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) 2002-2010, 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;
35 with Ada.Characters.Handling; use Ada.Characters.Handling;
38 with GNAT.Heap_Sort_G;
39 with GNAT.OS_Lib; use GNAT.OS_Lib;
42 package body GNAT.Perfect_Hash_Generators is
44 -- We are using the algorithm of J. Czech as described in Zbigniew J.
45 -- Czech, George Havas, and Bohdan S. Majewski ``An Optimal Algorithm for
46 -- Generating Minimal Perfect Hash Functions'', Information Processing
47 -- Letters, 43(1992) pp.257-264, Oct.1992
49 -- This minimal perfect hash function generator is based on random graphs
50 -- and produces a hash function of the form:
52 -- h (w) = (g (f1 (w)) + g (f2 (w))) mod m
54 -- where f1 and f2 are functions that map strings into integers, and g is
55 -- a function that maps integers into [0, m-1]. h can be order preserving.
56 -- For instance, let W = {w_0, ..., w_i, ..., w_m-1}, h can be defined
57 -- such that h (w_i) = i.
59 -- This algorithm defines two possible constructions of f1 and f2. Method
60 -- b) stores the hash function in less memory space at the expense of
63 -- a) fk (w) = sum (for i in 1 .. length (w)) (Tk (i, w (i))) mod n
65 -- size (Tk) = max (for w in W) (length (w)) * size (used char set)
67 -- b) fk (w) = sum (for i in 1 .. length (w)) (Tk (i) * w (i)) mod n
69 -- size (Tk) = max (for w in W) (length (w)) but the table lookups are
70 -- replaced by multiplications.
72 -- where Tk values are randomly generated. n is defined later on but the
73 -- algorithm recommends to use a value a little bit greater than 2m. Note
74 -- that for large values of m, the main memory space requirements comes
75 -- from the memory space for storing function g (>= 2m entries).
77 -- Random graphs are frequently used to solve difficult problems that do
78 -- not have polynomial solutions. This algorithm is based on a weighted
79 -- undirected graph. It comprises two steps: mapping and assignment.
81 -- In the mapping step, a graph G = (V, E) is constructed, where = {0, 1,
82 -- ..., n-1} and E = {(for w in W) (f1 (w), f2 (w))}. In order for the
83 -- assignment step to be successful, G has to be acyclic. To have a high
84 -- probability of generating an acyclic graph, n >= 2m. If it is not
85 -- acyclic, Tk have to be regenerated.
87 -- In the assignment step, the algorithm builds function g. As G is
88 -- acyclic, there is a vertex v1 with only one neighbor v2. Let w_i be
89 -- the word such that v1 = f1 (w_i) and v2 = f2 (w_i). Let g (v1) = 0 by
90 -- construction and g (v2) = (i - g (v1)) mod n (or h (i) - g (v1) mod n).
91 -- If word w_j is such that v2 = f1 (w_j) and v3 = f2 (w_j), g (v3) = (j -
92 -- g (v2)) mod (or to be general, (h (j) - g (v2)) mod n). If w_i has no
93 -- neighbor, then another vertex is selected. The algorithm traverses G to
94 -- assign values to all the vertices. It cannot assign a value to an
95 -- already assigned vertex as G is acyclic.
97 subtype Word_Id is Integer;
98 subtype Key_Id is Integer;
99 subtype Vertex_Id is Integer;
100 subtype Edge_Id is Integer;
101 subtype Table_Id is Integer;
103 No_Vertex : constant Vertex_Id := -1;
104 No_Edge : constant Edge_Id := -1;
105 No_Table : constant Table_Id := -1;
107 type Word_Type is new String_Access;
108 procedure Free_Word (W : in out Word_Type);
109 function New_Word (S : String) return Word_Type;
111 procedure Resize_Word (W : in out Word_Type; Len : Natural);
112 -- Resize string W to have a length Len
114 type Key_Type is record
117 -- A key corresponds to an edge in the algorithm graph
119 type Vertex_Type is record
123 -- A vertex can be involved in several edges. First and Last are the bounds
124 -- of an array of edges stored in a global edge table.
126 type Edge_Type is record
131 -- An edge is a peer of vertices. In the algorithm, a key is associated to
134 package WT is new GNAT.Table (Word_Type, Word_Id, 0, 32, 32);
135 package IT is new GNAT.Table (Integer, Integer, 0, 32, 32);
136 -- The two main tables. WT is used to store the words in their initial
137 -- version and in their reduced version (that is words reduced to their
138 -- significant characters). As an instance of GNAT.Table, WT does not
139 -- initialize string pointers to null. This initialization has to be done
140 -- manually when the table is allocated. IT is used to store several
141 -- tables of components containing only integers.
143 function Image (Int : Integer; W : Natural := 0) return String;
144 function Image (Str : String; W : Natural := 0) return String;
145 -- Return a string which includes string Str or integer Int preceded by
146 -- leading spaces if required by width W.
148 function Trim_Trailing_Nuls (Str : String) return String;
149 -- Return Str with trailing NUL characters removed
151 Output : File_Descriptor renames GNAT.OS_Lib.Standout;
154 EOL : constant Character := ASCII.LF;
156 Max : constant := 78;
158 Line : String (1 .. Max);
159 -- Use this line to provide buffered IO
161 procedure Add (C : Character);
162 procedure Add (S : String);
163 -- Add a character or a string in Line and update Last
166 (F : File_Descriptor;
174 -- Write string S into file F as a element of an array of one or two
175 -- dimensions. Fk (resp. Lk and Ck) indicates the first (resp last and
176 -- current) index in the k-th dimension. If F1 = L1 the array is considered
177 -- as a one dimension array. This dimension is described by F2 and L2. This
178 -- routine takes care of all the parenthesis, spaces and commas needed to
179 -- format correctly the array. Moreover, the array is well indented and is
180 -- wrapped to fit in a 80 col line. When the line is full, the routine
181 -- writes it into file F. When the array is completed, the routine adds
182 -- semi-colon and writes the line into file F.
184 procedure New_Line (File : File_Descriptor);
185 -- Simulate Ada.Text_IO.New_Line with GNAT.OS_Lib
187 procedure Put (File : File_Descriptor; Str : String);
188 -- Simulate Ada.Text_IO.Put with GNAT.OS_Lib
190 procedure Put_Used_Char_Set (File : File_Descriptor; Title : String);
191 -- Output a title and a used character set
193 procedure Put_Int_Vector
194 (File : File_Descriptor;
198 -- Output a title and a vector
200 procedure Put_Int_Matrix
201 (File : File_Descriptor;
206 -- Output a title and a matrix. When the matrix has only one non-empty
207 -- dimension (Len_2 = 0), output a vector.
