source: src/AST/SymbolTable.hpp @ e0069bd

//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// SymbolTable.hpp --
//
// Author           : Aaron B. Moss
// Created On       : Wed May 29 11:00:00 2019
// Last Modified By : Aaron B. Moss
// Last Modified On : Wed May 29 11:00:00 2019
// Update Count     : 1
//

#pragma once

#include <memory>                  // for shared_ptr, enable_shared_from_this
#include <vector>

#include "Fwd.hpp"
#include "Node.hpp"                // for ptr, readonly
#include "Common/CodeLocation.h"
#include "Common/PersistentMap.h"

namespace ResolvExpr {
        class Cost;
}

namespace ast {

/// Builds and stores the symbol table, mapping identifiers to declarations.
class SymbolTable final : public std::enable_shared_from_this<ast::SymbolTable> {
public:
        /// special functions stored in dedicated tables, with different lookup keys
        enum SpecialFunctionKind {CTOR, DTOR, ASSIGN, NUMBER_OF_KINDS};
        static SpecialFunctionKind getSpecialFunctionKind(const std::string & name);

        /// Stored information about a declaration
        struct IdData {
                readonly<DeclWithType> id = nullptr;  ///< Identifier of declaration
                readonly<Expr> baseExpr = nullptr;    ///< Implied containing aggregate (from WithExpr)
                readonly<Decl> deleter = nullptr;     ///< Node deleting this declaration (if non-null)
                unsigned long scope = 0;              ///< Scope of identifier

                IdData() = default;
                IdData( const DeclWithType * i, const Expr * base, const Decl * del, unsigned long s )
                : id( i ), baseExpr( base ), deleter( del ), scope( s ) {}

                /// Modify an existing node with a new deleter
                IdData( const IdData & o, const Decl * del )
                : id( o.id ), baseExpr( o.baseExpr ), deleter( del ), scope( o.scope ) {}

                /// Constructs an expression referring to this identifier.
                /// Increments `cost` by cost of reference conversion
                Expr * combine( const CodeLocation & loc, ResolvExpr::Cost & cost ) const;
        };

private:
        /// wraps a reference to D with a scope
        template<typename D>
        struct scoped {
                readonly<D> decl;     ///< wrapped declaration
                unsigned long scope;  ///< scope of this declaration

                scoped(const D * d, unsigned long s) : decl(d), scope(s) {}
        };

        using MangleTable = PersistentMap< std::string, IdData >;
        using IdTable = PersistentMap< std::string, MangleTable::Ptr >;
        using TypeTable = PersistentMap< std::string, scoped<NamedTypeDecl> >;
        using StructTable = PersistentMap< std::string, scoped<StructDecl> >;
        using EnumTable = PersistentMap< std::string, scoped<EnumDecl> >;
        using UnionTable = PersistentMap< std::string, scoped<UnionDecl> >;
        using TraitTable = PersistentMap< std::string, scoped<TraitDecl> >;

        IdTable::Ptr idTable;          ///< identifier namespace
        TypeTable::Ptr typeTable;      ///< type namespace
        StructTable::Ptr structTable;  ///< struct namespace
        EnumTable::Ptr enumTable;      ///< enum namespace
        UnionTable::Ptr unionTable;    ///< union namespace
        TraitTable::Ptr traitTable;    ///< trait namespace
        IdTable::Ptr specialFunctionTable[NUMBER_OF_KINDS];

        // using SpecialFuncTable = PersistentMap< std::string, IdTable::Ptr >; // fname (ctor/dtor/assign) - otypekey
        // SpecialFuncTable::Ptr specialFuncTable;

        using Ptr = std::shared_ptr<const SymbolTable>;

        Ptr prevScope;                 ///< Indexer for parent scope
        unsigned long scope;           ///< Scope index of this indexer
        unsigned long repScope;        ///< Scope index of currently represented scope

public:

        /// Mode to control when (during which pass) user-caused name-declaration errors get reported.
        /// The default setting `AssertClean` supports, "I expect all user-caused errors to have been
        /// reported by now," or, "I wouldn't know what to do with an error; are there even any here?"
        enum ErrorDetection {
                AssertClean,               ///< invalid user decls => assert fails during addFoo (default)
                ValidateOnAdd,             ///< invalid user decls => calls SemanticError during addFoo
                IgnoreErrors               ///< acts as if unspecified decls were removed, forcing validity
        };

        explicit SymbolTable(
                ErrorDetection             ///< mode for the lifetime of the symbol table (whole pass)
        );
        SymbolTable() : SymbolTable(AssertClean) {}
        ~SymbolTable();

        ErrorDetection getErrorMode() const {
                return errorMode;
        }

        // when using an indexer manually (e.g., within a mutator traversal), it is necessary to
        // tell the indexer explicitly when scopes begin and end
        void enterScope();
        void leaveScope();

        /// Gets all declarations with the given ID
        std::vector<IdData> lookupId( const std::string &id ) const;
        /// Gets special functions associated with a type; if no key is given, returns everything
        std::vector<IdData> specialLookupId( SpecialFunctionKind kind, const std::string & otypeKey = "" ) const;
        /// Gets the top-most type declaration with the given ID
        const NamedTypeDecl * lookupType( const std::string &id ) const;
        /// Gets the top-most struct declaration with the given ID
        const StructDecl * lookupStruct( const std::string &id ) const;
        /// Gets the top-most enum declaration with the given ID
        const EnumDecl * lookupEnum( const std::string &id ) const;
        /// Gets the top-most union declaration with the given ID
        const UnionDecl * lookupUnion( const std::string &id ) const;
        /// Gets the top-most trait declaration with the given ID
        const TraitDecl * lookupTrait( const std::string &id ) const;

