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# mako/ast.py
# Copyright (C) 2006-2015 the Mako authors and contributors <see AUTHORS file>
#
# This module is part of Mako and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""utilities for analyzing expressions and blocks of Python
code, as well as generating Python from AST nodes"""
from mako import exceptions, pyparser, compat
import re
class PythonCode(object):
"""represents information about a string containing Python code"""
def __init__(self, code, **exception_kwargs):
self.code = code
# represents all identifiers which are assigned to at some point in
# the code
self.declared_identifiers = set()
# represents all identifiers which are referenced before their
# assignment, if any
self.undeclared_identifiers = set()
# note that an identifier can be in both the undeclared and declared
# lists.
# using AST to parse instead of using code.co_varnames,
# code.co_names has several advantages:
# - we can locate an identifier as "undeclared" even if
# its declared later in the same block of code
# - AST is less likely to break with version changes
# (for example, the behavior of co_names changed a little bit
# in python version 2.5)
if isinstance(code, compat.string_types):
expr = pyparser.parse(code.lstrip(), "exec", **exception_kwargs)
else:
expr = code
f = pyparser.FindIdentifiers(self, **exception_kwargs)
f.visit(expr)
class ArgumentList(object):
"""parses a fragment of code as a comma-separated list of expressions"""
def __init__(self, code, **exception_kwargs):
self.codeargs = []
self.args = []
self.declared_identifiers = set()
self.undeclared_identifiers = set()
if isinstance(code, compat.string_types):
if re.match(r"\S", code) and not re.match(r",\s*$", code):
# if theres text and no trailing comma, insure its parsed
# as a tuple by adding a trailing comma
code += ","
expr = pyparser.parse(code, "exec", **exception_kwargs)
else:
expr = code
f = pyparser.FindTuple(self, PythonCode, **exception_kwargs)
f.visit(expr)
class PythonFragment(PythonCode):
"""extends PythonCode to provide identifier lookups in partial control
statements
e.g.
for x in 5:
elif y==9:
except (MyException, e):
etc.
"""
def __init__(self, code, **exception_kwargs):
m = re.match(r'^(\w+)(?:\s+(.*?))?:\s*(#|$)', code.strip(), re.S)
if not m:
raise exceptions.CompileException(
"Fragment '%s' is not a partial control statement" %
code, **exception_kwargs)
if m.group(3):
code = code[:m.start(3)]
(keyword, expr) = m.group(1,2)
if keyword in ['for','if', 'while']:
code = code + "pass"
elif keyword == 'try':
code = code + "pass\nexcept:pass"
elif keyword == 'elif' or keyword == 'else':
code = "if False:pass\n" + code + "pass"
elif keyword == 'except':
code = "try:pass\n" + code + "pass"
elif keyword == 'with':
code = code + "pass"
else:
raise exceptions.CompileException(
"Unsupported control keyword: '%s'" %
keyword, **exception_kwargs)
super(PythonFragment, self).__init__(code, **exception_kwargs)
class FunctionDecl(object):
"""function declaration"""
def __init__(self, code, allow_kwargs=True, **exception_kwargs):
self.code = code
expr = pyparser.parse(code, "exec", **exception_kwargs)
f = pyparser.ParseFunc(self, **exception_kwargs)
f.visit(expr)
if not hasattr(self, 'funcname'):
raise exceptions.CompileException(
"Code '%s' is not a function declaration" % code,
**exception_kwargs)
if not allow_kwargs and self.kwargs:
raise exceptions.CompileException(
"'**%s' keyword argument not allowed here" %
self.kwargnames[-1], **exception_kwargs)
def get_argument_expressions(self, as_call=False):
"""Return the argument declarations of this FunctionDecl as a printable
list.
By default the return value is appropriate for writing in a ``def``;
set `as_call` to true to build arguments to be passed to the function
instead (assuming locals with the same names as the arguments exist).
"""
namedecls = []
# Build in reverse order, since defaults and slurpy args come last
argnames = self.argnames[::-1]
kwargnames = self.kwargnames[::-1]
defaults = self.defaults[::-1]
kwdefaults = self.kwdefaults[::-1]
# Named arguments
if self.kwargs:
namedecls.append("**" + kwargnames.pop(0))
for name in kwargnames:
# Keyword-only arguments must always be used by name, so even if
# this is a call, print out `foo=foo`
if as_call:
namedecls.append("%s=%s" % (name, name))
elif kwdefaults:
default = kwdefaults.pop(0)
if default is None:
# The AST always gives kwargs a default, since you can do
# `def foo(*, a=1, b, c=3)`
namedecls.append(name)
else:
namedecls.append("%s=%s" % (
name, pyparser.ExpressionGenerator(default).value()))
else:
namedecls.append(name)
# Positional arguments
if self.varargs:
namedecls.append("*" + argnames.pop(0))
for name in argnames:
if as_call or not defaults:
namedecls.append(name)
else:
default = defaults.pop(0)
namedecls.append("%s=%s" % (
name, pyparser.ExpressionGenerator(default).value()))
namedecls.reverse()
return namedecls
@property
def allargnames(self):
return tuple(self.argnames) + tuple(self.kwargnames)
class FunctionArgs(FunctionDecl):
"""the argument portion of a function declaration"""
def __init__(self, code, **kwargs):
super(FunctionArgs, self).__init__("def ANON(%s):pass" % code,
**kwargs)
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