--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/eric6/Plugins/CheckerPlugins/CodeStyleChecker/Simplify/ast_unparse.py Wed Mar 31 19:51:41 2021 +0200
@@ -0,0 +1,959 @@
+"""
+ ast_unparse
+ ~~~~~~~~~~~
+
+ This module is a backport of the unparse function of the Python 3.9
+ ast module.
+
+ Original ast module code is
+ :copyright: Copyright 2008 by Armin Ronacher.
+ :license: Python License.
+"""
+
+import ast
+import sys
+from enum import IntEnum, auto
+from contextlib import contextmanager, nullcontext
+
+# Large float and imaginary literals get turned into infinities in the AST.
+# We unparse those infinities to INFSTR.
+_INFSTR = "1e" + repr(sys.float_info.max_10_exp + 1)
+
+class _Precedence(IntEnum):
+ """Precedence table that originated from python grammar."""
+
+ TUPLE = auto()
+ YIELD = auto() # 'yield', 'yield from'
+ TEST = auto() # 'if'-'else', 'lambda'
+ OR = auto() # 'or'
+ AND = auto() # 'and'
+ NOT = auto() # 'not'
+ CMP = auto() # '<', '>', '==', '>=', '<=', '!=',
+ # 'in', 'not in', 'is', 'is not'
+ EXPR = auto()
+ BOR = EXPR # '|'
+ BXOR = auto() # '^'
+ BAND = auto() # '&'
+ SHIFT = auto() # '<<', '>>'
+ ARITH = auto() # '+', '-'
+ TERM = auto() # '*', '@', '/', '%', '//'
+ FACTOR = auto() # unary '+', '-', '~'
+ POWER = auto() # '**'
+ AWAIT = auto() # 'await'
+ ATOM = auto()
+
+ def next(self):
+ try:
+ return self.__class__(self + 1)
+ except ValueError:
+ return self
+
+
+_SINGLE_QUOTES = ("'", '"')
+_MULTI_QUOTES = ('"""', "'''")
+_ALL_QUOTES = (*_SINGLE_QUOTES, *_MULTI_QUOTES)
+
+class _Unparser(ast.NodeVisitor):
+ """Methods in this class recursively traverse an AST and
+ output source code for the abstract syntax; original formatting
+ is disregarded."""
+
+ def __init__(self, *, _avoid_backslashes=False):
+ self._source = []
+ self._buffer = []
+ self._precedences = {}
+ self._type_ignores = {}
+ self._indent = 0
+ self._avoid_backslashes = _avoid_backslashes
+
+ def interleave(self, inter, f, seq):
+ """Call f on each item in seq, calling inter() in between."""
+ seq = iter(seq)
+ try:
+ f(next(seq))
+ except StopIteration:
+ pass
+ else:
+ for x in seq:
+ inter()
+ f(x)
+
+ def items_view(self, traverser, items):
+ """Traverse and separate the given *items* with a comma and append it to
+ the buffer. If *items* is a single item sequence, a trailing comma
+ will be added."""
+ if len(items) == 1:
+ traverser(items[0])
+ self.write(",")
+ else:
+ self.interleave(lambda: self.write(", "), traverser, items)
+
+ def maybe_newline(self):
+ """Adds a newline if it isn't the start of generated source"""
+ if self._source:
+ self.write("\n")
+
+ def fill(self, text=""):
+ """Indent a piece of text and append it, according to the current
+ indentation level"""
+ self.maybe_newline()
+ self.write(" " * self._indent + text)
+
+ def write(self, text):
+ """Append a piece of text"""
+ self._source.append(text)
+
+ def buffer_writer(self, text):
+ self._buffer.append(text)
+
+ @property
+ def buffer(self):
+ value = "".join(self._buffer)
+ self._buffer.clear()
+ return value
+
+ @contextmanager
+ def block(self, *, extra = None):
+ """A context manager for preparing the source for blocks. It adds
+ the character':', increases the indentation on enter and decreases
+ the indentation on exit. If *extra* is given, it will be directly
+ appended after the colon character.