209 procedure Put_Edges (File : File_Descriptor; Title : String);
210 -- Output a title and an edge table
212 procedure Put_Initial_Keys (File : File_Descriptor; Title : String);
213 -- Output a title and a key table
215 procedure Put_Reduced_Keys (File : File_Descriptor; Title : String);
216 -- Output a title and a key table
218 procedure Put_Vertex_Table (File : File_Descriptor; Title : String);
219 -- Output a title and a vertex table
221 function Ada_File_Base_Name (Pkg_Name : String) return String;
222 -- Return the base file name (i.e. without .ads/.adb extension) for an
223 -- Ada source file containing the named package, using the standard GNAT
224 -- file-naming convention. For example, if Pkg_Name is "Parent.Child", we
225 -- return "parent-child".
227 ----------------------------------
228 -- Character Position Selection --
229 ----------------------------------
231 -- We reduce the maximum key size by selecting representative positions
232 -- in these keys. We build a matrix with one word per line. We fill the
233 -- remaining space of a line with ASCII.NUL. The heuristic selects the
234 -- position that induces the minimum number of collisions. If there are
235 -- collisions, select another position on the reduced key set responsible
236 -- of the collisions. Apply the heuristic until there is no more collision.
238 procedure Apply_Position_Selection;
239 -- Apply Position selection and build the reduced key table
241 procedure Parse_Position_Selection (Argument : String);
242 -- Parse Argument and compute the position set. Argument is list of
243 -- substrings separated by commas. Each substring represents a position
244 -- or a range of positions (like x-y).
246 procedure Select_Character_Set;
247 -- Define an optimized used character set like Character'Pos in order not
248 -- to allocate tables of 256 entries.
250 procedure Select_Char_Position;
251 -- Find a min char position set in order to reduce the max key length. The
252 -- heuristic selects the position that induces the minimum number of
253 -- collisions. If there are collisions, select another position on the
254 -- reduced key set responsible of the collisions. Apply the heuristic until
255 -- there is no collision.
257 -----------------------------
258 -- Random Graph Generation --
259 -----------------------------
261 procedure Random (Seed : in out Natural);
262 -- Simulate Ada.Discrete_Numerics.Random
264 procedure Generate_Mapping_Table
268 Seed : in out Natural);
269 -- Random generation of the tables below. T is already allocated
271 procedure Generate_Mapping_Tables
273 Seed : in out Natural);
274 -- Generate the mapping tables T1 and T2. They are used to define fk (w) =
275 -- sum (for i in 1 .. length (w)) (Tk (i, w (i))) mod n. Keys, NK and Chars
276 -- are used to compute the matrix size.
278 ---------------------------
279 -- Algorithm Computation --
280 ---------------------------
282 procedure Compute_Edges_And_Vertices (Opt : Optimization);
283 -- Compute the edge and vertex tables. These are empty when a self loop is
284 -- detected (f1 (w) = f2 (w)). The edge table is sorted by X value and then
285 -- Y value. Keys is the key table and NK the number of keys. Chars is the
286 -- set of characters really used in Keys. NV is the number of vertices
287 -- recommended by the algorithm. T1 and T2 are the mapping tables needed to
288 -- compute f1 (w) and f2 (w).
290 function Acyclic return Boolean;
291 -- Return True when the graph is acyclic. Vertices is the current vertex
292 -- table and Edges the current edge table.
294 procedure Assign_Values_To_Vertices;
295 -- Execute the assignment step of the algorithm. Keys is the current key
296 -- table. Vertices and Edges represent the random graph. G is the result of
297 -- the assignment step such that:
298 -- h (w) = (g (f1 (w)) + g (f2 (w))) mod m
303 Opt : Optimization) return Natural;
304 -- For an optimization of CPU_Time return
305 -- fk (w) = sum (for i in 1 .. length (w)) (Tk (i, w (i))) mod n
306 -- For an optimization of Memory_Space return
307 -- fk (w) = sum (for i in 1 .. length (w)) (Tk (i) * w (i)) mod n
310 -------------------------------
311 -- Internal Table Management --
312 -------------------------------
314 function Allocate (N : Natural; S : Natural := 1) return Table_Id;
315 -- Allocate N * S ints from IT table
321 Keys : Table_Id := No_Table;
323 -- NK : Number of Keys
325 function Initial (K : Key_Id) return Word_Id;
326 pragma Inline (Initial);
328 function Reduced (K : Key_Id) return Word_Id;
329 pragma Inline (Reduced);
331 function Get_Key (N : Key_Id) return Key_Type;
332 procedure Set_Key (N : Key_Id; Item : Key_Type);
333 -- Get or Set Nth element of Keys table
339 Char_Pos_Set : Table_Id := No_Table;
340 Char_Pos_Set_Len : Natural;
341 -- Character Selected Position Set
343 function Get_Char_Pos (P : Natural) return Natural;
344 procedure Set_Char_Pos (P : Natural; Item : Natural);
345 -- Get or Set the string position of the Pth selected character
351 Used_Char_Set : Table_Id := No_Table;
352 Used_Char_Set_Len : Natural;
353 -- Used Character Set : Define a new character mapping. When all the
354 -- characters are not present in the keys, in order to reduce the size
355 -- of some tables, we redefine the character mapping.
357 function Get_Used_Char (C : Character) return Natural;
358 procedure Set_Used_Char (C : Character; Item : Natural);
364 T1 : Table_Id := No_Table;
365 T2 : Table_Id := No_Table;
368 -- T1 : Values table to compute F1
369 -- T2 : Values table to compute F2
371 function Get_Table (T : Integer; X, Y : Natural) return Natural;
372 procedure Set_Table (T : Integer; X, Y : Natural; Item : Natural);
378 G : Table_Id := No_Table;
380 -- Values table to compute G
382 NT : Natural := Default_Tries;
383 -- Number of tries running the algorithm before raising an error
385 function Get_Graph (N : Natural) return Integer;
386 procedure Set_Graph (N : Natural; Item : Integer);
387 -- Get or Set Nth element of graph
393 Edge_Size : constant := 3;
394 Edges : Table_Id := No_Table;
396 -- Edges : Edge table of the random graph G
398 function Get_Edges (F : Natural) return Edge_Type;
399 procedure Set_Edges (F : Natural; Item : Edge_Type);
405 Vertex_Size : constant := 2;
407 Vertices : Table_Id := No_Table;
408 -- Vertex table of the random graph G
411 -- Number of Vertices
413 function Get_Vertices (F : Natural) return Vertex_Type;
414 procedure Set_Vertices (F : Natural; Item : Vertex_Type);
415 -- Comments needed ???
