justinborromeo commented on a change in pull request #7388: Support LPAD and
RPAD sql function
URL: https://github.com/apache/incubator-druid/pull/7388#discussion_r273715180
##########
File path:
core/src/main/java/org/apache/druid/java/util/common/StringUtils.java
##########
@@ -360,4 +360,93 @@ public static String encodeBase64String(byte[] input)
{
return BASE64_DECODER.decode(input);
}
+
+ /**
+ * Returns the string left-padded with the string pad to a length of len
characters.
+ * If str is longer than len, the return value is shortened to len
characters.
+ *
+ * @param base The base string to be padded
+ * @param len The length of padded string
+ * @param pad The pad string
+ * @return the string left-padded with pad to a lenght of len
+ */
+ public static String lpad(String base, Integer len, String pad)
+ {
+ if (len < 0) {
+ return null;
+ } else if (len == 0) {
+ return "";
+ }
+
+ char[] data = new char[len];
+ char[] baseChars = base.toCharArray();
+ char[] padChars = pad.toCharArray();
+
+ // The length of the padding needed
+ int pos = Math.max(len - base.length(), 0);
+
+ // Copy the padding
Review comment:
For the sake of conciseness, can this be shortened to use for loops?
```
// Copy the padding
for (int i = 0; i < pos; i += pad.length()) {
for (int j = 0; j < pad.length() && j < pos - i; j++) {
data[i + j] = padChars[j];
}
}
// Copy the base
for (int i = 0; pos + i < len && i < base.length(); i++) {
data[pos + i] = baseChars[i];
}
```
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