artiq/artiq/compiler/unparse.py

import sys
import ast
import os

# 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)

def interleave(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)

class Unparser:
	"""Methods in this class recursively traverse an AST and
	output source code for the abstract syntax; original formatting
	is disregarded. """

	def __init__(self, tree, file = sys.stdout):
		"""Unparser(tree, file=sys.stdout) -> None.
		 Print the source for tree to file."""
		self.f = file
		self._indent = 0
		self.dispatch(tree)
		print("", file=self.f)
		self.f.flush()

	def fill(self, text = ""):
		"Indent a piece of text, according to the current indentation level"
		self.f.write("\n"+"    "*self._indent + text)

	def write(self, text):
		"Append a piece of text to the current line."
		self.f.write(text)

	def enter(self):
		"Print ':', and increase the indentation."
		self.write(":")
		self._indent += 1

	def leave(self):
		"Decrease the indentation level."
		self._indent -= 1

	def dispatch(self, tree):
		"Dispatcher function, dispatching tree type T to method _T."
		if isinstance(tree, list):
			for t in tree:
				self.dispatch(t)
			return
		meth = getattr(self, "_"+tree.__class__.__name__)
		meth(tree)


	############### Unparsing methods ######################
	# There should be one method per concrete grammar type #
	# Constructors should be grouped by sum type. Ideally, #
	# this would follow the order in the grammar, but      #
	# currently doesn't.                                   #
	########################################################

	def _Module(self, tree):
		for stmt in tree.body:
			self.dispatch(stmt)

	# stmt
	def _Expr(self, tree):
		self.fill()
		self.dispatch(tree.value)

	def _Import(self, t):
		self.fill("import ")
		interleave(lambda: self.write(", "), self.dispatch, t.names)

	def _ImportFrom(self, t):
		self.fill("from ")
		self.write("." * t.level)
		if t.module:
			self.write(t.module)
		self.write(" import ")
		interleave(lambda: self.write(", "), self.dispatch, t.names)

	def _Assign(self, t):
		self.fill()
		for target in t.targets:
			self.dispatch(target)
			self.write(" = ")
		self.dispatch(t.value)

	def _AugAssign(self, t):
		self.fill()
		self.dispatch(t.target)
		self.write(" "+self.binop[t.op.__class__.__name__]+"= ")
		self.dispatch(t.value)

	def _Return(self, t):
		self.fill("return")
		if t.value:
			self.write(" ")
			self.dispatch(t.value)

	def _Pass(self, t):
		self.fill("pass")

	def _Break(self, t):
		self.fill("break")

	def _Continue(self, t):
		self.fill("continue")

	def _Delete(self, t):
		self.fill("del ")
		interleave(lambda: self.write(", "), self.dispatch, t.targets)

	def _Assert(self, t):
		self.fill("assert ")
		self.dispatch(t.test)
		if t.msg:
			self.write(", ")
			self.dispatch(t.msg)

	def _Global(self, t):
		self.fill("global ")
		interleave(lambda: self.write(", "), self.write, t.names)

	def _Nonlocal(self, t):
		self.fill("nonlocal ")
		interleave(lambda: self.write(", "), self.write, t.names)

	def _Yield(self, t):
		self.write("(")
		self.write("yield")
		if t.value:
			self.write(" ")
			self.dispatch(t.value)
		self.write(")")

	def _YieldFrom(self, t):
		self.write("(")
		self.write("yield from")
		if t.value:
			self.write(" ")
			self.dispatch(t.value)
		self.write(")")

	def _Raise(self, t):
		self.fill("raise")
		if not t.exc:
			assert not t.cause
			return
		self.write(" ")
		self.dispatch(t.exc)
		if t.cause:
			self.write(" from ")
			self.dispatch(t.cause)

	def _Try(self, t):
		self.fill("try")
		self.enter()
		self.dispatch(t.body)
		self.leave()
		for ex in t.handlers:
			self.dispatch(ex)
		if t.orelse:
			self.fill("else")
			self.enter()
			self.dispatch(t.orelse)
			self.leave()
		if t.finalbody:
			self.fill("finally")
			self.enter()
			self.dispatch(t.finalbody)
			self.leave()

	def _ExceptHandler(self, t):
		self.fill("except")
		if t.type:
			self.write(" ")
			self.dispatch(t.type)
		if t.name:
			self.write(" as ")
			self.write(t.name)
		self.enter()
		self.dispatch(t.body)
		self.leave()

	def _ClassDef(self, t):
		self.write("\n")
		for deco in t.decorator_list:
			self.fill("@")
			self.dispatch(deco)
		self.fill("class "+t.name)
		self.write("(")
		comma = False
		for e in t.bases:
			if comma: self.write(", ")
			else: comma = True
			self.dispatch(e)
		for e in t.keywords:
			if comma: self.write(", ")
			else: comma = True
			self.dispatch(e)
		if t.starargs:
			if comma: self.write(", ")
			else: comma = True
			self.write("*")
			self.dispatch(t.starargs)
		if t.kwargs:
			if comma: self.write(", ")
			else: comma = True
			self.write("**")
			self.dispatch(t.kwargs)
		self.write(")")