418 -- Ratio between Keys and Vertices (parameter of Czech's algorithm)
421 -- Optimization mode (memory vs CPU)
423 Max_Key_Len : Natural := 0;
424 Min_Key_Len : Natural := 0;
425 -- Maximum and minimum of all the word length
430 function Type_Size (L : Natural) return Natural;
431 -- Given the last L of an unsigned integer type T, return its size
437 function Acyclic return Boolean is
438 Marks : array (0 .. NV - 1) of Vertex_Id := (others => No_Vertex);
440 function Traverse (Edge : Edge_Id; Mark : Vertex_Id) return Boolean;
441 -- Propagate Mark from X to Y. X is already marked. Mark Y and propagate
442 -- it to the edges of Y except the one representing the same key. Return
443 -- False when Y is marked with Mark.
449 function Traverse (Edge : Edge_Id; Mark : Vertex_Id) return Boolean is
450 E : constant Edge_Type := Get_Edges (Edge);
451 K : constant Key_Id := E.Key;
452 Y : constant Vertex_Id := E.Y;
453 M : constant Vertex_Id := Marks (E.Y);
460 elsif M = No_Vertex then
462 V := Get_Vertices (Y);
464 for J in V.First .. V.Last loop
466 -- Do not propagate to the edge representing the same key
468 if Get_Edges (J).Key /= K
469 and then not Traverse (J, Mark)
481 -- Start of processing for Acyclic
484 -- Edges valid range is
486 for J in 1 .. Edges_Len - 1 loop
488 Edge := Get_Edges (J);
490 -- Mark X of E when it has not been already done
492 if Marks (Edge.X) = No_Vertex then
493 Marks (Edge.X) := Edge.X;
496 -- Traverse E when this has not already been done
498 if Marks (Edge.Y) = No_Vertex
499 and then not Traverse (J, Edge.X)
508 ------------------------
509 -- Ada_File_Base_Name --
510 ------------------------
512 function Ada_File_Base_Name (Pkg_Name : String) return String is
514 -- Convert to lower case, then replace '.' with '-'
516 return Result : String := To_Lower (Pkg_Name) do
517 for J in Result'Range loop
518 if Result (J) = '.' then
523 end Ada_File_Base_Name;
529 procedure Add (C : Character) is
530 pragma Assert (C /= ASCII.NUL);
532 Line (Last + 1) := C;
540 procedure Add (S : String) is
541 Len : constant Natural := S'Length;
543 for J in S'Range loop
544 pragma Assert (S (J) /= ASCII.NUL);
548 Line (Last + 1 .. Last + Len) := S;
556 function Allocate (N : Natural; S : Natural := 1) return Table_Id is
557 L : constant Integer := IT.Last;
559 IT.Set_Last (L + N * S);
561 -- Initialize, so debugging printouts don't trip over uninitialized
564 for J in L + 1 .. IT.Last loop
571 ------------------------------
572 -- Apply_Position_Selection --
573 ------------------------------
575 procedure Apply_Position_Selection is
577 for J in 0 .. NK - 1 loop
579 IW : constant String := WT.Table (Initial (J)).all;
580 RW : String (1 .. IW'Length) := (others => ASCII.NUL);
581 N : Natural := IW'First - 1;
584 -- Select the characters of Word included in the position
587 for C in 0 .. Char_Pos_Set_Len - 1 loop
588 exit when IW (Get_Char_Pos (C)) = ASCII.NUL;
590 RW (N) := IW (Get_Char_Pos (C));
593 -- Build the new table with the reduced word. Be careful
594 -- to deallocate the old version to avoid memory leaks.
596 Free_Word (WT.Table (Reduced (J)));
597 WT.Table (Reduced (J)) := New_Word (RW);
598 Set_Key (J, (Edge => No_Edge));
601 end Apply_Position_Selection;
603 -------------------------------
604 -- Assign_Values_To_Vertices --
605 -------------------------------
607 procedure Assign_Values_To_Vertices is
610 procedure Assign (X : Vertex_Id);
611 -- Execute assignment on X's neighbors except the vertex that we are
612 -- coming from which is already assigned.
618 procedure Assign (X : Vertex_Id) is
620 V : constant Vertex_Type := Get_Vertices (X);
623 for J in V.First .. V.Last loop
626 if Get_Graph (E.Y) = -1 then
627 Set_Graph (E.Y, (E.Key - Get_Graph (X)) mod NK);
633 -- Start of processing for Assign_Values_To_Vertices
636 -- Value -1 denotes an uninitialized value as it is supposed to
637 -- be in the range 0 .. NK.
641 G := Allocate (G_Len, 1);
644 for J in 0 .. G_Len - 1 loop
648 for K in 0 .. NK - 1 loop
649 X := Get_Edges (Get_Key (K).Edge).X;
651 if Get_Graph (X) = -1 then
657 for J in 0 .. G_Len - 1 loop
658 if Get_Graph (J) = -1 then
664 Put_Int_Vector (Output, "Assign Values To Vertices", G, G_Len);
666 end Assign_Values_To_Vertices;
672 procedure Compute (Position : String := Default_Position) is
673 Success : Boolean := False;
677 raise Program_Error with "keywords set cannot be empty";
681 Put_Initial_Keys (Output, "Initial Key Table");
684 if Position'Length /= 0 then
685 Parse_Position_Selection (Position);
687 Select_Char_Position;
692 (Output, "Char Position Set", Char_Pos_Set, Char_Pos_Set_Len);
695 Apply_Position_Selection;
698 Put_Reduced_Keys (Output, "Reduced Keys Table");
701 Select_Character_Set;
704 Put_Used_Char_Set (Output, "Character Position Table");
707 -- Perform Czech's algorithm
709 for J in 1 .. NT loop
710 Generate_Mapping_Tables (Opt, S);
711 Compute_Edges_And_Vertices (Opt);
713 -- When graph is not empty (no self-loop from previous operation) and
716 if 0 < Edges_Len and then Acyclic then
723 raise Too_Many_Tries;
726 Assign_Values_To_Vertices;
729 --------------------------------
730 -- Compute_Edges_And_Vertices --
731 --------------------------------
733 procedure Compute_Edges_And_Vertices (Opt : Optimization) is
738 Vertex : Vertex_Type;
739 Not_Acyclic : Boolean := False;
741 procedure Move (From : Natural; To : Natural);
742 function Lt (L, R : Natural) return Boolean;
743 -- Subprograms needed for GNAT.Heap_Sort_G
749 function Lt (L, R : Natural) return Boolean is
750 EL : constant Edge_Type := Get_Edges (L);
751 ER : constant Edge_Type := Get_Edges (R);
753 return EL.X < ER.X or else (EL.X = ER.X and then EL.Y < ER.Y);
760 procedure Move (From : Natural; To : Natural) is
762 Set_Edges (To, Get_Edges (From));
765 package Sorting is new GNAT.Heap_Sort_G (Move, Lt);
