From: Ben Pfaff Date: Thu, 7 Jun 2007 05:36:24 +0000 (+0000) Subject: Add casereaders and casewriters, the basis of the new data processing X-Git-Tag: v0.6.0~445 X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ed88deded6a59254dd55883308c4c20966efc77e;p=pspp-builds.git Add casereaders and casewriters, the basis of the new data processing implementation. A casereader is a uniform interface to reading cases from a data source; a casewriter is a uniform interface to writing cases to a data sink. --- diff --git a/src/data/ChangeLog b/src/data/ChangeLog index 1e723f11..54a53a4d 100644 --- a/src/data/ChangeLog +++ b/src/data/ChangeLog @@ -1,3 +1,30 @@ +2007-06-06 Ben Pfaff + + Add casereaders and casewriters, the basis of the new data processing + implementation. A casereader is a uniform interface to reading cases + from a data source; a casewriter is a uniform interface to writing + cases to a data sink. + + * automake.mk: Add new files. + + * casereader-filter.c: New file. + + * casereader-provider.h: New file. + + * casereader-translator.c: New file. + + * casereader.c: New file. + + * casereader.h: New file. + + * casewriter-provider.h: New file. + + * casewriter-translator.c: New file. + + * casewriter.c: New file. + + * casewriter.h: New file. + 2007-06-06 Ben Pfaff "casewindow" data structure that extends the deque (from libpspp) diff --git a/src/data/automake.mk b/src/data/automake.mk index 9b084692..3f2b503f 100644 --- a/src/data/automake.mk +++ b/src/data/automake.mk @@ -19,8 +19,17 @@ src_data_libdata_a_SOURCES = \ src/data/casefile.c \ src/data/casefile-factory.h \ src/data/casefile-private.h \ + src/data/casereader-filter.c \ + src/data/casereader-provider.h \ + src/data/casereader-translator.c \ + src/data/casereader.c \ + src/data/casereader.h \ src/data/casewindow.c \ src/data/casewindow.h \ + src/data/casewriter-provider.h \ + src/data/casewriter-translator.c \ + src/data/casewriter.c \ + src/data/casewriter.h \ src/data/fastfile.c \ src/data/fastfile.h \ src/data/fastfile-factory.h \ diff --git a/src/data/casereader-filter.c b/src/data/casereader-filter.c new file mode 100644 index 00000000..88d798e3 --- /dev/null +++ b/src/data/casereader-filter.c @@ -0,0 +1,244 @@ +/* PSPP - computes sample statistics. + 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 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. */ + +#include + +#include + +#include + +#include +#include +#include +#include +#include +#include + +#include "xalloc.h" + +#include "gettext.h" +#define _(msgid) gettext (msgid) + +struct casereader_filter + { + struct casereader *subreader; + bool (*include) (const struct ccase *, void *aux); + bool (*destroy) (void *aux); + void *aux; + struct casewriter *exclude; + }; + +static struct casereader_class casereader_filter_class; + +struct casereader * +casereader_create_filter_func (struct casereader *subreader, + bool (*include) (const struct ccase *, + void *aux), + bool (*destroy) (void *aux), + void *aux, + struct casewriter *exclude) +{ + struct casereader_filter *filter = xmalloc (sizeof *filter); + struct casereader *reader; + filter->subreader = casereader_rename (subreader); + filter->include = include; + filter->destroy = destroy; + filter->aux = aux; + filter->exclude = exclude; + reader = casereader_create_sequential ( + NULL, casereader_get_value_cnt (filter->subreader), CASENUMBER_MAX, + &casereader_filter_class, filter); + taint_propagate (casereader_get_taint (filter->subreader), + casereader_get_taint (reader)); + return reader; +} + +static bool +casereader_filter_read (struct casereader *reader UNUSED, void *filter_, + struct ccase *c) + +{ + struct casereader_filter *filter = filter_; + for (;;) + { + if (!casereader_read (filter->subreader, c)) + return false; + else if (filter->include (c, filter->aux)) + return true; + else if (filter->exclude != NULL) + casewriter_write (filter->exclude, c); + else + case_destroy (c); + } +} + +static void +casereader_filter_destroy (struct casereader *reader, void *filter_) +{ + struct casereader_filter *filter = filter_; + casereader_destroy (filter->subreader); + if (filter->destroy != NULL && !filter->destroy (filter->aux)) + casereader_force_error (reader); + free (filter); +} + +static struct casereader_class casereader_filter_class = + { + casereader_filter_read, + casereader_filter_destroy, + + /* We could in fact delegate clone to the subreader, if the + filter function is required to have no memory and if we + added reference counting. But it might be useful to have + filter functions with memory and in any case this would + require a little extra work. */ + NULL, + NULL, + }; + +struct casereader_filter_weight + { + const struct variable *weight_var; + bool *warn_on_invalid; + bool local_warn_on_invalid; + }; + +static bool +casereader_filter_weight_include (const struct ccase *c, void *cfw_) +{ + struct casereader_filter_weight *cfw = cfw_; + double value = case_num (c, cfw->weight_var); + if (value >= 0.0 && !var_is_num_missing (cfw->weight_var, value, MV_ANY)) + return true; + else + { + if (*cfw->warn_on_invalid) + { + msg (SW, _("At least one case in the data read had a weight value " + "that was user-missing, system-missing, zero, or " + "negative. These case(s) were ignored.")); + *cfw->warn_on_invalid = false; + } + return false; + } +} + +static bool +casereader_filter_weight_destroy (void *cfw_) +{ + struct casereader_filter_weight *cfw = cfw_; + free (cfw); + return true; +} + +struct casereader * +casereader_create_filter_weight (struct casereader *reader, + const struct dictionary *dict, + bool *warn_on_invalid, + struct casewriter *exclude) +{ + struct variable *weight_var = dict_get_weight (dict); + if (weight_var != NULL) + { + struct casereader_filter_weight *cfw = xmalloc (sizeof *cfw); + cfw->weight_var = weight_var; + cfw->warn_on_invalid = (warn_on_invalid + ? warn_on_invalid + : &cfw->local_warn_on_invalid); + cfw->local_warn_on_invalid = true; + reader = casereader_create_filter_func (reader, + casereader_filter_weight_include, + casereader_filter_weight_destroy, + cfw, exclude); + } + else + reader = casereader_rename (reader); + return reader; +} + +struct casereader_filter_missing + { + struct variable **vars; + size_t