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remove_empty_columns verb: code only

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John Kerl 2018-12-08 22:09:49 -05:00
parent c07a5a71e2
commit ff657dd37b
4 changed files with 107 additions and 0 deletions
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1
c/cli/mlrcli.c
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@ -66,6 +66,7 @@ static mapper_setup_t* mapper_lookup_table[] = {
&mapper_nothing_setup,
&mapper_put_setup,
&mapper_regularize_setup,
&mapper_remove_empty_columns_setup,
&mapper_rename_setup,
&mapper_reorder_setup,
&mapper_repeat_setup,

1
c/mapping/Makefile.am
View file

@ -25,6 +25,7 @@ libmapping_la_SOURCES= \
mapper_fraction.c \
mapper_put_or_filter.c \
mapper_regularize.c \
mapper_remove_empty_columns.c \
mapper_rename.c \
mapper_reorder.c \
mapper_repeat.c \

104
c/mapping/mapper_remove_empty_columns.c Normal file
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@ -0,0 +1,104 @@
#include <stdio.h>
#include "lib/mlrutil.h"
#include "containers/sllv.h"
#include "containers/lhmsi.h"
#include "mapping/mappers.h"
typedef struct _mapper_remove_empty_columns_state_t {
sllv_t* precords;
lhmsi_t* pnames_with_nonempty_values;
} mapper_remove_empty_columns_state_t;
static void mapper_remove_empty_columns_usage(FILE* o, char* argv0, char* verb);
static mapper_t* mapper_remove_empty_columns_parse_cli(int* pargi, int argc, char** argv,
cli_reader_opts_t* _, cli_writer_opts_t* __);
static mapper_t* mapper_remove_empty_columns_alloc();
static void mapper_remove_empty_columns_free(mapper_t* pmapper, context_t* _);
static sllv_t* mapper_remove_empty_columns_process(lrec_t* pinrec, context_t* pctx, void* pvstate);
// ----------------------------------------------------------------
mapper_setup_t mapper_remove_empty_columns_setup = {
.verb = "remove-empty-columns",
.pusage_func = mapper_remove_empty_columns_usage,
.pparse_func = mapper_remove_empty_columns_parse_cli,
.ignores_input = FALSE,
};
// ----------------------------------------------------------------
static void mapper_remove_empty_columns_usage(FILE* o, char* argv0, char* verb) {
fprintf(o, "Usage: %s %s\n", argv0, verb);
fprintf(o, "Omits fields which are empty on every input row. Non-streaming.\n");
}
static mapper_t* mapper_remove_empty_columns_parse_cli(int* pargi, int argc, char** argv,
cli_reader_opts_t* _, cli_writer_opts_t* __)
{
if ((argc - *pargi) < 1) {
mapper_remove_empty_columns_usage(stderr, argv[0], argv[*pargi]);
return NULL;
}
mapper_t* pmapper = mapper_remove_empty_columns_alloc();
*pargi += 1;
return pmapper;
}
// ----------------------------------------------------------------
static mapper_t* mapper_remove_empty_columns_alloc() {
mapper_t* pmapper = mlr_malloc_or_die(sizeof(mapper_t));
mapper_remove_empty_columns_state_t* pstate = mlr_malloc_or_die(sizeof(mapper_remove_empty_columns_state_t));
pstate->precords = sllv_alloc();
pstate->pnames_with_nonempty_values = lhmsi_alloc();
pmapper->pvstate = pstate;
pmapper->pprocess_func = mapper_remove_empty_columns_process;
pmapper->pfree_func = mapper_remove_empty_columns_free;
return pmapper;
}
static void mapper_remove_empty_columns_free(mapper_t* pmapper, context_t* _) {
mapper_remove_empty_columns_state_t* pstate = pmapper->pvstate;
// Free the container
sllv_free(pstate->precords);
lhmsi_free(pstate->pnames_with_nonempty_values);
free(pstate);
free(pmapper);
}
// ----------------------------------------------------------------
static sllv_t* mapper_remove_empty_columns_process(lrec_t* pinrec, context_t* pctx, void* pvstate) {
mapper_remove_empty_columns_state_t* pstate = pvstate;
if (pinrec != NULL) {
// The caller will free the outrecs
sllv_append(pstate->precords, pinrec);
for (lrece_t* pe = pinrec->phead; pe != NULL; pe = pe->pnext) {
if (pe->value[0] != 0) {
if (!lhmsi_has_key(pstate->pnames_with_nonempty_values, pe->key)) {
lhmsi_put(pstate->pnames_with_nonempty_values, mlr_strdup_or_die(pe->key), 1, FREE_ENTRY_KEY);
}
}
}
return NULL;
}
else {
for (sllve_t* pe = pstate->precords->phead; pe != NULL; pe = pe->pnext) {
lrec_t* prec = pe->pvvalue;
lrece_t* pf = prec->phead;
while (pf != NULL) {
if (lhmsi_has_key(pstate->pnames_with_nonempty_values, pf->key)) {
pf = pf->pnext;
} else {
lrece_t* pnext = pf->pnext;
lrec_unlink_and_free(prec, pf);
pf = pnext;
}
}
}
sllv_append(pstate->precords, NULL);
sllv_t* retval = pstate->precords;
pstate->precords = sllv_alloc();
return retval;
}
}

1
c/mapping/mappers.h
View file

@ -32,6 +32,7 @@ extern mapper_setup_t mapper_nest_setup;
extern mapper_setup_t mapper_nothing_setup;
extern mapper_setup_t mapper_put_setup;
extern mapper_setup_t mapper_regularize_setup;
extern mapper_setup_t mapper_remove_empty_columns_setup;
extern mapper_setup_t mapper_rename_setup;
extern mapper_setup_t mapper_reorder_setup;
extern mapper_setup_t mapper_repeat_setup;