/**
* 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);
}
}
}
private RelDataType deriveType(
SqlValidator validator,
SqlValidatorScope scope,
SqlCall call,
boolean convertRowArgToColumnList) {
final SqlNode[] operands = call.operands;
RelDataType[] argTypes = new RelDataType[operands.length];
// Scope for operands. Usually the same as 'scope'.
final SqlValidatorScope operandScope = scope.getOperandScope(call);
// Indicate to the validator that we're validating a new function call
validator.pushFunctionCall();
try {
boolean containsRowArg = false;
for (int i = 0; i < operands.length; ++i) {
RelDataType nodeType;
// for row arguments that should be converted to ColumnList
// types, set the nodeType to a ColumnList type but defer
// validating the arguments of the row constructor until we know
// for sure that the row argument maps to a ColumnList type
if (operands[i].getKind() == SqlKind.ROW && convertRowArgToColumnList) {
containsRowArg = true;
RelDataTypeFactory typeFactory = validator.getTypeFactory();
nodeType = typeFactory.createSqlType(SqlTypeName.COLUMN_LIST);
} else {
nodeType = validator.deriveType(operandScope, operands[i]);
}
validator.setValidatedNodeType(operands[i], nodeType);
argTypes[i] = nodeType;
}
SqlFunction function =
SqlUtil.lookupRoutine(
validator.getOperatorTable(), getNameAsId(), argTypes, getFunctionType());
// if we have a match on function name and parameter count, but
// couldn't find a function with a COLUMN_LIST type, retry, but
// this time, don't convert the row argument to a COLUMN_LIST type;
// if we did find a match, go back and revalidate the row operands
// (corresponding to column references), now that we can set the
// scope to that of the source cursor referenced by that ColumnList
// type
if (containsRowArg) {
if ((function == null)
&& SqlUtil.matchRoutinesByParameterCount(
validator.getOperatorTable(), getNameAsId(), argTypes, getFunctionType())) {
// remove the already validated node types corresponding to
// row arguments before revalidating
for (SqlNode operand : operands) {
if (operand.getKind() == SqlKind.ROW) {
validator.removeValidatedNodeType(operand);
}
}
return deriveType(validator, scope, call, false);
} else if (function != null) {
validator.validateColumnListParams(function, argTypes, operands);
}
}
if (getFunctionType() == SqlFunctionCategory.UserDefinedConstructor) {
return validator.deriveConstructorType(scope, call, this, function, argTypes);
}
if (function == null) {
validator.handleUnresolvedFunction(call, this, argTypes);
}
// REVIEW jvs 25-Mar-2005: This is, in a sense, expanding
// identifiers, but we ignore shouldExpandIdentifiers()
// because otherwise later validation code will
// choke on the unresolved function.
call.setOperator(function);
return function.validateOperands(validator, operandScope, call);
} finally {
validator.popFunctionCall();
}
}