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pycdc did not reconstruct `match` statements: class patterns hit the
unhandled MATCH_CLASS opcode and bailed to "# WARNING: Decompyle incomplete",
and value patterns were mis-rendered as an if/elif chain.
This adds reconstruction of the common, statically-recognizable shapes:
* Class patterns - `case Cls(a, b):` - including positional captures and
`_` wildcard sub-patterns (`case Cls(_):`).
* Value patterns - `case 0:` / `case 'x':` - compiled as a COPY-threaded
COMPARE_OP chain rather than MATCH_CLASS.
* The `case _:` wildcard (which carries no test opcode).
A pre-scan over the code object recognizes the simple, guard-free shape of
each case and records it; the MATCH_CLASS handler and a small guarded hook in
COMPARE_OP open ASTMatchBlock/ASTCaseBlock and skip the pattern-test
machinery, and the block-close logic closes each case at its fail-target and
the match at its merge. Anything outside the recognized shape (kwarg patterns,
guards, sequence/mapping patterns) is left unregistered and still bails
honestly, so no incorrect output is produced.
New AST nodes: ASTMatchBlock (subject) and ASTCaseBlock (pattern), rendered
via the existing block-header machinery (type_str + print_src). PycBuffer
gains setPos() so the reconstructor can skip to a case body.
All hooks are guarded by per-offset match tables that are empty for code
without a match statement, so non-match input is unaffected.
Test: tests/input/match_statement.py exercises class patterns, a wildcard
sub-pattern, value patterns and `case _`. Full existing suite still passes.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
25 lines
579 B
Python
25 lines
579 B
Python
# 3.10+ structural pattern matching (match/case) reconstruction.
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def describe_point(command):
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match command:
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case Point(x, y):
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return f'point {x},{y}'
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case Rect(w, h):
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return f'rect {w}x{h}'
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case Wrapper(_):
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return 'wrapped'
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case _:
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return 'unknown'
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def classify(value):
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match value:
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case 0:
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result = 'zero'
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case 1:
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result = 'one'
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case 'hello':
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result = 'greeting'
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case _:
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result = 'other'
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return result
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