begin implementing inspection system for #2208

7 files changed, 115 insertions, 13 deletions

diff --git a/lib/sqlalchemy/__init__.py b/lib/sqlalchemy/__init__.py
index 4e00437ea..ee7bf4c6f 100644
--- a/lib/sqlalchemy/__init__.py
+++ b/lib/sqlalchemy/__init__.py
@@ -4,7 +4,7 @@
 # This module is part of SQLAlchemy and is released under
 # the MIT License: http://www.opensource.org/licenses/mit-license.php
 
-import inspect
+import inspect as _inspect
 import sys
 
 import sqlalchemy.exc as exceptions
@@ -111,15 +111,17 @@ from sqlalchemy.schema import (
     UniqueConstraint,
     )
 
+from sqlalchemy.inspection import inspect
+
 from sqlalchemy.engine import create_engine, engine_from_config
 
 
 __all__ = sorted(name for name, obj in locals().items()
-                 if not (name.startswith('_') or inspect.ismodule(obj)))
+                 if not (name.startswith('_') or _inspect.ismodule(obj)))
 
 __version__ = '0.7.7'
 
-del inspect, sys
+del _inspect, sys
 
 from sqlalchemy import util as _sa_util
 _sa_util.importlater.resolve_all()
diff --git a/lib/sqlalchemy/engine/reflection.py b/lib/sqlalchemy/engine/reflection.py
index 71d97e65f..b2a5a02ef 100644
--- a/lib/sqlalchemy/engine/reflection.py
+++ b/lib/sqlalchemy/engine/reflection.py
@@ -30,7 +30,8 @@ from sqlalchemy import util
 from sqlalchemy.util import topological
 from sqlalchemy.types import TypeEngine
 from sqlalchemy import schema as sa_schema
-
+from sqlalchemy import inspection
+from sqlalchemy.engine.base import Connectable
 
 @util.decorator
 def cache(fn, self, con, *args, **kw):
@@ -118,6 +119,10 @@ class Inspector(object):
             return bind.dialect.inspector(bind)
         return Inspector(bind)
 
+    @inspection._inspects(Connectable)
+    def _insp(bind):
+        return Inspector.from_engine(bind)
+
     @property
     def default_schema_name(self):
         """Return the default schema name presented by the dialect
diff --git a/lib/sqlalchemy/inspection.py b/lib/sqlalchemy/inspection.py
new file mode 100644
index 000000000..9ce52beab
--- /dev/null
+++ b/lib/sqlalchemy/inspection.py
@@ -0,0 +1,44 @@
+# sqlalchemy/inspect.py
+# Copyright (C) 2005-2012 the SQLAlchemy authors and contributors <see AUTHORS file>
+#
+# This module is part of SQLAlchemy and is released under
+# the MIT License: http://www.opensource.org/licenses/mit-license.php
+
+"""Base inspect API.
+
+:func:`.inspect` provides access to a contextual object
+regarding a subject.   
+
+Various subsections of SQLAlchemy,
+such as the :class:`.Inspector`, :class:`.Mapper`, and
+others register themselves with the "inspection registry" here
+so that they may return a context object given a certain kind
+of argument.
+"""
+
+from sqlalchemy import util
+_registrars = util.defaultdict(list)
+
+def inspect(subject):
+    type_ = type(subject)
+    for cls in type_.__mro__:
+        if cls in _registrars:
+            reg = _registrars[cls]
+            break
+    else:
+        raise exc.InvalidRequestError(
+                "No inspection system is "
+                "available for object of type %s" % 
+                type_)
+    return reg(subject)
+
+def _inspects(*types):
+    def decorate(fn_or_cls):
+        for type_ in types:
+            if type_ in _registrars:
+                raise AssertionError(
+                            "Type %s is already "
+                            "registered" % type_)
+            _registrars[type_] = fn_or_cls
+        return fn_or_cls
+    return decorate
diff --git a/lib/sqlalchemy/orm/instrumentation.py b/lib/sqlalchemy/orm/instrumentation.py
index af9ef7841..1012af67a 100644
--- a/lib/sqlalchemy/orm/instrumentation.py
+++ b/lib/sqlalchemy/orm/instrumentation.py
@@ -23,7 +23,7 @@ An example of full customization is in /examples/custom_attributes.
 
