laywerrobot/lib/python3.6/site-packages/astor/code_gen.py
2020-08-27 21:55:39 +02:00

825 lines
28 KiB
Python

# -*- 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_)