+ """
+ self.write(":")
+ if extra:
+ self.write(extra)
+ self._indent += 1
+ yield
+ self._indent -= 1
+
+ @contextmanager
+ def delimit(self, start, end):
+ """A context manager for preparing the source for expressions. It adds
+ *start* to the buffer and enters, after exit it adds *end*."""
+
+ self.write(start)
+ yield
+ self.write(end)
+
+ def delimit_if(self, start, end, condition):
+ if condition:
+ return self.delimit(start, end)
+ else:
+ return nullcontext()
+
+ def require_parens(self, precedence, node):
+ """Shortcut to adding precedence related parens"""
+ return self.delimit_if("(", ")", self.get_precedence(node) > precedence)
+
+ def get_precedence(self, node):
+ return self._precedences.get(node, _Precedence.TEST)
+
+ def set_precedence(self, precedence, *nodes):
+ for node in nodes:
+ self._precedences[node] = precedence
+
+ def get_raw_docstring(self, node):
+ """If a docstring node is found in the body of the *node* parameter,
+ return that docstring node, None otherwise.
+
+ Logic mirrored from ``_PyAST_GetDocString``."""
+ if not isinstance(
+ node, (ast.AsyncFunctionDef, ast.FunctionDef, ast.ClassDef,
+ ast.Module)
+ ) or len(node.body) < 1:
+ return None
+ node = node.body[0]
+ if not isinstance(node, ast.Expr):
+ return None
+ node = node.value
+ if isinstance(node, ast.Constant) and isinstance(node.value, str):
+ return node
+
+ def get_type_comment(self, node):
+ comment = self._type_ignores.get(node.lineno) or node.type_comment
+ if comment is not None:
+ return f" # type: {comment}"
+
+ def traverse(self, node):
+ if isinstance(node, list):
+ for item in node:
+ self.traverse(item)
+ else:
+ super().visit(node)
+
+ def visit(self, node):
+ """Outputs a source code string that, if converted back to an ast
+ (using ast.parse) will generate an AST equivalent to *node*"""
+ self._source = []
+ self.traverse(node)
+ return "".join(self._source)
+
+ def _write_docstring_and_traverse_body(self, node):
+ if (docstring := self.get_raw_docstring(node)):
+ self._write_docstring(docstring)
+ self.traverse(node.body[1:])
+ else:
+ self.traverse(node.body)
+
+ def visit_Module(self, node):
+ self._type_ignores = {
+ ignore.lineno: f"ignore{ignore.tag}"
+ for ignore in node.type_ignores
+ }
+ self._write_docstring_and_traverse_body(node)
+ self._type_ignores.clear()
+
+ def visit_FunctionType(self, node):
+ with self.delimit("(", ")"):
+ self.interleave(
+ lambda: self.write(", "), self.traverse, node.argtypes
+ )
+
+ self.write(" -> ")
+ self.traverse(node.returns)
+
+ def visit_Expr(self, node):
+ self.fill()
+ self.set_precedence(_Precedence.YIELD, node.value)
+ self.traverse(node.value)
+
+ def visit_NamedExpr(self, node):
+ with self.require_parens(_Precedence.TUPLE, node):
+ self.set_precedence(_Precedence.ATOM, node.target, node.value)
+ self.traverse(node.target)
+ self.write(" := ")
+ self.traverse(node.value)
+
+ def visit_Import(self, node):
+ self.fill("import ")
+ self.interleave(lambda: self.write(", "), self.traverse, node.names)
+
+ def visit_ImportFrom(self, node):
+ self.fill("from ")
+ self.write("." * node.level)
+ if node.module:
+ self.write(node.module)
+ self.write(" import ")
+ self.interleave(lambda: self.write(", "), self.traverse, node.names)
+
+ def visit_Assign(self, node):
+ self.fill()
+ for target in node.targets:
+ self.traverse(target)
+ self.write(" = ")
+ self.traverse(node.value)
+ if type_comment := self.get_type_comment(node):
+ self.write(type_comment)
+
+ def visit_AugAssign(self, node):
+ self.fill()
+ self.traverse(node.target)
+ self.write(" " + self.binop[node.op.__class__.__name__] + "= ")
