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- # -*- coding: utf-8 -*-
- """
- codegen
- ~~~~~~~
- Extension to ast that allow ast -> python code generation.
- :copyright: Copyright 2008 by Armin Ronacher.
- :license: BSD.
- """
- from ast import *
- BOOLOP_SYMBOLS = {
- And: 'and',
- Or: 'or'
- }
- BINOP_SYMBOLS = {
- Add: '+',
- Sub: '-',
- Mult: '*',
- Div: '/',
- FloorDiv: '//',
- Mod: '%',
- LShift: '<<',
- RShift: '>>',
- BitOr: '|',
- BitAnd: '&',
- BitXor: '^'
- }
- CMPOP_SYMBOLS = {
- Eq: '==',
- Gt: '>',
- GtE: '>=',
- In: 'in',
- Is: 'is',
- IsNot: 'is not',
- Lt: '<',
- LtE: '<=',
- NotEq: '!=',
- NotIn: 'not in'
- }
- UNARYOP_SYMBOLS = {
- Invert: '~',
- Not: 'not',
- UAdd: '+',
- USub: '-'
- }
- ALL_SYMBOLS = {}
- ALL_SYMBOLS.update(BOOLOP_SYMBOLS)
- ALL_SYMBOLS.update(BINOP_SYMBOLS)
- ALL_SYMBOLS.update(CMPOP_SYMBOLS)
- ALL_SYMBOLS.update(UNARYOP_SYMBOLS)
- def to_source(node, indent_with=' ' * 4, add_line_information=False):
- """This function can convert a node tree back into python sourcecode.
- This is useful for debugging purposes, especially if you're dealing with
- custom asts not generated by python itself.
- It could be that the sourcecode is evaluable when the AST itself is not
- compilable / evaluable. The reason for this is that the AST contains some
- more data than regular sourcecode does, which is dropped during
- conversion.
- Each level of indentation is replaced with `indent_with`. Per default this
- parameter is equal to four spaces as suggested by PEP 8, but it might be
- adjusted to match the application's styleguide.
- If `add_line_information` is set to `True` comments for the line numbers
- of the nodes are added to the output. This can be used to spot wrong line
- number information of statement nodes.
- """
- generator = SourceGenerator(indent_with, add_line_information)
- generator.visit(node)
- return ''.join(generator.result)
- class SourceGenerator(NodeVisitor):
- """This visitor is able to transform a well formed syntax tree into python
- sourcecode. For more details have a look at the docstring of the
- `node_to_source` function.
- """
- def __init__(self, indent_with, add_line_information=False):
- self.result = []
- self.indent_with = indent_with
- self.add_line_information = add_line_information
- self.indentation = 0
- self.new_lines = 0
- def write(self, x):
- if self.new_lines:
- if self.result:
- self.result.append('\n' * self.new_lines)
- self.result.append(self.indent_with * self.indentation)
- self.new_lines = 0
- self.result.append(x)
- def newline(self, node=None, extra=0):
- self.new_lines = max(self.new_lines, 1 + extra)
- if node is not None and self.add_line_information:
- self.write('# line: %s' % node.lineno)
- self.new_lines = 1
- def body(self, statements):
- self.new_line = True
- self.indentation += 1
- for stmt in statements:
- self.visit(stmt)
- self.indentation -= 1
- def body_or_else(self, node):
- self.body(node.body)
- if node.orelse:
- self.newline()
- self.write('else:')
- self.body(node.orelse)
- def signature(self, node):
- want_comma = []
- def write_comma():
- if want_comma:
- self.write(', ')
- else:
- want_comma.append(True)
- padding = [None] * (len(node.args) - len(node.defaults))
- for arg, default in zip(node.args, padding + node.defaults):
- write_comma()
- self.visit(arg)
- if default is not None:
- self.write('=')
- self.visit(default)
- if node.vararg is not None:
- write_comma()
- self.write('*' + node.vararg)
- if node.kwarg is not None:
- write_comma()
- self.write('**' + node.kwarg)
- def decorators(self, node):
- for decorator in node.decorator_list:
- self.newline(decorator)
- self.write('@')
- self.visit(decorator)
- # Statements
- def visit_Assign(self, node):
- self.newline(node)
- for idx, target in enumerate(node.targets):
- if idx:
- self.write(', ')
- self.visit(target)
- self.write(' = ')
- self.visit(node.value)
- def visit_AugAssign(self, node):
- self.newline(node)
- self.visit(node.target)
- self.write(BINOP_SYMBOLS[type(node.op)] + '=')
- self.visit(node.value)
- def visit_ImportFrom(self, node):
- self.newline(node)
- self.write('from %s%s import ' % ('.' * node.level, node.module))
- for idx, item in enumerate(node.names):
- if idx:
- self.write(', ')
- self.write(item)
- def visit_Import(self, node):
- self.newline(node)
- for item in node.names:
- self.write('import ')
- self.visit(item)
- def visit_Expr(self, node):
- self.newline(node)
- self.generic_visit(node)
- def visit_FunctionDef(self, node):
- self.newline(extra=1)
- self.decorators(node)
- self.newline(node)
- self.write('def %s(' % node.name)
- self.signature(node.args)
- self.write('):')
- self.body(node.body)
- def visit_ClassDef(self, node):
- have_args = []
- def paren_or_comma():
- if have_args:
- self.write(', ')
- else:
- have_args.append(True)
- self.write('(')
- self.newline(extra=2)
- self.decorators(node)
- self.newline(node)
- self.write('class %s' % node.name)
- for base in node.bases:
- paren_or_comma()
- self.visit(base)
- # XXX: the if here is used to keep this module compatible
- # with python 2.6.
