/**
* Creates a string in a specfied character set.
*
* @param value String constant, must not be null
* @param charsetName Name of the character set, may be null
* @param collation Collation, may be null
* @throws IllegalCharsetNameException If the given charset name is illegal
* @throws UnsupportedCharsetException If no support for the named charset is available in this
* instance of the Java virtual machine
* @throws RuntimeException If the given value cannot be represented in the given charset
*/
public NlsString(String value, String charsetName, SqlCollation collation) {
assert value != null;
if (null != charsetName) {
charsetName = charsetName.toUpperCase();
this.charsetName = charsetName;
String javaCharsetName = SqlUtil.translateCharacterSetName(charsetName);
if (javaCharsetName == null) {
throw new UnsupportedCharsetException(charsetName);
}
this.charset = Charset.forName(javaCharsetName);
CharsetEncoder encoder = charset.newEncoder();
// dry run to see if encoding hits any problems
try {
encoder.encode(CharBuffer.wrap(value));
} catch (CharacterCodingException ex) {
throw RESOURCE.charsetEncoding(value, javaCharsetName).ex();
}
} else {
this.charsetName = null;
this.charset = null;
}
this.collation = collation;
this.value = value;
}
/**
* Derives an alias for a node, and invents a mangled identifier if it cannot.
*
* <p>Examples:
*
* <ul>
* <li>Alias: "1 + 2 as foo" yields "foo"
* <li>Identifier: "foo.bar.baz" yields "baz"
* <li>Anything else yields "expr$<i>ordinal</i>"
* </ul>
*
* @return An alias, if one can be derived; or a synthetic alias "expr$<i>ordinal</i>" if ordinal
* >= 0; otherwise null
*/
public static String getAlias(SqlNode node, int ordinal) {
switch (node.getKind()) {
case AS:
// E.g. "1 + 2 as foo" --> "foo"
return ((SqlCall) node).getOperands()[1].toString();
case OVER:
// E.g. "bids over w" --> "bids"
return getAlias(((SqlCall) node).getOperands()[0], ordinal);
case IDENTIFIER:
// E.g. "foo.bar" --> "bar"
return Util.last(((SqlIdentifier) node).names);
default:
if (ordinal < 0) {
return null;
} else {
return SqlUtil.deriveAliasFromOrdinal(ordinal);
}
}
}
