PsiTag proposal for modifiers

Tagging is canonicalized as follows: See canonicalTagName below.

Proposal for improvement: if statement after mode

Example:

mytag ? [if xyz] = 42

sets mytag to 42 only if xyz is an existing tag

Syntax: tagging ? [ modifier ] mode content

where tagging, mode, and content are treated and defined as before,

modifier MUST NOT be multiline; and \[ is replaced into [ and \] into ]

modifer = submodifer1 &&& submodifer2 &&& submodifer3

\&&& is replaced into &&& for each submodifer.

The only submodifer type allowed for now is type if. And it is allowed only once.

submodifierOfTypeIf = if predicate

where

predicate = subpredicate1 SEPARATOR subpredicate2 SEPARATOR ...

If only one subpredicate is present SEPARATOR MUST be ommited.

Separator is one of || for logical OR, and && for logical AND.

For each subpredicate, \|| is replaced into || and \&& into &&.

subpredicate = tag

subpredicate = ! tag

subpredicate = tag == content

subpredicate = tag != content

subpredicate = tag1 == < tag2

subpredicate = tag1 != < tag2

Spaces are optional. Spaces before and after content will be part of content.

content MUST NOT be multiline; the whole predicate is within the line.

=cut

package PsiTag;