emora-stdm 1.8

Library for creating state-machine-based chatbots.

State Transition Dialogue Manager

Defines a dialogue management framework based on state machines and regular expressions.

Installation

Users install using pip install emora_stdm

Developers install using:

git clone https://github.com/emora-chat/emora_stdm.git
pip install -r emora_stdm/requirements.txt

Example usage

from emora_stdm import DialogueFlow
from enum import Enum

# states are typically represented as an enum
class State(Enum):
    START = 0
    FAM_ANS = 1
    FAM_Y = 2
    FAM_N = 3
    FAM_ERR = 4
    WHATEV = 5

# initialize the DialogueFlow object, which uses a state-machine to manage dialogue
df = DialogueFlow(State.START)

# add transitions to create an arbitrary graph for the state machine
df.add_system_transition(State.START, State.FAM_ANS, '[!do you have a $F={brother, sister, son, daughter, cousin}]')
df.add_user_transition(State.FAM_ANS, State.FAM_Y, '[{yes, yea, yup, yep, i do, yeah}]')
df.add_user_transition(State.FAM_ANS, State.FAM_N, '[{no, nope}]')
df.add_system_transition(State.FAM_Y, State.WHATEV, 'thats great i wish i had a $F')
df.add_system_transition(State.FAM_N, State.WHATEV, 'ok then')
df.add_system_transition(State.FAM_ERR, State.WHATEV, 'im not sure i understand')

# each state that will be reached on the user turn should define an error transition if no other transition matches
df.set_error_successor(State.FAM_ANS, State.FAM_ERR)
df.set_error_successor(State.WHATEV, State.START)

if __name__ == '__main__':
    # automatic verification of the DialogueFlow's structure (dumps warnings to stdout)
    df.check()
    # run the DialogueFlow in interactive mode to test
    df.run(debugging=True)

Class DialogueFlow is the main class to initialize. It defines a state machine that drives natural language conversation. State transitions in the state machine (alternately) represent either system or user turns.

dialogue_manager = DialogueFlow(start_state) initializes a new DialogueFlow object with start_state as the initial state of the state machine.

To add transitions, use either: .add_system_transition(source_state, target_state, NatexNLG) method to add a system transition, or .add_user_transition(source_state, target_state, NatexNLU) method to add a user transition.

The first two arguments are the source and target states of the transition, the third argument is a string that defines a set of natural language expressions given by a user that satisfy the transition (see NatexNLU/NatexNLG below).

NatexNLU

Strings created for transition NLU define a set of user expressions that satisfy the transition by compiling into regular expressions.

You can also create and test standalone Natex objects:

from emora_stdm import NatexNLU, NatexNLG

natex_nlu = NatexNLU('[{hi, hello} you]')
assert natex_nlu.match('hi there how are you', debugging=True)

natex_nlg = NatexNLG('[!well {hi, hello} there you look {good, fine, great} today]')
print(natex_nlg.generate(debugging=True))

Natex expressions can be formed using the below constructs, which are arbitrarily nestable and concatenable.

Literal

'hello there'

directly match a literal substring

Disjunction

'{hello there, hi}'

matches a substring containing exactly one term inside {}, in this case "hello there" and "hi" both match.

Conjunction

'<bob, hi>'

matches a substring that contains at least all terms inside <>, in this case, "hi bob" and "oh bob well hi there" both would match, but not "hi"

Flexible sequence

'[hi, bob, how, you]'

matches as long as the substring contains all terms inside [], and the terms are ordered properly within the utterance. Matches in the example include "hi bob how are you", but not "how are you bob". Note that this expression matches any amount of characters before and after the requisite sequence.

Inflexible sequence

'[!how, are, you]'

matches an exact sequence of terms with no words inserted between terms. The only utterance matching the example is "how are you". This construct is helpful with nested constructs inside of it that require an exact ordering, with no extra characters between each element.

Negation

'[!i am -bad]'

prepend - to negate the next term in the expression. The example will match any expression starting with "i am" where "bad" does NOT follow. Note that the scope of the negation extends to the end of the substring due to limitations in regex.

Regular expression

'/[A-Z a-z]+/'

substrings within // define a python regex directly.

Nesting

'[!{hi, hello} [how, weekend]]'

would match "hi how was your weekend", "oh hello so how is the weekend going", ...

Variable assignment

'[!i am $f={good, bad}]'

using $var= will assign variable var to the next term in the expression. The variable will persist until overwritten, and can be referenced in future NLU or NLG expressions. The example would match either "i am good" or "i am bad", and assigns variable "f" to either "good" or "bad" depending on what the user said.

Variable reference

'[!why are you $f today]'

using $ references a previously assigned variable. If no such variable exists, the expression as a whole returns with no match. The example would match "why are you good today" if f="good", but would not match if f="bad"

Macros

Macros define arbitrary functions that can run within NatexNLU or NatexNLG evaluation. Create a Macro as follows:

from emora_stdm import Macro


class MyMacro(Macro):

    # optionally, define constructor if macro needs access to additional data
    def __init__(self, x):
        self.x = x

    # define method to run when macro is evaluated in Natex
    def run(self, ngrams, vars, args):
        """
        :param ngrams: an Ngrams object defining the set of all ngrams in the
                       input utterance (for NLU) or vocabulary (for NLG). Treat
                        like a set for all ngrams, or get a specific ngram set
                        using ngrams[n]. Get original string using .text()
        :param vars: a reference to the dictionary of variables
        :param args: a list of arguments passed to the macro from the Natex
        :returns: string, set, boolean, or arbitrary object
                  returning a string will replace the macro call with that string
                  in the natex
                  returning a set of strings replaces macro with a disjunction
                  returning a boolean will replace the macro with wildcards (True)
                  or an unmatchable character sequence (False)
                  returning an arbitrary object is only used to pass data to other macros
        """
        return ' '.join(['hello ' + args[0]] * self.x)


from emora_stdm import NatexNLU

if __name__ == '__main__':
    natex = NatexNLU('[!oh #MyMacro(there) how are you]', macros={'MyMacro': MyMacro(2)})
    assert natex.match('oh hello there hello there how are you')

NatexNLG

NatexNLG objects work very similarly to NatexNLU objects, but they are used to create a response string instead of match a user utterance.

from emora_stdm import NatexNLG

natex = NatexNLG('[!{this, here} is a {example, test}]')
print(natex.generate())

Options (disjunctions) in a NatexNLG will result in one of the set of options to be selected to generate the response.

Some constructs (e.g. conjunction, negation) don't make sense in NatexNLGs. Here is the full list of supported constructs for NatexNLGs:

1. literal
2. rigid sequence [!...]
3. disjunction {...}
4. variable reference $var
5. variable assignment $var=...
6. macro call #MACRO(...)

All the above constructs share the same syntax as the NatexNLU syntax.