# -*- coding: utf-8 -*- """ Part of the astor library for Python AST manipulation. License: 3-clause BSD Copyright (c) 2008 Armin Ronacher Copyright (c) 2012-2017 Patrick Maupin Copyright (c) 2013-2017 Berker Peksag This module converts an AST into Python source code. Before being version-controlled as part of astor, this code came from here (in 2012): https://gist.github.com/1250562 """ import ast import math import sys from .op_util import get_op_symbol, get_op_precedence, Precedence from .node_util import ExplicitNodeVisitor from .string_repr import pretty_string, string_triplequote_repr from .source_repr import pretty_source def to_source(node, indent_with=' ' * 4, add_line_information=False, pretty_string=pretty_string, pretty_source=pretty_source): """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, pretty_string) generator.visit(node) generator.result.append('\n') if set(generator.result[0]) == set('\n'): generator.result[0] = '' return pretty_source(generator.result) def precedence_setter(AST=ast.AST, get_op_precedence=get_op_precedence, isinstance=isinstance, list=list): """ This only uses a closure for performance reasons, to reduce the number of attribute lookups. (set_precedence is called a lot of times.) """ def set_precedence(value, *nodes): """Set the precedence (of the parent) into the children. """ if isinstance(value, AST): value = get_op_precedence(value) for node in nodes: if isinstance(node, AST): node._pp = value elif isinstance(node, list): set_precedence(value, *node) else: assert node is None, node return set_precedence set_precedence = precedence_setter() class Delimit(object): """A context manager that can add enclosing delimiters around the output of a SourceGenerator method. By default, the parentheses are added, but the enclosed code may set discard=True to get rid of them. """ discard = False def __init__(self, tree, *args): """ use write instead of using result directly for initial data, because it may flush preceding data into result. """ delimiters = '()' node = None op = None for arg in args: if isinstance(arg, ast.AST): if node is None: node = arg else: op = arg else: delimiters = arg tree.write(delimiters[0]) result = self.result = tree.result self.index = len(result) self.closing = delimiters[1] if node is not None: self.p = p = get_op_precedence(op or node) self.pp = pp = tree.get__pp(node) self.discard = p >= pp def __enter__(self): return self def __exit__(self, *exc_info): result = self.result start = self.index - 1 if self.discard: result[start] = '' else: result.append(self.closing) class SourceGenerator(ExplicitNodeVisitor): """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. """ using_unicode_literals = False def __init__(self, indent_with, add_line_information=False, pretty_string=pretty_string, # constants len=len, isinstance=isinstance, callable=callable): self.result = [] self.indent_with = indent_with self.add_line_information = add_line_information self.indentation = 0 # Current indentation level self.new_lines = 0 # Number of lines to insert before next code self.colinfo = 0, 0 # index in result of string containing linefeed, and # position of last linefeed in that string self.pretty_string = pretty_string AST = ast.AST visit = self.visit newline = self.newline result = self.result append = result.append def write(*params): """ self.write is a closure for performance (to reduce the number of attribute lookups). """ for item in params: if isinstance(item, AST): visit(item) elif callable(item): item() elif item == '\n': newline() else: if self.new_lines: append('\n' * self.new_lines) self.colinfo = len(result), 0 append(self.indent_with * self.indentation) self.new_lines = 0 if item: append(item) self.write = write def __getattr__(self, name, defaults=dict(keywords=(), _pp=Precedence.highest).get): """ Get an attribute of the node. like dict.get (returns None if doesn't exist) """ if not name.startswith('get_'): raise AttributeError geta = getattr shortname = name[4:] default = defaults(shortname) def getter(node): return geta(node, shortname, default) setattr(self, name, getter) return getter def delimit(self, *args): return