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------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- L I B . L O A D -- -- -- -- S p e c -- -- -- -- Copyright (C) 1992-2011, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING3. If not, go to -- -- http://www.gnu.org/licenses for a complete copy of the license. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ -- This child package contains the function used to load a separately -- compiled unit, as well as the routine used to initialize the unit -- table and load the main source file. package Lib.Load is ------------------------------- -- Handling of Renamed Units -- ------------------------------- -- A compilation unit can be a renaming of another compilation unit. -- Such renamed units are not allowed as parent units, that is you -- cannot declare a unit: -- with x; -- package x.y is end; -- where x is a renaming of some other package. However you can refer -- to a renamed unit in a with clause: -- package p is end; -- package p.q is end; -- with p; -- package pr renames p; -- with pr.q .... -- This means that in the context of a with clause, the normal fixed -- correspondence between unit and file names is broken. In the above -- example, there is no file named pr-q.ads, since the actual child -- unit is p.q, and it will be found in file p-q.ads. -- In order to deal with this case, we have to first load pr.ads, and -- then discover that it is a renaming of p, so that we know that pr.q -- really refers to p.q. Furthermore this can happen at any level: -- with p.q; -- package p.r renames p.q; -- with p.q; -- package p.q.s is end; -- with p.r.s ... -- Now we have a case where the parent p.r is a child unit and is -- a renaming. This shows that renaming can occur at any level. -- Finally, consider: -- with pr.q.s ... -- Here the parent pr.q is not itself a renaming, but it really refers -- to the unit p.q, and again we cannot know this without loading the -- parent. The bottom line here is that while the file name of a unit -- always corresponds to the unit name, the unit name as given to the -- Load_Unit function may not be the real unit. ----------------- -- Subprograms -- ----------------- procedure Initialize; -- Initialize internal tables procedure Initialize_Version (U : Unit_Number_Type); -- This is called once the source file corresponding to unit U has been -- fully scanned. At that point the checksum is computed, and can be used -- to initialize the version number. procedure Load_Main_Source; -- Called at the start of compiling a new main source unit to initialize -- the library processing for the new main source. Establishes and -- initializes the units table entry for the new main unit (leaving -- the Unit_File_Name entry of Main_Unit set to No_File if there are no -- more files. Otherwise the main source file has been opened and read -- and then closed on return. function Load_Unit (Load_Name : Unit_Name_Type; Required : Boolean; Error_Node : Node_Id; Subunit : Boolean; Corr_Body : Unit_Number_Type := No_Unit; Renamings : Boolean := False; With_Node : Node_Id := Empty; PMES : Boolean := False) return Unit_Number_Type; -- This function loads and parses the unit specified by Load_Name (or -- returns the unit number for the previously constructed units table -- entry if this is not the first call for this unit). Required indicates -- the behavior on a file not found condition, as further described below, -- and Error_Node is the node in the calling program to which error -- messages are to be attached. -- -- If the corresponding file is found, the value returned by Load is the -- unit number that indexes the corresponding entry in the units table. If -- a serious enough parser error occurs to prevent subsequent semantic -- analysis, then the Fatal_Error flag of the returned entry is set and -- in addition, the fatal error flag of the calling unit is also set. -- -- If the corresponding file is not found, then the behavior depends on -- the setting of Required. If Required is False, then No_Unit is returned -- and no error messages are issued. If Required is True, then an error -- message is posted, and No_Unit is returned. -- -- A special case arises in the call from Rtsfind, where Error_Node is set -- to Empty. In this case Required is False, and the caller in any case -- treats any error as fatal. -- -- The Subunit parameter is True to load a subunit, and False to load -- any other kind of unit (including all specs, package bodies, and -- subprogram bodies). -- -- The Corr_Body argument is normally defaulted. It is set only in the -- case of loading the corresponding spec when the main unit is a body. -- In this case, Corr_Body is the unit number of this corresponding -- body. This is used to set the Serial_Ref_Unit field of the unit -- table entry. It is also used to deal with the special processing -- required by RM 10.1.4(4). See description in lib.ads. -- -- Renamings activates the handling of renamed units as separately -- described in the documentation of this unit. If this parameter is -- set to True, then Load_Name may not be the real unit name and it -- is necessary to load parents to find the real name. -- -- With_Node is set to the with_clause or limited_with_clause causing -- the unit to be loaded, and is used to bypass the circular dependency -- check in the case of a limited_with_clause (Ada 2005, AI-50217). -- -- PMES indicates the required setting of Parsing_Main_Extended_Unit during -- loading of the unit. This flag is saved and restored over the call. -- Note: PMES is false for the subunit case, which seems wrong??? procedure Change_Main_Unit_To_Spec; -- This procedure is called if the main unit file contains a No_Body pragma -- and no other tokens. The effect is, if possible, to change the main unit -- from the body it references now, to the corresponding spec. This has the -- effect of ignoring the body, which is what we want. If it is impossible -- to successfully make the change, then the call has no effect, and the -- file is unchanged (this will lead to an error complaining about the -- inappropriate No_Body spec). function Create_Dummy_Package_Unit (With_Node : Node_Id; Spec_Name : Unit_Name_Type) return Unit_Number_Type; -- With_Node is the Node_Id of a with statement for which the file could -- not be found, and Spec_Name is the corresponding unit name. This call -- creates a dummy package unit so that compilation can continue without -- blowing up when the missing unit is referenced. procedure Make_Child_Decl_Unit (N : Node_Id); -- For a child subprogram body without a spec, we create a subprogram -- declaration in order to attach the required parent link. We create -- a Units_Table entry for this declaration, in order to maintain a -- one-to-one correspondence between compilation units and table entries. procedure Make_Instance_Unit (N : Node_Id; In_Main : Boolean); -- When a compilation unit is an instantiation, it contains both the -- declaration and the body of the instance, each of which can have its -- own elaboration routine. The file itself corresponds to the declaration. -- We create an additional entry for the body, so that the binder can -- generate the proper elaboration calls to both. The argument N is the -- compilation unit node created for the body. -- -- If the instance is not the main program, we still generate the instance -- body even though we do not generate code for it. In that case we still -- generate a compilation unit node for it, and we need to make an entry -- for it in the units table, so as to maintain a one-to-one mapping -- between table and nodes. The table entry is used among other things to -- provide a canonical traversal order for context units for Inspector. -- The flag In_Main indicates whether the instance is the main unit. procedure Version_Update (U : Node_Id; From : Node_Id); -- This routine is called when unit U is found to be semantically -- dependent on unit From. It updates the version of U to register -- dependence on the version of From. The arguments are compilation -- unit nodes for the relevant library nodes. end Lib.Load;
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