parser/lexical.c, #10/10, add some comments

src/frontend/parser/lexical.c

@@ -63,7 +63,7 @@ static int numeofs = 0;
 
 
 /* Return a list of words, with backslash quoting and '' quoting done.
- * Strings en(void) closed in "" or `` are made single words and returned,
+ * Strings enclosed in "" or `` are made single words and returned,
  * but with the "" or `` still present. For the \ and '' cases, the
  * 8th bit is turned on (as in csh) to prevent them from being recognized,
  * and stripped off once all processing is done. We also have to deal with
@@ -169,6 +169,7 @@ nloop:
 
     for (;;) {
 
+        /* if string, read from string, else read from stdin */
         c = cp_readchar(&string, cp_inp_cur);
 
     gotchar:
@@ -185,17 +186,21 @@ nloop:
         if (c != EOF)           /* Don't need to do this really. */
             c = strip(c);
 
+        /* if '\' or '^', add following character to linebuf */
         if ((c == '\\' && DIR_TERM != '\\') || (c == '\026') /* ^V */ ) {
             c = quote(cp_readchar(&string, cp_inp_cur));
             push(&linebuf, strip(c));
         }
 
+        /* if reading from fcn backeval() for backquote subst. */
         if ((c == '\n') && cp_bqflag)
             c = ' ';
 
         if ((c == EOF) && cp_bqflag)
             c = '\n';
 
+        /* '#' as the first character in a line,
+           starts a comment line, drop it */
         if ((c == cp_hash) && !cp_interactive && (linebuf.i == 1)) {
             if (string) {
                 wl_free(wlist);
@@ -208,19 +213,24 @@ nloop:
             goto nloop;
         }
 
-        if ((c == '(') || (c == '[')) /* MW. Nedded by parse() */
+        /* check if we are inside of parens during reading:
+           if we are and ',' or ';' occur: no new line */
+        if ((c == '(') || (c == '['))
             paren++;
         else if ((c == ')') || (c == ']'))
             paren--;
 
+        /* What else has to be decided, depending on c ? */
         switch (c) {
 
+        /* new word to wordlist, when space or tab follow */
         case ' ':
         case '\t':
             if (buf.i > 0)
                 newword;
             break;
 
+        /* new word to wordlist, when \n follows */
         case '\n':
             if (buf.i)
                 newword;
@@ -228,6 +238,8 @@ nloop:
                 append(NULL);
             goto done;
 
+        /* if ' read until next ' is hit, will form a new word,
+           but without the ' */
         case '\'':
             while ((c = cp_readchar(&string, cp_inp_cur)) != '\'')
             {
@@ -239,6 +251,9 @@ nloop:
             push(&linebuf, '\'');
             break;
 
+        /* if " or `, read until next " or ` is hit, will form a new word,
+           including the quotes.
+           In case of \, the next character gets the eights bit set. */
         case '"':
         case '`':
             d = c;
@@ -263,6 +278,7 @@ nloop:
 
         case '\004':
         case EOF:
+            /* upon command completion, not used actually */
             if (cp_interactive && !cp_nocc && !string) {
 
                 if (linebuf.i == 0) {
@@ -306,6 +322,7 @@ nloop:
             return NULL;
 
         case ESCAPE:
+            /* upon command completion, not used actually */
             if (cp_interactive && !cp_nocc) {
                 push(&buf, '\0');
                 push(&linebuf, '\0');