named_arg_block.py

# Copyright (c) Microsoft. All rights reserved.

import logging
from re import compile
from typing import TYPE_CHECKING, Any, ClassVar, Optional

from pydantic import model_validator

from semantic_kernel.exceptions import NamedArgBlockSyntaxError
from semantic_kernel.template_engine.blocks.block import Block
from semantic_kernel.template_engine.blocks.block_types import BlockTypes
from semantic_kernel.template_engine.blocks.val_block import ValBlock
from semantic_kernel.template_engine.blocks.var_block import VarBlock

if TYPE_CHECKING:
    from semantic_kernel.functions.kernel_arguments import KernelArguments
    from semantic_kernel.kernel import Kernel

logger: logging.Logger = logging.getLogger(__name__)

NAMED_ARG_REGEX = r"^(?P<name>[0-9A-Za-z_]+)[=]{1}(?P<value>[${1}](?P<var_name>[0-9A-Za-z_]+)|(?P<quote>[\"'])(?P<val>.[^\"^']*)(?P=quote))$"  # noqa: E501

NAMED_ARG_MATCHER = compile(NAMED_ARG_REGEX)


class NamedArgBlock(Block):
    """Create a named argument block.

    A named arg block is used to add arguments to a function call.
    It needs to be combined with a function_id block to be useful.
    Inside a code block, if the first block is a function_id block,
    the first block can be a variable or value block, anything else
    must be a named arg block.

    The value inside the NamedArgBlock can be a ValBlock or a VarBlock.

    Examples:
        {{ plugin.function arg1=$var }}
        {{ plugin.function arg1='value' }}
        {{ plugin.function 'value' arg2=$var }}
        {{ plugin.function $var arg2='value' }}
        {{ plugin_function arg1=$var1 arg2=$var2 arg3='value' }}

    Args:
        content - str : The content of the named argument block,
            the name and value separated by an equal sign, for instance arg1=$var.
        name - str: The name of the argument.
        value - ValBlock: The value of the argument.
        variable - VarBlock: The variable of the argument.
            Either the value or variable field is used.

    Raises:
        NamedArgBlockSyntaxError: If the content does not match the named argument syntax.

    """

    type: ClassVar[BlockTypes] = BlockTypes.NAMED_ARG
    name: str | None = None
    value: ValBlock | None = None
    variable: VarBlock | None = None

    @model_validator(mode="before")
    @classmethod
    def parse_content(cls, fields: Any) -> Any:
        """Parse the content of the named argument block and extract the name and value.

        If the name and either value or variable is present the parsing is skipped.
        Otherwise, the content is parsed using a regex to extract the name and value.
        Those are then turned into Blocks.

        Raises:
            NamedArgBlockSyntaxError: If the content does not match the named argument syntax.
        """
        if isinstance(fields, Block) or ("name" in fields and ("value" in fields or "variable" in fields)):
            return fields
        content = fields.get("content", "").strip()
        matches = NAMED_ARG_MATCHER.match(content)
        if not matches:
            raise NamedArgBlockSyntaxError(content=content)
        matches_dict = matches.groupdict()
        if name := matches_dict.get("name"):
            fields["name"] = name
        if value := matches_dict.get("value"):
            if matches_dict.get("var_name"):
                fields["variable"] = VarBlock(content=value, name=matches_dict["var_name"])
            elif matches_dict.get("val"):
                fields["value"] = ValBlock(content=value, value=matches_dict["val"], quote=matches_dict["quote"])
        return fields

    def render(self, kernel: "Kernel", arguments: Optional["KernelArguments"] = None) -> Any:
        """Render the named argument block."""
        if self.value:
            return self.value.render()
        if arguments is None:
            return ""
        if self.variable:
            return self.variable.render(kernel, arguments)
        return None