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xgrammar

Backend class for XGrammar.

XGrammarBackend

Bases: BaseBackend

Backend for XGRammar.

Source code in outlines/backends/xgrammar.py 
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class XGrammarBackend(BaseBackend):
    """Backend for XGRammar."""

    def __init__(self, model: SteerableModel):
        """
        Parameters
        ----------
        model
            The Outlines model of the user.

        """
        import xgrammar as xgr
        from transformers import AutoConfig

        if not isinstance(model, Transformers):
            raise ValueError(
                "The xgrammar backend only supports Transformers models"
            )

        vocab_size = AutoConfig.from_pretrained(
            model.model.config._name_or_path
        ).vocab_size
        tokenizer_info = xgr.TokenizerInfo.from_huggingface(
            model.hf_tokenizer,
            vocab_size=vocab_size
        )
        self.grammar_compiler = xgr.GrammarCompiler(tokenizer_info)

    def get_json_schema_logits_processor(
        self, json_schema: str
    ) -> "LogitsProcessor":
        """Create a logits processor from a JSON schema.

        Parameters
        ----------
        json_schema: str
            The JSON schema to create a logits processor from.

        Returns
        -------
        LogitsProcessor
            The logits processor to use to constrain the generation.

        """
        compiled_grammar = self.grammar_compiler.compile_json_schema(
            json_schema
        )
        return XGrammarLogitsProcessor(compiled_grammar)

    def get_regex_logits_processor(self, regex: str) -> "LogitsProcessor":
        """Create a logits processor from a regex.

        Parameters
        ----------
        regex: str
            The regex to create a logits processor from.

        Returns
        -------
        LogitsProcessor
            The logits processor to use to constrain the generation.

        """
        compiled_grammar = self.grammar_compiler.compile_regex(regex)
        return XGrammarLogitsProcessor(compiled_grammar)

    def get_cfg_logits_processor(self, grammar: str) -> "LogitsProcessor":
        """Create a logits processor from a context-free grammar.

        Parameters
        ----------
        grammar: str
            The context-free grammar to create a logits processor from.

        Returns
        -------
        LogitsProcessor
            The logits processor to use to constrain the generation.

        """
        compiled_grammar = self.grammar_compiler.compile_grammar(grammar)
        return XGrammarLogitsProcessor(compiled_grammar)

__init__(model)

Parameters:

Name Type Description Default
model SteerableModel

The Outlines model of the user.

 required
Source code in outlines/backends/xgrammar.py 
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def __init__(self, model: SteerableModel):
    """
    Parameters
    ----------
    model
        The Outlines model of the user.

    """
    import xgrammar as xgr
    from transformers import AutoConfig

    if not isinstance(model, Transformers):
        raise ValueError(
            "The xgrammar backend only supports Transformers models"
        )

    vocab_size = AutoConfig.from_pretrained(
        model.model.config._name_or_path
    ).vocab_size
    tokenizer_info = xgr.TokenizerInfo.from_huggingface(
        model.hf_tokenizer,
        vocab_size=vocab_size
    )
    self.grammar_compiler = xgr.GrammarCompiler(tokenizer_info)

get_cfg_logits_processor(grammar)

Create a logits processor from a context-free grammar.

Parameters:

Name Type Description Default
grammar str

The context-free grammar to create a logits processor from.

 required

Returns:

Type Description
LogitsProcessor

The logits processor to use to constrain the generation.
Source code in outlines/backends/xgrammar.py 
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def get_cfg_logits_processor(self, grammar: str) -> "LogitsProcessor":
    """Create a logits processor from a context-free grammar.

    Parameters
    ----------
    grammar: str
        The context-free grammar to create a logits processor from.

    Returns
    -------
    LogitsProcessor
        The logits processor to use to constrain the generation.

    """
    compiled_grammar = self.grammar_compiler.compile_grammar(grammar)
    return XGrammarLogitsProcessor(compiled_grammar)

get_json_schema_logits_processor(json_schema)

Create a logits processor from a JSON schema.

