syntaxes.md

The following constructs will be supported for version 0.1:

1. * Matches the preceding expression zero, one or several times.
2. + Matches the preceding expression one or several times.
3. ? Matches the preceding expression once or not at all.
4. | Alternative between two expressions.
5. () Group expressions, but can not capture substrings for now.
6. \ Escape special characters, for now they are `* + ? | \ ( ).

Todo

1. 将悬空的边单独放在一起，加速map。