+++ /dev/null
-# This file is part of NIT ( http://www.nitlanguage.org ).
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-# http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-# Implementation of the method-related annotation `cached`
-#
-# The cached annotation is deprecated, use the `lazy` annotation instead.
-module cached
-
-import modelize
-private import parser_util
-import simple_misc_analysis
-private import annotation
-intrude import modelize::modelize_property
-
-redef class ToolContext
- # Process the `cached` annotation on methods
- var cached_phase: Phase = new CachedPhase(self, [modelize_property_phase])
-end
-
-private class CachedPhase
- super Phase
-
- init
- do
- # FIXME The phase has to be executed just after `modelize_property_phase`
- # But there is no simple way to express this
- # So, for the moment, I just looked at the linearization and see what phase is after `modelize_property_phase`
- # And inserted before it
- toolcontext.phases.add_edge(toolcontext.simple_misc_analysis_phase, self)
- end
-
- redef fun process_annotated_node(npropdef, nat)
- do
- # Skip if we are not interested
- if nat.name != "cached" then return
-
- # Do some validity checks and print errors if the annotation is used incorrectly
- var modelbuilder = toolcontext.modelbuilder
-
- if not npropdef isa AMethPropdef then
- modelbuilder.error(npropdef, "Syntax error: only a function can be cached.")
- return
- end
-
- var mpropdef = npropdef.mpropdef.as(not null)
-
- var mtype = mpropdef.msignature.return_mtype
- if mtype == null then
- modelbuilder.error(npropdef, "Syntax error: only a function can be cached.")
- return
- end
-
- if not npropdef.n_signature.n_params.is_empty then
- modelbuilder.error(npropdef, "Syntax error: only a function without arguments can be cached.")
- return
- end
-
- # OK, let we do some meta-programming...
-
- var location = npropdef.location
- var name = mpropdef.mproperty.name
- var nclassdef = npropdef.parent.as(AClassdef)
- var mclassdef = nclassdef.mclassdef.as(not null)
-
- if not mclassdef.mclass.kind.need_init then
- modelbuilder.error(npropdef, "Error: only abstract and concrete classes can have cached functions.")
- return
- end
-
- # Create a new private attribute to store the cache
- var cache_mpropdef = new MAttributeDef(mclassdef, new MAttribute(mclassdef, "@{name}<cache>", private_visibility), location)
- cache_mpropdef.static_mtype = mtype.as_nullable
-
- # Create another new private attribute to store the boolean «is the function cached?»
- # The point is to manage the case where `null` is a genuine return value of the method
- var is_cached_mpropdef = new MAttributeDef(mclassdef, new MAttribute(mclassdef, "@{name}<is_cached>", private_visibility), location)
- is_cached_mpropdef.static_mtype = mclassdef.mmodule.get_primitive_class("Bool").mclass_type
- # FIXME? Because there is a default value ("false") a real propdef is required
- var is_cached_npropdef = toolcontext.parse_propdef("var is_cached = false").as(AAttrPropdef)
- associate_propdef(is_cached_mpropdef, is_cached_npropdef)
-
- # Create a new private method to do the real work
- var real_mpropdef = new MMethodDef(mclassdef, new MMethod(mclassdef, "{name}<real>", private_visibility), location)
- real_mpropdef.msignature = mpropdef.msignature
- # FIXME: Again, if the engine require a real propdef even if it is empty
- var real_npropdef = toolcontext.parse_propdef("fun real do end").as(AMethPropdef)
- associate_propdef(real_mpropdef, real_npropdef)
- # Note: the body is set at the last line of this function
-
- # Save the original body
- var real_body = npropdef.n_block.as(not null)
-
- # Replace the original body with a new body that do the proxy'n'cache work
- var proxy_body = toolcontext.parse_stmts("if self._is_cached then return self._cache.as(not null)\nvar res = call_real\nself._cache_write = res\nself._is_cached_write = true\nreturn res")
- real_body.replace_with(proxy_body)
-
- # Do some transformation on the identifiers used on the proxy body so that correct entities are designated
- # FIXME: we just trick the following phases into associating by name some tokens with some model-entities
- # But this is bad at at least two levels
- # - we already know the real model-entities, so why doing latter the association and not now?
- # - associating by names may cause a useless fragility (name-conflicts, etc.)
- proxy_body.collect_tokens_by_text("_is_cached").first.text = is_cached_mpropdef.mproperty.name
- proxy_body.collect_tokens_by_text("_is_cached_write").first.text = is_cached_mpropdef.mproperty.name
- proxy_body.collect_tokens_by_text("_cache").first.text = cache_mpropdef.mproperty.name
- proxy_body.collect_tokens_by_text("_cache_write").first.text = cache_mpropdef.mproperty.name
- proxy_body.collect_tokens_by_text("call_real").first.text = real_mpropdef.mproperty.name
-
- # FIXME a last transformation cannot be done yet. So, the call to `super` (`ASuperExpr`) is broken in cached methods.
-
- # Give the original body to the private real methoddef
- real_npropdef.n_block.replace_with(real_body)
- end
-
- # Detach `n` from its original AST and attach it to `m` (and its related AST)
- # `n` must not be already attached to an existing model entity
- # `m` must not be already attached to an existing AST node
- fun associate_propdef(m: MPropDef, n: APropdef)
- do
- # FIXME: the model-AST relations **must** be rationalized:
- # * 1- fragility: the risk of inconsistencies is too hight
- # * 2- complexity: there is too much paths to access the same things
-
- # Easy attach
- assert n.mpropdef == null
- n.mpropdef = m
-
- # Required to so that look-for implementation works
- assert not toolcontext.modelbuilder.mpropdef2npropdef.has_key(m)
- toolcontext.modelbuilder.mpropdef2npropdef[m] = n
-
- var mclassdef = m.mclassdef
- var nclassdef = toolcontext.modelbuilder.mclassdef2nclassdef[mclassdef]
- # Sanity checks
- assert nclassdef.mclassdef == mclassdef
-
- if n isa AAttrPropdef then
- n.has_value = n.n_expr != null or n.n_block != null
- end
-
- # Required so that propdef are visited in visitors
- if not nclassdef.n_propdefs.has(n) then nclassdef.n_propdefs.add(n)
- end
-end
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