Source code for langchain.output_parsers.boolean
from langchain_core.output_parsers import BaseOutputParser
[docs]class BooleanOutputParser(BaseOutputParser[bool]):
"""Parse the output of an LLM call to a boolean."""
true_val: str = "YES"
"""The string value that should be parsed as True."""
false_val: str = "NO"
"""The string value that should be parsed as False."""
[docs] def parse(self, text: str) -> bool:
"""Parse the output of an LLM call to a boolean.
Args:
text: output of a language model
Returns:
boolean
"""
cleaned_text = text.strip()
if cleaned_text.upper() not in (self.true_val.upper(), self.false_val.upper()):
raise ValueError(
f"BooleanOutputParser expected output value to either be "
f"{self.true_val} or {self.false_val}. Received {cleaned_text}."
)
return cleaned_text.upper() == self.true_val.upper()
@property
def _type(self) -> str:
"""Snake-case string identifier for an output parser type."""
return "boolean_output_parser"