jp.skypencil.findbugs.slf4j.parameter.ArrayDataHandler Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of bug-pattern Show documentation
There is a newer version: 1.5.0
package jp.skypencil.findbugs.slf4j.parameter;

import edu.umd.cs.findbugs.OpcodeStack;
import edu.umd.cs.findbugs.OpcodeStack.Item;
import org.apache.bcel.Const;

/** This class is responsible to create/update ArrayData instance in userValue. */
public class ArrayDataHandler {
  private final Strategy strategy;

  ArrayDataHandler(Strategy strategy) {
    this.strategy = strategy;
  }

  void sawOpcode(OpcodeStack stack, int seen) {
    if (seen == Const.AASTORE) {
      checkStoredInstance(stack);
    }
  }

  /**
   * Call this method before #afterOpcode of detector. If this method returns new userValue, attach
   * it to the head value of stack after #afterOpcode of detector is called.
   *
   * @return non-null if seen == ANEWARRAY
   */
  ArrayData afterOpcode(OpcodeStack stack, int seen, String className, int pc) {
    if (seen != Const.ANEWARRAY) {
      return null;
    } else if (stack.isTop()) {
      // see https://github.com/KengoTODA/findbugs-slf4j/issues/29
      System.err.printf(
          "ArrayDataHandler: stack is TOP, cannot be analyzed. %s:%d%n", className, pc);
      return null;
    }
    return tryToDetectArraySize(stack);
  }

  private void checkStoredInstance(OpcodeStack stack) {
    Item storedValue = stack.getStackItem(0);
    Item arrayIndexItem = stack.getStackItem(1);
    Item targetArray = stack.getStackItem(2);
    Object arrayIndex = arrayIndexItem.getConstant();

    if (arrayIndex instanceof Number) {
      ArrayData data = (ArrayData) targetArray.getUserValue();
      Number index = (Number) arrayIndex;
      store(storedValue, data, index.intValue());
    }
  }

  private ArrayData tryToDetectArraySize(OpcodeStack stack) {
    Item arraySizeItem = stack.getStackItem(0);
    final int arraySize;

    if (arraySizeItem != null && arraySizeItem.getConstant() instanceof Number) {
      // save array size as "user value"
      arraySize = ((Number) arraySizeItem.getConstant()).intValue();
    } else {
      // currently we ignore array which gets variable as array size (like `new Object[a]`)
      arraySize = -1;
    }

    return new ArrayData(arraySize);
  }

  void store(Item storedItem, ArrayData arrayData, int index) {
    strategy.store(storedItem, arrayData, index);
  }

  public static interface Strategy {
    void store(Item storedItem, ArrayData arrayData, int index);
  }
}