767 -- Start of processing for Compute_Edges_And_Vertices
770 -- We store edges from 1 to 2 * NK and leave zero alone in order to use
773 Edges_Len := 2 * NK + 1;
775 if Edges = No_Table then
776 Edges := Allocate (Edges_Len, Edge_Size);
779 if Vertices = No_Table then
780 Vertices := Allocate (NV, Vertex_Size);
783 for J in 0 .. NV - 1 loop
784 Set_Vertices (J, (No_Vertex, No_Vertex - 1));
787 -- For each w, X = f1 (w) and Y = f2 (w)
789 for J in 0 .. NK - 1 loop
794 X := Sum (WT.Table (Reduced (J)), T1, Opt);
795 Y := Sum (WT.Table (Reduced (J)), T2, Opt);
797 -- Discard T1 and T2 as soon as we discover a self loop
804 -- We store (X, Y) and (Y, X) to ease assignment step
806 Set_Edges (2 * J + 1, (X, Y, J));
807 Set_Edges (2 * J + 2, (Y, X, J));
810 -- Return an empty graph when self loop detected
817 Put_Edges (Output, "Unsorted Edge Table");
818 Put_Int_Matrix (Output, "Function Table 1", T1,
820 Put_Int_Matrix (Output, "Function Table 2", T2,
824 -- Enforce consistency between edges and keys. Construct Vertices and
825 -- compute the list of neighbors of a vertex First .. Last as Edges
826 -- is sorted by X and then Y. To compute the neighbor list, sort the
829 Sorting.Sort (Edges_Len - 1);
832 Put_Edges (Output, "Sorted Edge Table");
833 Put_Int_Matrix (Output, "Function Table 1", T1,
835 Put_Int_Matrix (Output, "Function Table 2", T2,
839 -- Edges valid range is 1 .. 2 * NK
841 for E in 1 .. Edges_Len - 1 loop
842 Edge := Get_Edges (E);
843 Key := Get_Key (Edge.Key);
845 if Key.Edge = No_Edge then
847 Set_Key (Edge.Key, Key);
850 Vertex := Get_Vertices (Edge.X);
852 if Vertex.First = No_Edge then
857 Set_Vertices (Edge.X, Vertex);
861 Put_Reduced_Keys (Output, "Key Table");
862 Put_Edges (Output, "Edge Table");
863 Put_Vertex_Table (Output, "Vertex Table");
866 end Compute_Edges_And_Vertices;
874 Item_Size : out Natural;
875 Length_1 : out Natural;
876 Length_2 : out Natural)
880 when Character_Position =>
882 Length_1 := Char_Pos_Set_Len;
885 when Used_Character_Set =>
890 when Function_Table_1
891 | Function_Table_2 =>
892 Item_Size := Type_Size (NV);
897 Item_Size := Type_Size (NK);
907 procedure Finalize is
910 Put (Output, "Finalize");
914 -- Deallocate all the WT components (both initial and reduced
915 -- ones) to avoid memory leaks.
917 for W in 0 .. WT.Last loop
918 Free_Word (WT.Table (W));
923 -- Reset all variables for next usage
927 Char_Pos_Set := No_Table;
928 Char_Pos_Set_Len := 0;
930 Used_Char_Set := No_Table;
931 Used_Char_Set_Len := 0;
945 Vertices := No_Table;
957 procedure Free_Word (W : in out Word_Type) is
964 ----------------------------
965 -- Generate_Mapping_Table --
966 ----------------------------
968 procedure Generate_Mapping_Table
972 Seed : in out Natural)
975 for J in 0 .. L1 - 1 loop
976 for K in 0 .. L2 - 1 loop
978 Set_Table (Tab, J, K, Seed mod NV);
981 end Generate_Mapping_Table;
983 -----------------------------
984 -- Generate_Mapping_Tables --
985 -----------------------------
987 procedure Generate_Mapping_Tables
989 Seed : in out Natural)
992 -- If T1 and T2 are already allocated no need to do it twice. Reuse them
993 -- as their size has not changed.
995 if T1 = No_Table and then T2 = No_Table then
997 Used_Char_Last : Natural := 0;
1001 if Opt = CPU_Time then
1002 for P in reverse Character'Range loop
1003 Used_Char := Get_Used_Char (P);
1004 if Used_Char /= 0 then
1005 Used_Char_Last := Used_Char;
1011 T1_Len := Char_Pos_Set_Len;
1012 T2_Len := Used_Char_Last + 1;
1013 T1 := Allocate (T1_Len * T2_Len);
1014 T2 := Allocate (T1_Len * T2_Len);
1018 Generate_Mapping_Table (T1, T1_Len, T2_Len, Seed);
1019 Generate_Mapping_Table (T2, T1_Len, T2_Len, Seed);
1022 Put_Used_Char_Set (Output, "Used Character Set");
1023 Put_Int_Matrix (Output, "Function Table 1", T1,
1025 Put_Int_Matrix (Output, "Function Table 2", T2,
1028 end Generate_Mapping_Tables;
1034 function Get_Char_Pos (P : Natural) return Natural is
1035 N : constant Natural := Char_Pos_Set + P;
1037 return IT.Table (N);
1044 function Get_Edges (F : Natural) return Edge_Type is
1045 N : constant Natural := Edges + (F * Edge_Size);
1048 E.X := IT.Table (N);
1049 E.Y := IT.Table (N + 1);
1050 E.Key := IT.Table (N + 2);
1058 function Get_Graph (N : Natural) return Integer is
1060 return IT.Table (G + N);
1067 function Get_Key (N : Key_Id) return Key_Type is
1070 K.Edge := IT.Table (Keys + N);
1078 function Get_Table (T : Integer; X, Y : Natural) return Natural is
1079 N : constant Natural := T + (Y * T1_Len) + X;
1081 return IT.Table (N);
1088 function Get_Used_Char (C : Character) return Natural is
1089 N : constant Natural := Used_Char_Set + Character'Pos (C);
1091 return IT.Table (N);
1098 function Get_Vertices (F : Natural) return Vertex_Type is
1099 N : constant Natural := Vertices + (F * Vertex_Size);
1102 V.First := IT.Table (N);
1103 V.Last := IT.Table (N + 1);
1111 function Image (Int : Integer; W : Natural := 0) return String is
1112 B : String (1 .. 32);
1115 procedure Img (V : Natural);
1116 -- Compute image of V into B, starting at B (L), incrementing L
1122 procedure Img (V : Natural) is
1129 B (L) := Character'Val ((V mod 10) + Character'Pos ('0'));
1132 -- Start of processing for Image
1143 return Image (B (1 .. L), W);
1150 function Image (Str : String; W : Natural := 0) return String is
1151 Len : constant Natural := Str'Length;
1152 Max : Natural := Len;
1160 Buf : String (1 .. Max) := (1 .. Max => ' ');
1163 for J in 0 .. Len - 1 loop
1164 Buf (Max - Len + 1 + J) := Str (Str'First + J);
1175 function Initial (K : Key_Id) return Word_Id is
1184 procedure Initialize
1186 K_To_V : Float := Default_K_To_V;
1187 Optim : Optimization := Memory_Space;
1188 Tries : Positive := Default_Tries)
1192 Put (Output, "Initialize");
1196 -- Deallocate the part of the table concerning the reduced words.
