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Diffstat (limited to 'gcc-4.9/gcc/ada/sem_case.ads')
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diff --git a/gcc-4.9/gcc/ada/sem_case.ads b/gcc-4.9/gcc/ada/sem_case.ads new file mode 100644 index 000000000..c6917f068 --- /dev/null +++ b/gcc-4.9/gcc/ada/sem_case.ads @@ -0,0 +1,153 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- S E M _ C A S E -- +-- -- +-- S p e c -- +-- -- +-- Copyright (C) 1996-2013, 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. -- +-- -- +------------------------------------------------------------------------------ + +-- Package containing the routines to process a list of discrete choices. +-- Such lists can occur in two different constructs: case statements and +-- record variants. We have factorized what used to be two very similar +-- sets of routines in one place. These are not currently used for the +-- aggregate case, since issues with nested aggregates make that case +-- substantially different. + +-- The following processing is required for such cases: + +-- 1. Analysis of names of subtypes, constants, expressions appearing within +-- the choices. This must be done when the construct is encountered to get +-- proper visibility of names. + +-- 2. Checking for semantic correctness of the choices. A lot of this could +-- be done at the time when the construct is encountered, but not all, since +-- in the case of variants, statically predicated subtypes won't be frozen +-- (and the choice sets known) till the enclosing record type is frozen. So +-- at least the check for no overlaps and covering the range must be delayed +-- till the freeze point in this case. + +-- 3. Set the Others_Discrete_Choices list for an others choice. This is +-- used in various ways, e.g. to construct the disriminant checking function +-- for the case of a variant with an others choice. + +-- 4. In the case of static predicates, we need to expand out choices that +-- correspond to the predicate for the back end. This expansion destroys +-- the list of choices, so it should be delayed to expansion time. We do +-- not want to mess up the -gnatct ASIS tree, which needs to be able to + +-- Step 1 is performed by the generic procedure Analyze_Choices, which is +-- called when the variant record or case statement/expression is first +-- encountered. + +-- Step 2 is performed by the generic procedure Check_Choices. We decide to +-- do all semantic checking in that step, since as noted above some of this +-- has to be deferred to the freeze point in any case for variants. For case +-- statements and expressions, this procedure can be called at the time the +-- case construct is encountered (after calling Analyze_Choices). + +-- Step 3 is also performed by Check_Choices, since we need the static ranges +-- for predicated subtypes to accurately construct this. + +-- Step 4 is performed by the procedure Expand_Static_Predicates_In_Choices. +-- For case statements, this call only happens during expansion, so the tree +-- generated for ASIS does not have this expansion. For the Variant case, the +-- expansion is done in the ASIS -gnatct case, but with a proper Rewrite call +-- on the N_Variant node, so ASIS can retrieve the original. The reason we do +-- the expansion unconditionally for variants is that other processing, for +-- example for aggregates, relies on having a complete list of choices. + +-- Historical note: We used to perform all four of these functions at once in +-- a single procedure called Analyze_Choices. This routine was called at the +-- time the construct was first encountered. That seemed to work OK up to Ada +-- 2005, but the introduction of statically predicated subtypes with delayed +-- evaluation of the static ranges made this completely wrong, both because +-- the ASIS tree got destroyed by step 4, and steps 2 and 3 were too early +-- in the variant record case. + +with Types; use Types; + +package Sem_Case is + + procedure No_OP (C : Node_Id); + -- The no-operation routine. Does absolutely nothing. Can be used + -- in the following generics for the parameters Process_Empty_Choice, + -- or Process_Associated_Node. + + generic + with procedure Process_Associated_Node (A : Node_Id); + -- Associated with each case alternative or record variant A there is + -- a node or list of nodes that need additional processing. This routine + -- implements that processing. + + package Generic_Analyze_Choices is + + procedure Analyze_Choices + (Alternatives : List_Id; + Subtyp : Entity_Id); + -- From a case expression, case statement, or record variant, this + -- routine analyzes the corresponding list of discrete choices which + -- appear in each element of the list Alternatives (for the variant + -- part case, this is the variants, for a case expression or statement, + -- this is the Alternatives). + -- + -- Subtyp is the subtype of the discrete choices. The type against which + -- the discrete choices must be resolved is its base type. + + end Generic_Analyze_Choices; + + generic + with procedure Process_Empty_Choice (Choice : Node_Id); + -- Processing to carry out for an empty Choice. Set to No_Op (declared + -- above) if no such processing is required. + + with procedure Process_Non_Static_Choice (Choice : Node_Id); + -- Processing to carry out for a non static Choice (gives an error msg) + + with procedure Process_Associated_Node (A : Node_Id); + -- Associated with each case alternative or record variant A there is + -- a node or list of nodes that need semantic processing. This routine + -- implements that processing. + + package Generic_Check_Choices is + + procedure Check_Choices + (N : Node_Id; + Alternatives : List_Id; + Subtyp : Entity_Id; + Others_Present : out Boolean); + -- From a case expression, case statement, or record variant N, this + -- routine analyzes the corresponding list of discrete choices which + -- appear in each element of the list Alternatives (for the variant + -- part case, this is the variants, for a case expression or statement, + -- this is the Alternatives). + -- + -- Subtyp is the subtype of the discrete choices. The type against which + -- the discrete choices must be resolved is its base type. + -- + -- Others_Present is set to True if an Others choice is present in the + -- list of choices, and in this case Others_Discrete_Choices is set in + -- the N_Others_Choice node. + -- + -- If a Discrete_Choice list contains at least one instance of a subtype + -- with a static predicate, then the Has_SP_Choice flag is set true in + -- the parent node (N_Variant, N_Case_Expression/Statement_Alternative). + + end Generic_Check_Choices; +end Sem_Case; |