		self.enter()
		self.dispatch(t.body)
		self.leave()

	def _FunctionDef(self, t):
		self.write("\n")
		for deco in t.decorator_list:
			self.fill("@")
			self.dispatch(deco)
		self.fill("def "+t.name + "(")
		self.dispatch(t.args)
		self.write(")")
		if t.returns:
			self.write(" -> ")
			self.dispatch(t.returns)
		self.enter()
		self.dispatch(t.body)
		self.leave()

	def _For(self, t):
		self.fill("for ")
		self.dispatch(t.target)
		self.write(" in ")
		self.dispatch(t.iter)
		self.enter()
		self.dispatch(t.body)
		self.leave()
		if t.orelse:
			self.fill("else")
			self.enter()
			self.dispatch(t.orelse)
			self.leave()

	def _If(self, t):
		self.fill("if ")
		self.dispatch(t.test)
		self.enter()
		self.dispatch(t.body)
		self.leave()
		# collapse nested ifs into equivalent elifs.
		while (t.orelse and len(t.orelse) == 1 and
			   isinstance(t.orelse[0], ast.If)):
			t = t.orelse[0]
			self.fill("elif ")
			self.dispatch(t.test)
			self.enter()
			self.dispatch(t.body)
			self.leave()
		# final else
		if t.orelse:
			self.fill("else")
			self.enter()
			self.dispatch(t.orelse)
			self.leave()

	def _While(self, t):
		self.fill("while ")
		self.dispatch(t.test)
		self.enter()
		self.dispatch(t.body)
		self.leave()
		if t.orelse:
			self.fill("else")
			self.enter()
			self.dispatch(t.orelse)
			self.leave()

	def _With(self, t):
		self.fill("with ")
		interleave(lambda: self.write(", "), self.dispatch, t.items)
		self.enter()
		self.dispatch(t.body)
		self.leave()

	# expr
	def _Bytes(self, t):
		self.write(repr(t.s))

	def _Str(self, tree):
		self.write(repr(tree.s))

	def _Name(self, t):
		self.write(t.id)

	def _NameConstant(self, t):
		self.write(repr(t.value))

	def _Num(self, t):
		# Substitute overflowing decimal literal for AST infinities.
		self.write(repr(t.n).replace("inf", INFSTR))

	def _List(self, t):
		self.write("[")
		interleave(lambda: self.write(", "), self.dispatch, t.elts)
		self.write("]")

	def _ListComp(self, t):
		self.write("[")
		self.dispatch(t.elt)
		for gen in t.generators:
			self.dispatch(gen)
		self.write("]")

	def _GeneratorExp(self, t):
		self.write("(")
		self.dispatch(t.elt)
		for gen in t.generators:
			self.dispatch(gen)
		self.write(")")

	def _SetComp(self, t):
		self.write("{")
		self.dispatch(t.elt)
		for gen in t.generators:
			self.dispatch(gen)
		self.write("}")

	def _DictComp(self, t):
		self.write("{")
		self.dispatch(t.key)
		self.write(": ")
		self.dispatch(t.value)
		for gen in t.generators:
			self.dispatch(gen)
		self.write("}")

	def _comprehension(self, t):
		self.write(" for ")
		self.dispatch(t.target)
		self.write(" in ")
		self.dispatch(t.iter)
		for if_clause in t.ifs:
			self.write(" if ")
			self.dispatch(if_clause)

	def _IfExp(self, t):
		self.write("(")
		self.dispatch(t.body)
		self.write(" if ")
		self.dispatch(t.test)
		self.write(" else ")
		self.dispatch(t.orelse)
		self.write(")")

	def _Set(self, t):
		assert(t.elts) # should be at least one element
		self.write("{")
		interleave(lambda: self.write(", "), self.dispatch, t.elts)
		self.write("}")

	def _Dict(self, t):
		self.write("{")
		def write_pair(pair):
			(k, v) = pair
			self.dispatch(k)
			self.write(": ")
			self.dispatch(v)
		interleave(lambda: self.write(", "), write_pair, zip(t.keys, t.values))
		self.write("}")

	def _Tuple(self, t):
		self.write("(")
		if len(t.elts) == 1:
			(elt,) = t.elts
			self.dispatch(elt)
			self.write(",")
		else:
			interleave(lambda: self.write(", "), self.dispatch, t.elts)
		self.write(")")

	unop = {"Invert":"~", "Not": "not", "UAdd":"+", "USub":"-"}
	def _UnaryOp(self, t):
		self.write("(")
		self.write(self.unop[t.op.__class__.__name__])
		self.write(" ")
		self.dispatch(t.operand)
		self.write(")")

