COMMON: Added firstPathComponents() method.

A better name is welcome

common/str.cpp

@@ -543,6 +543,29 @@ String lastPathComponent(const String &path, const char sep) {
 	return String(first, last);
 }
 
+String firstPathComponents(const String &path, const char sep) {
+	const char *str = path.c_str();
+	const char *last = str + path.size();
+
+	// Skip over trailing slashes
+	while (last > str && *(last - 1) == sep)
+		--last;
+
+	// Path consisted of only slashes -> return empty string
+	if (last == str)
+		return String();
+
+	// Now scan the whole component
+	const char *first = last - 1;
+	while (first > str && *first != sep)
+		--first;
+
+	if (*first == sep)
+		first++;
+
+	return String(str, first);
+}
+
 String normalizePath(const String &path, const char sep) {
 	if (path.empty())
 		return path;

common/str.h

@@ -290,6 +290,20 @@ extern char *trim(char *t);
  */
 String lastPathComponent(const String &path, const char sep);
 
+/**
+ * Returns the first components of a given path (complementary to lastPathComponent)
+ *
+ * Examples:
+ *          /foo/bar.txt    would return '/foo/'
+ *          /foo/bar/       would return '/foo/'
+ *          /foo/./bar//    would return '/foo/./'
+ *
+ * @param path the path of which we want to know the last component
+ * @param sep character used to separate path components
+ * @return The all the components of the path except the last one.
+ */
+String firstPathComponents(const String &path, const char sep);
+
 /**
  * Normalize a given path to a canonical form. In particular:
  * - trailing separators are removed:  /foo/bar/ -> /foo/bar