60 lines
2.0 KiB
Python
60 lines
2.0 KiB
Python
"""
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This is a module for various lookup functions:
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functions that will find a semantic node by its name.
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"""
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from mypy.nodes import MypyFile, SymbolTableNode, TypeInfo
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from typing import Dict, Optional
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# TODO: gradually move existing lookup functions to this module.
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def lookup_fully_qualified(name: str, modules: Dict[str, MypyFile], *,
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raise_on_missing: bool = False) -> Optional[SymbolTableNode]:
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"""Find a symbol using it fully qualified name.
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The algorithm has two steps: first we try splitting the name on '.' to find
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the module, then iteratively look for each next chunk after a '.' (e.g. for
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nested classes).
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This function should *not* be used to find a module. Those should be looked
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in the modules dictionary.
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"""
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head = name
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rest = []
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# 1. Find a module tree in modules dictionary.
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while True:
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if '.' not in head:
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if raise_on_missing:
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assert '.' in head, f"Cannot find module for {name}"
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return None
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head, tail = head.rsplit('.', maxsplit=1)
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rest.append(tail)
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mod = modules.get(head)
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if mod is not None:
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break
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names = mod.names
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# 2. Find the symbol in the module tree.
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if not rest:
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# Looks like a module, don't use this to avoid confusions.
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if raise_on_missing:
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assert rest, f"Cannot find {name}, got a module symbol"
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return None
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while True:
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key = rest.pop()
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if key not in names:
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if raise_on_missing:
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assert key in names, f"Cannot find component {key!r} for {name!r}"
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return None
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stnode = names[key]
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if not rest:
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return stnode
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node = stnode.node
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# In fine-grained mode, could be a cross-reference to a deleted module
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# or a Var made up for a missing module.
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if not isinstance(node, TypeInfo):
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if raise_on_missing:
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assert node, f"Cannot find {name}"
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return None
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names = node.names
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