Markdown Extra Spec: Parsing Section

[John MacFarlane]

> If we're going this way, there's going to be a learning curve: for

> me, and for everyone trying to understand the syntax. I'd prefer to

> avoid forcing people to learn a new language only to understand the

> specification.


PS. Here's all you have to learn in order to write or read a PEG grammar.

A B C                 A followed by B followed by C
A | B                 A or B (ordered choice)
A+                    one or more As
A*                    zero or more As
A?                    optional A
!A                    not followed by A
&A                    followed by A (but does not consume A)
(A B)                 grouping
.                     matches any character
'x'                   matches the character 'x'
"string"              matches the string "string"
[a-z]                 matches a character from 'a' to 'z'

English could be used to specify how a semantic value is to be
constructed for each matching rule. This part would be implemented
differently in different languages, but the basic PEG grammar would be
the same.

John