mcpware

""" Utility functions for mcpware """ import logging import os import re from typing import Pattern logger = logging.getLogger(__name__) # Pre-compile regex pattern for better performance ENV_VAR_PATTERN: Pattern[str] = re.compile(r'\$\{([^}]+)\}') def substitute_env_vars(value: str, warn_missing: bool = True) -> str: """Substitute environment variables in a string. Args: value: String that may contain ${VAR_NAME} placeholders warn_missing: Whether to log warnings for missing variables Returns: String with environment variables substituted Example: >>> os.environ['TOKEN'] = 'secret123' >>> substitute_env_vars('Bearer ${TOKEN}') 'Bearer secret123' """ def replace_var(match: re.Match[str]) -> str: var_name = match.group(1) # Use walrus operator for cleaner code if (var_value := os.environ.get(var_name)) is not None: return var_value if warn_missing: logger.warning(f"Environment variable ${{{var_name}}} is not set") return match.group(0) # Return the original ${VAR_NAME} return ENV_VAR_PATTERN.sub(replace_var, value)