//===- MCExpr.h - Assembly Level Expressions --------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_MC_MCEXPR_H
#define LLVM_MC_MCEXPR_H

#include "llvm/Support/Casting.h"
#include "llvm/System/DataTypes.h"

namespace llvm {
class MCAsmInfo;
class MCContext;
class MCSymbol;
class MCValue;
class raw_ostream;
class StringRef;

/// MCExpr - Base class for the full range of assembler expressions which are
/// needed for parsing.
class MCExpr {
public:
  enum ExprKind {
    Binary,    ///< Binary expressions.
    Constant,  ///< Constant expressions.
    SymbolRef, ///< References to labels and assigned expressions.
    Unary      ///< Unary expressions.
  };

private:
  ExprKind Kind;

  MCExpr(const MCExpr&); // DO NOT IMPLEMENT
  void operator=(const MCExpr&); // DO NOT IMPLEMENT

protected:
  MCExpr(ExprKind _Kind) : Kind(_Kind) {}

public:
  /// @name Accessors
  /// @{

  ExprKind getKind() const { return Kind; }

  /// @}
  /// @name Utility Methods
  /// @{

  void print(raw_ostream &OS, const MCAsmInfo *MAI) const;
  void dump() const;

  /// @}
  /// @name Expression Evaluation
  /// @{

  /// EvaluateAsAbsolute - Try to evaluate the expression to an absolute value.
  ///
  /// @param Res - The absolute value, if evaluation succeeds.
  /// @result - True on success.
  bool EvaluateAsAbsolute(int64_t &Res) const;

  /// EvaluateAsRelocatable - Try to evaluate the expression to a relocatable
  /// value, i.e. an expression of the fixed form (a - b + constant).
  ///
  /// @param Res - The relocatable value, if evaluation succeeds.
  /// @result - True on success.
  bool EvaluateAsRelocatable(MCValue &Res) const;

  /// @}

  static bool classof(const MCExpr *) { return true; }
};

//// MCConstantExpr - Represent a constant integer expression.
class MCConstantExpr : public MCExpr {
  int64_t Value;

  MCConstantExpr(int64_t _Value)
    : MCExpr(MCExpr::Constant), Value(_Value) {}

public:
  /// @name Construction
  /// @{

  static const MCConstantExpr *Create(int64_t Value, MCContext &Ctx);

  /// @}
  /// @name Accessors
  /// @{

  int64_t getValue() const { return Value; }

  /// @}

  static bool classof(const MCExpr *E) {
    return E->getKind() == MCExpr::Constant;
  }
  static bool classof(const MCConstantExpr *) { return true; }
};

/// MCSymbolRefExpr - Represent a reference to a symbol from inside an
/// expression.
///
/// A symbol reference in an expression may be a use of a label, a use of an
/// assembler variable (defined constant), or constitute an implicit definition
/// of the symbol as external.
class MCSymbolRefExpr : public MCExpr {
  const MCSymbol *Symbol;

  MCSymbolRefExpr(const MCSymbol *_Symbol)
    : MCExpr(MCExpr::SymbolRef), Symbol(_Symbol) {}

public:
  /// @name Construction
  /// @{

  static const MCSymbolRefExpr *Create(const MCSymbol *Symbol, MCContext &Ctx);
  static const MCSymbolRefExpr *Create(StringRef Name, MCContext &Ctx);

  /// @}
  /// @name Accessors
  /// @{

  const MCSymbol &getSymbol() const { return *Symbol; }

  /// @}

  static bool classof(const MCExpr *E) {
    return E->getKind() == MCExpr::SymbolRef;
  }
  static bool classof(const MCSymbolRefExpr *) { return true; }
};

/// MCUnaryExpr - Unary assembler expressions.
class MCUnaryExpr : public MCExpr {
public:
  enum Opcode {
    LNot,  ///< Logical negation.
    Minus, ///< Unary minus.
    Not,   ///< Bitwise negation.
    Plus   ///< Unary plus.
  };

private:
  Opcode Op;
  const MCExpr *Expr;