 from sqlalchemy.orm import exc, collections, events
 from operator import attrgetter, itemgetter
-from sqlalchemy import event, util
+from sqlalchemy import event, util, inspection
 import weakref
 from sqlalchemy.orm import state, attributes
 
diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index e96b7549a..4fa8dfe24 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -33,6 +33,7 @@ from sqlalchemy.orm.util import _INSTRUMENTOR, _class_to_mapper, \
 import sys
 sessionlib = util.importlater("sqlalchemy.orm", "session")
 properties = util.importlater("sqlalchemy.orm", "properties")
+descriptor_props = util.importlater("sqlalchemy.orm", "descriptor_props")
 
 __all__ = (
     'Mapper',
@@ -1392,12 +1393,35 @@ class Mapper(object):
                         continue
                 yield c
 
-    @property
+    @util.memoized_property
     def properties(self):
-        raise NotImplementedError(
-                    "Public collection of MapperProperty objects is "
-                    "provided by the get_property() and iterate_properties "
-                    "accessors.")
+        if _new_mappers:
+            configure_mappers()
+        return util.ImmutableProperties(self._props)
+
+    @_memoized_configured_property
+    def synonyms(self):
+        return self._filter_properties(descriptor_props.SynonymProperty)
+
+    @_memoized_configured_property
+    def column_attrs(self):
+        return self._filter_properties(properties.ColumnProperty)
+
+    @_memoized_configured_property
+    def relationships(self):
+        return self._filter_properties(properties.RelationshipProperty)
+
+    @_memoized_configured_property
+    def composites(self):
+        return self._filter_properties(descriptor_props.CompositeProperty)
+
+    def _filter_properties(self, type_):
+        if _new_mappers:
+            configure_mappers()
+        return dict(
+            (k, v) for k, v in self._props.iteritems()
+            if isinstance(v, type_)
+        )
 
     @_memoized_configured_property
     def _get_clause(self):
diff --git a/lib/sqlalchemy/orm/state.py b/lib/sqlalchemy/orm/state.py
index 4803ecdc3..156686bc7 100644
--- a/lib/sqlalchemy/orm/state.py
+++ b/lib/sqlalchemy/orm/state.py
@@ -54,6 +54,10 @@ class InstanceState(object):
     def pending(self):
         return {}
 
+    @util.memoized_property
+    def mapper(self):
+        return self.manager.mapper
+
     @property
     def has_identity(self):
         return bool(self.key)
diff --git a/lib/sqlalchemy/orm/util.py b/lib/sqlalchemy/orm/util.py
index 0c5f203a7..8d334ce17 100644
--- a/lib/sqlalchemy/orm/util.py
+++ b/lib/sqlalchemy/orm/util.py
@@ -5,7 +5,7 @@
 # the MIT License: http://www.opensource.org/licenses/mit-license.php
 
 
-from sqlalchemy import sql, util, event, exc as sa_exc
+from sqlalchemy import sql, util, event, exc as sa_exc, inspection
 from sqlalchemy.sql import expression, util as sql_util, operators
 from sqlalchemy.orm.interfaces import MapperExtension, EXT_CONTINUE,\
                                 PropComparator, MapperProperty
@@ -616,15 +616,34 @@ def object_mapper(instance):
 
     Raises UnmappedInstanceError if no mapping is configured.
 
+    This function is available via the inspection system as::
+    
+        inspect(instance).mapper
+
+    """
+    return object_state(instance).mapper
+
+@inspection._inspects(object)
+def object_state(instance):
+    """Given an object, return the primary Mapper associated with the object
+    instance.
+
+    Raises UnmappedInstanceError if no mapping is configured.
+
+    This function is available via the inspection system as::
+    
+        inspect(instance)
+
     """
     try:
-        state = attributes.instance_state(instance)
-        return state.manager.mapper
+        return attributes.instance_state(instance)
     except exc.UnmappedClassError:
         raise exc.UnmappedInstanceError(instance)
     except exc.NO_STATE:
         raise exc.UnmappedInstanceError(instance)
 
+
+@inspection._inspects(type)
 def class_mapper(class_, compile=True):
     """Given a class, return the primary :class:`.Mapper` associated 
     with the key.
@@ -633,6 +652,10 @@ def class_mapper(class_, compile=True):
     on the given class, or :class:`.ArgumentError` if a non-class
     object is passed.
 
+    This function is available via the inspection system as::
+    
+        inspect(some_mapped_class)
+    
     """
 
     try: