P1-wifi-esp12e/P1_gateway_FW/lib/dsmr/util.h

/**
 * Arduino DSMR parser.
 *
 * This software is licensed under the MIT License.
 *
 * Copyright (c) 2015 Matthijs Kooijman <matthijs@stdin.nl>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * Various utility functions
 */

#ifndef DSMR_INCLUDE_UTIL_H
#define DSMR_INCLUDE_UTIL_H

#ifdef ARDUINO_ARCH_ESP8266
#define DSMR_PROGMEM
#else
#define DSMR_PROGMEM PROGMEM
#endif

#include <Arduino.h>

namespace dsmr {

/**
 * Small utility to get the length of an array at compiletime.
 */
template<typename T, unsigned int sz>
inline unsigned int lengthof(const T (&)[sz]) { return sz; }

// Hack until https://github.com/arduino/Arduino/pull/1936 is merged.
// This appends the given number of bytes from the given C string to the
// given Arduino string, without requiring a trailing NUL.
// Requires that there _is_ room for nul-termination
static void concat_hack(String& s, const char *append, size_t n) {
  // Add null termination. Inefficient, but it works...
  char buf[n + 1];
  memcpy(buf, append, n);
  buf[n] = 0;
  s.concat(buf);
}

/**
 * The ParseResult<T> class wraps the result of a parse function. The type
 * of the result is passed as a template parameter and can be void to
 * not return any result.
 *
 * A ParseResult can either:
 *  - Return an error. In this case, err is set to an error message, ctx
 *    is optionally set to where the error occurred. The result (if any)
 *    and the next pointer are meaningless.
 *  - Return succesfully. In this case, err and ctx are NULL, result
 *    contains the result (if any) and next points one past the last
 *    byte processed by the parser.
 *
 * The ParseResult class has some convenience functions:
 *  - succeed(result): sets the result to the given value and returns
 *    the ParseResult again.
 *  - fail(err): Set the err member to the error message passed,
 *    optionally sets the ctx and return the ParseResult again.
 *  - until(next): Set the next member and return the ParseResult again.
 *
 * Furthermore, ParseResults can be implicitely converted to other
 * types. In this case, the error message, context and and next pointer are
 * conserved, the return value is reset to the default value for the
 * target type.
 *
 * Note that ctx points into the string being parsed, so it does not
 * need to be freed, lives as long as the original string and is
 * probably way longer that needed.
 */

// Superclass for ParseResult so we can specialize for void without
// having to duplicate all content
template <typename P, typename T>
struct _ParseResult {
  T result;

  P& succeed(T& result) {
    this->result = result; return *static_cast<P*>(this);
  }
  P& succeed(T&& result) {
    this->result = result;
    return *static_cast<P*>(this);
  }
};

// partial specialization for void result
template <typename P>
struct _ParseResult<P, void> {
};

// Actual ParseResult class
template <typename T>
struct ParseResult : public _ParseResult<ParseResult<T>, T> {
  const char *next = NULL;
  const __FlashStringHelper *err = NULL;
  const char *ctx = NULL;

  ParseResult& fail(const __FlashStringHelper *err, const char* ctx = NULL) {
    this->err = err;
    this->ctx = ctx;
    return *this;
  }
  ParseResult& until(const char *next) {
    this->next = next;
    return *this;
  }
  ParseResult() = default;
  ParseResult(const ParseResult& other) = default;

  template <typename T2>
  ParseResult(const ParseResult<T2>& other): next(other.next), err(other.err), ctx(other.ctx) { }

  /**
   * Returns the error, including context in a fancy multi-line format.
   * The start and end passed are the first and one-past-the-end
   * characters in the total parsed string. These are needed to properly
   * limit the context output.
   */
  String fullError(const char* start, const char* end) const {
    String res;
    if (this->ctx && start && end) {
      // Find the entire line surrounding the context
      const char *line_end = this->ctx;
      while(line_end < end && line_end[0] != '\r' && line_end[0] != '\n') ++line_end;
      const char *line_start = this->ctx;
      while(line_start > start && line_start[-1] != '\r' && line_start[-1] != '\n') --line_start;

      // We can now predict the context string length, so let String allocate
      // memory in advance
      res.reserve((line_end - line_start) + 2 + (this->ctx - line_start) + 1 + 2);

      // Write the line
      concat_hack(res, line_start, line_end - line_start);
      res += "\r\n";

      // Write a marker to point out ctx
      while (line_start++ < this->ctx)
        res += ' ';
      res += '^';
      res += "\r\n";
    }
    res += this->err;
    return res;
  }
};

/**
 * An OBIS id is 6 bytes, usually noted as a-b:c.d.e.f. Here we put them
 * in an array for easy parsing.
 */
struct ObisId {
  uint8_t v[6];

  constexpr ObisId(uint8_t a, uint8_t b = 255, uint8_t c = 255, uint8_t d = 255, uint8_t e = 255, uint8_t f = 255)
    : v{a, b, c, d, e, f} { };
  constexpr ObisId() : v() {} // Zeroes

  bool operator==(const ObisId &other) const {
    return memcmp(&v, &other.v, sizeof(v)) == 0;
  }
};

} // namespace dsmr

#endif // DSMR_INCLUDE_UTIL_H