source: src/AST/Expr.hpp@ 54e41b3

//
// 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.
//
// Expr.hpp --
//
// Author           : Aaron B. Moss
// Created On       : Fri May 10 10:30:00 2019
// Last Modified By : Aaron B. Moss
// Created On       : Fri May 10 10:30:00 2019
// Update Count     : 1
//

#pragma once

#include <cassert>
#include <map>
#include <string>
#include <utility>        // for move
#include <vector>

#include "Fwd.hpp"        // for UniqueId
#include "Label.hpp"
#include "ParseNode.hpp"
#include "Visitor.hpp"

namespace ast {

/// Contains the ID of a declaration and a type that is derived from that declaration,
/// but subject to decay-to-pointer and type parameter renaming
struct ParamEntry {
        UniqueId decl;
        ptr<Type> actualType;
        ptr<Type> formalType;
        ptr<Expr> expr;

        ParamEntry() : decl( 0 ), actualType( nullptr ), formalType( nullptr ), expr( nullptr ) {}
        ParamEntry( UniqueId id, Type* actual, Type* formal, Expr* e )
        : decl( id ), actualType( actual ), formalType( formal ), expr( e ) {}
};

/// Pre-resolution list of parameters to infer
using ResnSlots = std::vector<UniqueId>;
/// Post-resolution map of inferred parameters
using InferredParams = std::map< UniqueId, ParamEntry >;

/// Base node for expressions
class Expr : public ParseNode {
public:
        /// Saves space (~16 bytes) by combining ResnSlots and InferredParams
        struct InferUnion {
                enum { Empty, Slots, Params } mode;
                union data_t {
                        char def;
                        ResnSlots resnSlots;
                        InferredParams inferParams;

                        data_t() : def('\0') {}
                        ~data_t() {}
                } data;

                /// initializes from other InferUnion
                void init_from( const InferUnion& o ) {
                        switch ( o.mode ) {
                        case Empty:  return;
                        case Slots:  new(&data.resnSlots) ResnSlots{ o.data.resnSlots }; return;
                        case Params: new(&data.inferParams) InferredParams{ o.data.inferParams }; return;
                        }
                }

                /// initializes from other InferUnion (move semantics)
                void init_from( InferUnion&& o ) {
                        switch ( o.mode ) {
                        case Empty:  return;
                        case Slots:  new(&data.resnSlots) ResnSlots{ std::move(o.data.resnSlots) }; return;
                        case Params:
                                new(&data.inferParams) InferredParams{ std::move(o.data.inferParams) }; return;
                        }
                }

                /// clears variant fields
                void reset() {
                        switch( mode ) {
                        case Empty:  return;
                        case Slots:  data.resnSlots.~ResnSlots(); return;
                        case Params: data.inferParams.~InferredParams(); return;
                        }
                }

                InferUnion() : mode(Empty), data() {}
                InferUnion( const InferUnion& o ) : mode( o.mode ), data() { init_from( o ); }
                InferUnion( InferUnion&& o ) : mode( o.mode ), data() { init_from( std::move(o) ); }
                InferUnion& operator= ( const InferUnion& ) = delete;
                InferUnion& operator= ( InferUnion&& ) = delete;
                ~InferUnion() { reset(); }

                ResnSlots& resnSlots() {
                        switch (mode) {
                        case Empty: new(&data.resnSlots) ResnSlots{}; mode = Slots; // fallthrough
                        case Slots: return data.resnSlots;
                        case Params: assert(!"Cannot return to resnSlots from Params");
                        }
                }

                InferredParams& inferParams() {
                        switch (mode) {
                        case Slots: data.resnSlots.~ResnSlots(); // fallthrough
                        case Empty: new(&data.inferParams) InferredParams{}; mode = Params; // fallthrough
                        case Params: return data.inferParams;
                        }
                }
        };

        ptr<Type> result;
        ptr<TypeSubstitution> env;
        InferUnion inferred;
        bool extension = false;

        Expr( const CodeLocation & loc, const Type * res = nullptr )
        : ParseNode( loc ), result( res ), env(), inferred() {}

        Expr * set_extension( bool ex ) { extension = ex; return this; }

        virtual const Expr * accept( Visitor & v ) const override = 0;
private:
        Expr * clone() const override = 0;
};

/// The application of a function to a set of parameters. 
/// Post-resolver form of `UntypedExpr`
class ApplicationExpr final : public Expr {
public:
        ptr<Expr> func;
        std::vector<ptr<Expr>> args;

