quick nse with lazy

a.py

'''
Examples
--------

In [1]: a
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-1-60b725f10c9c> in <module>()
----> 1 a

NameError: name 'a' is not defined

In [2]: b = 'b'

In [3]: from a import nse

In [4]: @nse
   ...: def f():
   ...:     return a
   ...:

In [5]: c = f()

In [6]: from lazy import parse

In [7]: parse(c)
Out[7]: Call(func=Normal(value=<function get_name at 0x7f5ab75c9ea0>), args=(Normal(value='a'), Normal(value=<frame object at 0x7f5ab723d408>)), kwargs={})

In [8]: parse(c).subs({'a': 'b'})
Out[8]: Call(func=Normal(value=<function get_name at 0x7f5ab75c9ea0>), args=(Normal(value='b'), Normal(value=<frame object at 0x7f5ab723d408>)), kwargs={})

In [9]: parse(c).subs({'a': 'b'}).lcompile()
Out[9]: 'b'

In [10]: c
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
/home/yui/.virtualenvs/lazy/lib/python3.4/site-packages/IPython/core/prefilter.py in prefilter_lines(self, lines, continue_prompt)
    348                              for lnum, line in enumerate(llines) ])
    349         else:
--> 350             out = self.prefilter_line(llines[0], continue_prompt)
    351
    352         return out

/home/yui/.virtualenvs/lazy/lib/python3.4/site-packages/IPython/core/prefilter.py in prefilter_line(self, line, continue_prompt)
    323             return normal_handler.handle(line_info)
    324
--> 325         prefiltered = self.prefilter_line_info(line_info)
    326         # print "prefiltered line: %r" % prefiltered
    327         return prefiltered

/home/yui/.virtualenvs/lazy/lib/python3.4/site-packages/IPython/core/prefilter.py in prefilter_line_info(self, line_info)
    265         """
    266         # print "prefilter_line_info: ", line_info
--> 267         handler = self.find_handler(line_info)
    268         return handler.handle(line_info)
    269

/home/yui/.virtualenvs/lazy/lib/python3.4/site-packages/IPython/core/prefilter.py in find_handler(self, line_info)
    272         for checker in self.checkers:
    273             if checker.enabled:
--> 274                 handler = checker.check(line_info)
    275                 if handler:
    276                     return handler

/home/yui/.virtualenvs/lazy/lib/python3.4/site-packages/IPython/core/prefilter.py in check(self, line_info)
    429     def check(self, line_info):
    430         obj = self.shell.user_ns.get(line_info.ifun)
--> 431         if isinstance(obj, Macro):
    432             return self.prefilter_manager.get_handler_by_name('macro')
    433         else:

/home/yui/projects/tmp/a.py in get_name(name, frame)
     38                 return getattr(builtins, name)
     39             except AttributeError:
---> 40                 raise NameError('name %r is not defined' % name) from None
     41
     42

NameError: name 'a' is not defined
'''

import builtins
from functools import partial
from sys import _getframe

from codetransformer import instructions, pattern
from lazy import thunk, strict, lazy_function
from lazy.bytecode import all_startcodes
from lazy.utils import instance


def get_name(name, frame):
    """Retrieve the value named `name` in the given stackframe.

    Parameters
    ----------
    name : str
        The name to look up.
    frame : frame
        The stackframe to look up `name` in.

    Returns
    -------
    val : any
        The value bound to `name` in `frame`.

    Raises
    ------
    NameError
        When `name` is not bound.
    """
    try:
        return frame.f_locals[name]
    except KeyError:
        try:
            return frame.f_globals[name]
        except KeyError:
            try:
                return getattr(builtins, name)
            except AttributeError:
                raise NameError('name %r is not defined' % name) from None


@instance
class nse(type(lazy_function)):
    @pattern(
        instructions.LOAD_GLOBAL |
        instructions.LOAD_NAME |
        instructions.LOAD_DEREF |
        instructions.LOAD_FAST,
        startcodes=all_startcodes,
    )
    def _load_name(self, instr):
        yield instructions.LOAD_CONST(partial(thunk, get_name, instr.arg))
        yield instructions.LOAD_CONST(partial(_getframe, 1))
        yield instructions.CALL_FUNCTION(0)
        yield instructions.CALL_FUNCTION(1)

    def __call__(self, *args, **kwargs):
        return strict(super().__call__(*args, **kwargs))