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# ast.py
# Copyright (C) Mako developers
#
# This module is part of Mako and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Handles parsing of Python code.
Parsing to AST is done via _ast on Python > 2.5, otherwise the compiler
module is used.
"""
from StringIO import StringIO
from mako import exceptions, util
import operator
if util.py3k:
# words that cannot be assigned to (notably
# smaller than the total keys in __builtins__)
reserved = set(['True', 'False', 'None', 'print'])
# the "id" attribute on a function node
arg_id = operator.attrgetter('arg')
else:
# words that cannot be assigned to (notably
# smaller than the total keys in __builtins__)
reserved = set(['True', 'False', 'None'])
# the "id" attribute on a function node
arg_id = operator.attrgetter('id')
try:
import _ast
util.restore__ast(_ast)
import _ast_util
except ImportError:
_ast = None
from compiler import parse as compiler_parse
from compiler import visitor
def parse(code, mode='exec', **exception_kwargs):
"""Parse an expression into AST"""
try:
if _ast:
return _ast_util.parse(code, '<unknown>', mode)
else:
if isinstance(code, unicode):
code = code.encode('ascii', 'backslashreplace')
return compiler_parse(code, mode)
except Exception, e:
raise exceptions.SyntaxException("(%s) %s (%s)" % (e.__class__.__name__, str(e), repr(code[0:50])), **exception_kwargs)
if _ast:
class FindIdentifiers(_ast_util.NodeVisitor):
def __init__(self, listener, **exception_kwargs):
self.in_function = False
self.in_assign_targets = False
self.local_ident_stack = {}
self.listener = listener
self.exception_kwargs = exception_kwargs
def _add_declared(self, name):
if not self.in_function:
self.listener.declared_identifiers.add(name)
def visit_ClassDef(self, node):
self._add_declared(node.name)
def visit_Assign(self, node):
# flip around the visiting of Assign so the expression gets evaluated first,
# in the case of a clause like "x=x+5" (x is undeclared)
self.visit(node.value)
in_a = self.in_assign_targets
self.in_assign_targets = True
for n in node.targets:
self.visit(n)
self.in_assign_targets = in_a
if util.py3k:
# ExceptHandler is in Python 2, but this
# block only works in Python 3 (and is required there)
def visit_ExceptHandler(self, node):
if node.name is not None:
self._add_declared(node.name)
if node.type is not None:
self.listener.undeclared_identifiers.add(node.type.id)
for statement in node.body:
self.visit(statement)
def visit_FunctionDef(self, node):
self._add_declared(node.name)
# push function state onto stack. dont log any
# more identifiers as "declared" until outside of the function,
# but keep logging identifiers as "undeclared".
# track argument names in each function header so they arent counted as "undeclared"
saved = {}
inf = self.in_function
self.in_function = True
for arg in node.args.args:
if arg_id(arg) in self.local_ident_stack:
saved[arg_id(arg)] = True
else:
self.local_ident_stack[arg_id(arg)] = True
for n in node.body:
self.visit(n)
self.in_function = inf
for arg in node.args.args:
if arg_id(arg) not in saved:
del self.local_ident_stack[arg_id(arg)]
def visit_For(self, node):
# flip around visit
self.visit(node.iter)
self.visit(node.target)
for statement in node.body:
self.visit(statement)
for statement in node.orelse:
self.visit(statement)
def visit_Name(self, node):
if isinstance(node.ctx, _ast.Store):
self._add_declared(node.id)
if node.id not in reserved and \
node.id not in self.listener.declared_identifiers and \
node.id not in self.local_ident_stack:
self.listener.undeclared_identifiers.add(node.id)
def visit_Import(self, node):
for name in node.names:
if name.asname is not None:
self._add_declared(name.asname)
else:
self._add_declared(name.name.split('.')[0])
def visit_ImportFrom(self, node):
for name in node.names:
if name.asname is not None:
self._add_declared(name.asname)
else:
if name.name == '*':
raise exceptions.CompileException("'import *' is not supported, since all identifier names must be explicitly declared. Please use the form 'from <modulename> import <name1>, <name2>, ...' instead.", **self.exception_kwargs)
self._add_declared(name.name)
class FindTuple(_ast_util.NodeVisitor):
def __init__(self, listener, code_factory, **exception_kwargs):
self.listener = listener
self.exception_kwargs = exception_kwargs
self.code_factory = code_factory
def visit_Tuple(self, node):
for n in node.elts:
p = self.code_factory(n, **self.exception_kwargs)
self.listener.codeargs.append(p)
