llama-index

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from typing import List
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from llama_index.legacy.prompts.base import BasePromptTemplate
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def get_empty_prompt_txt(prompt: BasePromptTemplate) -> str:
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    """Get empty prompt text.
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    Substitute empty strings in parts of the prompt that have
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    not yet been filled out. Skip variables that have already
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    been partially formatted. This is used to compute the initial tokens.
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    """
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    partial_kargs = prompt.kwargs
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    empty_kwargs = {v: "" for v in prompt.template_vars if v not in partial_kargs}
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    all_kwargs = {**partial_kargs, **empty_kwargs}
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    return prompt.format(llm=None, **all_kwargs)
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def get_biggest_prompt(prompts: List[BasePromptTemplate]) -> BasePromptTemplate:
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    """Get biggest prompt.
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    Oftentimes we need to fetch the biggest prompt, in order to
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    be the most conservative about chunking text. This
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    is a helper utility for that.
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    """
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    empty_prompt_txts = [get_empty_prompt_txt(prompt) for prompt in prompts]
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    empty_prompt_txt_lens = [len(txt) for txt in empty_prompt_txts]
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    return prompts[empty_prompt_txt_lens.index(max(empty_prompt_txt_lens))]
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