + 1 .. Len + FL) := FI;
1370 RI (Len + 1 .. Len + 4) := " .. ";
1372 RI (Len + 1 .. Len + LL) := LI;
1374 return RI (1 .. Len);
1381 function Type_Img (L : Natural) return String is
1382 S : constant String := Image (Type_Size (L));
1383 U : String := "Unsigned_ ";
1387 for J in S'Range loop
1399 PLen : constant Natural := Pkg_Name'Length;
1400 FName : String (1 .. PLen + 4);
1402 -- Start of processing for Produce
1405 FName (1 .. PLen) := Pkg_Name;
1406 for J in 1 .. PLen loop
1407 if FName (J) in 'A' .. 'Z' then
1408 FName (J) := Character'Val (Character'Pos (FName (J))
1409 - Character'Pos ('A')
1410 + Character'Pos ('a'));
1412 elsif FName (J) = '.' then
1417 FName (PLen + 1 .. PLen + 4) := ".ads";
1419 File := Create_File (FName, Binary);
1421 Put (File, "package ");
1422 Put (File, Pkg_Name);
1425 Put (File, " function Hash (S : String) return Natural;");
1428 Put (File, Pkg_Name);
1431 Close (File, Status);
1437 FName (PLen + 4) := 'b';
1439 File := Create_File (FName, Binary);
1441 Put (File, "with Interfaces; use Interfaces;");
1444 Put (File, "package body ");
1445 Put (File, Pkg_Name);
1450 if Opt = CPU_Time then
1451 Put (File, Array_Img ("C", Type_Img (256), "Character"));
1454 F := Character'Pos (Character'First);
1455 L := Character'Pos (Character'Last);
1457 for J in Character'Range loop
1458 P := Get_Used_Char (J);
1459 Put (File, Image (P), 1, 0, 1, F, L, Character'Pos (J));
1466 L := Char_Pos_Set_Len - 1;
1468 Put (File, Array_Img ("P", "Natural", Range_Img (F, L)));
1471 for J in F .. L loop
1472 Put (File, Image (Get_Char_Pos (J)), 1, 0, 1, F, L, J);
1477 if Opt = CPU_Time then
1480 Array_Img ("T1", Type_Img (NV),
1481 Range_Img (0, T1_Len - 1),
1482 Range_Img (0, T2_Len - 1, Type_Img (256))),
1483 T1, T1_Len, T2_Len);
1488 Array_Img ("T1", Type_Img (NV),
1489 Range_Img (0, T1_Len - 1)),
1495 if Opt = CPU_Time then
1498 Array_Img ("T2", Type_Img (NV),
1499 Range_Img (0, T1_Len - 1),
1500 Range_Img (0, T2_Len - 1, Type_Img (256))),
1501 T2, T1_Len, T2_Len);
1506 Array_Img ("T2", Type_Img (NV),
1507 Range_Img (0, T1_Len - 1)),
1515 Array_Img ("G", Type_Img (NK),
1516 Range_Img (0, G_Len - 1)),
1520 Put (File, " function Hash (S : String) return Natural is");
1522 Put (File, " F : constant Natural := S'First - 1;");
1524 Put (File, " L : constant Natural := S'Length;");
1526 Put (File, " F1, F2 : Natural := 0;");
1529 Put (File, " J : ");
1531 if Opt = CPU_Time then
1532 Put (File, Type_Img (256));
1534 Put (File, "Natural");
1540 Put (File, " begin");
1542 Put (File, " for K in P'Range loop");
1544 Put (File, " exit when L < P (K);");
1546 Put (File, " J := ");
1548 if Opt = CPU_Time then
1551 Put (File, "Character'Pos");
1554 Put (File, " (S (P (K) + F));");
1557 Put (File, " F1 := (F1 + Natural (T1 (K");
1559 if Opt = CPU_Time then
1565 if Opt = Memory_Space then
1569 Put (File, ") mod ");
1570 Put (File, Image (NV));
1574 Put (File, " F2 := (F2 + Natural (T2 (K");
1576 if Opt = CPU_Time then
1582 if Opt = Memory_Space then
1586 Put (File, ") mod ");
1587 Put (File, Image (NV));
1591 Put (File, " end loop;");
1595 " return (Natural (G (F1)) + Natural (G (F2))) mod ");
1597 Put (File, Image (NK));
1600 Put (File, " end Hash;");
1604 Put (File, Pkg_Name);
1607 Close (File, Status);
