-/* PSPP - computes sample statistics.
+/* PSPP - a program for statistical analysis.
Copyright (C) 2007 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 the Free Software Foundation; either version 2 of the
- License, or (at your option) any later version.
+ 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
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
- This program is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software
- Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
- 02110-1301, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
#include "xalloc.h"
/* A casereader. */
-struct casereader
+struct casereader
{
struct taint *taint; /* Corrupted? */
size_t value_cnt; /* Values per case. */
may be cloned in advance with casereader_clone, or
casereader_peek may be used instead. */
bool
-casereader_read (struct casereader *reader, struct ccase *c)
+casereader_read (struct casereader *reader, struct ccase *c)
{
- if (reader->case_cnt != 0 && reader->class->read (reader, reader->aux, c))
+ if (reader->case_cnt != 0)
{
- assert (case_get_value_cnt (c) == reader->value_cnt);
+ /* ->read may use casereader_swap to replace itself by
+ another reader and then delegate to that reader by
+ recursively calling casereader_read. Currently only
+ lazy_casereader does this and, with luck, nothing else
+ ever will.
+
+ To allow this to work, however, we must decrement
+ case_cnt before calling ->read. If we decremented
+ case_cnt after calling ->read, then this would actually
+ drop two cases from case_cnt instead of one, and we'd
+ lose the last case in the casereader. */
if (reader->case_cnt != CASENUMBER_MAX)
reader->case_cnt--;
- return true;
- }
- else
- {
- reader->case_cnt = 0;
- case_nullify (c);
- return false;
+ if (reader->class->read (reader, reader->aux, c))
+ {
+ assert (case_get_value_cnt (c) >= reader->value_cnt);
+ return true;
+ }
}
+ reader->case_cnt = 0;
+ case_nullify (c);
+ return false;
}
/* Destroys READER.
Returns false if an I/O error was detected on READER, true
otherwise. */
bool
-casereader_destroy (struct casereader *reader)
+casereader_destroy (struct casereader *reader)
{
bool ok = true;
- if (reader != NULL)
+ if (reader != NULL)
{
reader->class->destroy (reader, reader->aux);
ok = taint_destroy (reader->taint);
to read the same sequence of cases in the same order, barring
I/O errors. */
struct casereader *
-casereader_clone (const struct casereader *reader_)
+casereader_clone (const struct casereader *reader_)
{
struct casereader *reader = (struct casereader *) reader_;
struct casereader *clone;
+ if ( reader == NULL )
+ return NULL;
if (reader->class->clone == NULL)
insert_shim (reader);
*NEW2 (if NEW2 is non-null), then destroys ORIGINAL. */
void
casereader_split (struct casereader *original,
- struct casereader **new1, struct casereader **new2)
+ struct casereader **new1, struct casereader **new2)
{
- if (new1 != NULL && new2 != NULL)
+ if (new1 != NULL && new2 != NULL)
{
*new1 = casereader_rename (original);
*new2 = casereader_clone (*new1);
preventing the original owner from accessing the casereader
again. */
struct casereader *
-casereader_rename (struct casereader *reader)
+casereader_rename (struct casereader *reader)
{
struct casereader *new = xmemdup (reader, sizeof *reader);
free (reader);
/* Exchanges the casereaders referred to by A and B. */
void
-casereader_swap (struct casereader *a, struct casereader *b)
+casereader_swap (struct casereader *a, struct casereader *b)
{
- if (a != b)
+ if (a != b)
{
struct casereader tmp = *a;
*a = *b;
insert_shim (reader);
if (reader->class->peek (reader, reader->aux, idx, c))
return true;
- else if (casereader_error (reader))
+ else if (casereader_error (reader))
reader->case_cnt = 0;
}
if (reader->case_cnt > idx)
occurred on READER, a clone of READER, or on some object on
which READER's data has a dependency, false otherwise. */
bool
-casereader_error (const struct casereader *reader)
+casereader_error (const struct casereader *reader)
{
return taint_is_tainted (reader->taint);
}
taint_propagate to propagate to the casereader's taint
structure, which may be obtained via casereader_get_taint. */
void
-casereader_force_error (struct casereader *reader)
+casereader_force_error (struct casereader *reader)
{
taint_set_taint (reader->taint);
}
/* Returns READER's associate taint object, for use with
taint_propagate and other taint functions. */
const struct taint *
-casereader_get_taint (const struct casereader *reader)
+casereader_get_taint (const struct casereader *reader)
{
return reader->taint;
}
actual number of cases in such a casereader, use
casereader_count_cases. */
casenumber
-casereader_get_case_cnt (struct casereader *reader)
+casereader_get_case_cnt (struct casereader *reader)
{
return reader->case_cnt;
}
/* Returns the number of struct values in each case in READER. */
size_t
-casereader_get_value_cnt (struct casereader *reader)
+casereader_get_value_cnt (struct casereader *reader)
{
return reader->value_cnt;
}
struct casereader *
casereader_create_sequential (const struct taint *taint,
size_t value_cnt, casenumber case_cnt,
- const struct casereader_class *class, void *aux)
+ const struct casereader_class *class, void *aux)
{
struct casereader *reader = xmalloc (sizeof *reader);
reader->taint = taint != NULL ? taint_clone (taint) : taint_create ();
reader->aux = aux;
return reader;
}
+
+/* If READER is a casereader of the given CLASS, returns its
+ associated auxiliary data; otherwise, returns a null pointer.
