com.twineworks.tweakflow.lang.interpreter.ops.StringConcatOp Maven / Gradle / Ivy

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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.StringConcatNode;
import com.twineworks.tweakflow.lang.interpreter.EvaluationContext;
import com.twineworks.tweakflow.lang.interpreter.Stack;
import com.twineworks.tweakflow.lang.values.Value;
import com.twineworks.tweakflow.lang.values.Values;

import java.util.ArrayList;

final public class StringConcatOp implements ExpressionOp {

  final StringConcatNode node;
  private final ExpressionOp leftOp;
  private final ExpressionOp rightOp;

  public StringConcatOp(StringConcatNode node) {
    this.node = node;
    leftOp = node.getLeftExpression().getOp();
    rightOp = node.getRightExpression().getOp();
  }

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

    String left = leftOp.eval(stack, context).string();
    if (left == null) left = "nil";

    String right = rightOp.eval(stack, context).string();
    if (right == null) right = "nil";

    return Values.make(left+right);
  }

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

  @Override
  public ExpressionOp specialize() {

    boolean canFoldLeft = leftOp instanceof StringConcatOp || leftOp instanceof StringMultiConcatOp;
    boolean canFoldRight = rightOp instanceof StringConcatOp || rightOp instanceof StringMultiConcatOp;

    if (!canFoldLeft && !canFoldRight){
      return new StringConcatOp(node);
    }

    ArrayList ops = new ArrayList<>();

    if (canFoldLeft){
      if (leftOp instanceof StringConcatOp){
        StringConcatOp op = (StringConcatOp) leftOp;
        ops.add(op.node.getLeftExpression().getOp());
        ops.add(op.node.getRightExpression().getOp());
      }
      else if (leftOp instanceof StringMultiConcatOp){
        StringMultiConcatOp op = (StringMultiConcatOp) leftOp;
        ops.addAll(op.ops);
      }
    }
    else{
      ops.add(leftOp);
    }

    if (canFoldRight){
      if (rightOp instanceof StringConcatOp){
        StringConcatOp op = (StringConcatOp) rightOp;
        ops.add(op.node.getLeftExpression().getOp());
        ops.add(op.node.getRightExpression().getOp());
      }
      else if (rightOp instanceof StringMultiConcatOp){
        StringMultiConcatOp op = (StringMultiConcatOp) rightOp;
        ops.addAll(op.ops);
      }
    }
    else{
      ops.add(rightOp);
    }

    return new StringMultiConcatOp(ops).specialize();

  }

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

}