1618 procedure Put (File : File_Descriptor; Str : String) is
1619 Len : constant Natural := Str'Length;
1621 if Write (File, Str'Address, Len) /= Len then
1622 raise Program_Error;
1631 (F : File_Descriptor;
1640 Len : constant Natural := S'Length;
1643 -- Write current line, followed by LF
1651 Put (F, Line (1 .. Last));
1656 -- Start of processing for Put
1659 if C1 = F1 and then C2 = F2 then
1663 if Last + Len + 3 > Max then
1668 Line (Last + 1 .. Last + 5) := " ";
1672 if C1 = F1 and then C2 = F2 then
1696 Line (Last + 1 .. Last + Len) := S;
1725 procedure Put_Edges (File : File_Descriptor; Title : String) is
1727 F1 : constant Natural := 1;
1728 L1 : constant Natural := Edges_Len - 1;
1729 M : constant Natural := Max / 5;
1735 -- Edges valid range is 1 .. Edge_Len - 1
1737 for J in F1 .. L1 loop
1739 Put (File, Image (J, M), F1, L1, J, 1, 4, 1);
1740 Put (File, Image (E.X, M), F1, L1, J, 1, 4, 2);
1741 Put (File, Image (E.Y, M), F1, L1, J, 1, 4, 3);
1742 Put (File, Image (E.Key, M), F1, L1, J, 1, 4, 4);
1746 ----------------------
1747 -- Put_Initial_Keys --
1748 ----------------------
1750 procedure Put_Initial_Keys (File : File_Descriptor; Title : String) is
1751 F1 : constant Natural := 0;
1752 L1 : constant Natural := NK - 1;
1753 M : constant Natural := Max / 5;
1760 for J in F1 .. L1 loop
1762 Put (File, Image (J, M), F1, L1, J, 1, 3, 1);
1763 Put (File, Image (K.Edge, M), F1, L1, J, 1, 3, 2);
1764 Put (File, WT.Table (Initial (J)), F1, L1, J, 1, 3, 3);
1766 end Put_Initial_Keys;
1768 --------------------
1769 -- Put_Int_Matrix --
1770 --------------------
1772 procedure Put_Int_Matrix
1773 (File : File_Descriptor;
1779 F1 : constant Integer := 0;
1780 L1 : constant Integer := Len_1 - 1;
1781 F2 : constant Integer := 0;
1782 L2 : constant Integer := Len_2 - 1;
1790 for J in F1 .. L1 loop
1791 Ix := IT.Table (Table + J);
1792 Put (File, Image (Ix), 1, 0, 1, F1, L1, J);
1796 for J in F1 .. L1 loop
1797 for K in F2 .. L2 loop
1798 Ix := IT.Table (Table + J + K * Len_1);
1799 Put (File, Image (Ix), F1, L1, J, F2, L2, K);
1805 --------------------
1806 -- Put_Int_Vector --
1807 --------------------
1809 procedure Put_Int_Vector
1810 (File : File_Descriptor;
1815 F2 : constant Natural := 0;
1816 L2 : constant Natural := Length - 1;
1822 for J in F2 .. L2 loop
1823 Put (File, Image (IT.Table (Vector + J)), 1, 0, 1, F2, L2, J);
1827 ----------------------
1828 -- Put_Reduced_Keys --
1829 ----------------------
1831 procedure Put_Reduced_Keys (File : File_Descriptor; Title : String) is
1832 F1 : constant Natural := 0;
1833 L1 : constant Natural := NK - 1;
1834 M : constant Natural := Max / 5;
1841 for J in F1 .. L1 loop
1843 Put (File, Image (J, M), F1, L1, J, 1, 3, 1);
1844 Put (File, Image (K.Edge, M), F1, L1, J, 1, 3, 2);
1845 Put (File, WT.Table (Reduced (J)), F1, L1, J, 1, 3, 3);
1847 end Put_Reduced_Keys;
1849 -----------------------
1850 -- Put_Used_Char_Set --
1851 -----------------------
1853 procedure Put_Used_Char_Set (File : File_Descriptor; Title : String) is
1854 F : constant Natural := Character'Pos (Character'First);
1855 L : constant Natural := Character'Pos (Character'Last);
1861 for J in Character'Range loop
1863 (File, Image (Get_Used_Char (J)), 1, 0, 1, F, L, Character'Pos (J));
1865 end Put_Used_Char_Set;
