public static String extractScheme()

in commons-vfs2/src/main/java/org/apache/commons/vfs2/provider/UriParser.java [356:394]

27 lines of code
16 McCabe index (conditional complexity)


    public static String extractScheme(final String uri, final StringBuilder buffer) {
        if (buffer != null) {
            buffer.setLength(0);
            buffer.append(uri);
        }

        final int maxPos = uri.length();
        for (int pos = 0; pos < maxPos; pos++) {
            final char ch = uri.charAt(pos);

            if (ch == ':') {
                // Found the end of the scheme
                final String scheme = uri.substring(0, pos);
                if (scheme.length() <= 1 && SystemUtils.IS_OS_WINDOWS) {
                    // This is not a scheme, but a Windows drive letter
                    return null;
                }
                if (buffer != null) {
                    buffer.delete(0, pos + 1);
                }
                return scheme.intern();
            }

            if (ch >= 'a' && ch <= 'z' || ch >= 'A' && ch <= 'Z') {
                // A scheme character
                continue;
            }
            if (!(pos > 0 && (ch >= '0' && ch <= '9' || ch == '+' || ch == '-' || ch == '.'))) {
                // Not a scheme character
                break;
            }
            // A scheme character (these are not allowed as the first
            // character of the scheme), but can be used as subsequent
            // characters.
        }

        // No scheme in URI
        return null;
    }