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.
Creation
A macro can be defined by creating a class inheriting the abstract classMacro in STDM and overrides the run method:
#1: imports Macro from STDM.
#2: imports type hints from the package in Python.
#4
Currently, the run method returns True no matter what the input is.
Integration
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.
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.
Parameters
The run method has three parameters:
ngrams: is a set of strings representing every 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.
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
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):
Implementation
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
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 capability in Natex.
Can macros be mixed with other Natex expressions?
from emora_stdm import Macro, Ngrams
from typing import Dict, Any, List
class MacroGetName(Macro):
def run(self, ngrams: Ngrams, vars: Dict[str, Any], args: List[Any]):
return True
: creates the
MacroGetName
class inheriting
Macro
.
#5: overrides the run method declared in Macro.
#14: creates an object of MacroGetName and saves it to the alias GET_NAME.
args: is a list of strings representing arguments specified in the macro call.
: prints a set of n-grams.
: 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.