------------------------------------------------------------------------------
--                                                                          --
--                   ASIS-for-GNAT INTERFACE COMPONENTS                     --
--                                                                          --
--      A S I S . C O M P I L A T I O N _ U N I T S . R E L A T I O N S     --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--                            $Revision: 1.3 $
--                                                                          --
-- This   specification  is  adapted   from  the  Ada   Semantic  Interface --
-- Specification Standard (ISO/IEC 15291) for use with GNAT.  In accordance --
-- with the copyright of that document, you can freely copy and modify this --
-- specification, provided that if you redistribute a modified version, any --
-- changes that you have made are clearly indicated.                        --
--                                                                          --
------------------------------------------------------------------------------

------------------------------------------------------------------------------
--  12 package Asis.Compilation_Units.Relations
------------------------------------------------------------------------------
------------------------------------------------------------------------------
package Asis.Compilation_Units.Relations is
------------------------------------------------------------------------------
------------------------------------------------------------------------------
--  Asis.Compilation_Units.Relations encapsulates semantic relationship
--  concepts used in ASIS.
------------------------------------------------------------------------------
--  12.1  type Relationship
------------------------------------------------------------------------------
--  Relationship queries provide references to compilation units that are
--  related, in some specific fashion, to one or more given compilation units.
--  Compilation units located by these queries are returned as a set of
--  ordered lists.

   type Relationship
     (Consistent_Length   : Asis.ASIS_Natural;
      Inconsistent_Length : Asis.ASIS_Natural;
      Missing_Length      : Asis.ASIS_Natural;
      Circular_Length     : Asis.ASIS_Natural)
   is
      record
         Consistent   : Asis.Compilation_Unit_List (1 .. Consistent_Length);
         Inconsistent : Asis.Compilation_Unit_List (1 .. Inconsistent_Length);
         Missing      : Asis.Compilation_Unit_List (1 .. Missing_Length);
         Circular     : Asis.Compilation_Unit_List (1 .. Circular_Length);
      end record;

--  The following describes the semantics of the unit lists returned by the
--  queries Semantic_Dependence_Order and Elaboration_Order:
--
--  Each query returns a set of four lists.  Every unit returned will have the
--  same Enclosing_Context.  The lists are:
--
--    a) (Consistent)   A list of consistent ordered units.
--    b) (Inconsistent) A list of units that are inconsistent with one or
--                      more units on which they semantically depend.
--    c) (Missing)      A list of units that have missing (nonexistent) related
--                      units.
--    d) (Circular)     A list of circular semantic dependencies between units.
--
--
--  a) The consistent units list:
--
--     The semantics for the ordering of units in the first list are defined by
--     the individual queries.
--
--     Every unit in this list is unique.  No duplicates are returned; no
--     two units in the list are Is_Equal or Is_Identical.
--
--  b) The inconsistent units list:
--
--     The second list is made up of unit pairs.
--
--     Each pairing defines an inconsistent semantic dependence relationship.
--     The right unit of each pair semantically depends on the preceding left
--     unit. All rightmost units of each pair are always inconsistent, and will
--     not appear in the consistent units list. The leftmost unit can be either
--     consistent or inconsistent. If a leftmost units is consistent, then it
--     also appears in the consistent units list; otherwise the unit is part of
--     an inconsistent transitive relationship.
--
--     The unit pairs are ordered such that there are no forward semantic
--     dependencies between the inconsistent units.  Each inconsistent unit's
--     supporters always precede it in the list.
--
--     As an example, given four units, A withs B, B withs C, and C withs D;
--     if D is replaced, the inconsistent list contains six units with the
--     three pairs:
--
--        DC  CB  BA
--
--     The list indicates that units C, B, and A are inconsistent (the
--     rightmost units of each pair). Semantic dependencies such as B depends
--     on C also are indicated. The units C, B, and A are in an order that
--     could be submitted to the compiler (a possible recompilation order).
--
--     If a unit is inconsistent because the source for the unit has been
--     edited (or otherwise been made inconsistent by some action of the user
--     or implementation) then the unit references Nil_Compilation_Unit as the
--     cause of the inconsistency (e.g., (Nil A Nil B) is a list of two
--     inconsistent units, neither of which can point to a third unit as the
--     cause for their being inconsistent).
--
--  --|IP An implementation is allowed to use Nil_Compilation_Unit value for
--  --|IP the first unit of each pair if it cannot determine the supporting
--  --|IP unit causing the inconsistent semantic dependence.
--
--     For the above example, the list returned is:
--
--           DC DB DA CB CA BA
--
--     This list reports all dependencies:
--
--           D withed by C withed by B withed by A => DC DB DA
--                       C withed by B withed by A => CB CA
--                                   B withed by A => BA
--
--  c) The missing dependence list:
--
--     The third list is made up of unit pairs.   Each pairing consists of a
--     unit followed by a missing related unit needed by the first unit.
--     A missing unit is a required Compilation_Unit, with a known name, with a
--     Unit_Kind that is either A_Nonexistent_Declaration or
--     A_Nonexistent_Body.
--
--     For example:
--
--     Given a list containing the units:  AB AC
--
--     If Unit_Kind(B) = A_Nonexistent_Declaration and
--        Unit_Kind(C) = A_Nonexistent_Body then
--
--     It can be deduced that:
--        A is missing a needed supporter B (A depends semantically on B).
--        A is missing a needed related unit body C
--        (depending on the kind for A, C can be A's required body or some
--         subunit of A)
--
--     A unit is reported as missing only if the Post-Compilation Rules of Ada
--     determine it to be needed.  Reference Manual 10.2.
--
--  d) The circular dependence list:
--
--     Circular dependencies between compilation units are provided in the
--     fourth list.  There may be more than one set of circular dependencies.
--     The ordering of distinct sets in the list is implementation-defined.
--     This list will never contain nonexistent units.
--
--     The list is made up of unit pairs.  The second unit of each pair depends
--     semantically on the first unit.  A circularity is established when the
--     first unit of a pair also appears as the second unit of a later pair.
--     (See the unit A in the example below; it is the first unit of the first
--     pair and is the second unit of the third pair). The next set of circular
--     dependent units, if any, starts with the next unit in the list (the unit
--     D in the example below).
--
--     For example:
--
--     Given a list containing the units:  AC CB BA DG GF FE ED
--
--     It can be determined that there are two sets of circularly dependent
--     units:
--        {A, B, C} and {D, E, F, G}
--
--     The dependencies are:  A depends on B, B depends on C, C depends on A.
--            D depends on E, E depends on F, F depends on G, G depends on D.
--
--     Each circle of dependence is reported exactly once.  It is not reported
--     once for each unit in the circle.
--
------------------------------------------------------------------------------
--  12.2  constant Nil_Relationship
------------------------------------------------------------------------------

