Source code for lineapy.instrumentation.control_flow_tracker

from dataclasses import dataclass, field
from typing import List, Optional

from import ControlNode, LineaID

[docs]@dataclass class ControlFlowTracker: # When dealing with control flow, we might encounter nested structures like: # # if <condition>: # if <another condition>: # <body> # else: # <else body> # # To deal with such recursive structures, we maintain a stack like data # structure as is popular in compilers as # (a) it ensures we are able to keep track of the outer `if` while dealing # with the inner `if` # (b) we do not need to rewrite all existing node_visitor functions to # account for the additional bookkeeping, as would be the case in # functional coding # # Whenever we encounter a new control flow node, like `if` in the example # above, we call push_node() below to add the node to the stack. # While the control flow node is in scope, it is kept on the stack, and for # all other nodes created in that duration, we simply call the method # current_control_dependency (which returns the innermost control flow node # currently in scope) for marking out control dependencies of each newly # generated node. # When the control flow node goes out of scope, we call pop_node() to pop # the control flow node from the stack, so that nodes generated in the # future do not depend on the popped control flow node. control_flow_node_stack: List[LineaID] = field(default_factory=list) def push_node(self, control_node_id: LineaID) -> None: self.control_flow_node_stack.append(control_node_id) def pop_node(self) -> LineaID: return self.control_flow_node_stack.pop() def current_control_dependency(self) -> Optional[LineaID]: return ( self.control_flow_node_stack[-1] if len(self.control_flow_node_stack) > 0 else None )
[docs]@dataclass class ControlFlowContext: # Wrapper used for the ControlFlowTracker. This class is used as a context # manager to ensure the programmer does not need to remember to call # pop_node for every push_node in the ControlFlowTracker above. control_node: ControlNode control_flow_tracker: ControlFlowTracker def __enter__(self) -> ControlNode: self.control_flow_tracker.push_node( return self.control_node def __exit__(self, exc_type, exc_value, exc_tb) -> None: self.control_flow_tracker.pop_node()