+ self.traverse(node.value)
+
+ def visit_AnnAssign(self, node):
+ self.fill()
+ with self.delimit_if("(", ")", not node.simple and isinstance(node.target, ast.Name)):
+ self.traverse(node.target)
+ self.write(": ")
+ self.traverse(node.annotation)
+ if node.value:
+ self.write(" = ")
+ self.traverse(node.value)
+
+ def visit_Return(self, node):
+ self.fill("return")
+ if node.value:
+ self.write(" ")
+ self.traverse(node.value)
+
+ def visit_Pass(self, node):
+ self.fill("pass")
+
+ def visit_Break(self, node):
+ self.fill("break")
+
+ def visit_Continue(self, node):
+ self.fill("continue")
+
+ def visit_Delete(self, node):
+ self.fill("del ")
+ self.interleave(lambda: self.write(", "), self.traverse, node.targets)
+
+ def visit_Assert(self, node):
+ self.fill("assert ")
+ self.traverse(node.test)
+ if node.msg:
+ self.write(", ")
+ self.traverse(node.msg)
+
+ def visit_Global(self, node):
+ self.fill("global ")
+ self.interleave(lambda: self.write(", "), self.write, node.names)
+
+ def visit_Nonlocal(self, node):
+ self.fill("nonlocal ")
+ self.interleave(lambda: self.write(", "), self.write, node.names)
+
+ def visit_Await(self, node):
+ with self.require_parens(_Precedence.AWAIT, node):
+ self.write("await")
+ if node.value:
+ self.write(" ")
+ self.set_precedence(_Precedence.ATOM, node.value)
+ self.traverse(node.value)
+
+ def visit_Yield(self, node):
+ with self.require_parens(_Precedence.YIELD, node):
+ self.write("yield")
+ if node.value:
+ self.write(" ")
+ self.set_precedence(_Precedence.ATOM, node.value)
+ self.traverse(node.value)
+
+ def visit_YieldFrom(self, node):
+ with self.require_parens(_Precedence.YIELD, node):
+ self.write("yield from ")
+ if not node.value:
+ raise ValueError("Node can't be used without a value attribute.")
+ self.set_precedence(_Precedence.ATOM, node.value)
+ self.traverse(node.value)
+
+ def visit_Raise(self, node):
+ self.fill("raise")
+ if not node.exc:
+ if node.cause:
+ raise ValueError("Node can't use cause without an exception.")
+ return
+ self.write(" ")
+ self.traverse(node.exc)
+ if node.cause:
+ self.write(" from ")
+ self.traverse(node.cause)
+
+ def visit_Try(self, node):
+ self.fill("try")
+ with self.block():
+ self.traverse(node.body)
+ for ex in node.handlers:
+ self.traverse(ex)
+ if node.orelse:
+ self.fill("else")
+ with self.block():
+ self.traverse(node.orelse)
+ if node.finalbody:
+ self.fill("finally")
+ with self.block():
+ self.traverse(node.finalbody)
+
+ def visit_ExceptHandler(self, node):
+ self.fill("except")
+ if node.type:
+ self.write(" ")
+ self.traverse(node.type)
+ if node.name:
+ self.write(" as ")
+ self.write(node.name)
+ with self.block():
+ self.traverse(node.body)
+
+ def visit_ClassDef(self, node):
+ self.maybe_newline()
+ for deco in node.decorator_list:
+ self.fill("@")
+ self.traverse(deco)
+ self.fill("class " + node.name)
+ with self.delimit_if("(", ")", condition = node.bases or node.keywords):
+ comma = False
+ for e in node.bases:
+ if comma:
+ self.write(", ")
+ else:
+ comma = True
+ self.traverse(e)
+ for e in node.keywords:
+ if comma:
+ self.write(", ")
+ else:
+ comma = True
+ self.traverse(e)
+
+ with self.block():
+ self._write_docstring_and_traverse_body(node)
+
+ def visit_FunctionDef(self, node):
+ self._function_helper(node, "def")
+
+ def visit_AsyncFunctionDef(self, node):
+ self._function_helper(node, "async def")
+
+ def _function_helper(self, node, fill_suffix):
+ self.maybe_newline()
+ for deco in node.decorator_list:
+ self.fill("@")
+ self.traverse(deco)
+ def_str = fill_suffix + " " + node.name
