Annotation of /psiconv/trunk/docs/parsing

Major parsing routines are built according to this template:

      int psiconv_parse_TYPE (const psiconv_buffer buf, int lev,
                              psiconv_u32 off, int *length,
                              psiconv_TYPE *result)
      {
       int res = 0;
       int len = 0;
       int leng;

        psiconv_progress(lev+1,off,"Going to parse TYPE");
        if (!(*result = malloc(sizeof(**result)))) 
          goto ERROR1;

        /* Example of calling some other parse function */
        if ((res = psiconv_parse_TYPE2(buf,lev+2,off+len,&leng,
                                        &(*result)->FIELD2)))
          goto ERROR2;
        psiconv_debug(lev+2,off+len,"Some helpful message");
        len += leng;

        /* Example of reading some bytes directly */
        (*result)->FIELD1 = psiconv_read_u8(buf,lev+2,off+len,&res);
        if (!res)
          goto ERROR3;
        psiconv_debug(lev+2,off+len,"Some helpful message");
        len ++;

        psiconv_debug(lev+2,off+len,"Some helpful message");
        if (length)
          *length = len;
        psiconv_progress(lev+1,off+len-1,"End of TYPE (total length: %08x)",
                         len);
        return 0;

      ERROR3:
        free ((*result)->FIELD2)
      ERROR2:
        free (*result);
      ERROR1:
        psiconv_warn(lev+1,off,"Reading of TYPE failed");
        if (length)
          *length = 0;
        if (!res)
          return -PSICONV_E_NOMEM;
        else
          return res;
      }

If something unexpected happens half-way, but you can recover from it
(for example, an unexpected value in some well-defined field), call
psiconv_warn, but do not return with an error. The rule is that if
the result code of a procedure is not 0, you may assume that things
are hopeless, that nothing was allocated, and that every field contains
nonsense.
1	frodo	64	Major parsing routines are built according to this template:
2
3			int psiconv_parse_TYPE (const psiconv_buffer buf, int lev,
4			psiconv_u32 off, int *length,
5			psiconv_TYPE *result)
6			{
7			int res = 0;
8			int len = 0;
9			int leng;
10
11			psiconv_progress(lev+1,off,"Going to parse TYPE");
12			if (!(result = malloc(sizeof(*result))))
13			goto ERROR1;
14
15			/* Example of calling some other parse function */
16			if ((res = psiconv_parse_TYPE2(buf,lev+2,off+len,&leng,
17			&(*result)->FIELD2)))
18			goto ERROR2;
19			psiconv_debug(lev+2,off+len,"Some helpful message");
20			len += leng;
21
22			/* Example of reading some bytes directly */
23			(*result)->FIELD1 = psiconv_read_u8(buf,lev+2,off+len,&res);
24			if (!res)
25			goto ERROR3;
26			psiconv_debug(lev+2,off+len,"Some helpful message");
27			len ++;
28
29			psiconv_debug(lev+2,off+len,"Some helpful message");
30			if (length)
31			*length = len;
32			psiconv_progress(lev+1,off+len-1,"End of TYPE (total length: %08x)",
33			len);
34			return 0;
35
36			ERROR3:
37			free ((*result)->FIELD2)
38			ERROR2:
39			free (*result);
40			ERROR1:
41			psiconv_warn(lev+1,off,"Reading of TYPE failed");
42			if (length)
43			*length = 0;
44			if (!res)
45			return -PSICONV_E_NOMEM;
46			else
47			return res;
48			}
49
50			If something unexpected happens half-way, but you can recover from it
51			(for example, an unexpected value in some well-defined field), call
52			psiconv_warn, but do not return with an error. The rule is that if
53			the result code of a procedure is not 0, you may assume that things
54			are hopeless, that nothing was allocated, and that every field contains
55			nonsense.
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