   Nil_Relationship : constant Relationship :=
           (Consistent_Length   => 0,
            Inconsistent_Length => 0,
            Missing_Length      => 0,
            Circular_Length     => 0,
            Consistent          => Asis.Nil_Compilation_Unit_List,
            Inconsistent        => Asis.Nil_Compilation_Unit_List,
            Missing             => Asis.Nil_Compilation_Unit_List,
            Circular            => Asis.Nil_Compilation_Unit_List);

------------------------------------------------------------------------------
--  12.3  function Semantic_Dependence_Order
------------------------------------------------------------------------------
--  Semantic Dependence Relationships    - Reference Manual 10.1.1(24).
--  Elaboration Dependence Relationships - Reference Manual 10.1.1(25).
--
--  --|AN Application Note:
--  --|AN
--  --|AN To properly determine unit consistency, use one of the two semantic
--  --|AN dependence queries: Elaboration_Order or Semantic_Dependence_Order.
--  --|AN These queries return a value of the type Relationship, which contains
--  --|AN lists of consistent, inconsistent, missing and circular units.
--  --|AN
--  --|AN For these two queries, the existence of units in one or more of the
--  --|AN inconsistent, missing, or circular units list means that the
--  --|AN consistent unit list may not be complete.
--  --|AN
--  --|AN Applications that do not check for inconsistent, missing, or circular
--  --|AN units before using the consistent list might not operate as expected.
--  --|AN
------------------------------------------------------------------------------

   function Semantic_Dependence_Order
               (Compilation_Units : in Asis.Compilation_Unit_List;
                Dependent_Units   : in Asis.Compilation_Unit_List;
                The_Context       : in Asis.Context;
                Relation          : in Asis.Relation_Kinds)
               return Relationship;