1197 -- Initial words are already present in the table. We may have reduced
1198 -- words already there because a previous computation failed. We are
1199 -- currently retrying and the reduced words have to be deallocated.
1201 for W in Reduced (0) .. WT.Last loop
1202 Free_Word (WT.Table (W));
1207 -- Initialize of computation variables
1211 Char_Pos_Set := No_Table;
1212 Char_Pos_Set_Len := 0;
1214 Used_Char_Set := No_Table;
1215 Used_Char_Set_Len := 0;
1229 Vertices := No_Table;
1238 raise Program_Error with "K to V ratio cannot be lower than 2.0";
1241 -- Do not accept a value of K2V too close to 2.0 such that once
1242 -- rounded up, NV = 2 * NK because the algorithm would not converge.
1244 NV := Natural (Float (NK) * K2V);
1245 if NV <= 2 * NK then
1249 Keys := Allocate (NK);
1251 -- Resize initial words to have all of them at the same size
1252 -- (so the size of the largest one).
1254 for K in 0 .. NK - 1 loop
1255 Resize_Word (WT.Table (Initial (K)), Max_Key_Len);
1258 -- Allocated the table to store the reduced words. As WT is a
1259 -- GNAT.Table (using C memory management), pointers have to be
1260 -- explicitly initialized to null.
1262 WT.Set_Last (Reduced (NK - 1));
1263 for W in 0 .. NK - 1 loop
1264 WT.Table (Reduced (W)) := null;
1272 procedure Insert (Value : String) is
1273 Len : constant Natural := Value'Length;
1277 Put (Output, "Inserting """ & Value & """");
1281 for J in Value'Range loop
1282 pragma Assert (Value (J) /= ASCII.NUL);
1287 WT.Table (NK) := New_Word (Value);
1290 if Max_Key_Len < Len then
1294 if Min_Key_Len = 0 or else Len < Min_Key_Len then
1303 procedure New_Line (File : File_Descriptor) is
1305 if Write (File, EOL'Address, 1) /= 1 then
1306 raise Program_Error;
1314 function New_Word (S : String) return Word_Type is
1316 return new String'(S);
1319 ------------------------------
1320 -- Parse_Position_Selection --
1321 ------------------------------
1323 procedure Parse_Position_Selection (Argument : String) is
1324 N : Natural := Argument'First;
1325 L : constant Natural := Argument'Last;
1326 M : constant Natural := Max_Key_Len;
1328 T : array (1 .. M) of Boolean := (others => False);
1330 function Parse_Index return Natural;
1331 -- Parse argument starting at index N to find an index
1337 function Parse_Index return Natural is
1338 C : Character := Argument (N);
1347 if C not in '0' .. '9' then
1348 raise Program_Error with "cannot read position argument";
1351 while C in '0' .. '9' loop
1352 V := V * 10 + (Character'Pos (C) - Character'Pos ('0'));
1361 -- Start of processing for Parse_Position_Selection
1364 -- Empty specification means all the positions
1367 Char_Pos_Set_Len := M;
1368 Char_Pos_Set := Allocate (Char_Pos_Set_Len);
1370 for C in 0 .. Char_Pos_Set_Len - 1 loop
1371 Set_Char_Pos (C, C + 1);
1377 First, Last : Natural;
1380 First := Parse_Index;
1385 if N <= L and then Argument (N) = '-' then
1387 Last := Parse_Index;
1390 -- Include the positions in the selection
1392 for J in First .. Last loop
1399 if Argument (N) /= ',' then
1400 raise Program_Error with "cannot read position argument";
1406 -- Compute position selection length
1409 for J in T'Range loop
1415 -- Fill position selection
1417 Char_Pos_Set_Len := N;
1418 Char_Pos_Set := Allocate (Char_Pos_Set_Len);
1421 for J in T'Range loop
1423 Set_Char_Pos (N, J);
1428 end Parse_Position_Selection;
1434 procedure Produce (Pkg_Name : String := Default_Pkg_Name) is
1435 File : File_Descriptor;
1438 -- For call to Close
1440 function Array_Img (N, T, R1 : String; R2 : String := "") return String;
1441 -- Return string "N : constant array (R1[, R2]) of T;"
1443 function Range_Img (F, L : Natural; T : String := "") return String;
1444 -- Return string "[T range ]F .. L"
1446 function Type_Img (L : Natural) return String;
1447 -- Return the larger unsigned type T such that T'Last < L
1455 R2 : String := "") return String
1461 Add (" : constant array (");
1472 return Line (1 .. Last);
1479 function Range_Img (F, L : Natural; T : String := "") return String is
1480 FI : constant String := Image (F);
1481 FL : constant Natural := FI'Length;
1482 LI : constant String := Image (L);
1483 LL : constant Natural := LI'Length;
1484 TL : constant Natural := T'Length;
1485 RI : String (1 .. TL + 7 + FL + 4 + LL);
1490 RI (Len + 1 .. Len + TL) := T;
1492 RI (Len + 1 .. Len + 7) := " range ";
1496 RI (Len + 1 .. Len + FL) := FI;
1498 RI (Len + 1 .. Len + 4) := " .. ";
1500 RI (Len + 1 .. Len + LL) := LI;
1502 return RI (1 .. Len);
1509 function Type_Img (L : Natural) return String is
1510 S : constant String := Image (Type_Size (L));
1511 U : String := "Unsigned_ ";
1515 for J in S'Range loop
1527 FName : String := Ada_File_Base_Name (Pkg_Name) & ".ads";
1528 -- Initially, the name of the spec file; then modified to be the name of
1531 -- Start of processing for Produce
1537 "Producing " & Ada.Directories.Current_Directory & "/" & FName);
1541 File := Create_File (FName, Binary);
1543 if File = Invalid_FD then
1544 raise Program_Error with "cannot create: " & FName;
1547 Put (File, "package ");
1548 Put (File, Pkg_Name);
1551 Put (File, " function Hash (S : String) return Natural;");
1554 Put (File, Pkg_Name);
1557 Close (File, Status);
1563 FName (FName'Last) := 'b'; -- Set to body file name
1565 File := Create_File (FName, Binary);
1567 if File = Invalid_FD then
1568 raise Program_Error with "cannot create: " & FName;
1571 Put (File, "with Interfaces; use Interfaces;");
1574 Put (File, "package body ");
1575 Put (File, Pkg_Name);
1580 if Opt = CPU_Time then