1867 ----------------------
1868 -- Put_Vertex_Table --
1869 ----------------------
1871 procedure Put_Vertex_Table (File : File_Descriptor; Title : String) is
1872 F1 : constant Natural := 0;
1873 L1 : constant Natural := NV - 1;
1874 M : constant Natural := Max / 4;
1881 for J in F1 .. L1 loop
1882 V := Get_Vertices (J);
1883 Put (File, Image (J, M), F1, L1, J, 1, 3, 1);
1884 Put (File, Image (V.First, M), F1, L1, J, 1, 3, 2);
1885 Put (File, Image (V.Last, M), F1, L1, J, 1, 3, 3);
1887 end Put_Vertex_Table;
1893 procedure Random (Seed : in out Natural) is
1895 -- Park & Miller Standard Minimal using Schrage's algorithm to avoid
1896 -- overflow: Xn+1 = 16807 * Xn mod (2 ** 31 - 1)
1903 R := Seed mod 127773;
1905 X := 16807 * R - 2836 * Q;
1908 Seed := X + 2147483647;
1918 function Reduced (K : Key_Id) return Word_Id is
1923 --------------------------
1924 -- Select_Char_Position --
1925 --------------------------
1927 procedure Select_Char_Position is
1929 type Vertex_Table_Type is array (Natural range <>) of Vertex_Type;
1931 procedure Build_Identical_Keys_Sets
1932 (Table : in out Vertex_Table_Type;
1933 Last : in out Natural;
1935 -- Build a list of keys subsets that are identical with the current
1936 -- position selection plus Pos. Once this routine is called, reduced
1937 -- words are sorted by subsets and each item (First, Last) in Sets
1938 -- defines the range of identical keys.
1939 -- Need comment saying exactly what Last is ???
1941 function Count_Different_Keys
1942 (Table : Vertex_Table_Type;
1944 Pos : Natural) return Natural;
1945 -- For each subset in Sets, count the number of different keys if we add
1946 -- Pos to the current position selection.
1948 Sel_Position : IT.Table_Type (1 .. Max_Key_Len);
1949 Last_Sel_Pos : Natural := 0;
1950 Max_Sel_Pos : Natural := 0;
1952 -------------------------------
1953 -- Build_Identical_Keys_Sets --
1954 -------------------------------
1956 procedure Build_Identical_Keys_Sets
1957 (Table : in out Vertex_Table_Type;
1958 Last : in out Natural;
1961 S : constant Vertex_Table_Type := Table (Table'First .. Last);
1962 C : constant Natural := Pos;
1963 -- Shortcuts (why are these not renames ???)
1967 -- First and last words of a subset
1970 -- GNAT.Heap_Sort assumes that the first array index is 1. Offset
1971 -- defines the translation to operate.
1973 function Lt (L, R : Natural) return Boolean;
1974 procedure Move (From : Natural; To : Natural);
1975 -- Subprograms needed by GNAT.Heap_Sort_G
1981 function Lt (L, R : Natural) return Boolean is
1982 C : constant Natural := Pos;
1988 Left := Reduced (0) - 1;
1989 Right := Offset + R;
1992 Right := Reduced (0) - 1;
1995 Right := Offset + R;
1998 return WT.Table (Left)(C) < WT.Table (Right)(C);
2005 procedure Move (From : Natural; To : Natural) is
2006 Target, Source : Natural;
2010 Source := Reduced (0) - 1;
2011 Target := Offset + To;
2013 Source := Offset + From;
2014 Target := Reduced (0) - 1;
2016 Source := Offset + From;
2017 Target := Offset + To;
2020 WT.Table (Target) := WT.Table (Source);
2023 package Sorting is new GNAT.Heap_Sort_G (Move, Lt);
2025 -- Start of processing for Build_Identical_Key_Sets
2030 -- For each subset in S, extract the new subsets we have by adding C
2031 -- in the position selection.