  MCUnaryExpr(Opcode _Op, const MCExpr *_Expr)
    : MCExpr(MCExpr::Unary), Op(_Op), Expr(_Expr) {}

public:
  /// @name Construction
  /// @{

  static const MCUnaryExpr *Create(Opcode Op, const MCExpr *Expr,
                                   MCContext &Ctx);
  static const MCUnaryExpr *CreateLNot(const MCExpr *Expr, MCContext &Ctx) {
    return Create(LNot, Expr, Ctx);
  }
  static const MCUnaryExpr *CreateMinus(const MCExpr *Expr, MCContext &Ctx) {
    return Create(Minus, Expr, Ctx);
  }
  static const MCUnaryExpr *CreateNot(const MCExpr *Expr, MCContext &Ctx) {
    return Create(Not, Expr, Ctx);
  }
  static const MCUnaryExpr *CreatePlus(const MCExpr *Expr, MCContext &Ctx) {
    return Create(Plus, Expr, Ctx);
  }

  /// @}
  /// @name Accessors
  /// @{

  /// getOpcode - Get the kind of this unary expression.
  Opcode getOpcode() const { return Op; }

  /// getSubExpr - Get the child of this unary expression.
  const MCExpr *getSubExpr() const { return Expr; }

  /// @}

  static bool classof(const MCExpr *E) {
    return E->getKind() == MCExpr::Unary;
  }
  static bool classof(const MCUnaryExpr *) { return true; }
};

/// MCBinaryExpr - Binary assembler expressions.
class MCBinaryExpr : public MCExpr {
public:
  enum Opcode {
    Add,  ///< Addition.
    And,  ///< Bitwise and.
    Div,  ///< Division.
    EQ,   ///< Equality comparison.
    GT,   ///< Greater than comparison.
    GTE,  ///< Greater than or equal comparison.
    LAnd, ///< Logical and.
    LOr,  ///< Logical or.
    LT,   ///< Less than comparison.
    LTE,  ///< Less than or equal comparison.
    Mod,  ///< Modulus.
    Mul,  ///< Multiplication.
    NE,   ///< Inequality comparison.
    Or,   ///< Bitwise or.
    Shl,  ///< Bitwise shift left.
    Shr,  ///< Bitwise shift right.
    Sub,  ///< Subtraction.
    Xor   ///< Bitwise exclusive or.
  };

private:
  Opcode Op;
  const MCExpr *LHS, *RHS;

  MCBinaryExpr(Opcode _Op, const MCExpr *_LHS, const MCExpr *_RHS)
    : MCExpr(MCExpr::Binary), Op(_Op), LHS(_LHS), RHS(_RHS) {}

public:
  /// @name Construction
  /// @{

  static const MCBinaryExpr *Create(Opcode Op, const MCExpr *LHS,
                                    const MCExpr *RHS, MCContext &Ctx);
  static const MCBinaryExpr *CreateAdd(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(Add, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateAnd(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(And, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateDiv(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(Div, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateEQ(const MCExpr *LHS, const MCExpr *RHS,
                                      MCContext &Ctx) {
    return Create(EQ, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateGT(const MCExpr *LHS, const MCExpr *RHS,
                                      MCContext &Ctx) {
    return Create(GT, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateGTE(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(GTE, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateLAnd(const MCExpr *LHS, const MCExpr *RHS,
                                        MCContext &Ctx) {
    return Create(LAnd, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateLOr(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(LOr, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateLT(const MCExpr *LHS, const MCExpr *RHS,
                                      MCContext &Ctx) {
    return Create(LT, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateLTE(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(LTE, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateMod(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(Mod, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateMul(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(Mul, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateNE(const MCExpr *LHS, const MCExpr *RHS,
                                      MCContext &Ctx) {
    return Create(NE, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateOr(const MCExpr *LHS, const MCExpr *RHS,
                                      MCContext &Ctx) {
    return Create(Or, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateShl(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(Shl, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateShr(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(Shr, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateSub(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(Sub, LHS, RHS, Ctx);
  }
  static const MCBinaryExpr *CreateXor(const MCExpr *LHS, const MCExpr *RHS,
                                       MCContext &Ctx) {
    return Create(Xor, LHS, RHS, Ctx);
  }

  /// @}
  /// @name Accessors
  /// @{

  /// getOpcode - Get the kind of this binary expression.
  Opcode getOpcode() const { return Op; }

  /// getLHS - Get the left-hand side expression of the binary operator.
  const MCExpr *getLHS() const { return LHS; }

  /// getRHS - Get the right-hand side expression of the binary operator.
  const MCExpr *getRHS() const { return RHS; }

  /// @}

  static bool classof(const MCExpr *E) {
    return E->getKind() == MCExpr::Binary;
  }
  static bool classof(const MCBinaryExpr *) { return true; }
};

} // end namespace llvm

#endif