Initial revision

util/ceg/EM_parser/common/scan.c

@@ -0,0 +1,76 @@
+#include <stdio.h>
+
+FILE *infile = stdin;
+
+#define BUF_SIZE	16
+char buf[BUF_SIZE],	/* Bufer to save backc()-characters */
+     *bufptr = buf;	/* Pointer to space for backc()-character */
+int yylineno = 1;
+
+
+char nextc()
+{
+	if ( bufptr > buf)
+		return( *--bufptr);
+	else
+		return( getc( infile));
+}
+
+
+backc( c)
+char c;
+{
+	if ( bufptr > buf + BUF_SIZE)
+		error( "backc(), no space in buffer left!");
+	else {
+		if ( c == '\n')
+			yylineno--;
+		*bufptr++ = c;
+	}
+}
+
+
+char scanc()
+
+/* Get next character, but delete al C-comments */
+
+{
+	char c;
+
+	c = nextc();
+	while ( c == '/') {
+		c = nextc();
+		if ( c == '*') {	/* start of comment */
+			while ( nextc() != '*' || nextc() != '/')
+				;
+			c = nextc();
+		}
+		else {
+			backc( c);
+			return( '/');
+		}
+	}
+	if ( c == '\n')
+		yylineno++;
+	return( c);
+}
+
+
+FILE *switch_input( new)
+FILE *new;
+
+/* Return the current FILE, if buf[] can't be cleaned NULL will be returned */
+
+{
+	char *ptr; FILE *old;
+
+	/* Clean buf[] */
+	for ( ptr = buf; ptr < bufptr; ptr++)
+		if ( ungetc( *ptr, infile) == EOF && *ptr != EOF)
+			return( NULL);
+
+	bufptr = buf;
+	old = infile;
+	infile = new;
+	return( old);
+}