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102 lines
3.5 KiB
Python
102 lines
3.5 KiB
Python
"""Prompt schema definition."""
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from typing import Any, Dict, List, Sequence, Union
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from pydantic import BaseModel, Extra, root_validator
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from langchain.prompts.base import DEFAULT_FORMATTER_MAPPING, BasePrompt
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from langchain.prompts.data import BaseExample, convert_to_examples
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class Prompt(BaseModel, BasePrompt):
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"""Schema to represent a prompt for an LLM.
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Example:
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.. code-block:: python
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from langchain import Prompt
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prompt = Prompt(input_variables=["foo"], template="Say {foo}")
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"""
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input_variables: List[str]
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"""A list of the names of the variables the prompt template expects."""
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template: str
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"""The prompt template."""
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template_format: str = "f-string"
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"""The format of the prompt template. Options are: 'f-string'."""
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class Config:
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"""Configuration for this pydantic object."""
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extra = Extra.forbid
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def format(self, **kwargs: Any) -> str:
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"""Format the prompt with the inputs.
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Args:
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kwargs: Any arguments to be passed to the prompt template.
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Returns:
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A formatted string.
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Example:
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.. code-block:: python
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prompt.format(variable1="foo")
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"""
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return DEFAULT_FORMATTER_MAPPING[self.template_format](self.template, **kwargs)
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@root_validator()
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def template_is_valid(cls, values: Dict) -> Dict:
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"""Check that template and input variables are consistent."""
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input_variables = values["input_variables"]
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template = values["template"]
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template_format = values["template_format"]
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if template_format not in DEFAULT_FORMATTER_MAPPING:
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valid_formats = list(DEFAULT_FORMATTER_MAPPING)
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raise ValueError(
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f"Invalid template format. Got `{template_format}`;"
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f" should be one of {valid_formats}"
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)
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dummy_inputs = {input_variable: "foo" for input_variable in input_variables}
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try:
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formatter_func = DEFAULT_FORMATTER_MAPPING[template_format]
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formatter_func(template, **dummy_inputs)
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except KeyError:
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raise ValueError("Invalid prompt schema.")
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return values
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@classmethod
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def from_examples(
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cls,
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examples: Sequence[Union[BaseExample, str]],
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suffix: str,
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input_variables: List[str],
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example_separator: str = "\n\n",
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prefix: str = "",
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) -> "Prompt":
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"""Take examples in list format with prefix and suffix to create a prompt.
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Intended be used as a way to dynamically create a prompt from examples.
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Args:
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examples: List of examples to use in the prompt.
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suffix: String to go after the list of examples. Should generally
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set up the user's input.
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input_variables: A list of variable names the final prompt template
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will expect.
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example_separator: The seperator to use in between examples. Defaults
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to two new line characters.
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prefix: String that should go before any examples. Generally includes
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examples. Default to an empty string.
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Returns:
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The final prompt generated.
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"""
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full_examples = convert_to_examples(examples)
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data = [prefix] + [example.formatted for example in full_examples] + [suffix]
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template = example_separator.join(data)
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return cls(input_variables=input_variables, template=template)
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