- if hasattr(node, 'keywords'):
- for keyword in node.keywords:
- paren_or_comma()
- self.write(keyword.arg + '=')
- self.visit(keyword.value)
- if hasattr(node, 'starargs') and node.starargs is not None:
- paren_or_comma()
- self.write('*')
- self.visit(node.starargs)
- if hasattr(node, 'kwargs') and node.kwargs is not None:
- paren_or_comma()
- self.write('**')
- self.visit(node.kwargs)
- self.write(have_args and '):' or ':')
- self.body(node.body)
- def visit_If(self, node):
- self.newline(node)
- self.write('if ')
- self.visit(node.test)
- self.write(':')
- self.body(node.body)
- while True:
- else_ = node.orelse
- if len(else_) == 1 and isinstance(else_[0], If):
- node = else_[0]
- self.newline()
- self.write('elif ')
- self.visit(node.test)
- self.write(':')
- self.body(node.body)
- else:
- self.newline()
- self.write('else:')
- self.body(else_)
- break
- def visit_For(self, node):
- self.newline(node)
- self.write('for ')
- self.visit(node.target)
- self.write(' in ')
- self.visit(node.iter)
- self.write(':')
- self.body_or_else(node)
- def visit_While(self, node):
- self.newline(node)
- self.write('while ')
- self.visit(node.test)
- self.write(':')
- self.body_or_else(node)
- def visit_With(self, node):
- self.newline(node)
- self.write('with ')
- self.visit(node.context_expr)
- if node.optional_vars is not None:
- self.write(' as ')
- self.visit(node.optional_vars)
- self.write(':')
- self.body(node.body)
- def visit_Pass(self, node):
- self.newline(node)
- self.write('pass')
- def visit_Print(self, node):
- # XXX: python 2.6 only
- self.newline(node)
- self.write('print ')
- want_comma = False
- if node.dest is not None:
- self.write(' >> ')
- self.visit(node.dest)
- want_comma = True
- for value in node.values:
- if want_comma:
- self.write(', ')
- self.visit(value)
- want_comma = True
- if not node.nl:
- self.write(',')
- def visit_Delete(self, node):
- self.newline(node)
- self.write('del ')
- for idx, target in enumerate(node):
- if idx:
- self.write(', ')
- self.visit(target)
- def visit_TryExcept(self, node):
- self.newline(node)
- self.write('try:')
- self.body(node.body)
- for handler in node.handlers:
- self.visit(handler)
- def visit_TryFinally(self, node):
- self.newline(node)
- self.write('try:')
- self.body(node.body)
- self.newline(node)
- self.write('finally:')
- self.body(node.finalbody)
- def visit_Global(self, node):
- self.newline(node)
- self.write('global ' + ', '.join(node.names))
- def visit_Nonlocal(self, node):
- self.newline(node)
- self.write('nonlocal ' + ', '.join(node.names))
- def visit_Return(self, node):
- self.newline(node)
- self.write('return ')
- self.visit(node.value)
- def visit_Break(self, node):
- self.newline(node)
- self.write('break')
- def visit_Continue(self, node):
- self.newline(node)
- self.write('continue')
- def visit_Raise(self, node):
- # XXX: Python 2.6 / 3.0 compatibility
- self.newline(node)
- self.write('raise')
- if hasattr(node, 'exc') and node.exc is not None:
- self.write(' ')
- self.visit(node.exc)
- if node.cause is not None:
- self.write(' from ')
- self.visit(node.cause)
- elif hasattr(node, 'type') and node.type is not None:
- self.visit(node.type)
- if node.inst is not None:
- self.write(', ')
- self.visit(node.inst)
- if node.tback is not None:
- self.write(', ')
- self.visit(node.tback)
- # Expressions
- def visit_Attribute(self, node):
- self.visit(node.value)
- self.write('.' + node.attr)
- def visit_Call(self, node):
- want_comma = []
- def write_comma():
- if want_comma:
- self.write(', ')
- else:
- want_comma.append(True)
- self.visit(node.func)
- self.write('(')
- for arg in node.args:
- write_comma()
- self.visit(arg)
- for keyword in node.keywords:
- write_comma()
- self.write(keyword.arg + '=')
- self.visit(keyword.value)
- if hasattr(node, 'starargs') and node.starargs is not None:
- write_comma()
- self.write('*')
- self.visit(node.starargs)
- if hasattr(node, 'kwargs') and node.kwargs is not None:
- write_comma()
- self.write('**')
- self.visit(node.kwargs)
- self.write(')')