Delimit(self, *args) def conditional_write(self, *stuff): if stuff[-1] is not None: self.write(*stuff) # Inform the caller that we wrote return True 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.indentation += 1 self.write(*statements) self.indentation -= 1 def else_body(self, elsewhat): if elsewhat: self.write('\n', 'else:') self.body(elsewhat) def body_or_else(self, node): self.body(node.body) self.else_body(node.orelse) def visit_arguments(self, node): want_comma = [] def write_comma(): if want_comma: self.write(', ') else: want_comma.append(True) def loop_args(args, defaults): set_precedence(Precedence.Comma, defaults) padding = [None] * (len(args) - len(defaults)) for arg, default in zip(args, padding + defaults): self.write(write_comma, arg) self.conditional_write('=', default) loop_args(node.args, node.defaults) self.conditional_write(write_comma, '*', node.vararg) kwonlyargs = self.get_kwonlyargs(node) if kwonlyargs: if node.vararg is None: self.write(write_comma, '*') loop_args(kwonlyargs, node.kw_defaults) self.conditional_write(write_comma, '**', node.kwarg) def statement(self, node, *params, **kw): self.newline(node) self.write(*params) def decorators(self, node, extra): self.newline(extra=extra) for decorator in node.decorator_list: self.statement(decorator, '@', decorator) def comma_list(self, items, trailing=False): set_precedence(Precedence.Comma, *items) for idx, item in enumerate(items): self.write(', ' if idx else '', item) self.write(',' if trailing else '') # Statements def visit_Assign(self, node): set_precedence(node, node.value, *node.targets) self.newline(node) for target in node.targets: self.write(target, ' = ') self.visit(node.value) def visit_AugAssign(self, node): set_precedence(node, node.value, node.target) self.statement(node, node.target, get_op_symbol(node.op, ' %s= '), node.value) def visit_AnnAssign(self, node): set_precedence(node, node.target, node.annotation) set_precedence(Precedence.Comma, node.value) need_parens = isinstance(node.target, ast.Name) and not node.simple begin = '(' if need_parens else '' end = ')' if need_parens else '' self.statement(node, begin, node.target, end, ': ', node.annotation) self.conditional_write(' = ', node.value) def visit_ImportFrom(self, node): self.statement(node, 'from ', node.level * '.', node.module or '', ' import ') self.comma_list(node.names) # Goofy stuff for Python 2.7 _pyio module if node.module == '__future__' and 'unicode_literals' in ( x.name for x in node.names): self.using_unicode_literals = True def visit_Import(self, node): self.statement(node, 'import ') self.comma_list(node.names) def visit_Expr(self, node): set_precedence(node, node.value) self.statement(node) self.generic_visit(node) def visit_FunctionDef(self, node, is_async=False): prefix = 'async ' if is_async else '' self.decorators(node, 1 if self.indentation else 2) self.statement(node, '%sdef %s' % (prefix, node.name), '(') self.visit_arguments(node.args) self.write(')') self.conditional_write(' ->', self.get_returns(node)) self.write(':') self.body(node.body) if not self.indentation: self.newline(extra=2) # introduced in Python 3.5 def visit_AsyncFunctionDef(self, node): self.visit_FunctionDef(node, is_async=True) def visit_ClassDef(self, node): have_args = [] def paren_or_comma(): if have_args: self.write(', ') else: have_args.append(True) self.write('(') self.decorators(node, 2) self.statement(node, 'class %s' % node.name) for base in node.bases: self.write(paren_or_comma, base) # keywords not available in early version for keyword in self.get_keywords(node): self.write(paren_or_comma, keyword.arg or '', '=' if keyword.arg else '**', keyword.value) self.conditional_write(paren_or_comma, '*', self.get_starargs(node)) self.conditional_write(paren_or_comma, '**', self.get_kwargs(node)) self.write(have_args and '):' or ':') self.body(node.body) if not self.indentation: self.newline(extra=2) def visit_If(self, node): set_precedence(node, node.test) self.statement(node, 'if ', node.test, ':') self.body(node.body) while True: else_ = node.orelse if len(else_) == 1 and isinstance(else_[0], ast.If): node = else_[0] set_precedence(node, node.test) self.write('\n', 'elif ', node.test, ':') self.body(node.body) else: self.else_body(else_) break def visit_For(self, node, is_async=False): set_precedence(node, node.target) prefix = 'async ' if is_async else '' self.statement(node, '%sfor ' % prefix, node.target, ' in ', node.iter, ':') self.body_or_else(node) # introduced in Python 3.5 def visit_AsyncFor(self, node): self.visit_For(node, is_async=True) def visit_While(self, node): set_precedence(node, node.test) self.statement(node, 'while ', node.test, ':') self.body_or_else(node) def visit_With(self, node, is_async=False): prefix = 'async ' if is_async else '' self.statement(node, '%swith ' % prefix) if hasattr(node, "context_expr"): # Python < 3.3 self.visit_withitem(node) else: # Python >= 3.3 self.comma_list(node.items) self.write(':') self.body(node.body) # new for Python 3.5 def visit_AsyncWith(self, node): self.visit_With(node, is_async=True) # new for Python 3.3 def visit_withitem(self, node): self.write(node.context_expr) self.conditional_write(' as ', node.optional_vars) def visit_NameConstant(self, node): self.write(str(node.value)) def visit_Pass(self, node): self.statement(node, 'pass') def visit_Print(self, node): # XXX: python 2.6 only self.statement(node, 'print ') values = node.values if node.dest is not None: self.write(' >> ') values = [node.dest] + node.values self.comma_list(values, not node.nl) def visit_Delete(self, node): self.statement(node, 'del ') self.comma_list(node.targets) def visit_TryExcept(self, node): self.statement(node, 'try:') self.body(node.body) self.write(*node.handlers) self.else_body(node.orelse) # new for Python 3.3 def visit_Try(self, node): self.statement(node, 'try:') self.body(node.body) self.write(*node.handlers) self.else_body(node.orelse) if node.finalbody: self.statement(node, 'finally:') self.body(node.finalbody) def visit_ExceptHandler(self, node): self.statement(node, 'except') if self.conditional_write(' ', node.type): self.conditional_write(' as ', node.name) self.write(':') self.body(node.body) def visit_TryFinally(self, node): self.statement(node, 'try:') self.body(node.body) self.statement(node, 'finally:') self.body(node.finalbody) def visit_Exec(self, node): dicts = node.globals, node.locals dicts = dicts[::-1] if dicts[0] is None else dicts self.statement(node, 'exec ', node.body) self.conditional_write(' in ', dicts[0]) self.conditional_write(', ', dicts[1]) def visit_Assert(self, node): set_precedence(node, node.test, node.msg) self.statement(node, 'assert ', node.test) self.conditional_write(', ', node.msg) def visit_Global(self, node): self.statement(node, 'global ', ', '.join(node.names)) def visit_Nonlocal(self, node): self.statement(node, 'nonlocal ', ', '.join(node.names)) def visit_Return(self, node): set_precedence(node, node.value) self.statement(node, 'return') self.conditional_write(' ', node.value) def visit_Break(self, node): self.statement(node, 'break') def visit_Continue(self, node): self.statement(node, 'continue') def visit_Raise(self, node): # XXX: Python 2.6 / 3.0 compatibility self.statement(node, 'raise') if self.conditional_write(' ', self.get_exc(node)): self.conditional_write(' from ', node.cause) elif self.conditional_write(' ', self.get_type(node)): set_precedence(node, node.inst) self.conditional_write(', ', node.inst) self.conditional_write(', ', node.tback) # Expressions def visit_Attribute(self, node): self.write(node.value, '.', node.attr) def visit_Call(self, node, len=len): write = self.write want_comma = [] def write_comma(): if want_comma: write(', ') else: want_comma.append(True) args = node.args keywords = node.keywords starargs = self.get_starargs(node) kwargs = self.get_kwargs(node) numargs = len(args) + len(keywords) numargs += starargs is not None numargs += kwargs is not None p = Precedence.Comma if numargs > 1 else Precedence.call_one_arg set_precedence(p, *args) self.visit(node.func) write('(') for arg in args: write(write_comma, arg) set_precedence(Precedence.Comma, *(x.value for x in keywords)) for keyword in keywords: # a keyword.arg of None indicates dictionary unpacking # (Python >= 3.5) arg = keyword.arg