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85 lines
2.6 KiB
Python
Executable File
85 lines
2.6 KiB
Python
Executable File
#!/usr/bin/env python3
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from __future__ import print_function
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import sys
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from pycparser import c_parser, c_generator, c_ast, plyparser
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from pycparser.ply import yacc
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with open("paren/stddef") as f:
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STDDEF = f.read()
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class CParser(c_parser.CParser):
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def __init__(self, *a, **kw):
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super(CParser, self).__init__(*a, **kw)
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self.cparser = yacc.yacc(
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module=self,
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start='expression',
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debug=kw.get('yacc_debug', False),
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errorlog=yacc.NullLogger(),
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optimize=kw.get('yacc_optimize', True),
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tabmodule=kw.get('yacctab', 'yacctab'))
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def parse(self, text, filename='', debuglevel=0):
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self.clex.filename = filename
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self.clex.reset_lineno()
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self._scope_stack = [dict()]
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self._last_yielded_token = None
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for name in STDDEF.split('\n'):
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if name:
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self._add_typedef_name(name, None)
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return self.cparser.parse(
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input=text,
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lexer=self.clex,
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debug=debuglevel)
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class CGenerator(c_generator.CGenerator):
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def _is_simple_node(self, n):
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return isinstance(n, (c_ast.Constant, c_ast.ID, c_ast.FuncCall))
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def visit_UnaryOp(self, n):
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# don't parenthesize an operand to sizeof if it's not a type
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if n.op == 'sizeof':
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if isinstance(n.expr, c_ast.Typename):
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return 'sizeof (%s)' % self.visit(n.expr)
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else:
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return 'sizeof %s' % self._parenthesize_unless_simple(n.expr)
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else:
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operand = self.visit(n.expr)
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if isinstance(n.expr, c_ast.ArrayRef) or not self._is_simple_node(n.expr):
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operand = '(%s)' % operand
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if n.op in ('p++', 'p--'):
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return operand + n.op[1:]
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else:
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return n.op + operand
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def visit_TernaryOp(self, n):
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return '({0}) ? ({1}) : ({2})'.format(
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self.visit(n.cond),
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self.visit(n.iftrue),
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self.visit(n.iffalse))
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def visit_Assignment(self, n):
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return '%s %s %s' % (self.visit(n.lvalue), n.op, self._parenthesize_unless_simple(n.rvalue))
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def parenthesize(source):
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parser = CParser(yacc_optimize=False)
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try:
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ast = parser.parse(source, '<input>')
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except plyparser.ParseError as e:
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print("Error: " + e.args[0])
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return
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generator = CGenerator()
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print(generator.visit(ast))
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if __name__ == "__main__":
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if len(sys.argv) > 1:
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parenthesize(' '.join(sys.argv[1:]).rstrip(';'))
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elif len(sys.argv) == 1:
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print("Usage: paren <expression>")
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else:
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print('error')
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