2033 for J in S'Range loop
2034 if S (J).First = S (J).Last then
2038 Table (Last) := (F, L);
2041 Offset := Reduced (S (J).First) - 1;
2042 Sorting.Sort (S (J).Last - S (J).First + 1);
2046 for N in S (J).First .. S (J).Last loop
2048 -- For the last item, close the last subset
2050 if N = S (J).Last then
2052 Table (Last) := (F, N);
2054 -- Two contiguous words are identical when they have the
2055 -- same Cth character.
2057 elsif WT.Table (Reduced (N))(C) =
2058 WT.Table (Reduced (N + 1))(C)
2062 -- Find a new subset of identical keys. Store the current
2063 -- one and create a new subset.
2067 Table (Last) := (F, L);
2074 end Build_Identical_Keys_Sets;
2076 --------------------------
2077 -- Count_Different_Keys --
2078 --------------------------
2080 function Count_Different_Keys
2081 (Table : Vertex_Table_Type;
2083 Pos : Natural) return Natural
2085 N : array (Character) of Natural;
2090 -- For each subset, count the number of words that are still
2091 -- different when we include Pos in the position selection. Only
2092 -- focus on this position as the other positions already produce
2095 for S in 1 .. Last loop
2097 -- Count the occurrences of the different characters
2100 for K in Table (S).First .. Table (S).Last loop
2101 C := WT.Table (Reduced (K))(Pos);
2105 -- Update the number of different keys. Each character used
2106 -- denotes a different key.
2108 for J in N'Range loop
2116 end Count_Different_Keys;
2118 -- Start of processing for Select_Char_Position
2121 -- Initialize the reduced words set
2123 WT.Set_Last (2 * NK);
2124 for K in 0 .. NK - 1 loop
2125 WT.Table (Reduced (K)) := WT.Table (Initial (K));
2129 Differences : Natural;
2130 Max_Differences : Natural := 0;
2131 Old_Differences : Natural;
2132 Max_Diff_Sel_Pos : Natural := 0; -- init to kill warning
2133 Max_Diff_Sel_Pos_Idx : Natural := 0; -- init to kill warning
2134 Same_Keys_Sets_Table : Vertex_Table_Type (1 .. NK);
2135 Same_Keys_Sets_Last : Natural := 1;
2138 for C in Sel_Position'Range loop
2139 Sel_Position (C) := C;
2142 Same_Keys_Sets_Table (1) := (0, NK - 1);
2145 -- Preserve maximum number of different keys and check later on
2146 -- that this value is strictly incrementing. Otherwise, it means
2147 -- that two keys are strictly identical.
2149 Old_Differences := Max_Differences;
2151 -- The first position should not exceed the minimum key length.
2152 -- Otherwise, we may end up with an empty word once reduced.
2154 if Last_Sel_Pos = 0 then
2155 Max_Sel_Pos := Min_Key_Len;
2157 Max_Sel_Pos := Max_Key_Len;
2160 -- Find which position increases more the number of differences
2162 for J in Last_Sel_Pos + 1 .. Max_Sel_Pos loop
2163 Differences := Count_Different_Keys
2164 (Same_Keys_Sets_Table,
2165 Same_Keys_Sets_Last,
2170 "Selecting position" & Sel_Position (J)'Img &
2171 " results in" & Differences'Img &
2176 if Differences > Max_Differences then
2177 Max_Differences := Differences;
2178 Max_Diff_Sel_Pos := Sel_Position (J);
2179 Max_Diff_Sel_Pos_Idx := J;
2183 if Old_Differences = Max_Differences then
2184 raise Program_Error with "some keys are identical";
2187 -- Insert selected position and sort Sel_Position table
2189 Last_Sel_Pos := Last_Sel_Pos + 1;
2190 Sel_Position (Last_Sel_Pos + 1 .. Max_Diff_Sel_Pos_Idx) :=
2191 Sel_Position (Last_Sel_Pos .. Max_Diff_Sel_Pos_Idx - 1);
2192 Sel_Position (Last_Sel_Pos) := Max_Diff_Sel_Pos;
2194 for P in 1 .. Last_Sel_Pos - 1 loop
2195 if Max_Diff_Sel_Pos < Sel_Position (P) then
2196 Sel_Position (P + 1 .. Last_Sel_Pos) :=
2197 Sel_Position (P .. Last_Sel_Pos - 1);
2198 Sel_Position (P) := Max_Diff_Sel_Pos;
2203 exit when Max_Differences = NK;