        ApplicationExpr( const CodeLocation & loc, const Expr * f, std::vector<ptr<Expr>> && as = {} );

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        ApplicationExpr * clone() const override { return new ApplicationExpr{ *this }; }
};

/// The application of a function to a set of parameters, pre-overload resolution.
class UntypedExpr final : public Expr {
public:
        ptr<Expr> func;
        std::vector<ptr<Expr>> args;

        UntypedExpr( const CodeLocation & loc, const Expr * f, std::vector<ptr<Expr>> && as = {} )
        : Expr( loc ), func( f ), args( std::move(as) ) {}

        /// Creates a new dereference expression
        static UntypedExpr * createDeref( const CodeLocation & loc, Expr * arg );
        /// Creates a new assignment expression
        static UntypedExpr * createAssign( const CodeLocation & loc, Expr * lhs, Expr * rhs );

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        UntypedExpr * clone() const override { return new UntypedExpr{ *this }; }
};

/// A name whose name is as-yet undetermined.
/// May also be used to avoid name mangling in codegen phase.
class NameExpr final : public Expr {
public:
        std::string name;

        NameExpr( const CodeLocation & loc, const std::string & n ) : Expr( loc ), name( n ) {}

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        NameExpr * clone() const override { return new NameExpr{ *this }; }
};

/// Address-of expression `&e`
class AddressExpr final : public Expr {
public:
        ptr<Expr> arg;

        AddressExpr( const CodeLocation & loc, const Expr * a );

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        AddressExpr * clone() const override { return new AddressExpr{ *this }; }
};

/// GCC &&label
/// https://gcc.gnu.org/onlinedocs/gcc-3.4.2/gcc/Labels-as-Values.html
class LabelAddressExpr final : public Expr {
public:
        Label arg;

        LabelAddressExpr( const CodeLocation & loc, Label && a );

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        LabelAddressExpr * clone() const override { return new LabelAddressExpr{ *this }; }
};

/// Whether a cast existed in the program source or not
enum GeneratedFlag { ExplicitCast, GeneratedCast };

/// A type cast, e.g. `(int)e`
class CastExpr final : public Expr {
public:
        ptr<Expr> arg;
        GeneratedFlag isGenerated;

        CastExpr( const CodeLocation & loc, const Expr * a, const Type * to, 
                GeneratedFlag g = GeneratedCast ) : Expr( loc, to ), arg( a ), isGenerated( g ) {}
        /// Cast-to-void
        CastExpr( const CodeLocation & loc, const Expr * a, GeneratedFlag g = GeneratedCast );

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        CastExpr * clone() const override { return new CastExpr{ *this }; }
};

/// A cast to "keyword types", e.g. `(thread &)t`
class KeywordCastExpr final : public Expr {
public:
        ptr<Expr> arg;
        enum Target { Coroutine, Thread, Monitor, NUMBER_OF_TARGETS } target;

        KeywordCastExpr( const CodeLocation & loc, const Expr * a, Target t )
        : Expr( loc ), arg( a ), target( t ) {}

        /// Get a name for the target type
        const std::string& targetString() const;

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        KeywordCastExpr * clone() const override { return new KeywordCastExpr{ *this }; }
};

/// A virtual dynamic cast, e.g. `(virtual exception)e`
class VirtualCastExpr final : public Expr {
public:
        ptr<Expr> arg;

        VirtualCastExpr( const CodeLocation & loc, const Expr * a, const Type * to )
        : Expr( loc, to ), arg( a ) {}

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        VirtualCastExpr * clone() const override { return new VirtualCastExpr{ *this }; }
};

/// A member selection operation before expression resolution, e.g. `q.p`
class UntypedMemberExpr final : public Expr {
public:
        ptr<Expr> member;
        ptr<Expr> aggregate;

        UntypedMemberExpr( const CodeLocation & loc, const Expr * mem, const Expr * agg )
        : Expr( loc ), member( mem ), aggregate( agg ) { assert( aggregate ); }

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        UntypedMemberExpr * clone() const override { return new UntypedMemberExpr{ *this }; }
};

/// A member selection operation after expression resolution, e.g. `q.p`
class MemberExpr final : public Expr {
public:
        readonly<DeclWithType> member;
        ptr<Expr> aggregate;

        MemberExpr( const CodeLocation & loc, const DeclWithType * mem, const Expr * agg );

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        MemberExpr * clone() const override { return new MemberExpr{ *this }; }
};

