Feature ancestry (#598)

Ancestry exclusion for inline patterns.

Adds the ability for an inline pattern to define a list of ancestor tag names that should be avoided. If a pattern would create a descendant of one of the listed tag names, the pattern will not match. Fixes #596.

1 files changed, 5 insertions, 1 deletions

diff --git a/docs/extensions/api.txt b/docs/extensions/api.txt
index 9653883..246bb27 100644
--- a/docs/extensions/api.txt
+++ b/docs/extensions/api.txt
@@ -53,7 +53,7 @@ A pseudo example:
 Inline Patterns {: #inlinepatterns }
 ------------------------------------
 
-Inline Patterns implement the inline HTML element syntax for Markdown such as
+Inline Patterns implement the inline HTML element syntax for Markdown such as 
 `*emphasis*` or `[links](http://example.com)`. Pattern objects should be 
 instances of classes that inherit from `markdown.inlinepatterns.Pattern` or 
 one of its children. Each pattern object uses a single regular expression and 
@@ -68,6 +68,10 @@ must have the following methods:
     Accepts a match object and returns an ElementTree element of a plain 
     Unicode string.
 
+Also, Inline Patterns can define the property `ANCESTOR_EXCLUDES` with either 
+a list or tuple of undesirable ancestors. The pattern should not match if it 
+would cause the content to be a descendant of one of the defined tag names.
+
 Note that any regular expression returned by `getCompiledRegExp` must capture
 the whole block. Therefore, they should all start with `r'^(.*?)'` and end
 with `r'(.*?)!'`. When using the default `getCompiledRegExp()` method