self.listener.args.append(ExpressionGenerator(n).value())
self.listener.declared_identifiers = self.listener.declared_identifiers.union(p.declared_identifiers)
self.listener.undeclared_identifiers = self.listener.undeclared_identifiers.union(p.undeclared_identifiers)
class ParseFunc(_ast_util.NodeVisitor):
def __init__(self, listener, **exception_kwargs):
self.listener = listener
self.exception_kwargs = exception_kwargs
def visit_FunctionDef(self, node):
self.listener.funcname = node.name
argnames = [arg_id(arg) for arg in node.args.args]
if node.args.vararg:
argnames.append(node.args.vararg)
if node.args.kwarg:
argnames.append(node.args.kwarg)
self.listener.argnames = argnames
self.listener.defaults = node.args.defaults # ast
self.listener.varargs = node.args.vararg
self.listener.kwargs = node.args.kwarg
class ExpressionGenerator(object):
def __init__(self, astnode):
self.generator = _ast_util.SourceGenerator(' ' * 4)
self.generator.visit(astnode)
def value(self):
return ''.join(self.generator.result)
else:
class FindIdentifiers(object):
def __init__(self, listener, **exception_kwargs):
self.in_function = False
self.local_ident_stack = {}
self.listener = listener
self.exception_kwargs = exception_kwargs
def _add_declared(self, name):
if not self.in_function:
self.listener.declared_identifiers.add(name)
def visitClass(self, node, *args):
self._add_declared(node.name)
def visitAssName(self, node, *args):
self._add_declared(node.name)
def visitAssign(self, node, *args):
# flip around the visiting of Assign so the expression gets evaluated first,
# in the case of a clause like "x=x+5" (x is undeclared)
self.visit(node.expr, *args)
for n in node.nodes:
self.visit(n, *args)
def visitFunction(self,node, *args):
self._add_declared(node.name)
# push function state onto stack. dont log any
# more identifiers as "declared" until outside of the function,
# but keep logging identifiers as "undeclared".
# track argument names in each function header so they arent counted as "undeclared"
saved = {}
inf = self.in_function
self.in_function = True
for arg in node.argnames:
if arg in self.local_ident_stack:
saved[arg] = True
else:
self.local_ident_stack[arg] = True
for n in node.getChildNodes():
self.visit(n, *args)
self.in_function = inf
for arg in node.argnames:
if arg not in saved:
del self.local_ident_stack[arg]
def visitFor(self, node, *args):
# flip around visit
self.visit(node.list, *args)
self.visit(node.assign, *args)
self.visit(node.body, *args)
def visitName(self, node, *args):
if node.name not in reserved and node.name not in self.listener.declared_identifiers and node.name not in self.local_ident_stack:
self.listener.undeclared_identifiers.add(node.name)
def visitImport(self, node, *args):
for (mod, alias) in node.names:
if alias is not None:
self._add_declared(alias)
else:
self._add_declared(mod.split('.')[0])
def visitFrom(self, node, *args):
for (mod, alias) in node.names:
if alias is not None:
self._add_declared(alias)
else:
if mod == '*':
raise exceptions.CompileException("'import *' is not supported, since all identifier names must be explicitly declared. Please use the form 'from <modulename> import <name1>, <name2>, ...' instead.", **self.exception_kwargs)
self._add_declared(mod)
def visit(self, expr):
visitor.walk(expr, self) #, walker=walker())
class FindTuple(object):
def __init__(self, listener, code_factory, **exception_kwargs):
self.listener = listener
self.exception_kwargs = exception_kwargs
self.code_factory = code_factory
def visitTuple(self, node, *args):
for n in node.nodes:
p = self.code_factory(n, **self.exception_kwargs)
self.listener.codeargs.append(p)
self.listener.args.append(ExpressionGenerator(n).value())
self.listener.declared_identifiers = self.listener.declared_identifiers.union(p.declared_identifiers)
self.listener.undeclared_identifiers = self.listener.undeclared_identifiers.union(p.undeclared_identifiers)
def visit(self, expr):
visitor.walk(expr, self) #, walker=walker())
class ParseFunc(object):
def __init__(self, listener, **exception_kwargs):
self.listener = listener
self.exception_kwargs = exception_kwargs
def visitFunction(self, node, *args):
self.listener.funcname = node.name
self.listener.argnames = node.argnames
self.listener.defaults = node.defaults
self.listener.varargs = node.varargs
self.listener.kwargs = node.kwargs
def visit(self, expr):
visitor.walk(expr, self)
class ExpressionGenerator(object):
"""given an AST node, generates an equivalent literal Python expression."""
