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Title: bpo-33416: Add end positions to Python AST by ilevkivskyi · Pull Request #11605 · python/cpython · GitHub

Open Graph Title: bpo-33416: Add end positions to Python AST by ilevkivskyi · Pull Request #11605 · python/cpython

X Title: bpo-33416: Add end positions to Python AST by ilevkivskyi · Pull Request #11605 · python/cpython

Description: The majority of this PR is tediously passing end_lineno and end_col_offset everywhere. Here are non-trivial points: It is not possible to reconstruct end positions in AST "on the fly", some information is lost after an AST node is constructed, so we need two more attributes for every AST node end_lineno and end_col_offset. I add end position information to both CST and AST. Although it may be technically possible to avoid adding end positions to CST, the code becomes more cumbersome and less efficient. Since the end position is not known for non-leaf CST nodes while the next token is added, this requires a bit of extra care (see _PyNode_FinalizeEndPos). Unless I made some mistake, the algorithm should be linear. For statements, I "trim" the end position of suites to not include the terminal newlines and dedent (this seems to be what people would expect), for example in class C: pass pass the end line and end column for the class definition is (2, 8). For end_col_offset I use the common Python convention for indexing, for example for pass the end_col_offset is 4 (not 3), so that [0:4] gives one the source code that corresponds to the node. I added a helper function ast.get_source_segment(), to get source text segment corresponding to a given AST node. It is also useful for testing. An (inevitable) downside of this PR is that AST now takes almost 25% more memory. I think however it is probably justified by the benefits. https://bugs.python.org/issue33416

Open Graph Description: The majority of this PR is tediously passing end_lineno and end_col_offset everywhere. Here are non-trivial points: It is not possible to reconstruct end positions in AST "on the fly", s...

X Description: The majority of this PR is tediously passing end_lineno and end_col_offset everywhere. Here are non-trivial points: It is not possible to reconstruct end positions in AST "on the fly&...

Opengraph URL: https://github.com/python/cpython/pull/11605

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