+ self.fill(def_str)
+ with self.delimit("(", ")"):
+ self.traverse(node.args)
+ if node.returns:
+ self.write(" -> ")
+ self.traverse(node.returns)
+ with self.block(extra=self.get_type_comment(node)):
+ self._write_docstring_and_traverse_body(node)
+
+ def visit_For(self, node):
+ self._for_helper("for ", node)
+
+ def visit_AsyncFor(self, node):
+ self._for_helper("async for ", node)
+
+ def _for_helper(self, fill, node):
+ self.fill(fill)
+ self.traverse(node.target)
+ self.write(" in ")
+ self.traverse(node.iter)
+ with self.block(extra=self.get_type_comment(node)):
+ self.traverse(node.body)
+ if node.orelse:
+ self.fill("else")
+ with self.block():
+ self.traverse(node.orelse)
+
+ def visit_If(self, node):
+ self.fill("if ")
+ self.traverse(node.test)
+ with self.block():
+ self.traverse(node.body)
+ # collapse nested ifs into equivalent elifs.
+ while node.orelse and len(node.orelse) == 1 and isinstance(node.orelse[0], ast.If):
+ node = node.orelse[0]
+ self.fill("elif ")
+ self.traverse(node.test)
+ with self.block():
+ self.traverse(node.body)
+ # final else
+ if node.orelse:
+ self.fill("else")
+ with self.block():
+ self.traverse(node.orelse)
+
+ def visit_While(self, node):
+ self.fill("while ")
+ self.traverse(node.test)
+ with self.block():
+ self.traverse(node.body)
+ if node.orelse:
+ self.fill("else")
+ with self.block():
+ self.traverse(node.orelse)
+
+ def visit_With(self, node):
+ self.fill("with ")
+ self.interleave(lambda: self.write(", "), self.traverse, node.items)
+ with self.block(extra=self.get_type_comment(node)):
+ self.traverse(node.body)
+
+ def visit_AsyncWith(self, node):
+ self.fill("async with ")
+ self.interleave(lambda: self.write(", "), self.traverse, node.items)
+ with self.block(extra=self.get_type_comment(node)):
+ self.traverse(node.body)
+
+ def _str_literal_helper(
+ self, string, *, quote_types=_ALL_QUOTES, escape_special_whitespace=False
+ ):
+ """Helper for writing string literals, minimizing escapes.
+ Returns the tuple (string literal to write, possible quote types).
+ """
+ def escape_char(c):
+ # \n and \t are non-printable, but we only escape them if
+ # escape_special_whitespace is True
+ if not escape_special_whitespace and c in "\n\t":
+ return c
+ # Always escape backslashes and other non-printable characters
+ if c == "\\" or not c.isprintable():
+ return c.encode("unicode_escape").decode("ascii")
+ return c
+
+ escaped_string = "".join(map(escape_char, string))
+ possible_quotes = quote_types
+ if "\n" in escaped_string:
+ possible_quotes = [q for q in possible_quotes if q in _MULTI_QUOTES]
+ possible_quotes = [q for q in possible_quotes if q not in escaped_string]
+ if not possible_quotes:
+ # If there aren't any possible_quotes, fallback to using repr
+ # on the original string. Try to use a quote from quote_types,
+ # e.g., so that we use triple quotes for docstrings.
+ string = repr(string)
+ quote = next((q for q in quote_types if string[0] in q), string[0])
+ return string[1:-1], [quote]
+ if escaped_string:
+ # Sort so that we prefer '''"''' over """\""""
+ possible_quotes.sort(key=lambda q: q[0] == escaped_string[-1])
+ # If we're using triple quotes and we'd need to escape a final
+ # quote, escape it
+ if possible_quotes[0][0] == escaped_string[-1]:
+ assert len(possible_quotes[0]) == 3
+ escaped_string = escaped_string[:-1] + "\\" + escaped_string[-1]
+ return escaped_string, possible_quotes
+
+ def _write_str_avoiding_backslashes(self, string, *, quote_types=_ALL_QUOTES):
+ """Write string literal value with a best effort attempt to avoid backslashes."""