var_cnt; + enum mv_class class; + }; + +static bool +casereader_filter_missing_include (const struct ccase *c, void *cfm_) +{ + const struct casereader_filter_missing *cfm = cfm_; + size_t i; + + for (i = 0; i < cfm->var_cnt; i++) + { + struct variable *var = cfm->vars[i]; + const union value *value = case_data (c, var); + if (var_is_value_missing (var, value, cfm->class)) + return false; + } + return true; +} + +static bool +casereader_filter_missing_destroy (void *cfm_) +{ + struct casereader_filter_missing *cfm = cfm_; + free (cfm->vars); + free (cfm); + return true; +} + +struct casereader * +casereader_create_filter_missing (struct casereader *reader, + struct variable **vars, size_t var_cnt, + enum mv_class class, + struct casewriter *exclude) +{ + if (var_cnt > 0 && class != MV_NEVER) + { + struct casereader_filter_missing *cfm = xmalloc (sizeof *cfm); + cfm->vars = xmemdup (vars, sizeof *vars * var_cnt); + cfm->var_cnt = var_cnt; + cfm->class = class; + return casereader_create_filter_func (reader, + casereader_filter_missing_include, + casereader_filter_missing_destroy, + cfm, + exclude); + } + else + return casereader_rename (reader); +} + + +static bool +casereader_counter_include (const struct ccase *c UNUSED, void *counter_) +{ + casenumber *counter = counter_; + ++*counter; + return true; +} + +struct casereader * +casereader_create_counter (struct casereader *reader, casenumber *counter, + casenumber initial_value) +{ + *counter = initial_value; + return casereader_create_filter_func (reader, casereader_counter_include, + NULL, counter, NULL); +} diff --git a/src/data/casereader-provider.h b/src/data/casereader-provider.h new file mode 100644 index 00000000..2726f683 --- /dev/null +++ b/src/data/casereader-provider.h @@ -0,0 +1,161 @@ +/* PSPP - computes sample statistics. + 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 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. */ + +/* Definitions needed to implement a new type of casereader. + Code that only uses casereaders does not need this header. + + Two functions to create casereaders are supplied: + + - casereader_create_sequential, to create a casereader + for a data source that is naturally sequential. The + casereader layer will automatically, as needed, + simulate the ability to access cases randomly. + + - casereader_create_random, to create a casereader for a + data source that supports random access to cases. (This + function is in fact implemented as a set of wrappers + around casereader_create_sequential.) + + Which function is used has no effect on the set of operations + that may be performed on the resulting casereader, only on how + the casereader is implemented internally. */ + +#ifndef DATA_CASEREADER_PROVIDER_H +#define DATA_CASEREADER_PROVIDER_H 1 + +#include + +/* Casereader class for sequential data sources. */ +struct casereader_class + { + /* Mandatory. + + Reads the next case from READER into case C, which the + casereader must create and which the client is responsible + for destroying. If successful, returns true and advances + READER to the next case, so that the next call to this + function will read the next case. The case just read will + never be read again by a call to this function for READER. + + At end of file or upon an I/O error, returns false. After + false is returned once, this function will not be called + again for the given READER. + + If an I/O error occurs, this function should call + casereader_force_error on READER. */ + bool (*read) (struct casereader *reader, void *aux, struct ccase *c); + + /* Mandatory. + + Destroys READER. + + If an I/O error is detected during destruction, this + function should call casereader_force_error on READER. */ + void (*destroy) (struct casereader *reader, void *aux); + + /* Optional: if convenient and efficiently implementable, + supply this function as an optimization for use by + casereader_clone. (But it might be easier to use the + random-access casereader wrapper instead.) + + Creates and returns a clone of READER. The clone must + read the same case data in the same sequence as READER, + starting from the same position. The only allowable + exception to this rule is that I/O errors may force the + clone or the original casereader to stop reading after + differing numbers of cases. + + The clone should have a clone of READER's taint object, + accomplished by passing casereader_get_taint (READER) to + casereader_create. */ + struct casereader *(*clone) (struct casereader *reader, void *aux); + + /* Optional: if convenient and efficiently implementable, + supply as an optimization for use by casereader_peek. + (But it might be easier to use the random-access + casereader wrapper instead.) + + Reads the case at 0-based offset IDX from the beginning of + READER into case C, which the casereader must create and + which the client is responsible for destroying. + + At end of file or upon an I/O error, returns false. If + this function returns false, then it will never be called + again for an equal or greater value of IDX, and the "read" + member function will never be called to advance as far as + IDX cases further into the casereader. That is, returning + false indicates that the casereader has fewer than IDX + cases left. + + If an I/O error occurs, this function should call + casereader_force_error on READER. */ + bool (*peek) (struct casereader *reader, void *aux, casenumber idx, + struct ccase *c); + }; + +struct casereader * +casereader_create_sequential (const struct taint *, + size_t value_cnt, casenumber case_cnt, + const struct casereader_class *, void *); + +/* Casereader class for random-access data sources. */ +struct casereader_random_class + { + /* Mandatory. + + Reads the case at 0-based offset IDX from the beginning of + READER into case C, which the casereader must create and + which the client is responsible for destroying. + + At end of file or upon an I/O error, returns false. If + this function returns false, then it will never be called + again for an equal or greater value of IDX, and the "read" + member function will never be called to advance as far as + IDX cases further into the casereader. That is, returning + false indicates that the casereader has fewer