/// A reference to a named variable.
class VariableExpr final : public Expr {
public:
        readonly<DeclWithType> var;

        VariableExpr( const CodeLocation & loc, const DeclWithType * v );

        /// generates a function pointer for a given function
        static VariableExpr * functionPointer( const CodeLocation & loc, const FunctionDecl * decl );

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        VariableExpr * clone() const override { return new VariableExpr{ *this }; }
};

/// A compile-time constant
class ConstantExpr final : public Expr {
        union Val {
                unsigned long long ival;
                double dval;
                
                Val( unsigned long long i ) : ival( i ) {}
                Val( double d ) : dval( d ) {}
        } val;
public:
        std::string rep;

        ConstantExpr( 
                const CodeLocation & loc, const Type * ty, const std::string & r, unsigned long long v )
        : Expr( loc, ty ), val( v ), rep( r ) {}
        ConstantExpr( const CodeLocation & loc, const Type * ty, const std::string & r, double v )
        : Expr( loc, ty ), val( v ), rep( r ) {}
        
        /// Gets the value of this constant as an integer
        long long int intValue() const;
        /// Gets the value of this constant as floating point
        double floatValue() const;

        /// generates a boolean constant of the given bool
        static ConstantExpr * from_bool( const CodeLocation & loc, bool b );
        /// generates a char constant of the given char
        static ConstantExpr * from_char( const CodeLocation & loc, char c );
        /// generates an integer constant of the given int
        static ConstantExpr * from_int( const CodeLocation & loc, int i );
        /// generates an integer constant of the given unsigned long int
        static ConstantExpr * from_ulong( const CodeLocation & loc, unsigned long i );
        /// generates a floating point constant of the given double
        static ConstantExpr * from_double( const CodeLocation & loc, double d );
        /// generates an array of chars constant of the given string
        static ConstantExpr * from_string( const CodeLocation & loc, const std::string & s );
        /// generates a null pointer value for the given type. void * if omitted.
        static ConstantExpr * null( const CodeLocation & loc, const Type * ptrType = nullptr );

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        ConstantExpr * clone() const override { return new ConstantExpr{ *this }; }
};

/// sizeof expression, e.g. `sizeof(int)`, `sizeof 3+4`
class SizeofExpr final : public Expr {
public:
        ptr<Expr> expr;
        ptr<Type> type;

        SizeofExpr( const CodeLocation & loc, const Expr * e );
        SizeofExpr( const CodeLocation & loc, const Type * t );
        // deliberately no disambiguating overload for nullptr_t

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        SizeofExpr * clone() const override { return new SizeofExpr{ *this }; }
};

/// alignof expression, e.g. `alignof(int)`, `alignof 3+4`
class AlignofExpr final : public Expr {
public:
        ptr<Expr> expr;
        ptr<Type> type;

        AlignofExpr( const CodeLocation & loc, const Expr * e );
        AlignofExpr( const CodeLocation & loc, const Type * t );
        // deliberately no disambiguating overload for nullptr_t

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        AlignofExpr * clone() const override { return new AlignofExpr{ *this }; }
};

/// offsetof expression before resolver determines field, e.g. `offsetof(MyStruct, myfield)`
class UntypedOffsetofExpr final : public Expr {
public:
        ptr<Type> type;
        std::string member;

        UntypedOffsetofExpr( const CodeLocation & loc, const Type * ty, const std::string & mem )
        : Expr( loc ), type( ty ), member( mem ) {}

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        UntypedOffsetofExpr * clone() const override { return new UntypedOffsetofExpr{ *this }; }
};

/// offsetof expression after resolver determines field, e.g. `offsetof(MyStruct, myfield)`
class OffsetofExpr final : public Expr {
public:
        ptr<Type> type;
        readonly<DeclWithType> member;

        OffsetofExpr( const CodeLocation & loc, const Type * ty, const DeclWithType * mem );

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        OffsetofExpr * clone() const override { return new OffsetofExpr{ *this }; }
};

/// a pack of field-offsets for a generic type
class OffsetPackExpr final : public Expr {
public:
        ptr<StructInstType> type;

        OffsetPackExpr( const CodeLocation & loc, const StructInstType * ty );

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        OffsetPackExpr * clone() const override { return new OffsetPackExpr{ *this }; }
};

/// Variants of short-circuiting logical expression
enum LogicalFlag { OrExpr, AndExpr };

