utils.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
import ast
from exc import TemplateContextError


def resolve(token, context):
    """
    A context is a dict with keys and values. We resolve the values
    in the context based on their type.
    For example, for a variable {{ foo }} to be resolveld, the template has
    to be passed in the variable as context in its render function, like so:
        `myTemplate.render("template.html", context={'foo': 10})`
    or as Flask does it using kwargs:
        `myTemplate.render("template.html", foo=10)`
    """
    if '.' in token:
        return do_dots(token, context)
    else:
        try:
            rv = context[token]
        except KeyError:
            raise TemplateContextError(token)
        else:
            return rv


def do_dots(token, context):
    # handle dot attribute lookups!
    t_split = token.split('.')
    rv = context.get(t_split[0], None)
    if rv and t_split[1:]:
        for i in t_split[1:]:
            try:
                rv = getattr(rv, str(i))
            except AttributeError:
                rv = rv[str(i)]
            if callable(rv):
                rv = rv()
    return rv


def eval_expression(expr):
    try:
        return 'literal', ast.literal_eval(expr)
    except ValueError or IndentationError or SyntaxError:
        return 'name', expr