Examples with ExprType io.druid.math.expr.ExprType used on opensource projects

Example 1 with ExprType

use of io.druid.math.expr.ExprType in project druid by druid-io.

the class Expressions method toMathExpression.

/**
   * Translate a row-expression to a Druid math expression. One day, when possible, this could be folded into
   * {@link #toRowExtraction(DruidOperatorTable, PlannerContext, List, RexNode)}.
   *
   * @param rowOrder   order of fields in the Druid rows to be extracted from
   * @param expression expression meant to be applied on top of the rows
   *
   * @return expression referring to fields in rowOrder, or null if not possible
   */
public static String toMathExpression(final List<String> rowOrder, final RexNode expression) {
    final SqlKind kind = expression.getKind();
    final SqlTypeName sqlTypeName = expression.getType().getSqlTypeName();
    if (kind == SqlKind.INPUT_REF) {
        // Translate field references.
        final RexInputRef ref = (RexInputRef) expression;
        final String columnName = rowOrder.get(ref.getIndex());
        if (columnName == null) {
            throw new ISE("WTF?! Expression referred to nonexistent index[%d]", ref.getIndex());
        }
        return String.format("\"%s\"", escape(columnName));
    } else if (kind == SqlKind.CAST || kind == SqlKind.REINTERPRET) {
        // Translate casts.
        final RexNode operand = ((RexCall) expression).getOperands().get(0);
        final String operandExpression = toMathExpression(rowOrder, operand);
        if (operandExpression == null) {
            return null;
        }
        final ExprType fromType = MATH_TYPES.get(operand.getType().getSqlTypeName());
        final ExprType toType = MATH_TYPES.get(sqlTypeName);
        if (fromType != toType) {
            return String.format("CAST(%s, '%s')", operandExpression, toType.toString());
        } else {
            return operandExpression;
        }
    } else if (kind == SqlKind.TIMES || kind == SqlKind.DIVIDE || kind == SqlKind.PLUS || kind == SqlKind.MINUS) {
        // Translate simple arithmetic.
        final List<RexNode> operands = ((RexCall) expression).getOperands();
        final String lhsExpression = toMathExpression(rowOrder, operands.get(0));
        final String rhsExpression = toMathExpression(rowOrder, operands.get(1));
        if (lhsExpression == null || rhsExpression == null) {
            return null;
        }
        final String op = ImmutableMap.of(SqlKind.TIMES, "*", SqlKind.DIVIDE, "/", SqlKind.PLUS, "+", SqlKind.MINUS, "-").get(kind);
        return String.format("(%s %s %s)", lhsExpression, op, rhsExpression);
    } else if (kind == SqlKind.OTHER_FUNCTION) {
        final String calciteFunction = ((RexCall) expression).getOperator().getName();
        final String druidFunction = MATH_FUNCTIONS.get(calciteFunction);
        final List<String> functionArgs = Lists.newArrayList();
        for (final RexNode operand : ((RexCall) expression).getOperands()) {
            final String operandExpression = toMathExpression(rowOrder, operand);
            if (operandExpression == null) {
                return null;
            }
            functionArgs.add(operandExpression);
        }
        if ("MOD".equals(calciteFunction)) {
            // Special handling for MOD, which is a function in Calcite but a binary operator in Druid.
            Preconditions.checkState(functionArgs.size() == 2, "WTF?! Expected 2 args for MOD.");
            return String.format("(%s %s %s)", functionArgs.get(0), "%", functionArgs.get(1));
        }
        if (druidFunction == null) {
            return null;
        }
        return String.format("%s(%s)", druidFunction, Joiner.on(", ").join(functionArgs));
    } else if (kind == SqlKind.LITERAL) {
        // Translate literal.
        if (SqlTypeName.NUMERIC_TYPES.contains(sqlTypeName)) {
            // Include literal numbers as-is.
            return String.valueOf(RexLiteral.value(expression));
        } else if (SqlTypeName.STRING_TYPES.contains(sqlTypeName)) {
            // Quote literal strings.
            return "\'" + escape(RexLiteral.stringValue(expression)) + "\'";
        } else {
            // Can't translate other literals.
            return null;
        }
    } else {
        // Can't translate other kinds of expressions.
        return null;
    }
}