/// Short-circuiting boolean expression (`&&` or `||`)
class LogicalExpr final : public Expr {
public:
        ptr<Expr> arg1;
        ptr<Expr> arg2;
        LogicalFlag isAnd;

        LogicalExpr( const CodeLocation & loc, const Expr * a1, const Expr * a2, LogicalFlag ia );

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        LogicalExpr * clone() const override { return new LogicalExpr{ *this }; }
};

/// Three-argument conditional e.g. `p ? a : b`
class ConditionalExpr final : public Expr {
public:
        ptr<Expr> arg1;
        ptr<Expr> arg2;
        ptr<Expr> arg3;

        ConditionalExpr( const CodeLocation & loc, const Expr * a1, const Expr * a2, const Expr * a3 )
        : Expr( loc ), arg1( a1 ), arg2( a2 ), arg3( a3 ) {}

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        ConditionalExpr * clone() const override { return new ConditionalExpr{ *this }; }
};

/// Comma expression e.g. `( a , b )`
class CommaExpr final : public Expr {
public:
        ptr<Expr> arg1;
        ptr<Expr> arg2;

        CommaExpr( const CodeLocation & loc, const Expr * a1, const Expr * a2 ) 
        : Expr( loc ), arg1( a1 ), arg2( a2 ) {}

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        CommaExpr * clone() const override { return new CommaExpr{ *this }; }
};

/// A type used as an expression (e.g. a type generator parameter)
class TypeExpr final : public Expr {
public:
        ptr<Type> type;

        TypeExpr( const CodeLocation & loc, const Type * t ) : Expr(loc), type(t) {}

        const Expr * accept( Visitor & v ) const override { return v.visit( this ); }
private:
        TypeExpr * clone() const override { return new TypeExpr{ *this }; }
};

/// A GCC "asm constraint operand" used in an asm statement, e.g. `[output] "=f" (result)`.
/// https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gcc/Machine-Constraints.html#Machine-Constraints
class AsmExpr final : public Expr {
public:
        ptr<Expr> inout;
        ptr<Expr> constraint; 
};

//=================================================================================================
/// This disgusting and giant piece of boiler-plate is here to solve a cyclic dependency
/// remove only if there is a better solution
/// The problem is that ast::ptr< ... > uses increment/decrement which won't work well with
/// forward declarations
inline void increment( const class Expr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class Expr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class ApplicationExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class ApplicationExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class UntypedExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class UntypedExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class NameExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class NameExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class AddressExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class AddressExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class LabelAddressExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class LabelAddressExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class CastExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class CastExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class KeywordCastExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class KeywordCastExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class VirtualCastExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class VirtualCastExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class MemberExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class MemberExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class UntypedMemberExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class UntypedMemberExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class VariableExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class VariableExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class ConstantExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class ConstantExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class SizeofExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class SizeofExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class AlignofExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class AlignofExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class UntypedOffsetofExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class UntypedOffsetofExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class OffsetofExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class OffsetofExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class OffsetPackExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class OffsetPackExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class LogicalExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class LogicalExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class ConditionalExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class ConditionalExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class CommaExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class CommaExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class TypeExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class TypeExpr * node, Node::ref_type ref ) { node->decrement(ref); }
inline void increment( const class AsmExpr * node, Node::ref_type ref ) { node->increment(ref); }
inline void decrement( const class AsmExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class ImplicitCopyCtorExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class ImplicitCopyCtorExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class ConstructorExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class ConstructorExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class CompoundLiteralExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class CompoundLiteralExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class UntypedValofExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class UntypedValofExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class RangeExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class RangeExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class UntypedTupleExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class UntypedTupleExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class TupleExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class TupleExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class TupleIndexExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class TupleIndexExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class TupleAssignExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class TupleAssignExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class StmtExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class StmtExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class UniqueExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class UniqueExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class UntypedInitExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class UntypedInitExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class InitExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class InitExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class DeletedExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class DeletedExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class DefaultArgExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class DefaultArgExpr * node, Node::ref_type ref ) { node->decrement(ref); }
// inline void increment( const class GenericExpr * node, Node::ref_type ref ) { node->increment(ref); }
// inline void decrement( const class GenericExpr * node, Node::ref_type ref ) { node->decrement(ref); }
}

// Local Variables: //
// tab-width: 4 //
// mode: c++ //
// compile-command: "make install" //
// End: //