+
+ This function is intended for use from casereader
+ implementations, not by casereader users. Even within
+ casereader implementations, its usefulness is quite limited,
+ for at least two reasons. First, every casereader member
+ function already receives a pointer to the casereader's
+ auxiliary data. Second, a casereader's class can change
+ (through a call to casereader_swap) and this is in practice
+ quite common (e.g. any call to casereader_clone on a
+ casereader that does not directly support clone will cause the
+ casereader to be replaced by a shim caseader). */
+void *
+casereader_dynamic_cast (struct casereader *reader,
+ struct casereader_class *class)
+{
+ return reader->class == class ? reader->aux : NULL;
+}
\f
/* Random-access casereader implementation.
/* Returns the random_reader in which the given heap_node is
embedded. */
static struct random_reader *
-random_reader_from_heap_node (const struct heap_node *node)
+random_reader_from_heap_node (const struct heap_node *node)
{
return heap_data (node, struct random_reader, heap_node);
}
/* Data shared among clones of a random reader. */
-struct random_reader_shared
+struct random_reader_shared
{
struct heap *readers; /* Heap of struct random_readers. */
casenumber min_offset; /* Smallest offset of any random_reader. */
static int
compare_random_readers_by_offset (const struct heap_node *a_,
const struct heap_node *b_,
- const void *aux UNUSED)
+ const void *aux UNUSED)
{
const struct random_reader *a = random_reader_from_heap_node (a_);
const struct random_reader *b = random_reader_from_heap_node (b_);
struct casereader *
casereader_create_random (size_t value_cnt, casenumber case_cnt,
const struct casereader_random_class *class,
- void *aux)
+ void *aux)
{
struct random_reader_shared *shared = xmalloc (sizeof *shared);
shared->readers = heap_create (compare_random_readers_by_offset, NULL);
offset in the heap. */
static void
advance_random_reader (struct casereader *reader,
- struct random_reader_shared *shared)
+ struct random_reader_shared *shared)
{
casenumber old, new;
struct random_reader_shared *shared = br->shared;
if (shared->class->read (reader, shared->aux,
- br->offset - shared->min_offset, c))
+ br->offset - shared->min_offset, c))
{
br->offset++;
heap_changed (shared->readers, &br->heap_node);
- advance_random_reader (reader, shared);
+ advance_random_reader (reader, shared);
return true;
}
else
- return false;
+ return false;
}
/* struct casereader_class "destroy" function for random
reader. */
static void
-random_reader_destroy (struct casereader *reader, void *br_)
+random_reader_destroy (struct casereader *reader, void *br_)
{
struct random_reader *br = br_;
struct random_reader_shared *shared = br->shared;
heap_delete (shared->readers, &br->heap_node);
- if (heap_is_empty (shared->readers))
+ if (heap_is_empty (shared->readers))
{
heap_destroy (shared->readers);
shared->class->destroy (reader, shared->aux);
/* struct casereader_class "clone" function for random reader. */
static struct casereader *
-random_reader_clone (struct casereader *reader, void *br_)
+random_reader_clone (struct casereader *reader, void *br_)
{
struct random_reader *br = br_;
struct random_reader_shared *shared = br->shared;
/* struct casereader_class "peek" function for random reader. */
static bool
random_reader_peek (struct casereader *reader, void *br_,
- casenumber idx, struct ccase *c)
+ casenumber idx, struct ccase *c)
{
struct random_reader *br = br_;
struct random_reader_shared *shared = br->shared;
}
/* Casereader class for random reader. */
-static struct casereader_class random_reader_casereader_class =
+static struct casereader_class random_reader_casereader_class =
{
random_reader_read,
random_reader_destroy,
window of cases that spans the positions of the original
casereader and all of its clones (the "clone set"), from the
position of the casereader that has read the fewest cases to
- the position of the casereader that has read the most.
+ the position of the casereader that has read the most.
Thus, if all of the casereaders in the clone set are at
approximately the same position, only a few cases are buffered
/* A buffering shim for a non-clonable or non-peekable
casereader. */
-struct shim
+struct shim
{
struct casewindow *window; /* Window of buffered cases. */
struct casereader *subreader; /* Subordinate casereader. */
/* Interposes a buffering shim atop READER. */
static void
-insert_shim (struct casereader *reader)
+insert_shim (struct casereader *reader)
{
size_t value_cnt = casereader_get_value_cnt (reader);
casenumber case_cnt = casereader_get_case_cnt (reader);
Return true if successful, false upon reaching the end of B's
subreader or an I/O error. */
static bool
-prime_buffer (struct shim *b, casenumber case_cnt)
+prime_buffer (struct shim *b, casenumber case_cnt)
{
- while (casewindow_get_case_cnt (b->window) < case_cnt)
+ while (casewindow_get_case_cnt (b->window) < case_cnt)
{
struct ccase tmp;
if (!casereader_read (b->subreader, &tmp))
OFFSET is beyond the end of file or upon I/O error. */
static bool
shim_read (struct casereader *reader UNUSED, void *b_,
- casenumber offset, struct ccase *c)
+ casenumber offset, struct ccase *c)
{
struct shim *b = b_;
return (prime_buffer (b, offset + 1)
/* Destroys B. */
static void
-shim_destroy (struct casereader *reader UNUSED, void *b_)
+shim_destroy (struct casereader *reader UNUSED, void *b_)
{
struct shim *b = b_;
casewindow_destroy (b->window);
}
/* Class for the buffered reader. */
-static struct casereader_random_class shim_class =
+static struct casereader_random_class shim_class =
{
shim_read,
shim_destroy,