Source code for zope.tales.engine

##############################################################################
#
# Copyright (c) 2002 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Expression engine configuration and registration.

Each expression engine can have its own expression types and base names.
"""
from zope.tales.expressions import DeferExpr
from zope.tales.expressions import LazyExpr
from zope.tales.expressions import NotExpr
from zope.tales.expressions import PathExpr
from zope.tales.expressions import SimpleModuleImporter
from zope.tales.expressions import StringExpr
from zope.tales.pythonexpr import PythonExpr
from zope.tales.tales import ExpressionEngine




def DefaultEngine():
    """
    Create and return an instance of :class:`~.ExpressionEngine` (an
    implementation of
    :class:`zope.tal.interfaces.ITALExpressionCompiler`) with the
    following expression types registered:

    ``string``
        :class:`.StringExpr`
    ``python``
        :class:`.PythonExpr`
    ``not``
        :class:`.NotExpr`
    ``defer``
        :class:`.DeferExpr`
    ``lazy``
        :class:`.LazyExpr`
    ``modules``
        :class:`.SimpleModuleImporter`

    In addition, the default ``path`` expressions (``standard``, ``path``,
    ``exists`` and ``nocall``), all implemented by :class:`.PathExpr`, are
    registered.
    """
    e = ExpressionEngine()
    reg = e.registerType
    for pt in PathExpr._default_type_names:
        reg(pt, PathExpr)
    reg('string', StringExpr)
    reg('python', PythonExpr)
    reg('not', NotExpr)
    reg('defer', DeferExpr)
    reg('lazy', LazyExpr)
    e.registerBaseName('modules', SimpleModuleImporter())
    return e



Engine = DefaultEngine()