+ string, quote_types = self._str_literal_helper(string, quote_types=quote_types)
+ quote_type = quote_types[0]
+ self.write(f"{quote_type}{string}{quote_type}")
+
+ def visit_JoinedStr(self, node):
+ self.write("f")
+ if self._avoid_backslashes:
+ self._fstring_JoinedStr(node, self.buffer_writer)
+ self._write_str_avoiding_backslashes(self.buffer)
+ return
+
+ # If we don't need to avoid backslashes globally (i.e., we only need
+ # to avoid them inside FormattedValues), it's cosmetically preferred
+ # to use escaped whitespace. That is, it's preferred to use backslashes
+ # for cases like: f"{x}\n". To accomplish this, we keep track of what
+ # in our buffer corresponds to FormattedValues and what corresponds to
+ # Constant parts of the f-string, and allow escapes accordingly.
+ buffer = []
+ for value in node.values:
+ meth = getattr(self, "_fstring_" + type(value).__name__)
+ meth(value, self.buffer_writer)
+ buffer.append((self.buffer, isinstance(value, ast.Constant)))
+ new_buffer = []
+ quote_types = _ALL_QUOTES
+ for value, is_constant in buffer:
+ # Repeatedly narrow down the list of possible quote_types
+ value, quote_types = self._str_literal_helper(
+ value, quote_types=quote_types,
+ escape_special_whitespace=is_constant
+ )
+ new_buffer.append(value)
+ value = "".join(new_buffer)
+ quote_type = quote_types[0]
+ self.write(f"{quote_type}{value}{quote_type}")
+
+ def visit_FormattedValue(self, node):
+ self.write("f")
+ self._fstring_FormattedValue(node, self.buffer_writer)
+ self._write_str_avoiding_backslashes(self.buffer)
+
+ def _fstring_JoinedStr(self, node, write):
+ for value in node.values:
+ meth = getattr(self, "_fstring_" + type(value).__name__)
+ meth(value, write)
+
+ def _fstring_Constant(self, node, write):
+ if not isinstance(node.value, str):
+ raise ValueError("Constants inside JoinedStr should be a string.")
+ value = node.value.replace("{", "{{").replace("}", "}}")
+ write(value)
+
+ def _fstring_FormattedValue(self, node, write):
+ write("{")
+ unparser = type(self)(_avoid_backslashes=True)
+ unparser.set_precedence(_Precedence.TEST.next(), node.value)
+ expr = unparser.visit(node.value)
+ if expr.startswith("{"):
+ write(" ") # Separate pair of opening brackets as "{ {"
+ if "\\" in expr:
+ raise ValueError("Unable to avoid backslash in f-string expression part")
+ write(expr)
+ if node.conversion != -1:
+ conversion = chr(node.conversion)
+ if conversion not in "sra":
+ raise ValueError("Unknown f-string conversion.")
+ write(f"!{conversion}")
+ if node.format_spec:
+ write(":")
+ meth = getattr(self, "_fstring_" + type(node.format_spec).__name__)
+ meth(node.format_spec, write)
+ write("}")
+
+ def visit_Name(self, node):
+ self.write(node.id)
+
+ def _write_docstring(self, node):
+ self.fill()
+ if node.kind == "u":
+ self.write("u")
+ self._write_str_avoiding_backslashes(node.value, quote_types=_MULTI_QUOTES)
+
+ def _write_constant(self, value):
+ if isinstance(value, (float, complex)):
+ # Substitute overflowing decimal literal for AST infinities,
+ # and inf - inf for NaNs.
