text: /*
   * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  /**
   * @file
   * simple arithmetic expression evaluator
   */
  
  #ifndef AVUTIL_EVAL_H
  #define AVUTIL_EVAL_H
  
  #include "avutil.h"
  
  typedef struct AVExpr AVExpr;
  
  /**
   * Parse and evaluate an expression.
   * Note, this is significantly slower than av_expr_eval().
   *
   * @param res a pointer to a double where is put the result value of
   * the expression, or NAN in case of error
   * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
   * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
   * @param const_values a zero terminated array of values for the identifiers from const_names
   * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
   * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
   * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
   * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
   * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
   * @param log_ctx parent logging context
   * @return >= 0 in case of success, a negative value corresponding to an
   * AVERROR code otherwise
   */
  int av_expr_parse_and_eval(double *res, const char *s,
                             const char * const *const_names, const double *const_values,
                             const char * const *func1_names, double (* const *funcs1)(void *, double),
                             const char * const *func2_names, double (* const *funcs2)(void *, double, double),
                             void *opaque, int log_offset, void *log_ctx);
  
  /**
   * Parse an expression.
   *
   * @param expr a pointer where is put an AVExpr containing the parsed
   * value in case of successful parsing, or NULL otherwise.
   * The pointed to AVExpr must be freed with av_expr_free() by the user
   * when it is not needed anymore.
   * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
   * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
   * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
   * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
   * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
   * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
   * @param log_ctx parent logging context
   * @return >= 0 in case of success, a negative value corresponding to an
   * AVERROR code otherwise
   */
  int av_expr_parse(AVExpr **expr, const char *s,
                    const char * const *const_names,
                    const char * const *func1_names, double (* const *funcs1)(void *, double),
                    const char * const *func2_names, double (* const *funcs2)(void *, double, double),
                    int log_offset, void *log_ctx);
  
  /**
   * Evaluate a previously parsed expression.
   *
   * @param const_values a zero terminated array of values for the identifiers from av_expr_parse() const_names
   * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
   * @return the value of the expression
   */
  double av_expr_eval(AVExpr *e, const double *const_values, void *opaque);
  
  /**
   * Free a parsed expression previously created with av_expr_parse().
   */
  void av_expr_free(AVExpr *e);
  
  /**
   * Parse the string in numstr and return its value as a double. If
   * the string is empty, contains only whitespaces, or does not contain
   * an initial substring that has the expected syntax for a
   * floating-point number, no conversion is performed. In this case,
   * returns a value of zero and the value returned in tail is the value
   * of numstr.
   *
   * @param numstr a string representing a number, may contain one of
   * the International System number postfixes, for example 'K', 'M',
   * 'G'. If 'i' is appended after the postfix, powers of 2 are used
   * instead of powers of 10. The 'B' postfix multiplies the value by
   * 8, and can be appended after another postfix or used alone. This
   * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
   * @param tail if non-NULL puts here the pointer to the char next
   * after the last parsed character
   */
  double av_strtod(const char *numstr, char **tail);
  
  #endif /* AVUTIL_EVAL_H */
  