Examples with LogicalProject org.apache.calcite.rel.logical.LogicalProject used on opensource projects

Example 41 with LogicalProject

use of org.apache.calcite.rel.logical.LogicalProject in project drill by apache.

the class PreProcessLogicalRel method visit.

@Override
public RelNode visit(LogicalProject project) {
    final List<RexNode> projExpr = Lists.newArrayList();
    for (RexNode rexNode : project.getChildExps()) {
        projExpr.add(rexNode.accept(unwrappingExpressionVisitor));
    }
    project = project.copy(project.getTraitSet(), project.getInput(), projExpr, project.getRowType());
    List<RexNode> exprList = new ArrayList<>();
    boolean rewrite = false;
    for (RexNode rex : project.getChildExps()) {
        RexNode newExpr = rex;
        if (rex instanceof RexCall) {
            RexCall function = (RexCall) rex;
            String functionName = function.getOperator().getName();
            int nArgs = function.getOperands().size();
            // check if its a convert_from or convert_to function
            if (functionName.equalsIgnoreCase("convert_from") || functionName.equalsIgnoreCase("convert_to")) {
                String literal;
                if (nArgs == 2) {
                    if (function.getOperands().get(1) instanceof RexLiteral) {
                        try {
                            literal = ((NlsString) (((RexLiteral) function.getOperands().get(1)).getValue())).getValue();
                        } catch (final ClassCastException e) {
                            // Caused by user entering a value with a non-string literal
                            throw getConvertFunctionInvalidTypeException(function);
                        }
                    } else {
                        // caused by user entering a non-literal
                        throw getConvertFunctionInvalidTypeException(function);
                    }
                } else {
                    // Second operand is missing
                    throw UserException.parseError().message("'%s' expects a string literal as a second argument.", functionName).build(logger);
                }
                RexBuilder builder = new RexBuilder(factory);
                // construct the new function name based on the input argument
                String newFunctionName = functionName + literal;
                // Look up the new function name in the drill operator table
                List<SqlOperator> operatorList = table.getSqlOperator(newFunctionName);
                if (operatorList.size() == 0) {
                    // User typed in an invalid type name
                    throw getConvertFunctionException(functionName, literal);
                }
                SqlFunction newFunction = null;
                // Find the SqlFunction with the correct args
                for (SqlOperator op : operatorList) {
                    if (op.getOperandTypeChecker().getOperandCountRange().isValidCount(nArgs - 1)) {
                        newFunction = (SqlFunction) op;
                        break;
                    }
                }
                if (newFunction == null) {
                    // we are here because we found some dummy convert function. (See DummyConvertFrom and DummyConvertTo)
                    throw getConvertFunctionException(functionName, literal);
                }
                // create the new expression to be used in the rewritten project
                newExpr = builder.makeCall(newFunction, function.getOperands().subList(0, 1));
                rewrite = true;
            }
        }
        exprList.add(newExpr);
    }
    if (rewrite) {
        LogicalProject newProject = project.copy(project.getTraitSet(), project.getInput(0), exprList, project.getRowType());
        return visitChild(newProject, 0, project.getInput());
    }
    return visitChild(project, 0, project.getInput());
}