+ self.write(
+ repr(value)
+ .replace("inf", _INFSTR)
+ .replace("nan", f"({_INFSTR}-{_INFSTR})")
+ )
+ elif self._avoid_backslashes and isinstance(value, str):
+ self._write_str_avoiding_backslashes(value)
+ else:
+ self.write(repr(value))
+
+ def visit_Constant(self, node):
+ value = node.value
+ if isinstance(value, tuple):
+ with self.delimit("(", ")"):
+ self.items_view(self._write_constant, value)
+ elif value is ...:
+ self.write("...")
+ else:
+ if node.kind == "u":
+ self.write("u")
+ self._write_constant(node.value)
+
+ def visit_List(self, node):
+ with self.delimit("[", "]"):
+ self.interleave(lambda: self.write(", "), self.traverse, node.elts)
+
+ def visit_ListComp(self, node):
+ with self.delimit("[", "]"):
+ self.traverse(node.elt)
+ for gen in node.generators:
+ self.traverse(gen)
+
+ def visit_GeneratorExp(self, node):
+ with self.delimit("(", ")"):
+ self.traverse(node.elt)
+ for gen in node.generators:
+ self.traverse(gen)
+
+ def visit_SetComp(self, node):
+ with self.delimit("{", "}"):
+ self.traverse(node.elt)
+ for gen in node.generators:
+ self.traverse(gen)
+
+ def visit_DictComp(self, node):
+ with self.delimit("{", "}"):
+ self.traverse(node.key)
+ self.write(": ")
+ self.traverse(node.value)
+ for gen in node.generators:
+ self.traverse(gen)
+
+ def visit_comprehension(self, node):
+ if node.is_async:
+ self.write(" async for ")
+ else:
+ self.write(" for ")
+ self.set_precedence(_Precedence.TUPLE, node.target)
+ self.traverse(node.target)
+ self.write(" in ")
+ self.set_precedence(_Precedence.TEST.next(), node.iter, *node.ifs)
+ self.traverse(node.iter)
+ for if_clause in node.ifs:
+ self.write(" if ")
+ self.traverse(if_clause)
+
+ def visit_IfExp(self, node):
+ with self.require_parens(_Precedence.TEST, node):
+ self.set_precedence(_Precedence.TEST.next(), node.body, node.test)
+ self.traverse(node.body)
+ self.write(" if ")
+ self.traverse(node.test)
+ self.write(" else ")
+ self.set_precedence(_Precedence.TEST, node.orelse)
+ self.traverse(node.orelse)
+
+ def visit_Set(self, node):
+ if node.elts:
+ with self.delimit("{", "}"):
+ self.interleave(lambda: self.write(", "), self.traverse, node.elts)
+ else:
+ # `{}` would be interpreted as a dictionary literal, and
+ # `set` might be shadowed. Thus:
+ self.write('{*()}')
+
+ def visit_Dict(self, node):
+ def write_key_value_pair(k, v):
+ self.traverse(k)
+ self.write(": ")
+ self.traverse(v)
+
+ def write_item(item):
+ k, v = item
+ if k is None:
+ # for dictionary unpacking operator in dicts {**{'y': 2}}
+ # see PEP 448 for details
+ self.write("**")
+ self.set_precedence(_Precedence.EXPR, v)
+ self.traverse(v)
+ else:
+ write_key_value_pair(k, v)
+
+ with self.delimit("{", "}"):
+ self.interleave(
+ lambda: self.write(", "), write_item, zip(node.keys, node.values)
+ )
+
+ def visit_Tuple(self, node):
+ with self.delimit("(", ")"):
+ self.items_view(self.traverse, node.elts)
+
+ unop = {"Invert": "~", "Not": "not", "UAdd": "+", "USub": "-"}
+ unop_precedence = {
+ "not": _Precedence.NOT,
+ "~": _Precedence.FACTOR,
+ "+": _Precedence.FACTOR,
+ "-": _Precedence.FACTOR,
+ }
+
+ def visit_UnaryOp(self, node):