1581 Put (File, Array_Img ("C", Type_Img (256), "Character"));
1584 F := Character'Pos (Character'First);
1585 L := Character'Pos (Character'Last);
1587 for J in Character'Range loop
1588 P := Get_Used_Char (J);
1589 Put (File, Image (P), 1, 0, 1, F, L, Character'Pos (J));
1596 L := Char_Pos_Set_Len - 1;
1598 Put (File, Array_Img ("P", "Natural", Range_Img (F, L)));
1601 for J in F .. L loop
1602 Put (File, Image (Get_Char_Pos (J)), 1, 0, 1, F, L, J);
1611 Array_Img ("T1", Type_Img (NV),
1612 Range_Img (0, T1_Len - 1),
1613 Range_Img (0, T2_Len - 1, Type_Img (256))),
1614 T1, T1_Len, T2_Len);
1616 when Memory_Space =>
1619 Array_Img ("T1", Type_Img (NV),
1620 Range_Img (0, T1_Len - 1)),
1630 Array_Img ("T2", Type_Img (NV),
1631 Range_Img (0, T1_Len - 1),
1632 Range_Img (0, T2_Len - 1, Type_Img (256))),
1633 T2, T1_Len, T2_Len);
1635 when Memory_Space =>
1638 Array_Img ("T2", Type_Img (NV),
1639 Range_Img (0, T1_Len - 1)),
1647 Array_Img ("G", Type_Img (NK),
1648 Range_Img (0, G_Len - 1)),
1652 Put (File, " function Hash (S : String) return Natural is");
1654 Put (File, " F : constant Natural := S'First - 1;");
1656 Put (File, " L : constant Natural := S'Length;");
1658 Put (File, " F1, F2 : Natural := 0;");
1661 Put (File, " J : ");
1665 Put (File, Type_Img (256));
1666 when Memory_Space =>
1667 Put (File, "Natural");
1673 Put (File, " begin");
1675 Put (File, " for K in P'Range loop");
1677 Put (File, " exit when L < P (K);");
1679 Put (File, " J := ");
1684 when Memory_Space =>
1685 Put (File, "Character'Pos");
1688 Put (File, " (S (P (K) + F));");
1691 Put (File, " F1 := (F1 + Natural (T1 (K");
1693 if Opt = CPU_Time then
1699 if Opt = Memory_Space then
1703 Put (File, ") mod ");
1704 Put (File, Image (NV));
1708 Put (File, " F2 := (F2 + Natural (T2 (K");
1710 if Opt = CPU_Time then
1716 if Opt = Memory_Space then
1720 Put (File, ") mod ");
1721 Put (File, Image (NV));
1725 Put (File, " end loop;");
1729 " return (Natural (G (F1)) + Natural (G (F2))) mod ");
1731 Put (File, Image (NK));
1734 Put (File, " end Hash;");
1738 Put (File, Pkg_Name);
1741 Close (File, Status);
1752 procedure Put (File : File_Descriptor; Str : String) is
1753 Len : constant Natural := Str'Length;
1755 for J in Str'Range loop
1756 pragma Assert (Str (J) /= ASCII.NUL);
1760 if Write (File, Str'Address, Len) /= Len then
1761 raise Program_Error;
1770 (F : File_Descriptor;
1779 Len : constant Natural := S'Length;
1782 -- Write current line, followed by LF
1790 Put (F, Line (1 .. Last));
1795 -- Start of processing for Put
1798 if C1 = F1 and then C2 = F2 then
1802 if Last + Len + 3 >= Max then
1810 if C1 = F1 and then C2 = F2 then
1862 procedure Put_Edges (File : File_Descriptor; Title : String) is
1864 F1 : constant Natural := 1;
1865 L1 : constant Natural := Edges_Len - 1;
1866 M : constant Natural := Max / 5;
1872 -- Edges valid range is 1 .. Edge_Len - 1
1874 for J in F1 .. L1 loop
1876 Put (File, Image (J, M), F1, L1, J, 1, 4, 1);
1877 Put (File, Image (E.X, M), F1, L1, J, 1, 4, 2);
1878 Put (File, Image (E.Y, M), F1, L1, J, 1, 4, 3);
1879 Put (File, Image (E.Key, M), F1, L1, J, 1, 4, 4);
1883 ----------------------
1884 -- Put_Initial_Keys --
1885 ----------------------
1887 procedure Put_Initial_Keys (File : File_Descriptor; Title : String) is
1888 F1 : constant Natural := 0;
1889 L1 : constant Natural := NK - 1;
1890 M : constant Natural := Max / 5;
1897 for J in F1 .. L1 loop
1899 Put (File, Image (J, M), F1, L1, J, 1, 3, 1);
1900 Put (File, Image (K.Edge, M), F1, L1, J, 1, 3, 2);
1901 Put (File, Trim_Trailing_Nuls (WT.Table (Initial (J)).all),
1902 F1, L1, J, 1, 3, 3);
1904 end Put_Initial_Keys;
1906 --------------------
1907 -- Put_Int_Matrix --
1908 --------------------
1910 procedure Put_Int_Matrix
1911 (File : File_Descriptor;
1917 F1 : constant Integer := 0;
1918 L1 : constant Integer := Len_1 - 1;
1919 F2 : constant Integer := 0;
1920 L2 : constant Integer := Len_2 - 1;
1928 for J in F1 .. L1 loop
1929 Ix := IT.Table (Table + J);
1930 Put (File, Image (Ix), 1, 0, 1, F1, L1, J);
1934 for J in F1 .. L1 loop
1935 for K in F2 .. L2 loop
1936 Ix := IT.Table (Table + J + K * Len_1);
1937 Put (File, Image (Ix), F1, L1, J, F2, L2, K);
1943 --------------------
1944 -- Put_Int_Vector --
1945 --------------------
1947 procedure Put_Int_Vector
1948 (File : File_Descriptor;
1953 F2 : constant Natural := 0;
1954 L2 : constant Natural := Length - 1;
1960 for J in F2 .. L2 loop
1961 Put (File, Image (IT.Table (Vector + J)), 1, 0, 1, F2, L2, J);
1965 ----------------------
1966 -- Put_Reduced_Keys --
1967 ----------------------
1969 procedure Put_Reduced_Keys (File : File_Descriptor; Title : String) is
1970 F1 : constant Natural := 0;
1971 L1 : constant Natural := NK - 1;
1972 M : constant Natural := Max / 5;
1979 for J in F1 .. L1 loop
1981 Put (File, Image (J, M), F1, L1, J, 1, 3, 1);
1982 Put (File, Image (K.Edge, M), F1, L1, J, 1, 3, 2);
1983 Put (File, Trim_Trailing_Nuls (WT.Table (Reduced (J)).all),
1984 F1, L1, J, 1, 3, 3);
1986 end Put_Reduced_Keys;
1988 -----------------------
1989 -- Put_Used_Char_Set --
1990 -----------------------
1992 procedure Put_Used_Char_Set (File : File_Descriptor; Title : String) is
1993 F : constant Natural := Character'Pos (Character'First);
1994 L : constant Natural := Character'Pos (Character'Last);
2000 for J in Character'Range loop
2002 (File, Image (Get_Used_Char (J)), 1, 0, 1, F, L, Character'Pos (J));
2004 end Put_Used_Char_Set;
2006 ----------------------
2007 -- Put_Vertex_Table --
2008 ----------------------