than IDX + cases. + + If an I/O error occurs, this function should call + casereader_force_error on READER. */ + bool (*read) (struct casereader *reader, void *aux, casenumber idx, + struct ccase *c); + + /* Mandatory. + + Destroys READER. + + If an I/O error is detected during destruction, this + function should call casereader_force_error on READER. */ + void (*destroy) (struct casereader *reader, void *aux); + + /* Mandatory. + + A call to this function tells the callee that the CNT + cases at the beginning of READER will never be read again. + The casereader implementation should free any resources + associated with those cases. After this function returns, + the IDX argument in future calls to the "read" function + will be relative to remaining cases. */ + void (*advance) (struct casereader *reader, void *aux, casenumber cnt); + }; + +struct casereader * +casereader_create_random (size_t value_cnt, casenumber case_cnt, + const struct casereader_random_class *, void *aux); + +#endif /* data/casereader-provider.h */ diff --git a/src/data/casereader-translator.c b/src/data/casereader-translator.c new file mode 100644 index 00000000..f41dbb56 --- /dev/null +++ b/src/data/casereader-translator.c @@ -0,0 +1,96 @@ +/* PSPP - computes sample statistics. + 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 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. */ + +#include + +#include + +#include + +#include +#include + +#include "xalloc.h" + +struct casereader_translator + { + struct casereader *subreader; + + void (*translate) (const struct ccase *input, struct ccase *output, + void *aux); + bool (*destroy) (void *aux); + void *aux; + }; + +static struct casereader_class casereader_translator_class; + +struct casereader * +casereader_create_translator (struct casereader *subreader, + size_t output_value_cnt, + void (*translate) (const struct ccase *input, + struct ccase *output, + void *aux), + bool (*destroy) (void *aux), + void *aux) +{ + struct casereader_translator *ct = xmalloc (sizeof *ct); + struct casereader *reader; + ct->subreader = casereader_rename (subreader); + ct->translate = translate; + ct->destroy = destroy; + ct->aux = aux; + reader = casereader_create_sequential ( + NULL, output_value_cnt, casereader_get_case_cnt (ct->subreader), + &casereader_translator_class, ct); + taint_propagate (casereader_get_taint (ct->subreader), + casereader_get_taint (reader)); + return reader; +} + +static bool +casereader_translator_read (struct casereader *reader UNUSED, + void *ct_, struct ccase *c) +{ + struct casereader_translator *ct = ct_; + struct ccase tmp; + + if (casereader_read (ct->subreader, &tmp)) + { + ct->translate (&tmp, c, ct->aux); + return true; + } + else + return false; +} + +static void +casereader_translator_destroy (struct casereader *reader UNUSED, void *ct_) +{ + struct casereader_translator *ct = ct_; + casereader_destroy (ct->subreader); + ct->destroy (ct->aux); + free (ct); +} + +static struct casereader_class casereader_translator_class = + { + casereader_translator_read, + casereader_translator_destroy, + NULL, + NULL, + }; diff --git a/src/data/casereader.c b/src/data/casereader.c new file mode 100644 index 00000000..da49e032 --- /dev/null +++ b/src/data/casereader.c @@ -0,0 +1,605 @@ +/* PSPP - computes sample statistics. + 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 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. */ + +#include + +#include +#include + +#include + +#include +#include +#include +#include +#include +#include + +#include "xalloc.h" + +/* A casereader. */ +struct casereader + { + struct taint *taint; /* Corrupted? */ + size_t value_cnt; /* Values per case. */ + casenumber case_cnt; /* Number of cases, + CASENUMBER_MAX if unknown. */ + const struct casereader_class *class; /* Class. */ + void *aux; /* Auxiliary data for class. */ + }; + +static void insert_shim (struct casereader *); + +/* Creates a new case in C and reads the next case from READER + into it. The caller owns C and must destroy C when its data + is no longer needed. Return true if successful, false when + cases have been exhausted or upon detection of an I/O error. + In the latter case, C is set to the null case. + + The case returned is effectively consumed: it can never be + read again through READER. If this is inconvenient, READER + may be cloned in advance with casereader_clone, or + casereader_peek may be used instead. */ +bool +casereader_read (struct casereader *reader, struct ccase *c) +{ + if (reader->case_cnt != 0 && reader->class->read (reader, reader->aux, c)) + { + assert (case_get_value_cnt (c) == reader->value_cnt); + if (reader->case_cnt != CASENUMBER_MAX) + reader->case_cnt--; + return true; + } + else + { + 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) +{ + bool ok = true; + if (reader != NULL) + { + reader->class->destroy (reader, reader->aux); + ok = taint_destroy (reader->taint); + free (reader); + } + return ok; +} + +/* Returns a clone of READER. READER and its clone may be used + to read the same sequence of cases in the same order, barring + I/O errors. */ +struct casereader * +casereader_clone (const struct casereader *reader_) +{ + struct casereader *reader = (struct casereader *) reader_; + struct casereader *clone; + + if (reader->class->clone == NULL) + insert_shim (reader); + clone = reader->class->clone (reader, reader->aux); + assert (clone != NULL); + assert (clone != reader); + return clone; +} + +/* Makes a copy of ORIGINAL into *NEW1 (if NEW1 is non-null) and + *NEW2 (if NEW2 is non-null), then destroys ORIGINAL. */ +void +casereader_split (struct casereader *original, + struct casereader **new1, struct casereader **new2) +{ + if (new1 != NULL && new2 != NULL) + { + *new1 = casereader_rename (original); + *new2 = casereader_clone (*new1); + } + else if (new1 != NULL) + *new1 = casereader_rename (original); + else if (new2 != NULL) + *new2 = casereader_rename (original); + else + casereader_destroy (original); +} + +/* Returns a copy of READER, which is itself destroyed. + Useful for taking over ownership of a casereader, to enforce + preventing the original owner from accessing the casereader + again. */ +struct casereader * +casereader_rename (struct casereader *reader) +{ + struct casereader *new = xmemdup (reader, sizeof *reader); + free (reader); + return new; +} + +/* Exchanges the casereaders referred to by A and B. */ +void +casereader_swap (struct casereader *a, struct casereader *b) +{ + if (a != b) + { + struct casereader tmp = *a; + *a = *b; + *b = tmp; + } +} + +/* Creates a new case in C and reads the (IDX + 1)'th case from + READER into it. The caller owns C and must destroy C when its + data is no longer needed. Return true if successful, false + when cases have been exhausted or upon detection of an I/O + error. In the latter case, C is set to the null case. */ +bool +casereader_peek (struct casereader *reader, casenumber idx, struct ccase *c) +{ + if (idx < reader->case_cnt) + { + if (reader->class->peek == NULL) + insert_shim (reader); + if (reader->class->peek (reader, reader->aux, idx, c)) + return true; + else if (casereader_error (reader)) + reader->case_cnt = 0; + } + if (reader->case_cnt > idx) + reader->case_cnt = idx; + case_nullify (c); + return false; +} + +/* Returns true if an I/O error or another hard error has + 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) +{ + return taint_is_tainted (reader->taint); +} + +/* Marks READER as having encountered an error. + + Ordinarily, this function should be called by the + implementation of a casereader, not by the casereader's + client. Instead, casereader clients should usually ensure + that a casereader's error state is correct by using + 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) +{ + 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) +{ + return reader->taint; +} + +/* Returns the number of cases that will be read by successive + calls to casereader_read for READER, assuming that no errors + occur. Upon an error condition, the case count drops to 0, so + that no more cases can be obtained. + + Not all casereaders can predict the number of cases that they + will produce without actually reading all of them. In that + case, this function returns CASENUMBER_MAX. To obtain the + actual number of cases in such a casereader, use + casereader_count_cases. */ +casenumber +casereader_get_case_cnt (struct casereader *reader) +{ + return reader->case_cnt; +} + +/* Returns the number of cases that will be read by successive + calls to casereader_read for READER, assuming that no errors + occur. Upon an error condition, the case count drops to 0, so + that no more cases can be obtained. + + For a casereader that cannot predict the number of cases it + will produce, this function actually reads (and discards) all + of the contents of a clone of READER. Thus, the return value + is always correct in the absence of I/O errors. */ +casenumber +casereader_count_cases (struct casereader *reader) +{ + if (reader->case_cnt == CASENUMBER_MAX) + { + casenumber n_cases = 0; + struct ccase c; + + struct casereader *clone = casereader_clone (reader); + + for (; casereader_read (clone, &c); case_destroy (&c)) + n_cases++; + + casereader_destroy (clone); + reader->case_cnt = n_cases; + } + + return reader->case_cnt; +} + +/* Returns the number of struct values in each case in READER. */ +size_t +casereader_get_value_cnt (struct casereader *reader) +{ + return reader->value_cnt; +} + +/* Copies all the cases in READER to WRITER, propagating errors + appropriately. */ +void +casereader_transfer (struct casereader *reader, struct casewriter *writer) +{ + struct ccase c; + + taint_propagate (casereader_get_taint (reader), + casewriter_get_taint (writer)); + while (casereader_read (reader, &c)) + casewriter_write (writer, &c); + casereader_destroy (reader); +} + +/* Creates and returns a new casereader. This function is + intended for use by casereader implementations, not by + casereader clients. + + This function is most suited for creating a casereader for a + data source that is naturally sequential. + casereader_create_random may be more appropriate for a data + source that supports random access. + + Ordinarily, specify a null pointer for TAINT, in which case + the new casereader will have a new, unique taint object. If + the new casereader should have a clone of an existing taint + object, specify that object as TAINT. (This is most commonly + useful in an implementation of the "clone" casereader_class + function, in which case the cloned casereader should have the + same taint object as the original casereader.) + + VALUE_CNT must be the number of struct values per case read + from the casereader. + + CASE_CNT is an upper limit on the number of cases that + casereader_read will return from the casereader in successive + calls. Ordinarily, this is the actual number of cases in the + data source or CASENUMBER_MAX if the number of cases cannot be + predicted in advance. + + CLASS and AUX are a set of casereader implementation-specific + member functions and auxiliary data to pass to those member + functions, respectively. */ +struct casereader * +casereader_create_sequential (const struct taint *taint, + size_t value_cnt, casenumber case_cnt, + const struct casereader_class *class, void *aux) +{ + struct casereader *reader = xmalloc (sizeof *reader); + reader->taint = taint != NULL ? taint_clone (taint) : taint_create (); + reader->value_cnt = value_cnt; + reader->case_cnt = case_cnt; + reader->class = class; + reader->aux = aux; + return reader; +} + +/* Random-access casereader implementation. + + This is a set of wrappers around casereader_create_sequential + and struct casereader_class to make it easy to create + efficient casereaders for data sources that natively support + random access. */ + +/* One clone of a random reader. */ +struct random_reader + { + struct random_reader_shared *shared; /* Data shared among clones. */ + struct heap_node heap_node; /* Node in shared data's heap of readers. */ + casenumber offset; /* Number of cases already read. */ + }; + +/* 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) +{ + return heap_data (node, struct random_reader, heap_node); +} + +/* Data shared among clones of a random reader. */ +struct random_reader_shared + { + struct heap *readers; /* Heap of struct random_readers. */ + casenumber min_offset; /* Smallest offset of any random_reader. */ + const struct