map_location::DIRECTION map_location::parse_direction(const std::string& str)
{
if(str.empty()) {
return NDIRECTIONS;
}
// Syntax: [-] (n|ne|se|s|sw|nw) [:cw|:ccw]
// - means "take opposite direction" and has higher precedence
// :cw and :ccw mean "one step (counter-)clockwise"
// Parentheses can be used for grouping or to apply an operator more than once
const size_t open = str.find_first_of('('), close = str.find_last_of(')');
if (open != std::string::npos && close != std::string::npos) {
std::string sub = str.substr(open + 1, close - open - 1);
map_location::DIRECTION dir = parse_direction(sub);
sub = str;
sub.replace(open, close - open + 1, write_direction(dir));
return parse_direction(sub);
}
const size_t start = str[0] == '-' ? 1 : 0;
const size_t end = str.find_first_of(':');
const std::string& main_dir = str.substr(start, end - start);
map_location::DIRECTION dir;
if (main_dir == "n") {
dir = NORTH;
} else if (main_dir == "ne") {
dir = NORTH_EAST;
} else if (main_dir == "se") {
dir = SOUTH_EAST;
} else if (main_dir == "s") {
dir = SOUTH;
} else if (main_dir == "sw") {
dir = SOUTH_WEST;
} else if (main_dir == "nw") {
dir = NORTH_WEST;
} else {
return NDIRECTIONS;
}
if (start == 1) {
dir = get_opposite_dir(dir);
}
if (end != std::string::npos) {
const std::string rel_dir = str.substr(end + 1);
if (rel_dir == "cw") {
dir = rotate_right(dir, 1);
} else if (rel_dir == "ccw") {
dir = rotate_right(dir, -1);
} else {
return NDIRECTIONS;
}
}
return dir;
}
map_location map_location::get_direction(
map_location::DIRECTION dir, int n) const
{
if (n < 0 ) {
dir = get_opposite_dir(dir);
n = -n;
}
switch(dir) {
case NORTH: return map_location(x, y - n);
case SOUTH: return map_location(x, y + n);
case SOUTH_EAST: return map_location(x + n, y + (n+is_odd(x))/2 );
case SOUTH_WEST: return map_location(x - n, y + (n+is_odd(x))/2 );
case NORTH_EAST: return map_location(x + n, y - (n+is_even(x))/2 );
case NORTH_WEST: return map_location(x - n, y - (n+is_even(x))/2 );
default:
assert(false);
return map_location();
}
}
map_location::DIRECTION map_location::parse_direction(const std::string& str)
{
if(!str.empty()) {
if(str == "n") {
return NORTH;
} else if(str == "ne") {
return NORTH_EAST;
} else if(str == "se") {
return SOUTH_EAST;
} else if(str == "s") {
return SOUTH;
} else if(str == "sw") {
return SOUTH_WEST;
} else if(str == "nw") {
return NORTH_WEST;
} else if(str[0] == '-' && str.length() <= 10) {
// A minus sign reverses the direction
return get_opposite_dir(parse_direction(str.substr(1)));
}
}
return NDIRECTIONS;
}
inline map_location map_location::get_direction(
map_location::DIRECTION dir, signed int n) const
{
return (n >= 0) ? get_direction(dir, static_cast<unsigned int> (n)) : get_direction(get_opposite_dir(dir), static_cast<unsigned int> (-n));
}