2010 procedure Put_Vertex_Table (File : File_Descriptor; Title : String) is
2011 F1 : constant Natural := 0;
2012 L1 : constant Natural := NV - 1;
2013 M : constant Natural := Max / 4;
2020 for J in F1 .. L1 loop
2021 V := Get_Vertices (J);
2022 Put (File, Image (J, M), F1, L1, J, 1, 3, 1);
2023 Put (File, Image (V.First, M), F1, L1, J, 1, 3, 2);
2024 Put (File, Image (V.Last, M), F1, L1, J, 1, 3, 3);
2026 end Put_Vertex_Table;
2032 procedure Random (Seed : in out Natural) is
2034 -- Park & Miller Standard Minimal using Schrage's algorithm to avoid
2035 -- overflow: Xn+1 = 16807 * Xn mod (2 ** 31 - 1)
2042 R := Seed mod 127773;
2044 X := 16807 * R - 2836 * Q;
2046 Seed := (if X < 0 then X + 2147483647 else X);
2053 function Reduced (K : Key_Id) return Word_Id is
2062 procedure Resize_Word (W : in out Word_Type; Len : Natural) is
2063 S1 : constant String := W.all;
2064 S2 : String (1 .. Len) := (others => ASCII.NUL);
2065 L : constant Natural := S1'Length;
2074 --------------------------
2075 -- Select_Char_Position --
2076 --------------------------
2078 procedure Select_Char_Position is
2080 type Vertex_Table_Type is array (Natural range <>) of Vertex_Type;
2082 procedure Build_Identical_Keys_Sets
2083 (Table : in out Vertex_Table_Type;
2084 Last : in out Natural;
2086 -- Build a list of keys subsets that are identical with the current
2087 -- position selection plus Pos. Once this routine is called, reduced
2088 -- words are sorted by subsets and each item (First, Last) in Sets
2089 -- defines the range of identical keys.
2090 -- Need comment saying exactly what Last is ???
2092 function Count_Different_Keys
2093 (Table : Vertex_Table_Type;
2095 Pos : Natural) return Natural;
2096 -- For each subset in Sets, count the number of different keys if we add
2097 -- Pos to the current position selection.
2099 Sel_Position : IT.Table_Type (1 .. Max_Key_Len);
2100 Last_Sel_Pos : Natural := 0;
2101 Max_Sel_Pos : Natural := 0;
2103 -------------------------------
2104 -- Build_Identical_Keys_Sets --
2105 -------------------------------
2107 procedure Build_Identical_Keys_Sets
2108 (Table : in out Vertex_Table_Type;
2109 Last : in out Natural;
2112 S : constant Vertex_Table_Type := Table (Table'First .. Last);
2113 C : constant Natural := Pos;
2114 -- Shortcuts (why are these not renames ???)
2118 -- First and last words of a subset
2121 -- GNAT.Heap_Sort assumes that the first array index is 1. Offset
2122 -- defines the translation to operate.
2124 function Lt (L, R : Natural) return Boolean;
2125 procedure Move (From : Natural; To : Natural);
2126 -- Subprograms needed by GNAT.Heap_Sort_G
2132 function Lt (L, R : Natural) return Boolean is
2133 C : constant Natural := Pos;
2140 Right := Offset + R;
2146 Right := Offset + R;
2149 return WT.Table (Left)(C) < WT.Table (Right)(C);
2156 procedure Move (From : Natural; To : Natural) is
2157 Target, Source : Natural;
2162 Target := Offset + To;
2164 Source := Offset + From;
2167 Source := Offset + From;
2168 Target := Offset + To;
2171 WT.Table (Target) := WT.Table (Source);
2172 WT.Table (Source) := null;
2175 package Sorting is new GNAT.Heap_Sort_G (Move, Lt);
2177 -- Start of processing for Build_Identical_Key_Sets
2182 -- For each subset in S, extract the new subsets we have by adding C
2183 -- in the position selection.
2185 for J in S'Range loop
2186 if S (J).First = S (J).Last then
2190 Table (Last) := (F, L);
2193 Offset := Reduced (S (J).First) - 1;
2194 Sorting.Sort (S (J).Last - S (J).First + 1);
2198 for N in S (J).First .. S (J).Last loop
2200 -- For the last item, close the last subset
2202 if N = S (J).Last then
2204 Table (Last) := (F, N);
2206 -- Two contiguous words are identical when they have the
2207 -- same Cth character.
2209 elsif WT.Table (Reduced (N))(C) =
2210 WT.Table (Reduced (N + 1))(C)
2214 -- Find a new subset of identical keys. Store the current
2215 -- one and create a new subset.
2219 Table (Last) := (F, L);
2226 end Build_Identical_Keys_Sets;
2228 --------------------------
2229 -- Count_Different_Keys --
2230 --------------------------
2232 function Count_Different_Keys
2233 (Table : Vertex_Table_Type;
2235 Pos : Natural) return Natural
2237 N : array (Character) of Natural;
2242 -- For each subset, count the number of words that are still
2243 -- different when we include Pos in the position selection. Only
2244 -- focus on this position as the other positions already produce
2247 for S in 1 .. Last loop
2249 -- Count the occurrences of the different characters
2252 for K in Table (S).First .. Table (S).Last loop
2253 C := WT.Table (Reduced (K))(Pos);
2257 -- Update the number of different keys. Each character used
2258 -- denotes a different key.
2260 for J in N'Range loop
2268 end Count_Different_Keys;
2270 -- Start of processing for Select_Char_Position
2273 -- Initialize the reduced words set
2275 for K in 0 .. NK - 1 loop
2276 WT.Table (Reduced (K)) := New_Word (WT.Table (Initial (K)).all);
2280 Differences : Natural;
2281 Max_Differences : Natural := 0;
2282 Old_Differences : Natural;
2283 Max_Diff_Sel_Pos : Natural := 0; -- init to kill warning
2284 Max_Diff_Sel_Pos_Idx : Natural := 0; -- init to kill warning
2285 Same_Keys_Sets_Table : Vertex_Table_Type (1 .. NK);
2286 Same_Keys_Sets_Last : Natural := 1;
2289 for C in Sel_Position'Range loop
2290 Sel_Position (C) := C;
2293 Same_Keys_Sets_Table (1) := (0, NK - 1);
2296 -- Preserve maximum number of different keys and check later on
2297 -- that this value is strictly incrementing. Otherwise, it means
2298 -- that two keys are strictly identical.