2205 Build_Identical_Keys_Sets
2206 (Same_Keys_Sets_Table,
2207 Same_Keys_Sets_Last,
2212 "Selecting position" & Max_Diff_Sel_Pos'Img &
2213 " results in" & Max_Differences'Img &
2218 for J in 1 .. Same_Keys_Sets_Last loop
2220 Same_Keys_Sets_Table (J).First ..
2221 Same_Keys_Sets_Table (J).Last
2223 Put (Output, WT.Table (Reduced (K)));
2233 Char_Pos_Set_Len := Last_Sel_Pos;
2234 Char_Pos_Set := Allocate (Char_Pos_Set_Len);
2236 for C in 1 .. Last_Sel_Pos loop
2237 Set_Char_Pos (C - 1, Sel_Position (C));
2239 end Select_Char_Position;
2241 --------------------------
2242 -- Select_Character_Set --
2243 --------------------------
2245 procedure Select_Character_Set is
2246 Last : Natural := 0;
2247 Used : array (Character) of Boolean := (others => False);
2251 for J in 0 .. NK - 1 loop
2252 for K in 0 .. Char_Pos_Set_Len - 1 loop
2253 Char := WT.Table (Initial (J))(Get_Char_Pos (K));
2254 exit when Char = ASCII.NUL;
2255 Used (Char) := True;
2259 Used_Char_Set_Len := 256;
2260 Used_Char_Set := Allocate (Used_Char_Set_Len);
2262 for J in Used'Range loop
2264 Set_Used_Char (J, Last);
2267 Set_Used_Char (J, 0);
2270 end Select_Character_Set;
2276 procedure Set_Char_Pos (P : Natural; Item : Natural) is
2277 N : constant Natural := Char_Pos_Set + P;
2279 IT.Table (N) := Item;
2286 procedure Set_Edges (F : Natural; Item : Edge_Type) is
2287 N : constant Natural := Edges + (F * Edge_Size);
2289 IT.Table (N) := Item.X;
2290 IT.Table (N + 1) := Item.Y;
2291 IT.Table (N + 2) := Item.Key;
2298 procedure Set_Graph (N : Natural; Item : Integer) is
2300 IT.Table (G + N) := Item;
2307 procedure Set_Key (N : Key_Id; Item : Key_Type) is
2309 IT.Table (Keys + N) := Item.Edge;
2316 procedure Set_Table (T : Integer; X, Y : Natural; Item : Natural) is
2317 N : constant Natural := T + ((Y * T1_Len) + X);
2319 IT.Table (N) := Item;
2326 procedure Set_Used_Char (C : Character; Item : Natural) is
2327 N : constant Natural := Used_Char_Set + Character'Pos (C);
2329 IT.Table (N) := Item;
2336 procedure Set_Vertices (F : Natural; Item : Vertex_Type) is
2337 N : constant Natural := Vertices + (F * Vertex_Size);
2339 IT.Table (N) := Item.First;
2340 IT.Table (N + 1) := Item.Last;
2350 Opt : Optimization) return Natural
2356 if Opt = CPU_Time then
2357 for J in 0 .. T1_Len - 1 loop
2358 exit when Word (J + 1) = ASCII.NUL;
2359 R := Get_Table (Table, J, Get_Used_Char (Word (J + 1)));
2360 S := (S + R) mod NV;
2364 for J in 0 .. T1_Len - 1 loop
2365 exit when Word (J + 1) = ASCII.NUL;
2366 R := Get_Table (Table, J, 0);
2367 S := (S + R * Character'Pos (Word (J + 1))) mod NV;
2378 function Type_Size (L : Natural) return Natural is
2382 elsif L <= 2 ** 16 then
2396 K : Natural := 0) return Natural
2400 when Character_Position =>
2401 return Get_Char_Pos (J);
2403 when Used_Character_Set =>
2404 return Get_Used_Char (Character'Val (J));
2406 when Function_Table_1 =>
2407 return Get_Table (T1, J, K);
2409 when Function_Table_2 =>
2410 return Get_Table (T2, J, K);
2413 return Get_Graph (J);
2418 end GNAT.Perfect_Hash_Generators;