casereader_random_class *class; + void *aux; + }; + +static struct casereader_class random_reader_casereader_class; + +/* Creates and returns a new random_reader with the given SHARED + data and OFFSET. Inserts the new random reader into the + shared heap. */ +static struct random_reader * +make_random_reader (struct random_reader_shared *shared, casenumber offset) +{ + struct random_reader *br = xmalloc (sizeof *br); + br->offset = offset; + br->shared = shared; + heap_insert (shared->readers, &br->heap_node); + return br; +} + +/* Compares random_readers A and B by offset and returns a + strcmp()-like result. */ +static int +compare_random_readers_by_offset (const struct heap_node *a_, + const struct heap_node *b_, + 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_); + return a->offset < b->offset ? -1 : a->offset > b->offset; +} + +/* Creates and returns a new casereader. This function is + intended for use by casereader implementations, not by + casereader clients. + + This function is most suited for creating a casereader for a + data source that supports random access. + casereader_create_sequential is more appropriate for a data + source that is naturally sequential. + + VALUE_CNT must be the number of struct values per case read + from the casereader. + + CASE_CNT is an upper limit on the number of cases that + casereader_read will return from the casereader in successive + calls. Ordinarily, this is the actual number of cases in the + data source or CASENUMBER_MAX if the number of cases cannot be + predicted in advance. + + CLASS and AUX are a set of casereader implementation-specific + member functions and auxiliary data to pass to those member + functions, respectively. */ +struct casereader * +casereader_create_random (size_t value_cnt, casenumber case_cnt, + const struct casereader_random_class *class, + void *aux) +{ + struct random_reader_shared *shared = xmalloc (sizeof *shared); + shared->readers = heap_create (compare_random_readers_by_offset, NULL); + shared->class = class; + shared->aux = aux; + shared->min_offset = 0; + return casereader_create_sequential (NULL, value_cnt, case_cnt, + &random_reader_casereader_class, + make_random_reader (shared, 0)); +} + +/* Reassesses the min_offset in SHARED based on the minimum + offset in the heap. */ +static void +advance_random_reader (struct casereader *reader, + struct random_reader_shared *shared) +{ + casenumber old, new; + + old = shared->min_offset; + new = random_reader_from_heap_node (heap_minimum (shared->readers))->offset; + assert (new >= old); + if (new > old) + { + shared->min_offset = new; + shared->class->advance (reader, shared->aux, new - old); + } +} + +/* struct casereader_class "read" function for random reader. */ +static bool +random_reader_read (struct casereader *reader, void *br_, struct ccase *c) +{ + struct random_reader *br = br_; + struct random_reader_shared *shared = br->shared; + + if (shared->class->read (reader, shared->aux, + br->offset - shared->min_offset, c)) + { + br->offset++; + heap_changed (shared->readers, &br->heap_node); + advance_random_reader (reader, shared); + return true; + } + else + return false; +} + +/* struct casereader_class "destroy" function for random + reader. */ +static void +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)) + { + heap_destroy (shared->readers); + shared->class->destroy (reader, shared->aux); + free (shared); + } + else + advance_random_reader (reader, shared); + + free (br); +} + +/* struct casereader_class "clone" function for random reader. */ +static struct casereader * +random_reader_clone (struct casereader *reader, void *br_) +{ + struct random_reader *br = br_; + struct random_reader_shared *shared = br->shared; + return casereader_create_sequential (casereader_get_taint (reader), + casereader_get_value_cnt (reader), + casereader_get_case_cnt (reader), + &random_reader_casereader_class, + make_random_reader (shared, + br->offset)); +} + +/* struct casereader_class "peek" function for random reader. */ +static bool +random_reader_peek (struct casereader *reader, void *br_, + casenumber idx, struct ccase *c) +{ + struct random_reader *br = br_; + struct random_reader_shared *shared = br->shared; + + return shared->class->read (reader, shared->aux, + br->offset - shared->min_offset + idx, c); +} + +/* Casereader class for random reader. */ +static struct casereader_class random_reader_casereader_class = + { + random_reader_read, + random_reader_destroy, + random_reader_clone, + random_reader_peek, + }; + +/* Buffering shim for implementing clone and peek operations. + + The "clone" and "peek" operations aren't implemented by all + types of casereaders, but we have to expose a uniform + interface anyhow. We do this by interposing a buffering + casereader on top of the existing casereader on the first call + to "clone" or "peek". The buffering casereader maintains a + 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. + + Thus, if all of the casereaders in the clone set are at + approximately the same position, only a few cases are buffered + and there is little inefficiency. If, on the other hand, one + casereader is not used to read any cases at all, but another + one is used to read all of the cases, the entire contents of + the casereader is copied into the buffer. This still might + not be so inefficient, given that case data in memory is + shared across multiple identical copies, but in the worst case + the window implementation will write cases to disk instead of + maintaining them in-memory. */ + +/* A buffering shim for a non-clonable or non-peekable + casereader. */ +struct shim + { + struct casewindow *window; /* Window of buffered cases. */ + struct casereader *subreader; /* Subordinate casereader. */ + }; + +static struct casereader_random_class shim_class; + +/* Interposes a buffering shim atop READER. */ +static void +insert_shim (struct casereader *reader) +{ + size_t value_cnt = casereader_get_value_cnt (reader); + casenumber case_cnt = casereader_get_case_cnt (reader); + struct shim *b = xmalloc (sizeof *b); + b->window = casewindow_create (value_cnt, get_workspace_cases (value_cnt)); + b->subreader = casereader_create_random (value_cnt, case_cnt, + &shim_class, b); + casereader_swap (reader, b->subreader); + taint_propagate (casewindow_get_taint (b->window), + casereader_get_taint (reader)); + taint_propagate (casereader_get_taint (b->subreader), + casereader_get_taint (reader)); +} + +/* Ensures that B's window contains at least CASE_CNT cases. + 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) +{ + while (casewindow_get_case_cnt (b->window) < case_cnt) + { + struct ccase tmp; + if (!casereader_read (b->subreader, &tmp)) + return false; + casewindow_push_head (b->window, &tmp); + } + return true; +} + +/* Reads the case at the given 0-based OFFSET from the front of + the window into C. Returns true if successful, false if + 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) +{ + struct shim *b = b_; + return (prime_buffer (b, offset + 1) + && casewindow_get_case (b->window, offset, c)); +} + +/* Destroys B. */ +static void +shim_destroy (struct casereader *reader UNUSED, void *b_) +{ + struct shim *b = b_; + casewindow_destroy (b->window); + casereader_destroy (b->subreader); + free (b); +} + +/* Discards CNT cases from the front of B's window. */ +static void +shim_advance (struct casereader *reader UNUSED, void *b_, casenumber case_cnt) +{ + struct shim *b = b_; + casewindow_pop_tail (b->window, case_cnt); +} + +/* Class for the buffered reader. */ +static struct casereader_random_class shim_class = + { + shim_read, + shim_destroy, + shim_advance, + }; diff --git a/src/data/casereader.h b/src/data/casereader.h new file mode 100644 index 00000000..bd066a90 --- /dev/null +++ b/src/data/casereader.h @@ -0,0 +1,116 @@ +/* PSPP - computes sample statistics. + 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 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. */ + +/* Casereader client interface. + + A casereader abstracts interfaces through which cases may be + read. A casereader may be a front-end for a system file, a + portable file, the active file in a data set, or anything else + on which a casereader interface has been overlaid. Casereader + layering, in which a casereader acts as a filter or translator + on top of another casereader, is also supported. + + There is no central interface for obtaining casereaders: a + casereader for reading a system file is obtained from the + system file reading module, and so on. Once a casereader has + been obtained, by whatever means, the interface to it is + uniform. The most important functions for casereader usage + are: + + - casereader_read: Reads a case from the casereader. The + case is consumed and cannot be read again. The caller is + responsible for destroying the case. + + - casereader_clone: Makes a copy of a casereader. May be + used to read one or a set of cases from a casereader + repeatedly. + + - casereader_destroy: Destroys a casereader. + + Casereaders can encounter error conditions, such as I/O + errors, as they read cases. Error conditions prevent any more + cases from being read from the casereader. Error conditions + are reported by casereader_error. Error condition may be + propagated to or from a casereader with taint_propagate using + the casereader's taint object, which may be obtained with + casereader_get_taint. */ + +#ifndef DATA_CASEREADER_H +#define DATA_CASEREADER_H 1 + +#include +#include +#include + +struct dictionary; +struct casereader; +struct casewriter; + +bool casereader_read (struct casereader *, struct ccase *); +bool casereader_destroy (struct casereader *); + +struct casereader *casereader_clone (const struct casereader *); +void casereader_split (struct casereader *, + struct casereader **, struct casereader **); +struct casereader *casereader_rename (struct casereader *); +void casereader_swap (struct casereader *, struct casereader *); + +bool casereader_peek (struct casereader *, casenumber, struct ccase *) + WARN_UNUSED_RESULT; + +bool casereader_error (const struct casereader *); +void casereader_force_error (struct casereader *); +const struct taint *casereader_get_taint (const struct casereader *); + +casenumber casereader_get_case_cnt (struct casereader *); +casenumber casereader_count_cases (struct casereader *); +size_t casereader_get_value_cnt (struct casereader *); + +void casereader_transfer (struct casereader *, struct casewriter *); + +struct casereader * +casereader_create_filter_func (struct casereader *, + bool (*include) (const struct ccase *, + void *aux), + bool (*destroy) (void *aux), + void *aux, + struct casewriter *exclude); +struct casereader * +casereader_create_filter_weight (struct casereader *, + const struct dictionary *dict, + bool *warn_on_invalid, + struct casewriter *exclude); +struct casereader * +casereader_create_filter_missing (struct casereader *, + struct variable **vars, size_t var_cnt, + enum mv_class, + struct casewriter *exclude); + +struct casereader * +casereader_create_counter (struct casereader *, casenumber *counter, + casenumber initial_value); + +struct casereader * +casereader_create_translator (struct casereader *, size_t output_value_cnt, + void (*translate) (const struct ccase *input, + struct ccase *output, + void *aux), + bool (*destroy) (void *aux), + void *aux); + +#endif /* data/casereader.h */ diff --git a/src/data/casewriter-provider.h b/src/data/casewriter-provider.h new file mode 100644 index 00000000..1f4fcab6 --- /dev/null +++ b/src/data/casewriter-provider.h @@ -0,0 +1,63 @@ +/* PSPP - computes sample statistics. + Copyright (C) 2006 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 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. */ + +#ifndef DATA_CASEWRITER_PROVIDER_H +#define DATA_CASEWRITER_PROVIDER_H 1 + +#include + +struct casewriter_class + { + /* Mandatory. + + Writes case C to WRITER. Destroys C before returning. + + If an I/O error occurs, this function should call + casewriter_force_error on WRITER. Some I/O error + detection may be deferred to the "destroy" member function + (e.g. writes to disk need not be flushed by "write") . */ + void (*write) (struct casewriter *writer, void *aux, struct ccase *c); + + /* Mandatory. + + Finalizes output and destroys WRITER. + + If an I/O error is detected while finalizing output + (e.g. while flushing output to disk), this function should + call casewriter_force_error on WRITER. */ + void (*destroy) (struct casewriter *writer, void *aux); + + /* Optional: supply if practical and desired by clients. + + Finalizes output to WRITER, destroys WRITER, and in its + place returns a casereader that can be used to read back + the data written to WRITER. WRITER will not be used again + after calling this function, even as an argument to + casewriter_destroy. + + If an I/O error is detected while finalizing output + (e.g. while flushing output to disk), this function should + call casewriter_force_error on WRITER. The caller will + ensure that the error is propagated to the returned + casereader. */ + struct casereader *(*convert_to_reader) (struct casewriter *, void *aux); + }; + +struct casewriter *casewriter_create (const struct casewriter_class *, void *); + +#endif /* data/casewriter-provider.h */ diff --git a/src/data/casewriter-translator.c b/src/data/casewriter-translator.c new file mode 100644 index 00000000..0f47f76b --- /dev/null +++ b/src/data/casewriter-translator.c @@ -0,0 +1,98 @@ +/* PSPP - computes sample statistics. + 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 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. */ + +#include + +#include +#include + +#include + +#include + +#include "xalloc.h" + +struct casewriter_translator + { + struct casewriter *subwriter; + + void (*translate) (const struct ccase *input, struct ccase *output, + void *aux); + bool (*destroy) (void *aux); + void *aux; + }; + +static struct casewriter_class casewriter_translator_class; + +struct casewriter * +casewriter_create_translator (struct casewriter *subwriter, + void (*translate) (const struct ccase *input, + struct ccase *output, + void *aux), + bool (*destroy) (void *aux), + void *aux) +{ + struct casewriter_translator *ct = xmalloc (sizeof *ct); + struct casewriter *writer; + ct->subwriter = casewriter_rename (subwriter); + ct->translate = translate; + ct->destroy = destroy; + ct->aux = aux; + writer = casewriter_create (&casewriter_translator_class, ct); + taint_propagate (casewriter_get_taint (ct->subwriter), + casewriter_get_taint (writer)); + return writer; +} + +static void +casewriter_translator_write (struct casewriter *writer UNUSED, + void *ct_, struct ccase *c) +{ + struct casewriter_translator *ct = ct_; + struct ccase tmp; + + ct->translate (c, &tmp, ct->aux); + casewriter_write (ct->subwriter, &tmp); +} + +static void +casewriter_translator_destroy (struct casewriter *writer UNUSED, void *ct_) +{ + struct casewriter_translator *ct = ct_; + casewriter_destroy (ct->subwriter); + ct->destroy (ct->aux); + free (ct); +} + +static struct casereader * +casewriter_translator_convert_to_reader (struct casewriter *writer UNUSED, + void *ct_) +{ + struct casewriter_translator *ct = ct_; + struct casereader *reader = casewriter_make_reader (ct->subwriter); + free (ct); + ct->destroy (ct->aux); + return reader; +} + +static struct casewriter_class casewriter_translator_class = + { + casewriter_translator_write, + casewriter_translator_destroy, + casewriter_translator_convert_to_reader, + }; diff --git a/src/data/casewriter.c b/src/data/casewriter.c new file mode 100644 index 00000000..e277749c --- /dev/null +++ b/src/data/casewriter.c @@ -0,0 +1,287 @@ +/* PSPP - computes sample statistics. + 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 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. */ + +#include + +#include +#include + +#include +#include + +#include +#include +#include +#include +#include +#include + +#include "xalloc.h" + +/* A casewriter. */ +struct casewriter + { + struct taint *taint; + casenumber case_cnt; + const struct casewriter_class *class; + void *aux; + }; + +static struct casewriter *create_casewriter_window (size_t value_cnt, + casenumber max_in_core); + +/* Writes case C to WRITER. */ +void +casewriter_write (struct casewriter *writer, struct ccase *c) +{ + writer->class->write (writer, writer->aux, c); +} + +/* Destroys WRITER. + Returns true if successful, false if an I/O error was + encountered on WRITER or on some object on which WRITER has a + dependency. */ +bool +casewriter_destroy (struct casewriter *writer) +{ + bool ok = true; + if (writer != NULL) + { + writer->class->destroy (writer, writer->aux); + ok = taint_destroy (writer->taint); + free (writer); + } + return ok; +} + +/* Destroys WRITER and in its place returns a casereader that can + be used to read back the data written to WRITER. WRITER must + not be used again after calling this function, even as an + argument to casewriter_destroy. + + Not all casewriters implement this function. Behavior is + undefined if it is called on one that does not. + + If an I/O error was encountered on WRITER or on some object on + which WRITER has a dependency, then the error will be + propagated to the new casereader. */ +struct casereader * +casewriter_make_reader (struct casewriter *writer) +{ + struct casereader *reader; + reader = writer->class->convert_to_reader (writer, writer->aux); + taint_propagate (writer->taint, casereader_get_taint (reader)); + taint_destroy (writer->taint); + free (writer); + return reader; +} + +/* Returns a copy of WRITER, which is itself destroyed. + Useful for taking over ownership of a casewriter, to enforce + preventing the original owner from accessing the casewriter + again. */ +struct casewriter * +casewriter_rename (struct casewriter *writer) +{ + struct casewriter *new = xmemdup (writer, sizeof *writer); + free (writer); + return new; +} + +/* Returns true if an I/O error or another hard error has + occurred on WRITER, a clone of WRITER, or on some object on + which WRITER's data has a dependency, false otherwise. */ +bool +casewriter_error (const struct casewriter *writer) +{ + return taint_is_tainted (writer->taint); +} + +/* Marks WRITER as having encountered an error. + + Ordinarily, this function should be called by the + implementation of a casewriter, not by the casewriter's + client. Instead, casewriter clients should usually ensure + that a casewriter's error state is correct by using + taint_propagate to propagate to the casewriter's taint + structure, which may be obtained via casewriter_get_taint. */ +void +casewriter_force_error (struct casewriter *writer) +{ + taint_set_taint (writer->taint); +} + +/* Returns WRITER's associate taint object, for use with + taint_propagate and other taint functions. */ +const struct taint * +casewriter_get_taint (const struct casewriter *writer) +{ + return writer->taint; +} + +/* Creates and returns a new casewriter with the given CLASS and + auxiliary data AUX. */ +struct casewriter * +casewriter_create (const struct casewriter_class *class, void *aux) +{ + struct casewriter *writer = xmalloc (sizeof *writer); + writer->taint = taint_create (); + writer->case_cnt = 0; + writer->class = class; + writer->aux = aux; + return writer; +} + +/* Returns a casewriter for cases with VALUE_CNT struct values + per case. The cases written to the casewriter will be kept in + memory, unless the amount of memory used grows too large, in + which case they will be written to disk. + + A casewriter created with this function may be passed to + casewriter_make_reader. + + This is usually the right kind of casewriter to use. */ +struct casewriter * +autopaging_writer_create (size_t value_cnt) +{ + return create_casewriter_window (value_cnt, get_workspace_cases (value_cnt)); +} + +/* Returns a casewriter for cases with VALUE_CNT struct values + per case. The cases written to the casewriter will be kept in + memory. + + A casewriter created with this function may be passed to + casewriter_make_reader. */ +struct casewriter * +mem_writer_create (size_t value_cnt) +{ + return create_casewriter_window (value_cnt, CASENUMBER_MAX); +} + +/* Returns a casewriter for cases with VALUE_CNT struct values + per case. The cases written to the casewriter will be written + to disk. + + A casewriter created with this function may be passed to + casewriter_make_reader. */ +struct casewriter * +tmpfile_writer_create (size_t value_cnt) +{ + return create_casewriter_window (value_cnt, 0); +} + +static const struct casewriter_class casewriter_window_class; +static const struct casereader_random_class casereader_window_class; + +/* Creates and returns a new casewriter based on a casewindow. + Each of the casewriter's cases are composed of VALUE_CNT + struct values. The casewriter's cases will be maintained in + memory until MAX_IN_CORE_CASES have been written, at which + point they will be written to disk. */ +static struct casewriter * +create_casewriter_window (size_t value_cnt, casenumber max_in_core_cases) +{ + struct casewindow *window = casewindow_create (value_cnt, max_in_core_cases); + struct casewriter *writer = casewriter_create (&casewriter_window_class, + window); + taint_propagate (casewindow_get_taint (window), + casewriter_get_taint (writer)); + return writer; +} + +/* Writes case C to casewindow writer WINDOW. */ +static void +casewriter_window_write (struct casewriter *writer UNUSED, void *window_, + struct ccase *c) +{ + struct casewindow *window = window_; + casewindow_push_head (window, c); +} + +/* Destroys casewindow writer WINDOW. */ +static void +casewriter_window_destroy (struct casewriter *writer UNUSED, void *window_) +{ + struct casewindow *window = window_; + casewindow_destroy (window); +} + +/* Converts casewindow writer WINDOW to a casereader and returns + the casereader. */ +static struct casereader * +casewriter_window_convert_to_reader (struct casewriter *writer UNUSED, + void *window_) +{ + struct casewindow *window = window_; + struct casereader *reader; + reader = casereader_create_random (casewindow_get_value_cnt (window), + casewindow_get_case_cnt (window), + &casereader_window_class, window); + taint_propagate (casewindow_get_taint (window), + casereader_get_taint (reader)); + return reader; +} + +/* Reads the case at the given 0-based OFFSET from the front of + WINDOW into C. Returns true if successful, false if + OFFSET is beyond the end of file or upon I/O error. */ +static bool +casereader_window_read (struct casereader *reader UNUSED, void *window_, + casenumber offset, struct ccase *c) +{ + struct casewindow *window = window_; + if (offset >= casewindow_get_case_cnt (window)) + return false; + else + return casewindow_get_case (window, offset, c); +} + +/* Destroys casewindow reader WINDOW. */ +static void +casereader_window_destroy (struct casereader *reader UNUSED, void *window_) +{ + struct casewindow *window = window_; + casewindow_destroy (window); +} + +/* Discards CASE_CNT cases from the front of WINDOW. */ +static void +casereader_window_advance (struct casereader *reader UNUSED, void *window_, + casenumber case_cnt) +{ + struct casewindow *window = window_; + casewindow_pop_tail (window, case_cnt); +} + +/* Class for casewindow writer. */ +static const struct casewriter_class casewriter_window_class = + { + casewriter_window_write, + casewriter_window_destroy, + casewriter_window_convert_to_reader, + }; + +/* Class for casewindow reader. */ +static const struct casereader_random_class casereader_window_class = + { + casereader_window_read, + casereader_window_destroy, + casereader_window_advance, + }; + diff --git a/src/data/casewriter.h b/src/data/casewriter.h new file mode 100644 index 00000000..a1d0807e --- /dev/null +++ b/src/data/casewriter.h @@ -0,0 +1,52 @@ +/* PSPP - computes sample statistics. + 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 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. */ + +#ifndef DATA_CASEWRITER_H +#define DATA_CASEWRITER_H 1 + +#include +#include +#include +#include + +struct casewriter; + +void casewriter_write (struct casewriter *, struct ccase *); +bool casewriter_destroy (struct casewriter *); + +struct casereader *casewriter_make_reader (struct casewriter *); + +struct casewriter *casewriter_rename (struct casewriter *); + +bool casewriter_error (const struct casewriter *); +void casewriter_force_error (struct casewriter *); +const struct taint *casewriter_get_taint (const struct casewriter *); + +struct casewriter *mem_writer_create (size_t value_cnt); +struct casewriter *tmpfile_writer_create (size_t value_cnt); +struct casewriter *autopaging_writer_create (size_t value_cnt); + +struct casewriter * +casewriter_create_translator (struct casewriter *, + void (*translate) (const struct ccase *input, + struct ccase *output, + void *aux), + bool (*destroy) (void *aux), + void *aux); + +#endif /* data/casewriter.h */