- def visit_Name(self, node):
- self.write(node.id)
- def visit_Str(self, node):
- self.write(repr(node.s))
- def visit_Bytes(self, node):
- self.write(repr(node.s))
- def visit_Num(self, node):
- self.write(repr(node.n))
- def visit_Tuple(self, node):
- self.write('(')
- idx = -1
- for idx, item in enumerate(node.elts):
- if idx:
- self.write(', ')
- self.visit(item)
- self.write(idx and ')' or ',)')
- def sequence_visit(left, right):
- def visit(self, node):
- self.write(left)
- for idx, item in enumerate(node.elts):
- if idx:
- self.write(', ')
- self.visit(item)
- self.write(right)
- return visit
- visit_List = sequence_visit('[', ']')
- visit_Set = sequence_visit('{', '}')
- del sequence_visit
- def visit_Dict(self, node):
- self.write('{')
- for idx, (key, value) in enumerate(zip(node.keys, node.values)):
- if idx:
- self.write(', ')
- self.visit(key)
- self.write(': ')
- self.visit(value)
- self.write('}')
- def visit_BinOp(self, node):
- self.visit(node.left)
- self.write(' %s ' % BINOP_SYMBOLS[type(node.op)])
- self.visit(node.right)
- def visit_BoolOp(self, node):
- self.write('(')
- for idx, value in enumerate(node.values):
- if idx:
- self.write(' %s ' % BOOLOP_SYMBOLS[type(node.op)])
- self.visit(value)
- self.write(')')
- def visit_Compare(self, node):
- self.write('(')
- self.write(node.left)
- for op, right in zip(node.ops, node.comparators):
- self.write(' %s %%' % CMPOP_SYMBOLS[type(op)])
- self.visit(right)
- self.write(')')
- def visit_UnaryOp(self, node):
- self.write('(')
- op = UNARYOP_SYMBOLS[type(node.op)]
- self.write(op)
- if op == 'not':
- self.write(' ')
- self.visit(node.operand)
- self.write(')')
- def visit_Subscript(self, node):
- self.visit(node.value)
- self.write('[')
- self.visit(node.slice)
- self.write(']')
- def visit_Slice(self, node):
- if node.lower is not None:
- self.visit(node.lower)
- self.write(':')
- if node.upper is not None:
- self.visit(node.upper)
- if node.step is not None:
- self.write(':')
- if not (isinstance(node.step, Name) and node.step.id == 'None'):
- self.visit(node.step)
- def visit_ExtSlice(self, node):
- for idx, item in node.dims:
- if idx:
- self.write(', ')
- self.visit(item)
- def visit_Yield(self, node):
- self.write('yield ')
- self.visit(node.value)
- def visit_Lambda(self, node):
- self.write('lambda ')
- self.signature(node.args)
- self.write(': ')
- self.visit(node.body)
- def visit_Ellipsis(self, node):
- self.write('Ellipsis')
- def generator_visit(left, right):
- def visit(self, node):
- self.write(left)
- self.visit(node.elt)
- for comprehension in node.generators:
- self.visit(comprehension)
- self.write(right)
- return visit
- visit_ListComp = generator_visit('[', ']')
- visit_GeneratorExp = generator_visit('(', ')')
- visit_SetComp = generator_visit('{', '}')
- del generator_visit
- def visit_DictComp(self, node):
- self.write('{')
- self.visit(node.key)
- self.write(': ')
- self.visit(node.value)
- for comprehension in node.generators:
- self.visit(comprehension)
- self.write('}')
- def visit_IfExp(self, node):
- self.visit(node.body)
- self.write(' if ')
- self.visit(node.test)
- self.write(' else ')
- self.visit(node.orelse)
- def visit_Starred(self, node):
- self.write('*')
- self.visit(node.value)
- def visit_Repr(self, node):
- # XXX: python 2.6 only
- self.write('`')
- self.visit(node.value)
- self.write('`')
- # Helper Nodes
- def visit_alias(self, node):
- self.write(node.name)
- if node.asname is not None:
- self.write(' as ' + node.asname)
- def visit_comprehension(self, node):
- self.write(' for ')
- self.visit(node.target)
- self.write(' in ')
- self.visit(node.iter)
- if node.ifs:
- for if_ in node.ifs:
- self.write(' if ')
- self.visit(if_)
- def visit_excepthandler(self, node):
- self.newline(node)
- self.write('except')
- if node.type is not None:
- self.write(' ')
- self.visit(node.type)
- if node.name is not None:
- self.write(' as ')
- self.visit(node.name)
- self.write(':')
- self.body(node.body)
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