//

// str-flatten.c

//

// Copyright (c) 2014 Stephen Mathieson

// MIT licensed

//

#include <stdlib.h>

#include <string.h>

#include "str-flatten.h"

char *

str_flatten(const char *array[], int start, int end) {

  int count = end - start;

  size_t lengths[count];

  size_t size = 0;

  size_t pos = 0;

  for (int i = start, j = 0; i < end; ++i, ++j) {

    lengths[j] = strlen(array[i]);

    size += lengths[j];

  }

  char *str = malloc(size + count);

  str[size + count - 1] = '\0';

  for (int i = start, j = 0; i < (end - 1); ++i, ++j) {

    memcpy(str + pos + j

      // current index

      , array[i]

      // current index length

      , lengths[j]);

    // add space

    str[pos + lengths[j] + j] = ' ';

    // bump `pos`

    pos += lengths[j];

  }

  memcpy(str + pos + count - 1

    , array[end - 1]

    , lengths[count - 1]);

  return str;

}