Comments added

diff --git a/util/ceg/EM_parser/common/scan.c b/util/ceg/EM_parser/common/scan.c
index 44f1e13..a5e3679 100644 (file)
--- a/util/ceg/EM_parser/common/scan.c
+++ b/util/ceg/EM_parser/common/scan.c
@@ -1,14 +1,40 @@
 #include <stdio.h>
 
-FILE *infile = stdin;
+/* This file contains the scanner for mylex(), the following functions and 
+ * variables are exported :
+ *
+ *     int yylineno;                   - The current line number.
+ *
+ *     char scanc();                   - Return next character.
+ *
+ *     backc( c);                      - Push back one character.
+ *             char c;
+ *
+ *     FILE *switch_input( new);       - Scanner will from now on read from
+ *             FILE *new;              - 'new', old input-file is returned.
+ *
+ * The scanner must perform a lookahead of more than one character, so it uses
+ * it's own internal buffer.
+ */
+
 
-#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()
+/********* Internal variables + functions ***********************/
+
+
+#define BUF_SIZE       16
+
+static char buf[BUF_SIZE],     /* Bufer to save backc()-characters */
+            *bufptr = buf;     /* Pointer to space for backc()-character */
+
+static FILE *infile = stdin;
+
+
+
+
+static char nextc()
 {
        if ( bufptr > buf)
                return( *--bufptr);
@@ -17,25 +43,15 @@ char nextc()
 }
 
 
-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 */
+/* Get next character, but delete al C-comments and count lines */
 
 {
-       char c;
+       char c, nextc();
 
        c = nextc();
        while ( c == '/') {
@@ -56,10 +72,25 @@ char scanc()
 }
 
 
+backc( c)
+char c;
+{
+       if ( bufptr >= buf + BUF_SIZE)
+               error( "backc(), no space in buffer left!");
+       else {
+               if ( c == '\n')
+                       yylineno--;
+               *bufptr++ = c;
+       }
+}
+
+
 FILE *switch_input( new)
 FILE *new;
 
-/* Return the current FILE, if buf[] can't be cleaned NULL will be returned */
+/* Switch to a new input file, try to save the lookahead-characters in buf[]
+ * by calling ungetc(). If they can't be saved return NULL.
+ */
 
 {
        char *ptr; FILE *old;