or '' write(write_comma, arg, '=' if arg else '**', keyword.value) # 3.5 no longer has these self.conditional_write(write_comma, '*', starargs) self.conditional_write(write_comma, '**', kwargs) write(')') def visit_Name(self, node): self.write(node.id) def visit_JoinedStr(self, node): self.visit_Str(node, True) def visit_Str(self, node, is_joined=False): # embedded is used to control when we might want # to use a triple-quoted string. We determine # if we are in an assignment and/or in an expression precedence = self.get__pp(node) embedded = ((precedence > Precedence.Expr) + (precedence >= Precedence.Assign)) # Flush any pending newlines, because we're about # to severely abuse the result list. self.write('') result = self.result # Calculate the string representing the line # we are working on, up to but not including # the string we are adding. res_index, str_index = self.colinfo current_line = self.result[res_index:] if str_index: current_line[0] = current_line[0][str_index:] current_line = ''.join(current_line) if is_joined: # Handle new f-strings. This is a bit complicated, because # the tree can contain subnodes that recurse back to JoinedStr # subnodes... def recurse(node): for value in node.values: if isinstance(value, ast.Str): self.write(value.s) elif isinstance(value, ast.FormattedValue): with self.delimit('{}'): self.visit(value.value) if value.conversion != -1: self.write('!%s' % chr(value.conversion)) if value.format_spec is not None: self.write(':') recurse(value.format_spec) else: kind = type(value).__name__ assert False, 'Invalid node %s inside JoinedStr' % kind index = len(result) recurse(node) # Flush trailing newlines (so that they are part of mystr) self.write('') mystr = ''.join(result[index:]) del result[index:] self.colinfo = res_index, str_index # Put it back like we found it uni_lit = False # No formatted byte strings else: mystr = node.s uni_lit = self.using_unicode_literals mystr = self.pretty_string(mystr, embedded, current_line, uni_lit) if is_joined: mystr = 'f' + mystr self.write(mystr) lf = mystr.rfind('\n') + 1 if lf: self.colinfo = len(result) - 1, lf def visit_Bytes(self, node): self.write(repr(node.s)) def visit_Num(self, node, # constants new=sys.version_info >= (3, 0)): with self.delimit(node) as delimiters: x = node.n def part(p, imaginary): # Represent infinity as 1e1000 and NaN as 1e1000-1e1000. s = 'j' if imaginary else '' if math.isinf(p): if p < 0: return '-1e1000' + s return '1e1000' + s if math.isnan(p): return '(1e1000%s-1e1000%s)' % (s, s) return repr(p) + s real = part(x.real if isinstance(x, complex) else x, imaginary=False) if isinstance(x, complex): imag = part(x.imag, imaginary=True) if x.real == 0: s = imag elif x.imag == 0: s = '(%s+0j)' % real else: # x has nonzero real and imaginary parts. s = '(%s%s%s)' % (real, ['+', ''][imag.startswith('-')], imag) else: s = real self.write(s) # The Python 2.x compiler merges a unary minus # with a number. This is a premature optimization # that we deal with here... if not new and delimiters.discard: if not isinstance(node.n, complex) and node.n < 0: pow_lhs = Precedence.Pow + 1 delimiters.discard = delimiters.pp != pow_lhs else: op = self.get__p_op(node) delimiters.discard = not isinstance(op, ast.USub) def visit_Tuple(self, node): with self.delimit(node) as delimiters: # Two things are special about tuples: # 1) We cannot discard the enclosing parentheses if empty # 2) We need the trailing comma if only one item elts = node.elts delimiters.discard = delimiters.discard and elts self.comma_list(elts, len(elts) == 1) def visit_List(self, node): with self.delimit('[]'): self.comma_list(node.elts) def visit_Set(self, node): if node.elts: with self.delimit('{}'): self.comma_list(node.elts) else: # If we tried to use "{}" to represent an empty set, it would be # interpreted as an empty dictionary. We can't use "set()" either # because the name "set" might be rebound. self.write('{1}.