expr.h

#ifndef EXPR_H
#define EXPR_H

#include "dberror.h"
#include "tables.h"

// datatype for arguments of expressions used in conditions
typedef enum ExprType {
  EXPR_OP,
  EXPR_CONST,
  EXPR_ATTRREF
} ExprType;

typedef struct Expr {
  ExprType type;
  union expr {
    Value *cons;
    int attrRef;
    struct Operator *op;
  } expr;
} Expr;

// comparison operators
typedef enum OpType {
  OP_BOOL_AND,
  OP_BOOL_OR,
  OP_BOOL_NOT,
  OP_COMP_EQUAL,
  OP_COMP_SMALLER
} OpType;

typedef struct Operator {
  OpType type;
  Expr **args;
} Operator;

// expression evaluation methods
extern RC valueEquals (Value *left, Value *right, Value *result);
extern RC valueSmaller (Value *left, Value *right, Value *result);
extern RC boolNot (Value *input, Value *result);
extern RC boolAnd (Value *left, Value *right, Value *result);
extern RC boolOr (Value *left, Value *right, Value *result);
extern RC evalExpr (Record *record, Schema *schema, Expr *expr, Value **result);
extern RC freeExpr (Expr *expr);
extern void freeVal(Value *val);


#define CPVAL(_result,_input)						\
  do {									\
    (_result)->dt = _input->dt;						\
  switch(_input->dt)							\
    {									\
    case DT_INT:							\
      (_result)->v.intV = _input->v.intV;					\
      break;								\
    case DT_STRING:							\
      (_result)->v.stringV = (char *) malloc(strlen(_input->v.stringV));	\
      strcpy((_result)->v.stringV, _input->v.stringV);			\
      break;								\
    case DT_FLOAT:							\
      (_result)->v.floatV = _input->v.floatV;				\
      break;								\
    case DT_BOOL:							\
      (_result)->v.boolV = _input->v.boolV;				\
      break;								\
    }									\
} while(0)

#define MAKE_BINOP_EXPR(_result,_left,_right,_optype)			\
    do {								\
      Operator *_op = (Operator *) malloc(sizeof(Operator));		\
      _result = (Expr *) malloc(sizeof(Expr));				\
      _result->type = EXPR_OP;						\
      _result->expr.op = _op;						\
      _op->type = _optype;						\
      _op->args = (Expr **) malloc(2 * sizeof(Expr*));			\
      _op->args[0] = _left;						\
      _op->args[1] = _right;						\
    } while (0)

#define MAKE_UNOP_EXPR(_result,_input,_optype)				\
  do {									\
    Operator *_op = (Operator *) malloc(sizeof(Operator));		\
    _result = (Expr *) malloc(sizeof(Expr));				\
    _result->type = EXPR_OP;						\
    _result->expr.op = _op;						\
    _op->type = _optype;						\
    _op->args = (Expr **) malloc(sizeof(Expr*));			\
    _op->args[0] = _input;						\
  } while (0)

#define MAKE_ATTRREF(_result,_attr)					\
  do {									\
    _result = (Expr *) malloc(sizeof(Expr));				\
    _result->type = EXPR_ATTRREF;					\
    _result->expr.attrRef = _attr;					\
  } while(0)

#define MAKE_CONS(_result,_value)					\
  do {									\
    _result = (Expr *) malloc(sizeof(Expr));				\
    _result->type = EXPR_CONST;						\
    _result->expr.cons = _value;					\
  } while(0)



#endif // EXPR