Parameters:

Name Type Description Default
json_schema str

The JSON schema to create a logits processor from.

 required

Returns:

Type Description
LogitsProcessor

The logits processor to use to constrain the generation.
Source code in outlines/backends/xgrammar.py 
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def get_json_schema_logits_processor(
    self, json_schema: str
) -> "LogitsProcessor":
    """Create a logits processor from a JSON schema.

    Parameters
    ----------
    json_schema: str
        The JSON schema to create a logits processor from.

    Returns
    -------
    LogitsProcessor
        The logits processor to use to constrain the generation.

    """
    compiled_grammar = self.grammar_compiler.compile_json_schema(
        json_schema
    )
    return XGrammarLogitsProcessor(compiled_grammar)

get_regex_logits_processor(regex)

Create a logits processor from a regex.

Parameters:

Name Type Description Default
regex str

The regex to create a logits processor from.

 required

Returns:

Type Description
LogitsProcessor

The logits processor to use to constrain the generation.
Source code in outlines/backends/xgrammar.py 
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def get_regex_logits_processor(self, regex: str) -> "LogitsProcessor":
    """Create a logits processor from a regex.

    Parameters
    ----------
    regex: str
        The regex to create a logits processor from.

    Returns
    -------
    LogitsProcessor
        The logits processor to use to constrain the generation.

    """
    compiled_grammar = self.grammar_compiler.compile_regex(regex)
    return XGrammarLogitsProcessor(compiled_grammar)

XGrammarLogitsProcessor

Bases: OutlinesLogitsProcessor

Logits processor for XGrammar.

This class wraps the xgr.contrib.hf.LogitsProcessor class and adds a reset method to reset the logits processor for a new generation.

Source code in outlines/backends/xgrammar.py 
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class XGrammarLogitsProcessor(OutlinesLogitsProcessor):
    """Logits processor for XGrammar.

    This class wraps the `xgr.contrib.hf.LogitsProcessor` class and adds
    a `reset` method to reset the logits processor for a new generation.

    """

    def __init__(self, compiled_grammar: str):
        """
        Parameters
        ----------
        compiled_grammar: str
            The compiled grammar to use to create the logits processor.

        """
        import xgrammar as xgr

        self.xgr = xgr
        self.compiled_grammar = compiled_grammar
        self.xgrammar_logits_processor = None
        super().__init__("torch")

    def reset(self):
        """Reset the logits processor for a new generation."""
        self.xgrammar_logits_processor = None

    def process_logits(self, input_ids: TensorType, logits: TensorType) -> TensorType:
        """Bias the logits."""
        if self.xgrammar_logits_processor is None:
            self.xgrammar_logits_processor = self.xgr.contrib.hf.LogitsProcessor(
                self.compiled_grammar
            )
        return self.xgrammar_logits_processor(input_ids, logits) # type: ignore

__init__(compiled_grammar)

Parameters:

Name Type Description Default
compiled_grammar str

The compiled grammar to use to create the logits processor.

 required
Source code in outlines/backends/xgrammar.py 
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def __init__(self, compiled_grammar: str):
    """
    Parameters
    ----------
    compiled_grammar: str
        The compiled grammar to use to create the logits processor.

    """
    import xgrammar as xgr

    self.xgr = xgr
    self.compiled_grammar = compiled_grammar
    self.xgrammar_logits_processor = None
    super().__init__("torch")

process_logits(input_ids, logits)

Bias the logits.

Source code in outlines/backends/xgrammar.py 
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def process_logits(self, input_ids: TensorType, logits: TensorType) -> TensorType:
    """Bias the logits."""
    if self.xgrammar_logits_processor is None:
        self.xgrammar_logits_processor = self.xgr.contrib.hf.LogitsProcessor(
            self.compiled_grammar
        )
    return self.xgrammar_logits_processor(input_ids, logits) # type: ignore

reset()

Reset the logits processor for a new generation.

Source code in outlines/backends/xgrammar.py 
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def reset(self):
    """Reset the logits processor for a new generation."""
    self.xgrammar_logits_processor = None