281 lines
9.5 KiB
Python
281 lines
9.5 KiB
Python
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#
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# TreeFragments - parsing of strings to trees
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#
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"""
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Support for parsing strings into code trees.
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"""
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from __future__ import absolute_import
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import re
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from io import StringIO
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from .Scanning import PyrexScanner, StringSourceDescriptor
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from .Symtab import ModuleScope
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from . import PyrexTypes
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from .Visitor import VisitorTransform
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from .Nodes import Node, StatListNode
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from .ExprNodes import NameNode
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from .StringEncoding import _unicode
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from . import Parsing
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from . import Main
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from . import UtilNodes
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class StringParseContext(Main.Context):
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def __init__(self, name, include_directories=None, compiler_directives=None, cpp=False):
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if include_directories is None:
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include_directories = []
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if compiler_directives is None:
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compiler_directives = {}
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Main.Context.__init__(self, include_directories, compiler_directives, cpp=cpp, language_level='3str')
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self.module_name = name
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def find_module(self, module_name, from_module=None, pos=None, need_pxd=1, absolute_fallback=True, relative_import=False):
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if module_name not in (self.module_name, 'cython'):
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raise AssertionError("Not yet supporting any cimports/includes from string code snippets")
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return ModuleScope(module_name, parent_module=None, context=self)
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def parse_from_strings(name, code, pxds=None, level=None, initial_pos=None,
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context=None, allow_struct_enum_decorator=False,
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in_utility_code=False):
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"""
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Utility method to parse a (unicode) string of code. This is mostly
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used for internal Cython compiler purposes (creating code snippets
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that transforms should emit, as well as unit testing).
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code - a unicode string containing Cython (module-level) code
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name - a descriptive name for the code source (to use in error messages etc.)
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in_utility_code - used to suppress some messages from utility code. False by default
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because some generated code snippets like properties and dataclasses
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probably want to see those messages.
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RETURNS
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The tree, i.e. a ModuleNode. The ModuleNode's scope attribute is
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set to the scope used when parsing.
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"""
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if context is None:
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context = StringParseContext(name)
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# Since source files carry an encoding, it makes sense in this context
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# to use a unicode string so that code fragments don't have to bother
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# with encoding. This means that test code passed in should not have an
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# encoding header.
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assert isinstance(code, _unicode), "unicode code snippets only please"
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encoding = "UTF-8"
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module_name = name
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if initial_pos is None:
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initial_pos = (name, 1, 0)
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code_source = StringSourceDescriptor(name, code)
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if in_utility_code:
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code_source.in_utility_code = True
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scope = context.find_module(module_name, pos=initial_pos, need_pxd=False)
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buf = StringIO(code)
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scanner = PyrexScanner(buf, code_source, source_encoding = encoding,
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scope = scope, context = context, initial_pos = initial_pos)
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ctx = Parsing.Ctx(allow_struct_enum_decorator=allow_struct_enum_decorator)
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if level is None:
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tree = Parsing.p_module(scanner, 0, module_name, ctx=ctx)
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tree.scope = scope
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tree.is_pxd = False
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else:
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tree = Parsing.p_code(scanner, level=level, ctx=ctx)
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tree.scope = scope
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return tree
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class TreeCopier(VisitorTransform):
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def visit_Node(self, node):
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if node is None:
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return node
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else:
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c = node.clone_node()
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self.visitchildren(c)
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return c
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class ApplyPositionAndCopy(TreeCopier):
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def __init__(self, pos):
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super(ApplyPositionAndCopy, self).__init__()
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self.pos = pos
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def visit_Node(self, node):
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copy = super(ApplyPositionAndCopy, self).visit_Node(node)
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copy.pos = self.pos
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return copy
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class TemplateTransform(VisitorTransform):
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"""
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Makes a copy of a template tree while doing substitutions.
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A dictionary "substitutions" should be passed in when calling
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the transform; mapping names to replacement nodes. Then replacement
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happens like this:
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- If an ExprStatNode contains a single NameNode, whose name is
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a key in the substitutions dictionary, the ExprStatNode is
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replaced with a copy of the tree given in the dictionary.
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It is the responsibility of the caller that the replacement
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node is a valid statement.
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- If a single NameNode is otherwise encountered, it is replaced
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if its name is listed in the substitutions dictionary in the
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same way. It is the responsibility of the caller to make sure
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that the replacement nodes is a valid expression.
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Also a list "temps" should be passed. Any names listed will
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be transformed into anonymous, temporary names.
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Currently supported for tempnames is:
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NameNode
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(various function and class definition nodes etc. should be added to this)
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Each replacement node gets the position of the substituted node
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recursively applied to every member node.
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"""
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temp_name_counter = 0
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def __call__(self, node, substitutions, temps, pos):
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self.substitutions = substitutions
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self.pos = pos
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tempmap = {}
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temphandles = []
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for temp in temps:
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TemplateTransform.temp_name_counter += 1
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handle = UtilNodes.TempHandle(PyrexTypes.py_object_type)
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tempmap[temp] = handle
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temphandles.append(handle)
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self.tempmap = tempmap
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result = super(TemplateTransform, self).__call__(node)
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if temps:
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result = UtilNodes.TempsBlockNode(self.get_pos(node),
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temps=temphandles,
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body=result)
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return result
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def get_pos(self, node):
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if self.pos:
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return self.pos
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else:
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return node.pos
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def visit_Node(self, node):
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if node is None:
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return None
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else:
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c = node.clone_node()
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if self.pos is not None:
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c.pos = self.pos
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self.visitchildren(c)
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return c
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def try_substitution(self, node, key):
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sub = self.substitutions.get(key)
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if sub is not None:
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pos = self.pos
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if pos is None: pos = node.pos
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return ApplyPositionAndCopy(pos)(sub)
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else:
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return self.visit_Node(node) # make copy as usual
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def visit_NameNode(self, node):
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temphandle = self.tempmap.get(node.name)
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if temphandle:
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# Replace name with temporary
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return temphandle.ref(self.get_pos(node))
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else:
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return self.try_substitution(node, node.name)
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def visit_ExprStatNode(self, node):
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# If an expression-as-statement consists of only a replaceable
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# NameNode, we replace the entire statement, not only the NameNode
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if isinstance(node.expr, NameNode):
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return self.try_substitution(node, node.expr.name)
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else:
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return self.visit_Node(node)
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def copy_code_tree(node):
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return TreeCopier()(node)
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_match_indent = re.compile(u"^ *").match
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def strip_common_indent(lines):
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"""Strips empty lines and common indentation from the list of strings given in lines"""
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# TODO: Facilitate textwrap.indent instead
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lines = [x for x in lines if x.strip() != u""]
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if lines:
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minindent = min([len(_match_indent(x).group(0)) for x in lines])
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lines = [x[minindent:] for x in lines]
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return lines
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class TreeFragment(object):
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def __init__(self, code, name=None, pxds=None, temps=None, pipeline=None, level=None, initial_pos=None):
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if pxds is None:
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pxds = {}
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if temps is None:
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temps = []
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if pipeline is None:
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pipeline = []
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if not name:
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name = "(tree fragment)"
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if isinstance(code, _unicode):
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def fmt(x): return u"\n".join(strip_common_indent(x.split(u"\n")))
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fmt_code = fmt(code)
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fmt_pxds = {}
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for key, value in pxds.items():
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fmt_pxds[key] = fmt(value)
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mod = t = parse_from_strings(name, fmt_code, fmt_pxds, level=level, initial_pos=initial_pos)
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if level is None:
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t = t.body # Make sure a StatListNode is at the top
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if not isinstance(t, StatListNode):
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t = StatListNode(pos=mod.pos, stats=[t])
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for transform in pipeline:
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if transform is None:
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continue
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t = transform(t)
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self.root = t
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elif isinstance(code, Node):
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if pxds:
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raise NotImplementedError()
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self.root = code
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else:
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raise ValueError("Unrecognized code format (accepts unicode and Node)")
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self.temps = temps
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def copy(self):
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return copy_code_tree(self.root)
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def substitute(self, nodes=None, temps=None, pos = None):
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if nodes is None:
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nodes = {}
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if temps is None:
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temps = []
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return TemplateTransform()(self.root,
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substitutions = nodes,
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temps = self.temps + temps, pos = pos)
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class SetPosTransform(VisitorTransform):
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def __init__(self, pos):
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super(SetPosTransform, self).__init__()
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self.pos = pos
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def visit_Node(self, node):
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node.pos = self.pos
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self.visitchildren(node)
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return node
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