+ operator = self.unop[node.op.__class__.__name__]
+ operator_precedence = self.unop_precedence[operator]
+ with self.require_parens(operator_precedence, node):
+ self.write(operator)
+ # factor prefixes (+, -, ~) shouldn't be seperated
+ # from the value they belong, (e.g: +1 instead of + 1)
+ if operator_precedence is not _Precedence.FACTOR:
+ self.write(" ")
+ self.set_precedence(operator_precedence, node.operand)
+ self.traverse(node.operand)
+
+ binop = {
+ "Add": "+",
+ "Sub": "-",
+ "Mult": "*",
+ "MatMult": "@",
+ "Div": "/",
+ "Mod": "%",
+ "LShift": "<<",
+ "RShift": ">>",
+ "BitOr": "|",
+ "BitXor": "^",
+ "BitAnd": "&",
+ "FloorDiv": "//",
+ "Pow": "**",
+ }
+
+ binop_precedence = {
+ "+": _Precedence.ARITH,
+ "-": _Precedence.ARITH,
+ "*": _Precedence.TERM,
+ "@": _Precedence.TERM,
+ "/": _Precedence.TERM,
+ "%": _Precedence.TERM,
+ "<<": _Precedence.SHIFT,
+ ">>": _Precedence.SHIFT,
+ "|": _Precedence.BOR,
+ "^": _Precedence.BXOR,
+ "&": _Precedence.BAND,
+ "//": _Precedence.TERM,
+ "**": _Precedence.POWER,
+ }
+
+ binop_rassoc = frozenset(("**",))
+ def visit_BinOp(self, node):
+ operator = self.binop[node.op.__class__.__name__]
+ operator_precedence = self.binop_precedence[operator]
+ with self.require_parens(operator_precedence, node):
+ if operator in self.binop_rassoc:
+ left_precedence = operator_precedence.next()
+ right_precedence = operator_precedence
+ else:
+ left_precedence = operator_precedence
+ right_precedence = operator_precedence.next()
+
+ self.set_precedence(left_precedence, node.left)
+ self.traverse(node.left)
+ self.write(f" {operator} ")
+ self.set_precedence(right_precedence, node.right)
+ self.traverse(node.right)
+
+ cmpops = {
+ "Eq": "==",
+ "NotEq": "!=",
+ "Lt": "<",
+ "LtE": "<=",
+ "Gt": ">",
+ "GtE": ">=",
+ "Is": "is",
+ "IsNot": "is not",
+ "In": "in",
+ "NotIn": "not in",
+ }
+
+ def visit_Compare(self, node):
+ with self.require_parens(_Precedence.CMP, node):
+ self.set_precedence(_Precedence.CMP.next(), node.left, *node.comparators)
+ self.traverse(node.left)
+ for o, e in zip(node.ops, node.comparators):
+ self.write(" " + self.cmpops[o.__class__.__name__] + " ")
+ self.traverse(e)
+
+ boolops = {"And": "and", "Or": "or"}
+ boolop_precedence = {"and": _Precedence.AND, "or": _Precedence.OR}
+
+ def visit_BoolOp(self, node):
+ operator = self.boolops[node.op.__class__.__name__]
+ operator_precedence = self.boolop_precedence[operator]
+
+ def increasing_level_traverse(node):
+ nonlocal operator_precedence
+ operator_precedence = operator_precedence.next()
+ self.set_precedence(operator_precedence, node)
+ self.traverse(node)
+
+ with self.require_parens(operator_precedence, node):
+ s = f" {operator} "
+ self.interleave(lambda: self.write(s), increasing_level_traverse, node.values)
+
+ def visit_Attribute(self, node):
+ self.set_precedence(_Precedence.ATOM, node.value)
+ self.traverse(node.value)
+ # Special case: 3.__abs__() is a syntax error, so if node.value
+ # is an integer literal then we need to either parenthesize
+ # it or add an extra space to get 3 .__abs__().
+ if isinstance(node.value, ast.Constant) and isinstance(node.value.value, int):
+ self.write(" ")
+ self.write(".")
