How to use macro functions for matching in Natex.
The most powerful aspect of Natex is its ability to integrate pattern matching with arbitrary code. This allows you to integrate regular expressions, NLP models, or custom algorithms into Natex.
A macro can be defined by creating a class inheriting the abstract class Macro
in STDM and overrides the run
method:
#1
: imports Macro
from STDM.
#2
: imports type hints from the typing
package in Python.
#4
: creates the MacroGetName
class inheriting Macro
.
#5
: overrides the run
method declared in Macro
.
Currently, the run
method returns True
no matter what the input is.
Let us create transitions using this macro. A macro is represented by an alias preceded by the pound sign (#
):
#4
: calls the macro #GET_NAME
that is an alias of MacroGetName
.
#13
: creates a dictionary defining aliases for macros.
#14
: creates an object of MacroGetName
and saves it to the alias GET_NAME
.
To call the macro, we need to add the alias dictionary macros
to the dialogue flow:
#3
: adds all macros defined in macros
to the dialogue flow df
.
The run
method has three parameters:
ngrams
: is a set of strings representing every n-gram of the input matched by the Natex.
vars
: is the variable dictionary, maintained by a DialogueFlow
object, where the keys and values are variable names and objects corresponding to their values.
args
: is a list of strings representing arguments specified in the macro call.
Let us modify the run
method to see what ngrams
and vars
give:
#2
: prints the original string of the matched input span before preprocessing.
#3
: prints the input span, preprocessed by STDM and matched by the Natex.
#4
: prints a set of n-grams.
When you interact with the the dialogue flow by running it (df.run()
), it prints the followings:
The raw_text
method returns the original input:
The text
method returns the preprocessed input used to match the Natex:
The ngrams
gives a set of all possible n-grams in text()
:
Finally, the vars
gives a dictionary consisting of both system-level and user-custom variables (no user-custom variables are saved at the moment):
Let us update the run
method that matches the title, first name, and last name in the input and saves them to the variables $TITLE
, $FIRSTNAME
, and $LASTNAME
, respectively:
#2
: creates a regular expression to match the title, first name and last name.
#3
: searches for the span to match.
#4
: returns False
if no match is found.
#6-18
-> exercise.
#20-22
: saves the recognized title, first name, and last name to the corresponding variables.
#24
: returns True
as the regular expression matches the input span.
Given the updated macro, the above transitions can be modified as follow:
#5
: uses the variables $FIRSTNAME
and $LASTNAME
retrieved by the macro to generate the output.
The followings show outputs:
Although the last name is not recognized, and thus, it leaves a blank in the output, it is still considered "matched" because run()
returns True
for this case. Such output can be handled better by using the language generation capability in Natex.
Can macros be mixed with other Natex expressions?