def __init__(self, astnode):
self.buf = StringIO()
visitor.walk(astnode, self) #, walker=walker())
def value(self):
return self.buf.getvalue()
def operator(self, op, node, *args):
self.buf.write("(")
self.visit(node.left, *args)
self.buf.write(" %s " % op)
self.visit(node.right, *args)
self.buf.write(")")
def booleanop(self, op, node, *args):
self.visit(node.nodes[0])
for n in node.nodes[1:]:
self.buf.write(" " + op + " ")
self.visit(n, *args)
def visitConst(self, node, *args):
self.buf.write(repr(node.value))
def visitAssName(self, node, *args):
# TODO: figure out OP_ASSIGN, other OP_s
self.buf.write(node.name)
def visitName(self, node, *args):
self.buf.write(node.name)
def visitMul(self, node, *args):
self.operator("*", node, *args)
def visitAnd(self, node, *args):
self.booleanop("and", node, *args)
def visitOr(self, node, *args):
self.booleanop("or", node, *args)
def visitBitand(self, node, *args):
self.booleanop("&", node, *args)
def visitBitor(self, node, *args):
self.booleanop("|", node, *args)
def visitBitxor(self, node, *args):
self.booleanop("^", node, *args)
def visitAdd(self, node, *args):
self.operator("+", node, *args)
def visitGetattr(self, node, *args):
self.visit(node.expr, *args)
self.buf.write(".%s" % node.attrname)
def visitSub(self, node, *args):
self.operator("-", node, *args)
def visitNot(self, node, *args):
self.buf.write("not ")
self.visit(node.expr)
def visitDiv(self, node, *args):
self.operator("/", node, *args)
def visitFloorDiv(self, node, *args):
self.operator("//", node, *args)
def visitSubscript(self, node, *args):
self.visit(node.expr)
self.buf.write("[")
[self.visit(x) for x in node.subs]
self.buf.write("]")
def visitUnarySub(self, node, *args):
self.buf.write("-")
self.visit(node.expr)
def visitUnaryAdd(self, node, *args):
self.buf.write("-")
self.visit(node.expr)
def visitSlice(self, node, *args):
self.visit(node.expr)
self.buf.write("[")
if node.lower is not None:
self.visit(node.lower)
self.buf.write(":")
if node.upper is not None:
self.visit(node.upper)
self.buf.write("]")
def visitDict(self, node):
self.buf.write("{")
c = node.getChildren()
for i in range(0, len(c), 2):
self.visit(c[i])
self.buf.write(": ")
self.visit(c[i+1])
if i<len(c) -2:
self.buf.write(", ")
self.buf.write("}")
def visitTuple(self, node):
self.buf.write("(")
c = node.getChildren()
for i in range(0, len(c)):
self.visit(c[i])
if i<len(c) - 1:
self.buf.write(", ")
self.buf.write(")")
def visitList(self, node):
self.buf.write("[")
c = node.getChildren()
for i in range(0, len(c)):
self.visit(c[i])
if i<len(c) - 1:
self.buf.write(", ")
self.buf.write("]")
def visitListComp(self, node):
self.buf.write("[")
self.visit(node.expr)
self.buf.write(" ")
for n in node.quals:
self.visit(n)
self.buf.write("]")
def visitListCompFor(self, node):
self.buf.write(" for ")
self.visit(node.assign)
self.buf.write(" in ")
self.visit(node.list)
for n in node.ifs:
self.visit(n)
def visitListCompIf(self, node):
self.buf.write(" if ")
self.visit(node.test)
def visitCompare(self, node):
self.visit(node.expr)
for tup in node.ops:
self.buf.write(tup[0])
self.visit(tup[1])
def visitCallFunc(self, node, *args):
self.visit(node.node)
self.buf.write("(")
if len(node.args):
self.visit(node.args[0])
for a in node.args[1:]:
self.buf.write(", ")
self.visit(a)
self.buf.write(")")
class walker(visitor.ASTVisitor):
def dispatch(self, node, *args):
print "Node:", str(node)
#print "dir:", dir(node)
return visitor.ASTVisitor.dispatch(self, node, *args)
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