	binop = { "Add":"+", "Sub":"-", "Mult":"*", "Div":"/", "Mod":"%",
					"LShift":"<<", "RShift":">>", "BitOr":"|", "BitXor":"^", "BitAnd":"&",
					"FloorDiv":"//", "Pow": "**"}
	def _BinOp(self, t):
		self.write("(")
		self.dispatch(t.left)
		self.write(" " + self.binop[t.op.__class__.__name__] + " ")
		self.dispatch(t.right)
		self.write(")")

	cmpops = {"Eq":"==", "NotEq":"!=", "Lt":"<", "LtE":"<=", "Gt":">", "GtE":">=",
						"Is":"is", "IsNot":"is not", "In":"in", "NotIn":"not in"}
	def _Compare(self, t):
		self.write("(")
		self.dispatch(t.left)
		for o, e in zip(t.ops, t.comparators):
			self.write(" " + self.cmpops[o.__class__.__name__] + " ")
			self.dispatch(e)
		self.write(")")

	boolops = {ast.And: 'and', ast.Or: 'or'}
	def _BoolOp(self, t):
		self.write("(")
		s = " %s " % self.boolops[t.op.__class__]
		interleave(lambda: self.write(s), self.dispatch, t.values)
		self.write(")")

	def _Attribute(self,t):
		self.dispatch(t.value)
		# Special case: 3.__abs__() is a syntax error, so if t.value
		# is an integer literal then we need to either parenthesize
		# it or add an extra space to get 3 .__abs__().
		if isinstance(t.value, ast.Num) and isinstance(t.value.n, int):
			self.write(" ")
		self.write(".")
		self.write(t.attr)

	def _Call(self, t):
		self.dispatch(t.func)
		self.write("(")
		comma = False
		for e in t.args:
			if comma: self.write(", ")
			else: comma = True
			self.dispatch(e)
		for e in t.keywords:
			if comma: self.write(", ")
			else: comma = True
			self.dispatch(e)
		if t.starargs:
			if comma: self.write(", ")
			else: comma = True
			self.write("*")
			self.dispatch(t.starargs)
		if t.kwargs:
			if comma: self.write(", ")
			else: comma = True
			self.write("**")
			self.dispatch(t.kwargs)
		self.write(")")

	def _Subscript(self, t):
		self.dispatch(t.value)
		self.write("[")
		self.dispatch(t.slice)
		self.write("]")

	def _Starred(self, t):
		self.write("*")
		self.dispatch(t.value)

	# slice
	def _Ellipsis(self, t):
		self.write("...")

	def _Index(self, t):
		self.dispatch(t.value)

	def _Slice(self, t):
		if t.lower:
			self.dispatch(t.lower)
		self.write(":")
		if t.upper:
			self.dispatch(t.upper)
		if t.step:
			self.write(":")
			self.dispatch(t.step)

	def _ExtSlice(self, t):
		interleave(lambda: self.write(', '), self.dispatch, t.dims)

	# argument
	def _arg(self, t):
		self.write(t.arg)
		if t.annotation:
			self.write(": ")
			self.dispatch(t.annotation)

	# others
	def _arguments(self, t):
		first = True
		# normal arguments
		defaults = [None] * (len(t.args) - len(t.defaults)) + t.defaults
		for a, d in zip(t.args, defaults):
			if first:first = False
			else: self.write(", ")
			self.dispatch(a)
			if d:
				self.write("=")
				self.dispatch(d)

		# varargs, or bare '*' if no varargs but keyword-only arguments present
		if t.vararg or t.kwonlyargs:
			if first:first = False
			else: self.write(", ")
			self.write("*")
			if t.vararg:
				self.write(t.vararg.arg)
				if t.vararg.annotation:
					self.write(": ")
					self.dispatch(t.vararg.annotation)

		# keyword-only arguments
		if t.kwonlyargs:
			for a, d in zip(t.kwonlyargs, t.kw_defaults):
				if first:first = False
				else: self.write(", ")
				self.dispatch(a),
				if d:
					self.write("=")
					self.dispatch(d)

		# kwargs
		if t.kwarg:
			if first:first = False
			else: self.write(", ")
			self.write("**"+t.kwarg.arg)
			if t.kwarg.annotation:
				self.write(": ")
				self.dispatch(t.kwarg.annotation)

	def _keyword(self, t):
		self.write(t.arg)
		self.write("=")
		self.dispatch(t.value)

	def _Lambda(self, t):
		self.write("(")
		self.write("lambda ")
		self.dispatch(t.args)
		self.write(": ")
		self.dispatch(t.body)
		self.write(")")

	def _alias(self, t):
		self.write(t.name)
		if t.asname:
			self.write(" as "+t.asname)

	def _withitem(self, t):
		self.dispatch(t.context_expr)
		if t.optional_vars:
			self.write(" as ")
			self.dispatch(t.optional_vars)