Re: Code Folding in 8.5

[Seth Dillingham]

On 9/11/2006, Graham Nelson said:

Thanks - but I was asking if it's possible to use PCREs for things _other_
than functions, for instance, to specify comment opening and closing,
and/or block opening and closing, etc. Somebody here said that it was, but
that this isn't documented yet!

Yes, that was me.

There are at least two other supported patterns: one for 
strings, and one for comments.

Here's an example string pattern which supports both single and 
double quotes, and forces strings to stop at the end of the line.

<key>String Pattern</key>
<string>(?x:
    (?&gt;  '   (?s: \\.  | [^'] )*?    (?: ' | $ ) ) |
    (?&gt;  "   (?s: \\.  | [^"] )*?    (?: " | $ ) )
)</string>

The "(?x:" puts the pattern into extended mode (I think that's 
what it's called), and remember the "(?&gt;" is just the 
XML-entity version of "(?>" because the above is taken from a 
.plist XML file.

Comments work the same way. Here's a pattern that supports both 
/* inline */ and // rest-of-line comment syntax:

<key>Comment Pattern</key>
<string>(?x:
    (?&gt;  //      .*          $               ) |
    (?&gt;  /\*     (?s:.*?)    (?: \*/ | \z )  )
)</string>

BBEdit actually sets these up as "named subpatterns", so that 
you can reference them (function, comment, and string) within 
each other. For example, your function pattern might look like this:

<key>Function Pattern</key>
<string>(?x:
    (?P&lt;function&gt;

        (?P&lt;function_name&gt;
            [ _0-9A-Za-z]+
        )

        \s*

        (?&gt;
            (?P&gt;comment)

            \s*
        )*

        \s*

        (?P&lt;block&gt;
            \{
                (?:
                    (?&gt;
                        (?&gt; [^[{}]+ ) |

                        (?: - (?!-) ) |

                        (?: / (?!\*) ) |

                        (?P&gt;comment) |

                        (?P&gt;string) |

                        (?P&gt;function) |

                        (?P&gt;block)
                    )
                )*
            \}
        )
    )
)</string>

(That's perhaps not the most useful example, as it's too simple 
for many languages, but it does demonstrate how you'd refer from 
one pattern to another, and how a pattern can even refer to itself.

Seth


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