Package com.android.dx.cf.code

Class ExecutionStack

java.lang.Object
com.android.dx.util.MutabilityControl
com.android.dx.cf.code.ExecutionStack
public final class ExecutionStack extends MutabilityControl
Representation of a Java method execution stack.

Note: For the most part, the documentation for this class ignores the distinction between Type and TypeBearer.

  • Constructor Details

    • ExecutionStack

      public ExecutionStack(int maxStack)
      Constructs an instance.
      Parameters:
      maxStack - >= 0; the maximum size of the stack for this instance

  • Method Details

    • copy

      public ExecutionStack copy()
      Makes and returns a mutable copy of this instance.
      Returns:
      non-null; the copy

    • annotate

      public void annotate(ExceptionWithContext ex)
      Annotates (adds context to) the given exception with information about this instance.
      Parameters:
      ex - non-null; the exception to annotate

    • makeInitialized

      public void makeInitialized(Type type)
      Replaces all the occurrences of the given uninitialized type in this stack with its initialized equivalent.
      Parameters:
      type - non-null; type to replace

    • getMaxStack

      public int getMaxStack()
      Gets the maximum stack size for this instance.
      Returns:
      >= 0; the max stack size

    • size

      public int size()
      Gets the current stack size.
      Returns:
      >= 0, < getMaxStack(); the current stack size

    • clear

      public void clear()
      Clears the stack. (That is, this method pops everything off.)

    • push

      public void push(TypeBearer type)
      Pushes a value of the given type onto the stack.
      Parameters:
      type - non-null; type of the value
      Throws:
      SimException - thrown if there is insufficient room on the stack for the value

    • setLocal

      public void setLocal()
      Flags the next value pushed onto the stack as having local info.

    • peek

      public TypeBearer peek(int n)
      Peeks at the nth element down from the top of the stack. n == 0 means to peek at the top of the stack. Note that this will return null if the indicated element is the deeper half of a category-2 value.
      Parameters:
      n - >= 0; which element to peek at
      Returns:
      null-ok; the type of value stored at that element
      Throws:
      SimException - thrown if n >= size()

    • peekLocal

      public boolean peekLocal(int n)
      Peeks at the nth element down from the top of the stack, returning whether or not it has local info.
      Parameters:
      n - >= 0; which element to peek at
      Returns:
      true if the value has local info, false otherwise
      Throws:
      SimException - thrown if n >= size()

    • peekType

      public Type peekType(int n)
      Peeks at the nth element down from the top of the stack, returning the type per se, as opposed to the type-bearer. This method is just a convenient shorthand for peek(n).getType().
      See Also:

    • pop

      public TypeBearer pop()
      Pops the top element off of the stack.
      Returns:
      non-null; the type formerly on the top of the stack
      Throws:
      SimException - thrown if the stack is empty

    • change

      public void change(int n, TypeBearer type)
      Changes an element already on a stack. This method is useful in limited contexts, particularly when merging two instances. As such, it places the following restriction on its behavior: You may only replace values with other values of the same category.
      Parameters:
      n - >= 0; which element to change, where 0 is the top element of the stack
      type - non-null; type of the new value
      Throws:
      SimException - thrown if n >= size() or the action is otherwise prohibited

    • merge

      public ExecutionStack merge(ExecutionStack other)
      Merges this stack with another stack. A new instance is returned if this merge results in a change. If no change results, this instance is returned. See Merger.mergeStack()
      Parameters:
      other - non-null; a stack to merge with
      Returns:
      non-null; the result of the merge