diff options
Diffstat (limited to 'gcc/ada/g-pehage.ads')
| -rw-r--r-- | gcc/ada/g-pehage.ads | 32 |
1 files changed, 19 insertions, 13 deletions
diff --git a/gcc/ada/g-pehage.ads b/gcc/ada/g-pehage.ads index b2aea490eed..8b75f2e8803 100644 --- a/gcc/ada/g-pehage.ads +++ b/gcc/ada/g-pehage.ads @@ -6,7 +6,7 @@ -- -- -- S p e c -- -- -- --- Copyright (C) 2002-2005, AdaCore -- +-- Copyright (C) 2002-2008, AdaCore -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- @@ -60,7 +60,7 @@ -- The hash table size corresponds to the exact size of W and *no larger*. -- This represents the "minimal" property. --- The functions generated by this package require the key set to be known in +-- The functions generated by this package require the words to be known in -- advance (they are "static" hash functions). The hash functions are also -- order preserving. If w2 is inserted after w1 in the generator, then (w1) -- < f (w2). These hashing functions are convenient for use with realtime @@ -101,25 +101,31 @@ package GNAT.Perfect_Hash_Generators is Tries : Positive := Default_Tries); -- Initialize the generator and its internal structures. Set the ratio of -- vertices over keys in the random graphs. This value has to be greater - -- than 2.0 in order for the algorithm to succeed. The key set is not + -- than 2.0 in order for the algorithm to succeed. The word set is not -- modified (in particular when it is already set). For instance, it is -- possible to run several times the generator with different settings on - -- the same key set. + -- the same words. + -- + -- A classical way of doing is to Insert all the words and then to invoke + -- Initialize and Compute. If Compute fails to find a perfect hash + -- function, invoke Initialize another time with other configuration + -- parameters (probably with a greater K_To_V ratio). Once successful, + -- invoke Produce and Finalize. procedure Finalize; - -- Deallocate the internal structures and the key table + -- Deallocate the internal structures and the words table procedure Insert (Value : String); - -- Insert a new key in the table + -- Insert a new word in the table Too_Many_Tries : exception; -- Raised after Tries unsuccessful runs procedure Compute (Position : String := Default_Position); -- Compute the hash function. Position allows to define selection of - -- character positions used in the keywords hash function. Positions can be + -- character positions used in the word hash function. Positions can be -- separated by commas and range like x-y may be used. Character '$' - -- represents the final character of a key. With an empty position, the + -- represents the final character of a word. With an empty position, the -- generator automatically produces positions to reduce the memory usage. -- Raise Too_Many_Tries in case that the algorithm does not succeed in less -- than Tries attempts (see Initialize). @@ -144,7 +150,7 @@ package GNAT.Perfect_Hash_Generators is -- F1 and F2 are two functions based on two function tables T1 and T2. -- Their definition depends on the chosen optimization mode. - -- Only some character positions are used in the keys because they are + -- Only some character positions are used in the words because they are -- significant. They are listed in a character position table (P in the -- pseudo-code below). For instance, in {"jan", "feb", "mar", "apr", "jun", -- "jul", "aug", "sep", "oct", "nov", "dec"}, only positions 2 and 3 are @@ -152,7 +158,7 @@ package GNAT.Perfect_Hash_Generators is -- {2, 3} -- When Optimization is CPU_Time, the first dimension of T1 and T2 - -- corresponds to the character position in the key and the second to the + -- corresponds to the character position in the word and the second to the -- character set. As all the character set is not used, we define a used -- character table which associates a distinct index to each used character -- (unused characters are mapped to zero). In this case, the second @@ -177,7 +183,7 @@ package GNAT.Perfect_Hash_Generators is -- end Hash; -- When Optimization is Memory_Space, the first dimension of T1 and T2 - -- corresponds to the character position in the key and the second + -- corresponds to the character position in the word and the second -- dimension is ignored. T1 and T2 are no longer matrices but vectors. -- Therefore, the used character table is not available. The hash function -- has the following form: @@ -213,8 +219,8 @@ package GNAT.Perfect_Hash_Generators is Length_2 : out Natural); -- Return the definition of the table Name. This includes the length of -- dimensions 1 and 2 and the size of an unsigned integer item. When - -- Length_2 is zero, the table has only one dimension. All the ranges start - -- from zero. + -- Length_2 is zero, the table has only one dimension. All the ranges + -- start from zero. function Value (Name : Table_Name; |