qse/samples/awk/awk03.c

#include <qse/awk/stdawk.h>
#include <qse/cmn/str.h>
#include <qse/si/sio.h>
#include <qse/cmn/main.h>
#include "awk00.h"

/* i'll print records with the second field grater than 4. 
 * at the end, we'll print the number of records seen so far */
static const qse_char_t* script =
	QSE_T("$2 > 4 { print $0; } END { print NR; }");

struct console_t
{
	/* console input */
	const qse_char_t* conin;
	qse_size_t coninpos;

	/* console output */
	qse_char_t conout[10000]; /* fixed-size console buffer for demo only */
	qse_size_t conoutpos;
};

typedef struct console_t console_t;

/* this is the console I/O handler */
static qse_ssize_t handle_console (
     qse_awk_rtx_t*      rtx,
     qse_awk_rio_cmd_t   cmd,
     qse_awk_rio_arg_t*  arg,
     qse_char_t*         data,
     qse_size_t          count)
{
	console_t* con = qse_awk_rtx_getxtn(rtx);

	/* this function is called separately for the console input and console
	 * output. however, since i don't maintain underlying resources like
	 * file handles, i don't really check if it's input or output.
	 * you can check the value of #qse_awk_rio_mode_t in the arg->mode 
	 * field if you want to tell. 
	 */
	switch (cmd)
	{
		case QSE_AWK_RIO_OPEN:
			/* 0 for success, -1 for failure. */
			return 0;

		case QSE_AWK_RIO_CLOSE:
			/* 0 for success, -1 for failure. */
			return 0;

		case QSE_AWK_RIO_READ:
		{
			qse_ssize_t len = 0;

			while (con->conin[con->coninpos] && len < count) 
				data[len++] = con->conin[con->coninpos++];

			/* 0 for EOF, -1 for failure. 
			   positive numbers for the number of characters read */
			return len;
		}

		case QSE_AWK_RIO_WRITE:
			con->conoutpos += qse_strxncpy (
				&con->conout[con->conoutpos], QSE_COUNTOF(con->conout) - con->conoutpos, 
				data, count);
			/* 0 for EOF, -1 for failure. 
			   positive numbers for the number of characters written */
			return count;
		
		case QSE_AWK_RIO_FLUSH:
			/* 0 for success, -1 for failure. */
			return 0;

		case QSE_AWK_RIO_NEXT:
			/* 0 for success, -1 for failure. */
			return 0;
	}

	/* this part will never be reached */
	return -1;
}


static int awk_main (int argc, qse_char_t* argv[])
{
	qse_awk_t* awk = QSE_NULL;
	qse_awk_rtx_t* rtx = QSE_NULL;
	qse_awk_val_t* retv;
	qse_awk_parsestd_t psin[2];
	qse_awk_rio_t rio;
	int ret = -1;
	console_t* con;

	/* create an awk object */
	awk = qse_awk_openstd (0, QSE_NULL);
	if (awk == QSE_NULL)  
	{
		qse_fprintf (QSE_STDERR, QSE_T("ERROR: cannot open awk\n"));
		goto oops;
	}

	/* prepare a script to parse */
	psin[0].type = QSE_AWK_PARSESTD_STR;
	psin[0].u.str.ptr = script;
	psin[0].u.str.len = qse_strlen(script);
	psin[1].type = QSE_AWK_PARSESTD_NULL;

	/* parse a script in a string */
	if (qse_awk_parsestd (awk, psin, QSE_NULL) <= -1)
	{
		qse_fprintf (QSE_STDERR, QSE_T("ERROR: %s\n"), qse_awk_geterrmsg(awk));
		goto oops;
	}

	/* open a runtime context */
	rtx = qse_awk_rtx_openstd (
		awk, 
		QSE_SIZEOF(console_t), /* the size of extenstion area */
		QSE_T("awk01"),
		QSE_NULL, /* stdin */
		QSE_NULL, /* stdout */               
		QSE_NULL  /* default cmgr */
	);
	if (rtx == QSE_NULL) 
	{
		qse_fprintf (QSE_STDERR, QSE_T("ERROR: %s\n"), qse_awk_geterrmsg(awk));
		goto oops;
	}

	/* get the pointer to the extension area. */
	con = (console_t*)qse_awk_rtx_getxtn(rtx);
	/* initialize fields that require non-zero values. 
	 * the entire extension area was initialized to zeros 
	 * when it was created. */
	con->conin = QSE_T("Beth 4.00 0\nDan  3.74 0\nKathy     4.00 10\nMark 5.00 20\nMary 5.50 22\nSusie     4.25 18\n");
	
	/* retrieve the I/O handlers created by qse_awk_rtx_openstd() */
	qse_awk_rtx_getrio (rtx, &rio);
	/* override the console handler */
	rio.console = handle_console;
	/* update the I/O handlers */
	qse_awk_rtx_setrio (rtx, &rio);

	/* execute pattern-action blocks */
	retv = qse_awk_rtx_loop (rtx);
	if (retv == QSE_NULL)
	{
		qse_fprintf (QSE_STDERR, QSE_T("ERROR: %s\n"), qse_awk_rtx_geterrmsg(rtx));
		goto oops;
	}

	/* decrement the reference count of the return value */
	qse_awk_rtx_refdownval (rtx, retv);

	/* the buffer is available during the runtime context is alive */
	qse_printf (QSE_T("Console Output:\n================\n%.*s\n"), (int)con->conoutpos, con->conout);

	ret = 0;

oops:
	/* destroy the runtime context */
	if (rtx) qse_awk_rtx_close (rtx);

	/* destroy the awk object */
	if (awk) qse_awk_close (awk);

	return ret;
}

int qse_main (int argc, qse_achar_t* argv[])
{
	int x;
	qse_open_stdsios ();
	init_awk_sample_locale ();
	x = qse_run_main (argc, argv, awk_main);
	qse_close_stdsios ();
	return x;
}