X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fdata%2Fcase.h;h=0bfc62cdce96054fe461043ac2cb44bf39436c03;hb=8830c95bb9e8d72621787866141a27fc22e8c786;hp=10963a6e7bbe8cd211843e5b00e12d4e0f22c228;hpb=43b1296aafe7582e7dbe6c2b6a8b478d7d9b0fcf;p=pspp-builds.git diff --git a/src/data/case.h b/src/data/case.h index 10963a6e..0bfc62cd 100644 --- a/src/data/case.h +++ b/src/data/case.h @@ -1,5 +1,5 @@ /* PSPP - a program for statistical analysis. - Copyright (C) 2004, 2007 Free Software Foundation, Inc. + Copyright (C) 2004, 2007, 2009 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -14,13 +14,15 @@ You should have received a copy of the GNU General Public License along with this program. If not, see . */ -#ifndef HEADER_CASE -#define HEADER_CASE +#ifndef DATA_CASE_H +#define DATA_CASE_H 1 #include #include #include -#include "value.h" +#include +#include +#include struct variable; @@ -29,57 +31,148 @@ struct variable; #define CASENUMBER_MAX LONG_MAX typedef long int casenumber; -/* Opaque structure that represents a case. Use accessor - functions instead of accessing any members directly. Use - case_move() or case_clone() instead of copying. */ +/* Reference-counted case implementation. + + A newly created case has a single owner (the code that created + it), represented by an initial reference count of 1. Other + code that receives the case may keep a virtual copy of it by + calling case_ref, which increments the case's reference count. + When this is done, the case becomes shared between its + original owner and each piece of code that incremented the + reference count. + + A shared case (one whose reference count is greater than 1) + must not be modified, because this would make the case change + in the view of every reference count holder, not just the one + that intended to change the case. Because the purpose of + keeping the reference count is to make a virtual copy of the + case, this is undesirable behavior. The case_unshare function + provides a solution, by making a new, unshared copy of a + shared case. */ struct ccase { - struct case_data *case_data; /* Actual data. */ + struct caseproto *proto; /* Case prototype. */ + size_t ref_cnt; /* Reference count. */ + union value values[1]; /* Values. */ }; -void case_nullify (struct ccase *); -bool case_is_null (const struct ccase *); +struct ccase *case_create (const struct caseproto *) MALLOC_LIKE; +struct ccase *case_try_create (const struct caseproto *) MALLOC_LIKE; +struct ccase *case_clone (const struct ccase *) MALLOC_LIKE; -void case_create (struct ccase *, size_t value_cnt); -void case_clone (struct ccase *, const struct ccase *); -void case_move (struct ccase *, struct ccase *); -void case_destroy (struct ccase *); +static inline struct ccase *case_unshare (struct ccase *) WARN_UNUSED_RESULT; +static inline struct ccase *case_ref (const struct ccase *); +static inline void case_unref (struct ccase *); +static inline bool case_is_shared (const struct ccase *); -size_t case_get_value_cnt (const struct ccase *); +static inline size_t case_get_value_cnt (const struct ccase *); +static inline const struct caseproto *case_get_proto (const struct ccase *); -void case_resize (struct ccase *, size_t new_cnt); -void case_swap (struct ccase *, struct ccase *); +size_t case_get_cost (const struct caseproto *); -bool case_try_create (struct ccase *, size_t value_cnt); -bool case_try_clone (struct ccase *, const struct ccase *); +struct ccase *case_resize (struct ccase *, const struct caseproto *) + WARN_UNUSED_RESULT; +struct ccase *case_unshare_and_resize (struct ccase *, + const struct caseproto *) + WARN_UNUSED_RESULT; + +void case_set_missing (struct ccase *); void case_copy (struct ccase *dst, size_t dst_idx, const struct ccase *src, size_t src_idx, size_t cnt); - void case_copy_out (const struct ccase *, - size_t start_idx, union value *, size_t value_cnt); + size_t start_idx, union value *, size_t n_values); void case_copy_in (struct ccase *, - size_t start_idx, const union value *, size_t value_cnt); + size_t start_idx, const union value *, size_t n_values); const union value *case_data (const struct ccase *, const struct variable *); -double case_num (const struct ccase *, const struct variable *); -const char *case_str (const struct ccase *, const struct variable *); +const union value *case_data_idx (const struct ccase *, size_t idx); union value *case_data_rw (struct ccase *, const struct variable *); +union value *case_data_rw_idx (struct ccase *, size_t idx); -const union value *case_data_idx (const struct ccase *, size_t idx); +double case_num (const struct ccase *, const struct variable *); double case_num_idx (const struct ccase *, size_t idx); -const char *case_str_idx (const struct ccase *, size_t idx); -union value *case_data_rw_idx (struct ccase *, size_t idx); + +const uint8_t *case_str (const struct ccase *, const struct variable *); +const uint8_t *case_str_idx (const struct ccase *, size_t idx); +uint8_t *case_str_rw (struct ccase *, const struct variable *); +uint8_t *case_str_rw_idx (struct ccase *, size_t idx); int case_compare (const struct ccase *, const struct ccase *, - const struct variable *const *, size_t var_cnt); + const struct variable *const *, size_t n_vars); int case_compare_2dict (const struct ccase *, const struct ccase *, const struct variable *const *, const struct variable *const *, - size_t var_cnt); + size_t n_vars); const union value *case_data_all (const struct ccase *); union value *case_data_all_rw (struct ccase *); - -#endif /* case.h */ + +struct ccase *case_unshare__ (struct ccase *); +void case_unref__ (struct ccase *); + +/* If C is a shared case, that is, if it has a reference count + greater than 1, makes a new unshared copy and returns it, + decrementing C's reference count. If C is not shared (its + reference count is 1), returns C. + + This function should be used before attempting to modify any + of the data in a case that might be shared, e.g.: + c = case_unshare (c); // Make sure that C is not shared. + case_data_rw (c, myvar)->f = 1; // Modify data in C. +*/ +static inline struct ccase * +case_unshare (struct ccase *c) +{ + if (case_is_shared (c)) + c = case_unshare__ (c); + return c; +} + +/* Increments case C's reference count and returns C. Afterward, + case C is shared among its reference count holders. */ +static inline struct ccase * +case_ref (const struct ccase *c_) +{ + struct ccase *c = (struct ccase *) c_; + c->ref_cnt++; + return c; +} + +/* Decrements case C's reference count. Frees C if its + reference count drops to 0. + + If C is a null pointer, this function has no effect. */ +static inline void +case_unref (struct ccase *c) +{ + if (c != NULL && !--c->ref_cnt) + case_unref__ (c); +} + +/* Returns true if case C is shared. A case that is shared + cannot be modified directly. Instead, an unshared copy must + first be made with case_unshare(). */ +static inline bool +case_is_shared (const struct ccase *c) +{ + return c->ref_cnt > 1; +} + +/* Returns the number of union values in C. */ +static inline size_t +case_get_value_cnt (const struct ccase *c) +{ + return caseproto_get_n_widths (c->proto); +} + +/* Returns the prototype that describes the format of case C. + The caller must not unref the returned prototype. */ +static inline const struct caseproto * +case_get_proto (const struct ccase *c) +{ + return c->proto; +} + +#endif /* data/case.h */