+
+Rectangle
+Rectangle::intersection (Rectangle const & other) const
+{
+ int const tx = max (x, other.x);
+ int const ty = max (y, other.y);
+
+ return Rectangle (
+ tx, ty,
+ min (x + width, other.x + other.width) - tx,
+ min (y + height, other.y + other.height) - ty
+ );
+}
+
+int
+round_up (int a, int t)
+{
+ a += (t - 1);
+ return a - (a % t);
+}
+
+multimap<string, string>
+read_key_value (istream &s)
+{
+ multimap<string, string> kv;
+
+ string line;
+ while (getline (s, line)) {
+ if (line.empty ()) {
+ continue;
+ }
+
+ if (line[0] == '#') {
+ continue;
+ }
+
+ if (line[line.size() - 1] == '\r') {
+ line = line.substr (0, line.size() - 1);
+ }
+
+ size_t const s = line.find (' ');
+ if (s == string::npos) {
+ continue;
+ }
+
+ kv.insert (make_pair (line.substr (0, s), line.substr (s + 1)));
+ }
+
+ return kv;
+}
+
+string
+get_required_string (multimap<string, string> const & kv, string k)
+{
+ if (kv.count (k) > 1) {
+ throw StringError ("unexpected multiple keys in key-value set");
+ }
+
+ multimap<string, string>::const_iterator i = kv.find (k);
+
+ if (i == kv.end ()) {
+ throw StringError (String::compose ("missing key %1 in key-value set", k));
+ }
+
+ return i->second;
+}
+
+int
+get_required_int (multimap<string, string> const & kv, string k)
+{
+ string const v = get_required_string (kv, k);
+ return lexical_cast<int> (v);
+}
+
+string
+get_optional_string (multimap<string, string> const & kv, string k)
+{
+ if (kv.count (k) > 1) {
+ throw StringError ("unexpected multiple keys in key-value set");
+ }
+
+ multimap<string, string>::const_iterator i = kv.find (k);
+ if (i == kv.end ()) {
+ return "";
+ }
+
+ return i->second;
+}
+
+int
+get_optional_int (multimap<string, string> const & kv, string k)
+{
+ if (kv.count (k) > 1) {
+ throw StringError ("unexpected multiple keys in key-value set");
+ }
+
+ multimap<string, string>::const_iterator i = kv.find (k);
+ if (i == kv.end ()) {
+ return 0;
+ }
+
+ return lexical_cast<int> (i->second);
+}