#ifndef FUNC_H
#define FUNC_H

#define MAX_FUNC_NAME_LENGTH 20

typedef enum
             /* The purpose of this enum is to enforce backward compatibility
		of numeric function identifiers which may be recorded in old
		save files. Hence, do NOT change the order of the items in this
		enum, merely add new identifiers at the end, just before
		N_FUNCTION_IDENTIFIERS.
	     */
{
 NOT_A_FUNCTION = -1,
 FIRST_FUNCTION = 0,
 FUNC_AT_SYMBOL = 0, FUNC_AMPERSAND, FUNC_X, FUNC_Y, FUNC_Z, FUNC_EVAL,
 FUNC_ERROR, FUNC_STRING, FUNC_SUM, FUNC_N, FUNC_INT, FUNC_FRAC, FUNC_LEN,
 FUNC_MIN, FUNC_MAX, FUNC_ABS, FUNC_DOLLAR_SIGN, FUNC_FLOAT, FUNC_STRFTIME,
 FUNC_CLOCK, FUNC_POLY, FUNC_E, FUNC_LOG, FUNC_SIN, FUNC_COS, FUNC_TAN,
 FUNC_SINH, FUNC_COSH, FUNC_TANH, FUNC_ASIN, FUNC_ACOS, FUNC_ATAN,
 FUNC_ARSINH, FUNC_ARCOSH, FUNC_ARTANH, FUNC_DEG2RAD, FUNC_RAD2DEG,
 FUNC_RND, FUNC_SUBSTR, FUNC_STRPTIME, FUNC_TIME, FUNC_BITAND, FUNC_BITOR,
 FUNC_R, FUNC_D, FUNC_CAP_X, FUNC_X_AMPERSAND, FUNC_NEGATE, FUNC_PLUS_SYMBOL,
 FUNC_MINUS_SYMBOL, FUNC_ASTERISK, FUNC_SLASH,
 /* Note use of thes in the macro below */
 FUNC_LESS_EQUAL, FUNC_GREATER_EQUAL, FUNC_LESS_THAN, FUNC_GREATER_THAN,
 FUNC_EQUAL_EQUAL, FUNC_TILDE_EQUAL, FUNC_BANG_EQUAL,

 FUNC_CARET,
 FUNC_PER_CENT, FUNC_CONCAT, FUNC_TAU, FUNC_SQRT, FUNC_FLOOR, FUNC_CEIL,
 FUNC_TRUNC, FUNC_ROUND, FUNC_DECIMAL, FUNC_SCIENTIFIC, FUNC_COMPACT,
 FUNC_HEXACT, FUNC_RIGHT, FUNC_LEFT, FUNC_DOWN, FUNC_UP, FUNC_BELOW, FUNC_ABOVE,
 FUNC_TRUE, FUNC_FALSE, FUNC_AND, FUNC_OR,

 N_FUNCTION_IDS
} FunctionIdentifier;

#define IS_RELATION_FUNC(f) (((f) >= FUNC_LESS_EQUAL) && ((f) <= FUNC_BANG_EQUAL))

/* Forward declaration of Token, since this header is used in scanner.h */
typedef struct Token_struc Token;

typedef enum /* In increasing order of precedence */
  {
   NO_PRECEDENCE, INFIX_CONC, INFIX_BOOL, INFIX_REL, INFIX_PLUS, INFIX_MUL,
   PREFIX_NEG, INFIX_POW, PREFIX_FUNC
  } FunctionPrecedence;

typedef enum { FUNCT, MACRO } EvaluationStrategy;

typedef struct 
{
  const char name[MAX_FUNC_NAME_LENGTH + 1];
  Token (*func)(FunctionIdentifier self, int, const Token*);
  FunctionPrecedence precedence;
  EvaluationStrategy eval_as;
  const char* display_symbol;
} Tfunc;

FunctionIdentifier identcode(const char *s, size_t len);
extern Tfunc tfunc[];

#endif