2300 Old_Differences := Max_Differences;
2302 -- The first position should not exceed the minimum key length.
2303 -- Otherwise, we may end up with an empty word once reduced.
2306 (if Last_Sel_Pos = 0 then Min_Key_Len else Max_Key_Len);
2308 -- Find which position increases more the number of differences
2310 for J in Last_Sel_Pos + 1 .. Max_Sel_Pos loop
2311 Differences := Count_Different_Keys
2312 (Same_Keys_Sets_Table,
2313 Same_Keys_Sets_Last,
2318 "Selecting position" & Sel_Position (J)'Img &
2319 " results in" & Differences'Img &
2324 if Differences > Max_Differences then
2325 Max_Differences := Differences;
2326 Max_Diff_Sel_Pos := Sel_Position (J);
2327 Max_Diff_Sel_Pos_Idx := J;
2331 if Old_Differences = Max_Differences then
2332 raise Program_Error with "some keys are identical";
2335 -- Insert selected position and sort Sel_Position table
2337 Last_Sel_Pos := Last_Sel_Pos + 1;
2338 Sel_Position (Last_Sel_Pos + 1 .. Max_Diff_Sel_Pos_Idx) :=
2339 Sel_Position (Last_Sel_Pos .. Max_Diff_Sel_Pos_Idx - 1);
2340 Sel_Position (Last_Sel_Pos) := Max_Diff_Sel_Pos;
2342 for P in 1 .. Last_Sel_Pos - 1 loop
2343 if Max_Diff_Sel_Pos < Sel_Position (P) then
2344 Sel_Position (P + 1 .. Last_Sel_Pos) :=
2345 Sel_Position (P .. Last_Sel_Pos - 1);
2346 Sel_Position (P) := Max_Diff_Sel_Pos;
2351 exit when Max_Differences = NK;
2353 Build_Identical_Keys_Sets
2354 (Same_Keys_Sets_Table,
2355 Same_Keys_Sets_Last,
2360 "Selecting position" & Max_Diff_Sel_Pos'Img &
2361 " results in" & Max_Differences'Img &
2366 for J in 1 .. Same_Keys_Sets_Last loop
2368 Same_Keys_Sets_Table (J).First ..
2369 Same_Keys_Sets_Table (J).Last
2372 Trim_Trailing_Nuls (WT.Table (Reduced (K)).all));
2382 Char_Pos_Set_Len := Last_Sel_Pos;
2383 Char_Pos_Set := Allocate (Char_Pos_Set_Len);
2385 for C in 1 .. Last_Sel_Pos loop
2386 Set_Char_Pos (C - 1, Sel_Position (C));
2388 end Select_Char_Position;
2390 --------------------------
2391 -- Select_Character_Set --
2392 --------------------------
2394 procedure Select_Character_Set is
2395 Last : Natural := 0;
2396 Used : array (Character) of Boolean := (others => False);
2400 for J in 0 .. NK - 1 loop
2401 for K in 0 .. Char_Pos_Set_Len - 1 loop
2402 Char := WT.Table (Initial (J))(Get_Char_Pos (K));
2403 exit when Char = ASCII.NUL;
2404 Used (Char) := True;
2408 Used_Char_Set_Len := 256;
2409 Used_Char_Set := Allocate (Used_Char_Set_Len);
2411 for J in Used'Range loop
2413 Set_Used_Char (J, Last);
2416 Set_Used_Char (J, 0);
2419 end Select_Character_Set;
2425 procedure Set_Char_Pos (P : Natural; Item : Natural) is
2426 N : constant Natural := Char_Pos_Set + P;
2428 IT.Table (N) := Item;
2435 procedure Set_Edges (F : Natural; Item : Edge_Type) is
2436 N : constant Natural := Edges + (F * Edge_Size);
2438 IT.Table (N) := Item.X;
2439 IT.Table (N + 1) := Item.Y;
2440 IT.Table (N + 2) := Item.Key;
2447 procedure Set_Graph (N : Natural; Item : Integer) is
2449 IT.Table (G + N) := Item;
2456 procedure Set_Key (N : Key_Id; Item : Key_Type) is
2458 IT.Table (Keys + N) := Item.Edge;
2465 procedure Set_Table (T : Integer; X, Y : Natural; Item : Natural) is
2466 N : constant Natural := T + ((Y * T1_Len) + X);
2468 IT.Table (N) := Item;
2475 procedure Set_Used_Char (C : Character; Item : Natural) is
2476 N : constant Natural := Used_Char_Set + Character'Pos (C);
2478 IT.Table (N) := Item;
2485 procedure Set_Vertices (F : Natural; Item : Vertex_Type) is
2486 N : constant Natural := Vertices + (F * Vertex_Size);
2488 IT.Table (N) := Item.First;
2489 IT.Table (N + 1) := Item.Last;
2499 Opt : Optimization) return Natural
2507 for J in 0 .. T1_Len - 1 loop
2508 exit when Word (J + 1) = ASCII.NUL;
2509 R := Get_Table (Table, J, Get_Used_Char (Word (J + 1)));
2510 S := (S + R) mod NV;
2513 when Memory_Space =>
2514 for J in 0 .. T1_Len - 1 loop
2515 exit when Word (J + 1) = ASCII.NUL;
2516 R := Get_Table (Table, J, 0);
2517 S := (S + R * Character'Pos (Word (J + 1))) mod NV;
2524 ------------------------
2525 -- Trim_Trailing_Nuls --
2526 ------------------------
2528 function Trim_Trailing_Nuls (Str : String) return String is
2530 for J in reverse Str'Range loop
2531 if Str (J) /= ASCII.NUL then
2532 return Str (Str'First .. J);
2537 end Trim_Trailing_Nuls;
2543 function Type_Size (L : Natural) return Natural is
2547 elsif L <= 2 ** 16 then
2561 K : Natural := 0) return Natural
2565 when Character_Position =>
2566 return Get_Char_Pos (J);
2568 when Used_Character_Set =>
2569 return Get_Used_Char (Character'Val (J));
2571 when Function_Table_1 =>
2572 return Get_Table (T1, J, K);
2574 when Function_Table_2 =>
2575 return Get_Table (T2, J, K);
2578 return Get_Graph (J);
2583 end GNAT.Perfect_Hash_Generators;