/**
* Returns str, left-padded with pad to a length of len. For example: ('hi', 5, '??') =>
* '???hi' ('hi', 1, '??') => 'h'
*/
public UTF8String lpad(int len, UTF8String pad) {
int spaces = len - this.numChars(); // number of char need to pad
if (spaces <= 0 || pad.numBytes() == 0) {
// no padding at all, return the substring of the current string
return substring(0, len);
} else {
int padChars = pad.numChars();
int count = spaces / padChars; // how many padding string needed
// the partial string of the padding
UTF8String remain = pad.substring(0, spaces - padChars * count);
byte[] data = new byte[this.numBytes + pad.numBytes * count + remain.numBytes];
int offset = 0;
int idx = 0;
while (idx < count) {
copyMemory(pad.base, pad.offset, data, BYTE_ARRAY_OFFSET + offset, pad.numBytes);
++idx;
offset += pad.numBytes;
}
copyMemory(remain.base, remain.offset, data, BYTE_ARRAY_OFFSET + offset, remain.numBytes);
offset += remain.numBytes;
copyMemory(this.base, this.offset, data, BYTE_ARRAY_OFFSET + offset, numBytes());
return UTF8String.fromBytes(data);
}
}
/**
* Returns the position of the first occurrence of substr in current string from the specified
* position (0-based index).
*
* @param v the string to be searched
* @param start the start position of the current string for searching
* @return the position of the first occurrence of substr, if not found, -1 returned.
*/
public int indexOf(UTF8String v, int start) {
if (v.numBytes() == 0) {
return 0;
}
// locate to the start position.
int i = 0; // position in byte
int c = 0; // position in character
while (i < numBytes && c < start) {
i += numBytesForFirstByte(getByte(i));
c += 1;
}
do {
if (i + v.numBytes > numBytes) {
return -1;
}
if (ByteArrayMethods.arrayEquals(base, offset + i, v.base, v.offset, v.numBytes)) {
return c;
}
i += numBytesForFirstByte(getByte(i));
c += 1;
} while (i < numBytes);
return -1;
}