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Viewing changes to pypy/module/recparser/hooksamples/tracer.py

  • Committer: Bazaar Package Importer
  • Author(s): Alexandre Fayolle
  • Date: 2007-04-13 09:33:09 UTC
  • Revision ID: james.westby@ubuntu.com-20070413093309-yoojh4jcoocu2krz
Tags: upstream-1.0.0
Import upstream version 1.0.0

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pypy/module/recparser/hooksamples/tracer.py
 
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"""this one logs simple assignments and somewhat clearly shows
 
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that we need a nice API to define "joinpoints". Maybe a SAX-like
 
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(i.e. event-based) API ?
 
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XXX: crashes on everything else than simple assignment (AssAttr, etc.)
 
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"""
 
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from parser import ASTPrintnl, ASTConst, ASTName, ASTAssign, ASTMutator
 
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from parser import install_compiler_hook, source2ast
 
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BEFORE_LOG_SOURCE = """if '%s' in locals() or '%s' in globals():
 
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    print '(before) %s <--', locals().get('%s', globals().get('%s', '<XXX>'))
 
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"""
 
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AFTER_LOG_SOURCE = "print '(after) %s <--', %s"
 
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def get_statements(source):
 
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    module = source2ast(source)
 
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    return module.node.nodes
 
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class Tracer(ASTMutator):
 
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    def visitAssName(self, assname):
 
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        assign = assname
 
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        while not isinstance(assign, ASTAssign):
 
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            assign = assign.parent
 
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        stmt = assign.parent
 
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        varname = assname.name
 
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        before_stmts = get_statements(BEFORE_LOG_SOURCE % ((varname,) * 5))
 
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        after_stmts = get_statements(AFTER_LOG_SOURCE % (varname, varname))
 
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        stmt.insert_before(assign, before_stmts)
 
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        stmt.insert_after(assign, after_stmts)
 
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        return assname
 
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def _trace(ast, enc, filename):
 
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    return ast.accept(Tracer())
 
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install_compiler_hook(_trace)
 
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code = """
 
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a = 3
 
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b = 2
 
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a = 1
 
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"""
 
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exec code