Module Property_status


module Property_status: sig .. end
Status of properties.
Since Nitrogen-20111001


Local status

A local status (shortly, a status) of a property is a status directly set by an emitter. Thus a property may have several distinct status according to who attempts the verification.

Emitting a status



type emitted_status =
| True (*for each execution path ep from the program entry point to s, the formula (/\_ h) ==> P(ep) is true*)
| False_if_reachable (*for each execution path ep from the program entry point to s, the formula (/\_ h) ==> P(ep) is false*)
| False_and_reachable (*it exists an execution path ep from the program entry point to s such that the formula (/\_ h) ==> P(ep) is false*)
| Dont_know (*any other case*)
Type of status emitted by analyzers. Each Property is attached to a program point s and implicitely depends on an execution path from the program entry point to s. It also depends on an explicit set of hypotheses H indicating when emitting the property (see function Property_status.emit).
module Emitted_status: Datatype.S  with type t = emitted_status
exception Inconsistent_emitted_status of emitted_status * emitted_status
val emit : Emitter.t ->
hyps:Property.t list ->
Property.t -> ?distinct:bool -> emitted_status -> unit
emit e ~hyps p s indicates that the status of p is s, is emitted by e, and is based on the list of hypothesis hyps. If e previously emitted another status s', it must be emitted with the same hypotheses and a consistency check is performed between s and s' and the best (by default the strongest) status is kept. If distinct is true (default is false), then we consider than the given property may merge into one single point several distinct statuses. The strategy for computing the best status is changed accordingly. One example when ~distinct:true is required is when emitting a status for a pre-condition of a function f since the status associated to a pre-condition p merges all statuses of p at each callsite of the function f.
Raises Inconsistent_emitted_status when emiting False after emiting True or conversely
Returns the kept status.
val emit_and_get : Emitter.t ->
hyps:Property.t list ->
Property.t ->
?distinct:bool ->
emitted_status -> emitted_status
Like Property_status.emit but also returns the computed status.
val logical_consequence : Emitter.t -> Property.t -> Property.t list -> unit
logical_consequence e ppt list indicates that the emitter e considers that ppt is a logical consequence of the conjunction of properties list. Thus it lets the kernel automatically computes it: e must not call functions emit* itself on this property, but the kernel ensures that the status will be up-to-date when getting it.
val self : State.t
The state which stores the computed status.

Getting a (local) status



type emitter_with_properties = private {
   emitter : Emitter.Usable_emitter.t;
   properties : Property.t list;
   logical_consequence : bool; (*Is the emitted status automatically infered?*)
}
type inconsistent = private {
   valid : emitter_with_properties list;
   invalid : emitter_with_properties list;
}
type status = private
| Never_tried (*Nobody tries to verify the property*)
| Best of emitted_status * emitter_with_properties list (*who attempt the verification under which hypotheses*)
| Inconsistent of inconsistent (*someone says the property is valid and someone else says it is invalid.*)
Type of known precise status of a property.
include Datatype.S
val get : Property.t -> status
Returns the most precise status and all its emitters.

Consolidated status


module Consolidation: sig .. end
Consolidation of a property status according to the (consolidated) status of the hypotheses of the property.
module Feedback: sig .. end
Lighter version than Consolidation
module Consolidation_graph: sig .. end
See the consolidated status of a property in a graph, which all its dependencies and their consolidated status.

Access to the registered properties


val iter : (Property.t -> unit) -> unit
val fold : (Property.t -> 'a -> 'a) -> 'a -> 'a

API not for casual users


val register : Property.t -> unit
Register the given property. It must not be already registered.
val remove : Property.t -> unit
val merge : old:Property.t list -> Property.t list -> unit
merge old new registers properties in new which are not in old and removes properties in old which are not in new.
val automatically_proven : Property.t -> bool
Is the status of the given property only automatically handled by the kernel?