/[public]/psiconv/tags/rel-0-9-4/docs/parsing
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Contents of /psiconv/tags/rel-0-9-4/docs/parsing

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Revision 243 - (show annotations)
Wed Mar 17 17:31:13 2004 UTC (15 years, 11 months ago) by (unknown author)
File size: 1857 byte(s)
This commit was manufactured by cvs2svn to create tag 'rel-0-9-4'.
1 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.

frodo@frodo.looijaard.name
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