__class__()') def visit_Dict(self, node): set_precedence(Precedence.Comma, *node.values) with self.delimit('{}'): for idx, (key, value) in enumerate(zip(node.keys, node.values)): self.write(', ' if idx else '', key if key else '', ': ' if key else '**', value) def visit_BinOp(self, node): op, left, right = node.op, node.left, node.right with self.delimit(node, op) as delimiters: ispow = isinstance(op, ast.Pow) p = delimiters.p set_precedence((Precedence.Pow + 1) if ispow else p, left) set_precedence(Precedence.PowRHS if ispow else (p + 1), right) self.write(left, get_op_symbol(op, ' %s '), right) def visit_BoolOp(self, node): with self.delimit(node, node.op) as delimiters: op = get_op_symbol(node.op, ' %s ') set_precedence(delimiters.p + 1, *node.values) for idx, value in enumerate(node.values): self.write(idx and op or '', value) def visit_Compare(self, node): with self.delimit(node, node.ops[0]) as delimiters: set_precedence(delimiters.p + 1, node.left, *node.comparators) self.visit(node.left) for op, right in zip(node.ops, node.comparators): self.write(get_op_symbol(op, ' %s '), right) def visit_UnaryOp(self, node): with self.delimit(node, node.op) as delimiters: set_precedence(delimiters.p, node.operand) # In Python 2.x, a unary negative of a literal # number is merged into the number itself. This # bit of ugliness means it is useful to know # what the parent operation was... node.operand._p_op = node.op sym = get_op_symbol(node.op) self.write(sym, ' ' if sym.isalpha() else '', node.operand) def visit_Subscript(self, node): set_precedence(node, node.slice) self.write(node.value, '[', node.slice, ']') def visit_Slice(self, node): set_precedence(node, node.lower, node.upper, node.step) self.conditional_write(node.lower) self.write(':') self.conditional_write(node.upper) if node.step is not None: self.write(':') if not (isinstance(node.step, ast.Name) and node.step.id == 'None'): self.visit(node.step) def visit_Index(self, node): with self.delimit(node) as delimiters: set_precedence(delimiters.p, node.value) self.visit(node.value) def visit_ExtSlice(self, node): dims = node.dims set_precedence(node, *dims) self.comma_list(dims, len(dims) == 1) def visit_Yield(self, node): with self.delimit(node): set_precedence(get_op_precedence(node) + 1, node.value) self.write('yield') self.conditional_write(' ', node.value) # new for Python 3.3 def visit_YieldFrom(self, node): with self.delimit(node): self.write('yield from ', node.value) # new for Python 3.5 def visit_Await(self, node): with self.delimit(node): self.write('await ', node.value) def visit_Lambda(self, node): with self.delimit(node) as delimiters: set_precedence(delimiters.p, node.body) self.write('lambda ') self.visit_arguments(node.args) self.write(': ', node.body) def visit_Ellipsis(self, node): self.write('...') def visit_ListComp(self, node): with self.delimit('[]'): self.write(node.elt, *node.generators) def visit_GeneratorExp(self, node): with self.delimit(node) as delimiters: if delimiters.pp == Precedence.call_one_arg: delimiters.discard = True set_precedence(Precedence.Comma, node.elt) self.write(node.elt, *node.generators) def visit_SetComp(self, node): with self.delimit('{}'): self.write(node.elt, *node.generators) def visit_DictComp(self, node): with self.delimit('{}'): self.write(node.key, ': ', node.value, *node.generators) def visit_IfExp(self, node): with self.delimit(node) as delimiters: set_precedence(delimiters.p + 1, node.body, node.test) set_precedence(delimiters.p, node.orelse) self.write(node.body, ' if ', node.test, ' else ', node.orelse) def visit_Starred(self, node): self.write('*', node.value) def visit_Repr(self, node): # XXX: python 2.6 only with self.delimit('``'): self.visit(node.value) def visit_Module(self, node): self.write(*node.body) visit_Interactive = visit_Module def visit_Expression(self, node): self.visit(node.body) # Helper Nodes def visit_arg(self, node): self.write(node.arg) self.conditional_write(': ', node.annotation) def visit_alias(self, node): self.write(node.name) self.conditional_write(' as ', node.asname) def visit_comprehension(self, node): set_precedence(node, node.iter, *node.ifs) set_precedence(Precedence.comprehension_target, node.target) stmt = ' async for ' if self.get_is_async(node) else ' for ' self.write(stmt, node.target, ' in ', node.iter) for if_ in node.ifs: self.write(' if ', if_)