Any one of the child nodes.
This is often thought of as OR because it matches node one or node two or ...
The example will match either of the following two sub-strings:
A
B
Each of the child nodes, in the order defined.
This is sometimes thought of as AND because it matches node one and then node two and then ...
In the example the following sub-string will match:
AB
Zero or more instances of the child node.
In the example, the following sub-strings, including the empty string, will match:
A
AA
AAA
AAAA
...
This indicates a pattern that needs to be matched, but the matching sub-string is not consumed, and is thus available for subsequent patterns.
In the example, the following sub-string will match (and the B will be the first character for subsequent pattern matching):
AB
A terminal matches one of the characters listed within the square brackets.
Here is the complete 7-bit ASCII range in familiar form:
[\x00-\x06\a\b\t\n\v\f\r\x0E-\x1F !\"#$%&\'()*+,\-\./0-9:;<=>?@A-Z\[\\\]^_`a-z{|}~\x7F]
In the example, any of the following ten single character length sub-strings will match:
0
1
2
3
4
5
6
7
8
9
These are the special terminals that have meaning other than as a single character match.
If this node is reached, then only the most direct path is kept, and alternate match paths are discarded. This is useful, for example, when writing a telnet line based interpreter, or to speed up complicated parsers.
Matches no character whatsoever. This never matches. Compare with "Match Nothing" below.
Match the zero length string. This always matches. Compare with "Never Match" above.
Match only if at the start of a line.
Match only if at the end of the file.
