120 lines
3.9 KiB
Python
120 lines
3.9 KiB
Python
# -*- coding: utf-8 -*-
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"""Interpret PEP 345 environment markers.
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EXPR [in|==|!=|not in] EXPR [or|and] ...
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where EXPR belongs to any of those:
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python_version = '%s.%s' % (sys.version_info[0], sys.version_info[1])
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python_full_version = sys.version.split()[0]
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os.name = os.name
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sys.platform = sys.platform
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platform.version = platform.version()
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platform.machine = platform.machine()
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platform.python_implementation = platform.python_implementation()
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a free string, like '2.6', or 'win32'
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"""
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__all__ = ['default_environment', 'compile', 'interpret']
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import ast
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import os
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import platform
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import sys
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import weakref
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_builtin_compile = compile
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try:
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from platform import python_implementation
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except ImportError:
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if os.name == "java":
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# Jython 2.5 has ast module, but not platform.python_implementation() function.
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def python_implementation():
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return "Jython"
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else:
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raise
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# restricted set of variables
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_VARS = {'sys.platform': sys.platform,
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'python_version': '%s.%s' % sys.version_info[:2],
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# FIXME parsing sys.platform is not reliable, but there is no other
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# way to get e.g. 2.7.2+, and the PEP is defined with sys.version
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'python_full_version': sys.version.split(' ', 1)[0],
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'os.name': os.name,
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'platform.version': platform.version(),
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'platform.machine': platform.machine(),
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'platform.python_implementation': python_implementation(),
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'extra': None # wheel extension
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}
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for var in list(_VARS.keys()):
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if '.' in var:
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_VARS[var.replace('.', '_')] = _VARS[var]
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def default_environment():
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"""Return copy of default PEP 385 globals dictionary."""
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return dict(_VARS)
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class ASTWhitelist(ast.NodeTransformer):
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def __init__(self, statement):
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self.statement = statement # for error messages
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ALLOWED = (ast.Compare, ast.BoolOp, ast.Attribute, ast.Name, ast.Load, ast.Str)
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# Bool operations
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ALLOWED += (ast.And, ast.Or)
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# Comparison operations
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ALLOWED += (ast.Eq, ast.Gt, ast.GtE, ast.In, ast.Is, ast.IsNot, ast.Lt, ast.LtE, ast.NotEq, ast.NotIn)
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def visit(self, node):
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"""Ensure statement only contains allowed nodes."""
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if not isinstance(node, self.ALLOWED):
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raise SyntaxError('Not allowed in environment markers.\n%s\n%s' %
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(self.statement,
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(' ' * node.col_offset) + '^'))
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return ast.NodeTransformer.visit(self, node)
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def visit_Attribute(self, node):
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"""Flatten one level of attribute access."""
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new_node = ast.Name("%s.%s" % (node.value.id, node.attr), node.ctx)
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return ast.copy_location(new_node, node)
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def parse_marker(marker):
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tree = ast.parse(marker, mode='eval')
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new_tree = ASTWhitelist(marker).generic_visit(tree)
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return new_tree
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def compile_marker(parsed_marker):
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return _builtin_compile(parsed_marker, '<environment marker>', 'eval',
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dont_inherit=True)
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_cache = weakref.WeakValueDictionary()
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def compile(marker):
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"""Return compiled marker as a function accepting an environment dict."""
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try:
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return _cache[marker]
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except KeyError:
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pass
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if not marker.strip():
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def marker_fn(environment=None, override=None):
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""""""
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return True
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else:
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compiled_marker = compile_marker(parse_marker(marker))
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def marker_fn(environment=None, override=None):
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"""override updates environment"""
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if override is None:
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override = {}
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if environment is None:
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environment = default_environment()
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environment.update(override)
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return eval(compiled_marker, environment)
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marker_fn.__doc__ = marker
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_cache[marker] = marker_fn
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return _cache[marker]
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def interpret(marker, environment=None):
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return compile(marker)(environment)
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