test_optimizer.py

from jinja2 import Environment
from jinja2.compiler import generate
from jinja2.optimizer import optimize


env = Environment()
forums = [
    {'id': 1, 'name': u'Example'},
    {'id': 2, 'name': u'Foobar'},
    {'id': 3, 'name': u'<42>'}
]
ast = env.parse("""
    Hi {{ "<blub>"|e }},
    how are you?

    {% for forum in forums %}
        {{ readstatus(forum.id) }} {{ forum.id|e }} {{ forum.name|e }}
    {% endfor %}

    {% navigation = [('#foo', 'Foo'), ('#bar', 'Bar'), ('#baz', 42 * 2 + 23)] %}
    <ul>
    {% for key, value in navigation %}
        <li>{{ loop.index }}: <a href="{{ key[1:].upper()|e }}">{{ value|e }}</a></li>
    {% endfor %}
    </ul>
""")
print ast
print
print generate(ast, env, "foo.html")
print
ast = optimize(ast, env, context_hint={'forums': forums})
print ast
print
print generate(ast, env, "foo.html")