AIML Pattern Matching

Pattern Matching

The AIML 1.0 wildcards * and _ are defined so that they match one or more words. AIML 2.0 introductes two new wildcards, ^ and #, defined to match zero or more words. As a shorthand description, we refer to these as “zero+ wildcards”.

Both ^ and # are defined to match 0 or more words. The difference between them is the same as the difference between * and _. The # matching operator has highest priority in matching, followed by _, followed by an exact word match, followed by ^, and finally * has the lowest matching priority. When defining a zero+ wildcard it is necessary to consider what the value of (as well as and ) should be when the wildcard match has zero length. In AIML 2.0 we leave this up to the botmaster. Each bot can have a global property named nullstar which the botmaster can set to “”, “unknown”, or any other value.

Matching Order

• Priority Word
• # ( Zero or more )
• _ ( One or more )
• word
• ^ ( Zero or more )
• * ( One or more )