        /// Gets the type declaration with the given ID at global scope
        const NamedTypeDecl * globalLookupType( const std::string &id ) const;
        /// Gets the struct declaration with the given ID at global scope
        const StructDecl * globalLookupStruct( const std::string &id ) const;
        /// Gets the union declaration with the given ID at global scope
        const UnionDecl * globalLookupUnion( const std::string &id ) const;
        /// Gets the enum declaration with the given ID at global scope
        const EnumDecl * globalLookupEnum( const std::string &id ) const;

        /// Adds an identifier declaration to the symbol table
        void addId( const DeclWithType * decl, const Expr * baseExpr = nullptr );
        /// Adds a deleted identifier declaration to the symbol table
        void addDeletedId( const DeclWithType * decl, const Decl * deleter );

        /// Adds a type to the symbol table
        void addType( const NamedTypeDecl * decl );
        /// Adds a struct declaration to the symbol table by name
        void addStructId( const std::string & id );
        /// Adds a struct declaration to the symbol table
        void addStruct( const StructDecl * decl );
        /// Adds an enum declaration to the symbol table
        void addEnum( const EnumDecl * decl );
        /// Adds a union declaration to the symbol table by name
        void addUnionId( const std::string & id );
        /// Adds a union declaration to the symbol table
        void addUnion( const UnionDecl * decl );
        /// Adds a trait declaration to the symbol table
        void addTrait( const TraitDecl * decl );

        /// adds all of the IDs from WithStmt exprs
        void addWith( const std::vector< ptr<Expr> > & withExprs, const Decl * withStmt );

        /// convenience function for adding a list of Ids to the indexer
        void addIds( const std::vector< ptr<DeclWithType> > & decls );

        /// convenience function for adding a list of forall parameters to the indexer
        void addTypes( const std::vector< ptr<TypeDecl> > & tds );

        /// convenience function for adding all of the declarations in a function type to the indexer
        void addFunction( const FunctionDecl * );

private:
        void OnFindError( CodeLocation location, std::string error ) const;

        template< typename T >
        void OnFindError( const T * obj, const std::string & error ) const {
                OnFindError( obj->location, toString( error, obj ) );
        }

        template< typename T >
        void OnFindError( CodeLocation location, const T * obj, const std::string & error ) const {
                OnFindError( location, toString( error, obj ) );
        }

        /// Ensures that a proper backtracking scope exists before a mutation
        void lazyInitScope();

        /// Gets the symbol table at a given scope
        const SymbolTable * atScope( unsigned long i ) const;

        /// Removes matching autogenerated constructors and destructors so that they will not be
        /// selected. If returns false, passed decl should not be added.
        bool removeSpecialOverrides( IdData & decl, MangleTable::Ptr & mangleTable );

        /// Error detection mode given at construction (pass-specific).
        /// Logically const, except that the symbol table's push-pop is achieved by autogenerated
        /// assignment onto self.  The feield is left motuable to keep this code-gen simple.
        /// Conceptual constness is preserved by all SymbolTable in a stack sharing the same mode.
        ErrorDetection errorMode;

        /// Options for handling identifier conflicts.
        /// Varies according to AST location during traversal: captures semantics of the construct
        /// being visited as "would shadow" vs "must not collide."
        /// At a given AST location, is the same for every pass.
        struct OnConflict {
                enum {
                        Error,  ///< Follow the current pass's ErrorDetection mode (may throw a semantic error)
                        Delete  ///< Delete the earlier version with the delete statement
                } mode;
                const Decl * deleter;  ///< Statement that deletes this expression

        private:
                OnConflict() : mode(Error), deleter(nullptr) {}
                OnConflict( const Decl * d ) : mode(Delete), deleter(d) {}
        public:
                OnConflict( const OnConflict& ) = default;

                static OnConflict error() { return {}; }
                static OnConflict deleteWith( const Decl * d ) { return { d }; }
        };

        /// true if the existing identifier conflicts with the added identifier
        bool addedIdConflicts(
                const IdData & existing, const DeclWithType * added, OnConflict handleConflicts,
                const Decl * deleter );

        /// true if redeclaration conflict between two types
        bool addedTypeConflicts( const NamedTypeDecl * existing, const NamedTypeDecl * added ) const;

        /// true if redeclaration conflict between two aggregate declarations
        bool addedDeclConflicts( const AggregateDecl * existing, const AggregateDecl * added ) const;

        /// common code for addId, addDeletedId, etc.
        void addIdCommon(
                const DeclWithType * decl, OnConflict handleConflicts,
                const Expr * baseExpr = nullptr, const Decl * deleter = nullptr );

        /// common code for addId when special decls are placed into separate tables
        void addIdToTable(
                const DeclWithType * decl, const std::string & lookupKey,
                IdTable::Ptr & idTable, OnConflict handleConflicts,
                const Expr * baseExpr = nullptr, const Decl * deleter = nullptr);

        /// adds all of the members of the Aggregate (addWith helper)
        void addMembers( const AggregateDecl * aggr, const Expr * expr, OnConflict handleConflicts );

        /// returns true if there exists a declaration with C linkage and the given name with the same mangled name
        bool hasCompatibleCDecl( const std::string &id, const std::string &mangleName ) const;
        /// returns true if there exists a declaration with C linkage and the given name with a different mangled name
        bool hasIncompatibleCDecl( const std::string &id, const std::string &mangleName ) const;
};

}


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