93 lines
2.8 KiB
Python
93 lines
2.8 KiB
Python
"""
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This module provides helper functions to find the first line of a function
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body.
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"""
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import ast
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class FindDefFirstLine(ast.NodeVisitor):
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"""
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Attributes
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----------
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first_stmt_line : int or None
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This stores the first statement line number if the definition is found.
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Or, ``None`` if the definition is not found.
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"""
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def __init__(self, code):
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"""
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Parameters
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----------
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code :
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The function's code object.
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"""
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self._co_name = code.co_name
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self._co_firstlineno = code.co_firstlineno
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self.first_stmt_line = None
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def _visit_children(self, node):
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for child in ast.iter_child_nodes(node):
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super().visit(child)
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def visit_FunctionDef(self, node: ast.FunctionDef):
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if node.name == self._co_name:
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# Name of function matches.
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# The `def` line may match co_firstlineno.
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possible_start_lines = set([node.lineno])
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if node.decorator_list:
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# Has decorators.
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# The first decorator line may match co_firstlineno.
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first_decor = node.decorator_list[0]
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possible_start_lines.add(first_decor.lineno)
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# Does the first lineno match?
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if self._co_firstlineno in possible_start_lines:
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# Yes, we found the function.
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# So, use the first statement line as the first line.
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if node.body:
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first_stmt = node.body[0]
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if _is_docstring(first_stmt):
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# Skip docstring
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first_stmt = node.body[1]
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self.first_stmt_line = first_stmt.lineno
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return
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else:
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# This is probably unreachable.
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# Function body cannot be bare. It must at least have
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# A const string for docstring or a `pass`.
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pass
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self._visit_children(node)
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def _is_docstring(node):
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if isinstance(node, ast.Expr):
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if (isinstance(node.value, ast.Constant)
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and isinstance(node.value.value, str)):
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return True
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return False
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def get_func_body_first_lineno(pyfunc):
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"""
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Look up the first line of function body using the file in
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``pyfunc.__code__.co_filename``.
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Returns
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-------
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lineno : int; or None
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The first line number of the function body; or ``None`` if the first
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line cannot be determined.
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"""
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co = pyfunc.__code__
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try:
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with open(co.co_filename) as fin:
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file_content = fin.read()
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except (FileNotFoundError, OSError):
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return
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else:
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tree = ast.parse(file_content)
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finder = FindDefFirstLine(co)
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finder.visit(tree)
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return finder.first_stmt_line
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