wehub-resource-sync
100 lines
3.4 KiB
Python
100 lines
3.4 KiB
Python
# Copyright (c) Microsoft. All rights reserved.
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import logging
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from re import compile
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from typing import TYPE_CHECKING, Any, ClassVar, Optional
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from pydantic import model_validator
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from semantic_kernel.exceptions import VarBlockRenderError, VarBlockSyntaxError
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from semantic_kernel.template_engine.blocks.block import Block
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from semantic_kernel.template_engine.blocks.block_types import BlockTypes
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from semantic_kernel.template_engine.blocks.symbols import Symbols
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if TYPE_CHECKING:
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from semantic_kernel.functions.kernel_arguments import KernelArguments
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from semantic_kernel.kernel import Kernel
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logger: logging.Logger = logging.getLogger(__name__)
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VAR_BLOCK_REGEX = r"^[${1}](?P<name>[0-9A-Za-z_]+)$"
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VAR_BLOCK_MATCHER = compile(VAR_BLOCK_REGEX)
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class VarBlock(Block):
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"""Create a variable block.
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A variable block is used to add a variable to a template.
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It gets rendered from KernelArguments, if the variable is not found
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a warning is logged and an empty string is returned.
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The variable must start with $ and be followed by a valid variable name.
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A valid variable name is a string of letters, numbers and underscores.
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Examples:
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$var
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$test_var
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Args:
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content - str : The content of the variable block, the name of the variable.
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name - str: The name of the variable.
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Raises:
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VarBlockSyntaxError: If the content does not match the variable syntax.
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"""
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type: ClassVar[BlockTypes] = BlockTypes.VARIABLE
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name: str = ""
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@model_validator(mode="before")
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@classmethod
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def parse_content(cls, fields: Any) -> Any:
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"""Parse the content and extract the name.
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The parsing is based on a regex that returns the name.
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if the 'name' is already present then the parsing is skipped.
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"""
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if isinstance(fields, Block) or "name" in fields:
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return fields
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content = fields.get("content", "").strip()
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matches = VAR_BLOCK_MATCHER.match(content)
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if not matches:
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raise VarBlockSyntaxError(content=content)
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if name := matches.groupdict().get("name"):
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fields["name"] = name
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return fields
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def render(self, _: "Kernel", arguments: Optional["KernelArguments"] = None) -> str:
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"""Render the variable block with the given arguments.
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If the variable is not found in the arguments, return an empty string.
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"""
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if arguments is None:
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return ""
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value = arguments.get(self.name, None)
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if value is None:
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logger.warning(f"Variable `{Symbols.VAR_PREFIX}: {self.name}` not found in the KernelArguments")
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return ""
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try:
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return str(value)
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except Exception as e:
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raise VarBlockRenderError(
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f"Block {self.name} failed to be parsed to a string, type is {type(value)}"
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) from e
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def get_value(self, arguments: "KernelArguments | None" = None) -> Any:
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"""Get the raw value of the variable from arguments without converting to string.
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This is used when passing arguments to functions to preserve their original types.
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Args:
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arguments: The KernelArguments to get the value from.
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Returns:
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The raw value from the arguments, or None if not found.
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"""
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if arguments is None:
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return None
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return arguments.get(self.name, None)
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