+ self.write(node.attr)
+
+ def visit_Call(self, node):
+ self.set_precedence(_Precedence.ATOM, node.func)
+ self.traverse(node.func)
+ with self.delimit("(", ")"):
+ comma = False
+ for e in node.args:
+ if comma:
+ self.write(", ")
+ else:
+ comma = True
+ self.traverse(e)
+ for e in node.keywords:
+ if comma:
+ self.write(", ")
+ else:
+ comma = True
+ self.traverse(e)
+
+ def visit_Subscript(self, node):
+ def is_simple_tuple(slice_value):
+ # when unparsing a non-empty tuple, the parantheses can be safely
+ # omitted if there aren't any elements that explicitly requires
+ # parantheses (such as starred expressions).
+ return (
+ isinstance(slice_value, ast.Tuple)
+ and slice_value.elts
+ and not any(isinstance(elt, ast.Starred) for elt in slice_value.elts)
+ )
+
+ self.set_precedence(_Precedence.ATOM, node.value)
+ self.traverse(node.value)
+ with self.delimit("[", "]"):
+ if is_simple_tuple(node.slice):
+ self.items_view(self.traverse, node.slice.elts)
+ else:
+ self.traverse(node.slice)
+
+ def visit_Starred(self, node):
+ self.write("*")
+ self.set_precedence(_Precedence.EXPR, node.value)
+ self.traverse(node.value)
+
+ def visit_Ellipsis(self, node):
+ self.write("...")
+
+ def visit_Slice(self, node):
+ if node.lower:
+ self.traverse(node.lower)
+ self.write(":")
+ if node.upper:
+ self.traverse(node.upper)
+ if node.step:
+ self.write(":")
+ self.traverse(node.step)
+
+ def visit_arg(self, node):
+ self.write(node.arg)
+ if node.annotation:
+ self.write(": ")
+ self.traverse(node.annotation)
+
+ def visit_arguments(self, node):
+ first = True
+ # normal arguments
+ all_args = node.posonlyargs + node.args
+ defaults = [None] * (len(all_args) - len(node.defaults)) + node.defaults
+ for index, elements in enumerate(zip(all_args, defaults), 1):
+ a, d = elements
+ if first:
+ first = False
+ else:
+ self.write(", ")
+ self.traverse(a)
+ if d:
+ self.write("=")
+ self.traverse(d)
+ if index == len(node.posonlyargs):
+ self.write(", /")
+
+ # varargs, or bare '*' if no varargs but keyword-only arguments present
+ if node.vararg or node.kwonlyargs:
+ if first:
+ first = False
+ else:
+ self.write(", ")
+ self.write("*")
+ if node.vararg:
+ self.write(node.vararg.arg)
+ if node.vararg.annotation:
+ self.write(": ")
+ self.traverse(node.vararg.annotation)
+
+ # keyword-only arguments
+ if node.kwonlyargs:
+ for a, d in zip(node.kwonlyargs, node.kw_defaults):
+ self.write(", ")
+ self.traverse(a)
+ if d:
+ self.write("=")
+ self.traverse(d)
+
+ # kwargs
+ if node.kwarg:
+ if first:
+ first = False
+ else:
+ self.write(", ")
+ self.write("**" + node.kwarg.arg)
+ if node.kwarg.annotation:
+ self.write(": ")
+ self.traverse(node.kwarg.annotation)
+
+ def visit_keyword(self, node):
+ if node.arg is None:
+ self.write("**")
+ else:
+ self.write(node.arg)
+ self.write("=")
+ self.traverse(node.value)
+
+ def visit_Lambda(self, node):
+ with self.require_parens(_Precedence.TEST, node):
+ self.write("lambda ")
+ self.traverse(node.args)
+ self.write(": ")
+ self.set_precedence(_Precedence.TEST, node.body)
+ self.traverse(node.body)
+
+ def visit_alias(self, node):
+ self.write(node.name)
+ if node.asname:
+ self.write(" as " + node.asname)
+
+ def visit_withitem(self, node):
+ self.traverse(node.context_expr)
+ if node.optional_vars:
+ self.write(" as ")
+ self.traverse(node.optional_vars)
+
+def unparse(ast_obj):
+ unparser = _Unparser()
+ return unparser.visit(ast_obj)
