c/input/lrec_reader_stdio_xtab.c

// ================================================================
// Note: there are multiple process methods with a lot of code duplication.
// This is intentional. Much of Miller's measured processing time is in the
// lrec-reader process methods. This is code which needs to execute on every
// byte of input and even moving a single runtime if-statement into a
// function-pointer assignment at alloc time can have noticeable effects on
// performance (5-10% in some cases).
// ================================================================

#include <stdio.h>
#include <stdlib.h>
#include "cli/comment_handling.h"
#include "lib/mlrutil.h"
#include "input/file_reader_stdio.h"
#include "input/line_readers.h"
#include "input/lrec_readers.h"

typedef struct _lrec_reader_stdio_xtab_state_t {
	char*  ifs;
	char*  ips;
	int    ifslen;
	int    ipslen;
	int    allow_repeat_ips;
	int    do_auto_line_term;
	int    at_eof;
	comment_handling_t comment_handling;
	char*  comment_string;
	size_t line_length;
} lrec_reader_stdio_xtab_state_t;

static void    lrec_reader_stdio_xtab_free(lrec_reader_t* preader);
static void    lrec_reader_stdio_xtab_sof(void* pvstate, void* pvhandle);
static lrec_t* lrec_reader_stdio_xtab_process(void* pvstate, void* pvhandle, context_t* pctx);

// ----------------------------------------------------------------
lrec_reader_t* lrec_reader_stdio_xtab_alloc(char* ifs, char* ips, int allow_repeat_ips,
	comment_handling_t comment_handling, char* comment_string)
{
	lrec_reader_t* plrec_reader = mlr_malloc_or_die(sizeof(lrec_reader_t));

	lrec_reader_stdio_xtab_state_t* pstate = mlr_malloc_or_die(sizeof(lrec_reader_stdio_xtab_state_t));
	pstate->ifs               = ifs;
	pstate->ips               = ips;
	pstate->ifslen            = strlen(ifs);
	pstate->ipslen            = strlen(ips);
	pstate->allow_repeat_ips  = allow_repeat_ips;
	pstate->do_auto_line_term = FALSE;
	pstate->at_eof            = FALSE;
	pstate->comment_handling  = comment_handling;
	pstate->comment_string    = comment_string;
	// This is used to track nominal line length over the file read. Bootstrap with a default length.
	pstate->line_length       = MLR_ALLOC_READ_LINE_INITIAL_SIZE;

	if (streq(ifs, "auto")) {
		pstate->do_auto_line_term = TRUE;
		pstate->ifs = "\n";
		pstate->ifslen = 1;
	}

	plrec_reader->pvstate       = (void*)pstate;
	plrec_reader->popen_func    = file_reader_stdio_vopen;
	plrec_reader->pclose_func   = file_reader_stdio_vclose;
	plrec_reader->pprocess_func = lrec_reader_stdio_xtab_process;
	plrec_reader->psof_func     = lrec_reader_stdio_xtab_sof;
	plrec_reader->pfree_func    = lrec_reader_stdio_xtab_free;

	return plrec_reader;
}

static void lrec_reader_stdio_xtab_free(lrec_reader_t* preader) {
	free(preader->pvstate);
	free(preader);
}

static void lrec_reader_stdio_xtab_sof(void* pvstate, void* pvhandle) {
	lrec_reader_stdio_xtab_state_t* pstate = pvstate;
	pstate->at_eof = FALSE;
}

// ----------------------------------------------------------------
static lrec_t* lrec_reader_stdio_xtab_process(void* pvstate, void* pvhandle, context_t* pctx) {
	FILE* input_stream = pvhandle;
	lrec_reader_stdio_xtab_state_t* pstate = pvstate;

	if (pstate->at_eof)
		return NULL;

	slls_t* pxtab_lines = slls_alloc();

	while (TRUE) {
		char* line = NULL;

		if (pstate->comment_handling == COMMENTS_ARE_DATA) {
			if (pstate->ifslen == 1)
				line = mlr_alloc_read_line_single_delimiter(input_stream, pstate->ifs[0],
					&pstate->line_length, pstate->do_auto_line_term, pctx);
			else
				line = mlr_alloc_read_line_multiple_delimiter(input_stream, pstate->ifs, pstate->ifslen,
					&pstate->line_length);
		} else {
			if (pstate->ifslen == 1)
				line = mlr_alloc_read_line_single_delimiter_stripping_comments(input_stream, pstate->ifs[0],
					&pstate->line_length, pstate->do_auto_line_term,
					pstate->comment_handling, pstate->comment_string, pctx);
			else
				line = mlr_alloc_read_line_multiple_delimiter_stripping_comments(input_stream,
					pstate->ifs, pstate->ifslen, &pstate->line_length,
					pstate->comment_handling, pstate->comment_string);
		}

		if (line == NULL) { // EOF
			// EOF or blank line terminates the stanza.
			pstate->at_eof = TRUE;
			if (pxtab_lines->length == 0) {
				slls_free(pxtab_lines);
				return NULL;
			} else {
				return (pstate->ipslen == 1)
					? lrec_parse_stdio_xtab_single_ips(pxtab_lines, pstate->ips[0], pstate->allow_repeat_ips)
					: lrec_parse_stdio_xtab_multi_ips(pxtab_lines, pstate->ips, pstate->ipslen,
						pstate->allow_repeat_ips);
			}

		} else if (*line == '\0') {
			free(line);
			if (pxtab_lines->length > 0) {
				return (pstate->ipslen == 1)
					? lrec_parse_stdio_xtab_single_ips(pxtab_lines, pstate->ips[0], pstate->allow_repeat_ips)
					: lrec_parse_stdio_xtab_multi_ips(pxtab_lines, pstate->ips, pstate->ipslen,
						pstate->allow_repeat_ips);
			}

		} else {
			slls_append_with_free(pxtab_lines, line);
		}
	}
}

// ----------------------------------------------------------------
lrec_t* lrec_parse_stdio_xtab_single_ips(slls_t* pxtab_lines, char ips, int allow_repeat_ips) {
	lrec_t* prec = lrec_xtab_alloc(pxtab_lines);

	for (sllse_t* pe = pxtab_lines->phead; pe != NULL; pe = pe->pnext) {
		char* line = pe->value;
		char* p = line;
		char* key = p;

		while (*p != 0 && *p != ips)
			p++;
		if (*p == 0) {
			lrec_put(prec, key, "", NO_FREE);
		} else {
			while (*p != 0 && *p == ips) {
				*p = 0;
				p++;
			}
			lrec_put(prec, key, p, NO_FREE);
		}
	}

	return prec;
}

lrec_t* lrec_parse_stdio_xtab_multi_ips(slls_t* pxtab_lines, char* ips, int ipslen, int allow_repeat_ips) {
	lrec_t* prec = lrec_xtab_alloc(pxtab_lines);

	for (sllse_t* pe = pxtab_lines->phead; pe != NULL; pe = pe->pnext) {
		char* line = pe->value;
		char* p = line;
		char* key = p;

		while (*p != 0 && !streqn(p, ips, ipslen))
			p++; // Advance by only 1 in case of subsequent match
		if (*p == 0) {
			lrec_put(prec, key, "", NO_FREE);
		} else {
			while (*p != 0 && streqn(p, ips, ipslen)) {
				*p = 0;
				p += ipslen;
			}
			lrec_put(prec, key, p, NO_FREE);
		}
	}

	return prec;
}