------------------------------------------------------------------------------
--  Compilation_Units   - Specifies a list of pertinent units
--  Dependent_Units     - Specifies dependents used to limit the query
--  The_Context         - Specifies a program Context for context
--  Relation            - Specifies the relationship to query
--
--  Produces a Relationship value containing compilation_unit elements related
--  to the given Compilation_Units by the specified relation.
--
--  The compilation_unit elements in the consistent units list are ordered such
--  that there are no forward semantic dependencies.
--
--  Dependent_Units are ignored unless the Relation is Descendants or
--  Dependents.  The union of units in the needed units of the Dependent_Units
--  list provide a limiting context for the query.  Only members of these
--  needed units are present in the result.
--
--  If the Dependent_Units list is Is_Nil, the context for the search is the
--  entire Context.  The result of such a query is the full (unlimited)
--  list of Dependents for the Compilation_Units.
--
--  All units in the result will have an Enclosing_Context value that
--  Is_Identical to The_Context.
--

--  Appropriate Unit_Kinds:
--       A_Procedure
--       A_Function
--       A_Package
--       A_Generic_Procedure
--       A_Generic_Function
--       A_Generic_Package
--       A_Procedure_Instance
--       A_Function_Instance
--       A_Package_Instance
--       A_Procedure_Renaming
--       A_Function_Renaming
--       A_Package_Renaming
--       A_Generic_Procedure_Renaming
--       A_Generic_Function_Renaming
--       A_Generic_Package_Renaming
--       A_Procedure_Body
--       A_Function_Body
--       A_Package_Body
--       A_Procedure_Body_Subunit
--       A_Function_Body_Subunit
--       A_Package_Body_Subunit
--       A_Task_Body_Subunit
--       A_Protected_Body_Subunit
--       An_Unknown_Unit            -- See Implementation Permissions
--
--  The Semantic_Dependence_Order query should never raise an exception
--  when processing inconsistent unit (sub)sets.  This query is the only
--  means for an application to know if a given unit is consistent with
--  (some of) its supporters (dependents), and therefore the related
--  semantic processing can give valuable results for this unit.
--
--  --|IP Implementation Permissions:
--  --|IP
--  --|IP The handling of An_Unknown_Unit is implementation specific. It can be
--  --|IP possible to obtain Semantic Dependence Relationships when starting
--  --|IP with a list containing one or more units that are An_Unknown_Unit.
--  --|IP However, results may vary across ASIS implementations.
--  --|AN----------------------------------------------------------------------
--  --|AN Semantic_Dependence_Order defines consistent units to be ordered such
--  --|AN that there are no forward semantic dependencies.
--
------------------------------------------------------------------------------
--  12.4  function Elaboration_Order
------------------------------------------------------------------------------

   function Elaboration_Order
               (Compilation_Units : in Asis.Compilation_Unit_List;
                The_Context       : in Asis.Context)
               return Relationship;

------------------------------------------------------------------------------
--  Compilation_Units   - Specifies a list of units to elaborate
--  The_Context         - Specifies a program Context for context
--
--  Produces, in elaboration order, a Relationship value containing compilation
--  units required to elaborate the given compilation units.
--
--  The return value contains the set of ordered lists described above for the
--  queries on Semantic Dependence Relationships.  If the inconsistent,
--  missing, and circular lists are empty, the consistent list will contain
--  all units required to elaborate the arguments.
--  --|IP
--  --|IP The Relationship value may include any number of
--  --|IP implementation-specific runtime support packages.
--
--  The first unit in the Consistent units list will always be the
--  specification for package Standard.  The list will contain all units
--  required to elaborate the arguments.
--
--  Use the Context_Clause_Elements query to get pragma Elaborate elements
--  for a compilation unit.
--
--  Appropriate Unit_Kinds:
--       A_Procedure
--       A_Function
--       A_Package
--       A_Generic_Procedure
--       A_Generic_Function
--       A_Generic_Package
--       A_Procedure_Instance
--       A_Function_Instance
--       A_Package_Instance
--       A_Procedure_Renaming
--       A_Function_Renaming
--       A_Package_Renaming
--       A_Generic_Procedure_Renaming
--       A_Generic_Function_Renaming
--       A_Generic_Package_Renaming
--       A_Procedure_Body
--       A_Function_Body
--       A_Package_Body
--       A_Procedure_Body_Subunit
--       A_Function_Body_Subunit
--       A_Package_Body_Subunit
--       A_Task_Body_Subunit
--       A_Protected_Body_Subunit
--       An_Unknown_Unit            -- See Implementation Permissions
--
--  --|IP Implementation Permissions:
--  --|IP
--  --|IP The handling of An_Unknown_Unit is implementation specific.  It can
--  --|IP be possible to obtain Semantic Dependence Relationships when starting
--  --|IP with a list containing one or more units that are An_Unknown_Unit.
--  --|IP However, results may vary across ASIS implementations.
--
------------------------------------------------------------------------------
end Asis.Compilation_Units.Relations;