changed readme

README.md

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 SLRE: Super Light Regular Expression library
 ============================================
 
-SLRE documentation is at [http://cesanta.com/docs.shtml](http://cesanta.com/docs.html?SLRE.md)
+SLRE is an ISO C library that implements a subset of Perl regular
+expression syntax. Main features of SLRE are:
+
+   * Written in strict ANSI C'89
+   * Small size (compiled x86 code is about 5kB)
+   * Uses little stack and does no dynamic memory allocation
+   * Provides simple intuitive API
+   * Implements most useful subset of Perl regex syntax (see below)
+   * Easily extensible. E.g. if one wants to introduce a new
+metacharacter `\i`, meaning "IPv4 address", it is easy to do so with SLRE.
+
+SLRE is perfect for tasks like parsing network requests, configuration
+files, user input, etc, when libraries like [PCRE](http://pcre.org) are too
+heavyweight for the given task. Developers of embedded systems would benefit
+most.
+
+## Supported Syntax
+
+    (?i)    Must be at the beginning of the regex. Makes match case-insensitive
+    ^       Match beginning of a buffer
+    $       Match end of a buffer
+    ()      Grouping and substring capturing
+    \s      Match whitespace
+    \S      Match non-whitespace
+    \d      Match decimal digit
+    +       Match one or more times (greedy)
+    +?      Match one or more times (non-greedy)
+    *       Match zero or more times (greedy)
+    *?      Match zero or more times (non-greedy)
+    ?       Match zero or once (non-greedy)
+    x|y     Match x or y (alternation operator)
+    \meta   Match one of the meta character: ^$().[]*+?|\
+    \xHH    Match byte with hex value 0xHH, e.g. \x4a
+    [...]   Match any character from set. Ranges like [a-z] are supported
+    [^...]  Match any character but ones from set
+
+Under development: Unicode support.
+
+## API
+
+    int slre_match(const char *regexp, const char *buf, int buf_len,
+                   struct slre_cap *caps, int num_caps);
+
+`slre_match()` matches string buffer `buf` of length `buf_len` against
+regular expression `regexp`, which should conform the syntax outlined
+above. If regular expression `regexp` contains brackets, `slre_match()`
+can capture the respective substrings into the array of `struct slre_cap`
+structures:
+
+    /* Stores matched fragment for the expression inside brackets */
+    struct slre_cap {
+      const char *ptr;  /* Points to the matched fragment */
+      int len;          /* Length of the matched fragment */
+    };
+
+N-th member of the `caps` array will contain fragment that corresponds to the
+N-th opening bracket in the `regex`, N is zero-based. `slre_match()` returns
+number of bytes scanned from the beginning of the string. If return value is
+greater or equal to 0, there is a match. If return value is less then 0, there
+is no match. Negative return codes are as follows:
+
+    #define SLRE_NO_MATCH               -1
+    #define SLRE_UNEXPECTED_QUANTIFIER  -2
+    #define SLRE_UNBALANCED_BRACKETS    -3
+    #define SLRE_INTERNAL_ERROR         -4
+    #define SLRE_INVALID_CHARACTER_SET  -5
+    #define SLRE_INVALID_METACHARACTER  -6
+    #define SLRE_CAPS_ARRAY_TOO_SMALL   -7
+    #define SLRE_TOO_MANY_BRANCHES      -8
+    #define SLRE_TOO_MANY_BRACKETS      -9
+
+
+## Example: parsing HTTP request line
+
+    const char *request = " GET /index.html HTTP/1.0\r\n\r\n";
+    struct slre_cap caps[4];
+
+    if (slre_match("^\\s*(\\S+)\\s+(\\S+)\\s+HTTP/(\\d)\\.(\\d)",
+                   request, strlen(request), caps, 4) > 0) {
+      printf("Method: [%.*s], URI: [%.*s]\n",
+             caps[0].len, caps[0].ptr,
+             caps[1].len, caps[1].ptr);
+    } else {
+      printf("Error parsing [%s]\n", request);
+    }
+
+## Example: find all URLs in a string
+
+    static const char *str =
+      "<img src=\"HTTPS://FOO.COM/x?b#c=tab1\"/> "
+      "  <a href=\"http://cesanta.com\">some link</a>";
+
+    static const char *regex = "(?i)((https?://)[^\\s/'\"<>]+/?[^\\s'\"<>]*)";
+    struct slre_cap caps[2];
+    int i, j = 0, str_len = strlen(str);
+
+    while (j < str_len &&
+           (i = slre_match(regex, str + j, str_len - j, caps, 2, NULL)) > 0) {
+      printf("Found URL: [%.*s]\n", caps[0].len, caps[0].ptr);
+      j += i;
+    }
+
+Output:
+
+    Found URL: [HTTPS://FOO.COM/x?b#c=tab1]
+    Found URL: [http://cesanta.com]
+
+# License
+
+SLRE is released under
+[GNU GPL v.2](http://www.gnu.org/licenses/old-licenses/gpl-2.0.html).
+Businesses have an option to get non-restrictive, royalty-free commercial
+license and professional support from
+[Cesanta Software](http://cesanta.com).
+
+[Super Light DNS Resolver](https://github.com/cesanta/sldr),
+[Mongoose web server](https://github.com/cesanta/mongoose)
+are other projects by Cesanta Software, developed with the same philosophy
+of functionality and simplicity.