/*

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license restricting its use.

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this product is incorporated in whole or part. You may copy and extend
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distribution of Interface Definition Language CFE as permitted herein.

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and documentation for the Interface Definition Language CFE.

INTERFACE DEFINITION LANGUAGE CFE IS PROVIDED AS IS WITH NO WARRANTIES OF
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 */

#ifndef _AST_EXPRESSION_AST_EXPRESSION_HH
#define _AST_EXPRESSION_AST_EXPRESSION_HH

// Representation of expression values

/*
** DEPENDENCIES: NONE
**
** USE: Included from ast.hh
*/

// An expression (and maybe its value, if computed)
class	AST_Expression {
public:
  // Enum to define all the different operators to combine expressions
  enum ExprComb {
      EC_add		// '+'
    , EC_minus		// '-'
    , EC_mul		// '*'
    , EC_div		// '/'
    , EC_mod		// '%'
    , EC_or		// '|'
    , EC_xor		// '^'
    , EC_and		// '&'
    , EC_left		// '<<'
    , EC_right		// '>>'
    , EC_u_plus		// unary '+'
    , EC_u_minus	// unary '-'
    , EC_bit_neg	// '~'
    , EC_none		// No operator (missing)
    , EC_symbol		// a symbol (function or constant name)
  };
  
  // Enum to define the different kinds of evaluation possible
  // Extend this for more kinds of evaluation as required
  enum EvalKind {
      EK_const			// Must evaluate to constant
    , EK_positive_int		// Must evaluate to positive integer
  };

  // Enum to define expression type
  enum ExprType {
      EV_short			// Expression value is short
    , EV_ushort			// Expression value is unsigned short
    , EV_long			// Expression value is long
    , EV_ulong			// Expression value is unsigned long
    , EV_longlong		// Expression value is long long
    , EV_ulonglong		// Expression value is unsigned long long
    , EV_float			// Expression value is 32-bit float
    , EV_double			// Expression value is 64-bit float
    , EV_longdouble		// Expression value is 128-bit float
    , EV_char			// Expression value is char
    , EV_wchar			// Expression value is wide char	
    , EV_octet			// Expression value is unsigned char
    , EV_bool			// Expression value is boolean
    , EV_string			// Expression value is char *
    , EV_wstring		// Expression value is wchar_t *
    , EV_any			// Expression value is any of above
    , EV_void			// Expression value is void (absent)
    , EV_none			// Expression value is missing
  };

  // Structure to descrive value of constant expression and its type
  struct AST_ExprValue {
    union {
      short		sval;	// Contains short expression value
      unsigned short	usval;	// Contains unsigned short expr value
      long		lval;	// Contains long expression value
      unsigned long	ulval;	// Contains unsigned long expr value
      unsigned long	bval;	// Contains boolean expression value
      float		fval;	// Contains 32-bit float expr value
      double		dval;	// Contains 64-bit float expr value
      char		cval;	// Contains char expression value
      unsigned char	oval;	// Contains unsigned char expr value
      String	        *strval; // Contains String * expr value
      unsigned long	eval;	// Contains enumeration value
    } u;
    ExprType et;
  };

  // Operations

  // Constructor(s)
  AST_Expression(AST_Expression *v, ExprType t);

  AST_Expression(ExprComb c, AST_Expression *v1, AST_Expression *v2);

  AST_Expression(short		s);
  AST_Expression(unsigned short	us);
  AST_Expression(long		l);
  AST_Expression(long		l, ExprType t);
  AST_Expression(unsigned long	ul);
  AST_Expression(float		f);
  AST_Expression(double		d);
  AST_Expression(char		c);
  AST_Expression(unsigned char	uc);
  AST_Expression(String		*s);
  AST_Expression(UTL_ScopedName	*n);
  virtual ~AST_Expression () {}

  // Data Accessors
  UTL_Scope *defined_in();
  void set_defined_in(UTL_Scope *d);
  long line();
  void set_line(long l);
  String *file_name();
  void set_file_name(String *f);
  ExprComb ec();
  void set_ec(ExprComb new_ec);
  AST_ExprValue	*ev();
  void set_ev(AST_ExprValue *new_ev);
  AST_Expression *v1();
  void set_v1(AST_Expression *e);
  AST_Expression *v2();
  void set_v2(AST_Expression *e);
  UTL_ScopedName *n();
  void set_n(UTL_ScopedName *new_n);

  // AST Dumping
  virtual void			dump(std::ostream &o);

  // Other operations

  // Evaluation and value coercion
  virtual AST_ExprValue		*eval(EvalKind ek);
  virtual AST_ExprValue		*coerce(ExprType t);

  // Evaluate then store value inside this AST_Expression
  virtual void			evaluate(EvalKind ek);

  // Compare to AST_Expressions
  virtual long			operator==(AST_Expression *vc);
  virtual long			compare(AST_Expression *vc);

protected:
  // Evaluate different sets of operators
  virtual AST_ExprValue	*eval_bin_op(EvalKind ek);
  virtual AST_ExprValue	*eval_bit_op(EvalKind ek);
  virtual AST_ExprValue	*eval_un_op(EvalKind ek);
  virtual AST_ExprValue	*eval_symbol(EvalKind ek);

private:
  // Data
  UTL_Scope			*pd_defined_in;	// Scope
  long				pd_line;	// Line defined in
  String			*pd_file_name;	// What file defined in

  ExprComb			pd_ec;		// What combinator
  AST_ExprValue			*pd_ev;		// computed value
  AST_Expression		*pd_v1;		// 1st sub-expression
  AST_Expression		*pd_v2;		// 2nd sub-expression
  UTL_ScopedName		*pd_n;		// symbolic name (if any)

  // Operations

  // Fill out the lineno, filename and definition scope details
  void				fill_definition_details();

  // Internal evaluation
  virtual AST_ExprValue *eval_internal(EvalKind ek);
};

#endif           // _AST_EXPR_VAL_AST_EXPR_VAL_HH


