ConfigParser

    struct Config
    {
        struct Entry
        {
            ulong key;
            string value;
        }

        Entry entry;
    }

    enum CONFIG_STR = `
; The first test config
  [ ENTRY ]
  value = the value
  key = 1234567891011
`;

    auto parser = ConfigParser!Config(CONFIG_STR);
    assert(parser.entry.key == 1234567891011);
    assert(parser.entry.value == "the value");

    struct Config
    {
        struct Server
        {
            string address;
            ushort port;
        }

        Server server;

        struct Route
        {
            string url;
            string path;
            uint response_code;
        }

        Route route;
    }

    enum CONFIG_STR = `

;
; Server configuration
;

[ Server ]

  ADDRESS       = 127.0.0.1

  PORT          = 32768

;
; Index route
;

[ Route ]

  URL           = /index.html

  PATH          = public/index.html

  RESPONSE_CODE = 200

`;

    auto parser = ConfigParser!Config(CONFIG_STR);
    assert(parser.server.address == "127.0.0.1");
    assert(parser.server.port == 32768);
    assert(parser.route.url == "/index.html");
    assert(parser.route.path == "public/index.html");
    assert(parser.route.response_code == 200);

    struct Config
    {
        struct MixedValues
        {
            uint integer;
            double decimal;
            bool flag;
            string text;
        }

        MixedValues mixed_values;
    }

    enum CONFIG_STR = `
[MixedValues]
integer = 42
decimal = 66.6
flag = true
text = This is some text
`;

    auto parser = ConfigParser!Config(CONFIG_STR);
    assert(parser.mixed_values.integer == 42);
    assert(parser.mixed_values.decimal == 66.6);
    assert(parser.mixed_values.flag == true);
    assert(parser.mixed_values.text == "This is some text");

1     import std.exception;
2 
3     /**
4      * Too few categories
5      */
6 
7     struct Config
8     {
9         struct CatOne
10         {
11             uint x;
12         }
13 
14         CatOne one;
15 
16         struct CatTwo
17         {
18             uint y;
19             uint z;
20         }
21 
22         CatTwo two;
23     }
24 
25     enum CONFIG_STR_TOO_FEW_CATS = `
26 [CatOne]
27 x = 1
28 `;
29 
30     assertThrown!ConfigException(ConfigParser!Config(CONFIG_STR_TOO_FEW_CATS));
31 
32     /**
33      * Expected category
34      */
35 
36     enum CONFIG_STR_CAT_EXPECTED = `
37 x = 1
38 [CatOne]
39 x = 1
40 
41 [CatTwo]
42 y = 2
43 z = 3
44 `;
45 
46     assertThrown!ConfigException(ConfigParser!Config(CONFIG_STR_CAT_EXPECTED));
47 
48     /**
49      * Wrong category name
50      */
51 
52     enum CONFIG_STR_WRONG_CAT = `
53 [CatOne]
54 x = 1
55 [CatTwoooo]
56 y = 2
57 z = 3
58 `;
59 
60     assertThrown!ConfigException(ConfigParser!Config(CONFIG_STR_WRONG_CAT));
61 
62     /**
63      * Empty category
64      */
65 
66     enum CONFIG_STR_EMPTY_CAT = `
67 [CatOne]
68 [CatTwo]
69 y = 2
70 z = 3
71 `;
72 
73     assertThrown!ConfigException(ConfigParser!Config(CONFIG_STR_EMPTY_CAT));
74 
75     /**
76      * Too many fields
77      */
78 
79     enum CONFIG_STR_TOO_MANY_FIELDS = `
80 [CatOne]
81 x = 1
82 y = 2
83 [CatTwo]
84 y = 2
85 z = 3
86 `;
87 
88     assertThrown!ConfigException(ConfigParser!Config(CONFIG_STR_TOO_MANY_FIELDS));
89 
90     /**
91      * Too few fields
92      */
93 
94     enum CONFIG_STR_TOO_FEW_FIELDS = `
95 [CatOne]
96 x = 1
97 [CatTwo]
98 y = 2
99 `;
100 
101     assertThrown!ConfigException(ConfigParser!Config(CONFIG_STR_TOO_FEW_FIELDS));
102 
103     /**
104      * Missing =
105      */
106 
107     enum CONFIG_STR_MISSING_EQUALS = `
108 [CatOne]
109 x = 1
110 [CatTwo]
111 y 2
112 z = 3
113 `;
114 
115     assertThrown!ConfigException(ConfigParser!Config(CONFIG_STR_MISSING_EQUALS));
116 
117     /**
118      * Missing assignment
119      */
120 
121     enum CONFIG_STR_MISSING_ASSIGN = `
122 [CatOne]
123 x
124 [CatTwo]
125 y = 2
126 z = 3
127 `;
128 
129     assertThrown!ConfigException(ConfigParser!Config(CONFIG_STR_MISSING_ASSIGN));
130 
131     /**
132      * Wrong field
133      */
134 
135     enum CONFIG_STR_WRONG_FIELD = `
136 [CatOne]
137 x = 1
138 [CatTwo]
139 b = 2
140 c = 3
141 `;
142     assertThrown!ConfigException(ConfigParser!Config(CONFIG_STR_WRONG_FIELD));
143 
144     /**
145      * Wrong type
146      */
147 
148     enum CONFIG_STR_WRONG_TYPE = `
149 [CatOne]
150 x = 1
151 [CatTwo]
152 y = hello
153 z = 3
154 `;
155 
156     assertThrown!ConfigException(ConfigParser!Config(CONFIG_STR_WRONG_TYPE));