1 
2 
3 //          Copyright Ferdinand Majerech 2011.
4 // Distributed under the Boost Software License, Version 1.0.
5 //    (See accompanying file LICENSE_1_0.txt or copy at
6 //          http://www.boost.org/LICENSE_1_0.txt)
7 
8 module dyaml.escapes;
9 
10 package:
11 
12 /// All YAML escapes.
13 immutable dchar[] escapes = ['0', 'a', 'b', 't', '\t', 'n', 'v', 'f', 'r', 'e', ' ',
14                              '\"', '\\', 'N', '_', 'L', 'P'];
15 
16 /// YAML hex codes specifying the length of the hex number.
17 immutable dchar[] escapeHexCodeList = ['x', 'u', 'U'];
18 
19 /// Convert a YAML escape to a dchar.
20 dchar fromEscape(dchar escape) @safe pure nothrow @nogc
21 {
22     switch(escape)
23     {
24         case '0':  return '\0';
25         case 'a':  return '\x07';
26         case 'b':  return '\x08';
27         case 't':  return '\x09';
28         case '\t': return '\x09';
29         case 'n':  return '\x0A';
30         case 'v':  return '\x0B';
31         case 'f':  return '\x0C';
32         case 'r':  return '\x0D';
33         case 'e':  return '\x1B';
34         case ' ':  return '\x20';
35         case '\"': return '\"';
36         case '\\': return '\\';
37         case 'N':  return '\x85'; //'\u0085';
38         case '_':  return '\xA0';
39         case 'L':  return '\u2028';
40         case 'P':  return '\u2029';
41         default:   assert(false, "No such YAML escape");
42     }
43 }
44 
45 /**
46  * Convert a dchar to a YAML escape.
47  *
48  * Params:
49  *      value = The possibly escapable character.
50  *
51  * Returns:
52  *      If the character passed as parameter can be escaped, returns the matching
53  *      escape, otherwise returns a null character.
54  */
55 dchar toEscape(dchar value) @safe pure nothrow @nogc
56 {
57     switch(value)
58     {
59         case '\0':   return '0';
60         case '\x07': return 'a';
61         case '\x08': return 'b';
62         case '\x09': return 't';
63         case '\x0A': return 'n';
64         case '\x0B': return 'v';
65         case '\x0C': return 'f';
66         case '\x0D': return 'r';
67         case '\x1B': return 'e';
68         case '\"':   return '\"';
69         case '\\':   return '\\';
70         case '\xA0': return '_';
71         case '\x85': return 'N';
72         case '\u2028': return 'L';
73         case '\u2029': return 'P';
74         default: return 0;
75     }
76 }
77 
78 /// Get the length of a hexadecimal number determined by its hex code.
79 ///
80 /// Need a function as associative arrays don't work with @nogc.
81 /// (And this may be even faster with a function.)
82 uint escapeHexLength(dchar hexCode) @safe pure nothrow @nogc
83 {
84     switch(hexCode)
85     {
86         case 'x': return 2;
87         case 'u': return 4;
88         case 'U': return 8;
89         default:  assert(false, "No such YAML hex code");
90     }
91 }
92