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Embeddable expression language for Java.
There is a newer version: 1.4.4
/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2019 Twineworks GmbH
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.twineworks.tweakflow.lang.interpreter.ops;

import com.twineworks.tweakflow.lang.ast.expressions.MultNode;
import com.twineworks.tweakflow.lang.errors.LangError;
import com.twineworks.tweakflow.lang.errors.LangException;
import com.twineworks.tweakflow.lang.interpreter.EvaluationContext;
import com.twineworks.tweakflow.lang.interpreter.Stack;
import com.twineworks.tweakflow.lang.types.Type;
import com.twineworks.tweakflow.lang.types.Types;
import com.twineworks.tweakflow.lang.values.Value;
import com.twineworks.tweakflow.lang.values.Values;

import java.math.BigDecimal;

final public class MultOp implements ExpressionOp {

  private final MultNode node;
  private final ExpressionOp leftOp;
  private final ExpressionOp rightOp;

  public MultOp(MultNode node) {
    this.node = node;
    leftOp = node.getLeftExpression().getOp();
    rightOp = node.getRightExpression().getOp();
  }

  @Override
  public Value eval(Stack stack, EvaluationContext context) {

    Value left = leftOp.eval(stack, context);
    Value right = rightOp.eval(stack, context);

    ensureValidTypes(left, right, stack);

    if (left == Values.NIL) return Values.NIL;
    if (right == Values.NIL) return Values.NIL;

    Type leftType = left.type();
    Type rightType = right.type();

    if (leftType == Types.LONG){
      if (rightType == Types.LONG){
        return Values.make(left.longNum() * right.longNum());
      }
      if (rightType == Types.DOUBLE){
        return Values.make(left.longNum() * right.doubleNum());
      }
      if (rightType == Types.DECIMAL){
        return Values.make(BigDecimal.valueOf(left.longNum()).multiply(right.decimal()));
      }
    }
    else if (leftType == Types.DOUBLE){
      if (rightType == Types.LONG){
        return Values.make(left.doubleNum() * right.longNum());
      }
      if (rightType == Types.DOUBLE){
        return Values.make(left.doubleNum() * right.doubleNum());
      }
      if (rightType == Types.DECIMAL){
        double d = left.doubleNum();
        if (Double.isFinite(d)){
          return Values.make(BigDecimal.valueOf(d).multiply(right.decimal()));
        }
        else {
          // NaN * some_d -> NaN
          if (Double.isNaN(d)) return Values.NAN;
          // Infinity * some_d > 0 -> Infinity
          // Infinity * some_d < 0 -> -Infinity
          // Infinity * 0 -> NaN
          int cmp = right.decimal().compareTo(BigDecimal.ZERO);
          if (cmp == 0) return Values.NAN;
          if (cmp > 0) return left;
          return Values.make(-d);
        }
      }
    }
    else if (leftType == Types.DECIMAL){
      if (rightType == Types.LONG){
        return Values.make(left.decimal().multiply(BigDecimal.valueOf(right.longNum())));
      }
      if (rightType == Types.DOUBLE){
        Double d = right.doubleNum();
        if (Double.isFinite(d)){
          return Values.make(left.decimal().multiply(BigDecimal.valueOf(d)));
        }
        else{
          // some_d * NaN -> NaN
          if (Double.isNaN(d)) return right;
          // some_d > 0 * Infinity -> Infinity
          // some_d < 0 * Infinity -> -Infinity
          // 0 * Infinity -> NaN
          int cmp = left.decimal().compareTo(BigDecimal.ZERO);
          if (cmp == 0) return Values.NAN;
          if (cmp > 0) return right;
          return Values.make(-d);
        }
      }
      if (rightType == Types.DECIMAL){
        return Values.make(left.decimal().multiply(right.decimal()));
      }
    }
    throw new LangException(LangError.CAST_ERROR, "cannot multiply types: "+leftType.name()+" and "+rightType.name(), stack, node.getSourceInfo());

  }

  private void ensureValidTypes(Value left, Value right, Stack stack){
    Type leftType = left.type();
    Type rightType = right.type();

    if ((left == Values.NIL || leftType.isNumeric()) &&
        (right == Values.NIL || rightType.isNumeric())){
      return;
    }

    throw new LangException(LangError.CAST_ERROR, "cannot multiply types: "+left.type().name()+" and " + right.type().name(), stack, node.getSourceInfo());

  }

  @Override
  public boolean isConstant() {
    return leftOp.isConstant() && rightOp.isConstant();
  }

  @Override
  public ExpressionOp specialize() {

    Type leftType = node.getLeftExpression().getValueType();
    Type rightType = node.getRightExpression().getValueType();

    try {

      if (leftType == rightType) {
        if (leftType == Types.DOUBLE) {
          return new MultOpDD(node);
        }
        if (leftType == Types.LONG) {
          return new MultOpLL(node);
        }
        if (leftType == Types.DECIMAL) {
          return new MultOpDecDec(node);
        }
      }
    } catch (LangException ignored) {
    }

    return new MultOp(node);
  }

  @Override
  public ExpressionOp refresh() {
    return new MultOp(node);
  }


}