Package com.tonic.analysis.simulation.state

Class StackState

  • public final class StackState
extends Object
    Immutable operand stack snapshot used during simulation.

    • Method Detail

      • empty

        public static StackState empty()
        Returns:
        a stack with no slots and a maximum depth of zero

      • of

        public static StackState of​(List<SimValue> values)
        Creates a stack preloaded with slots.
        Parameters:
        values - the slot contents, bottom to top
        Returns:
        a stack holding a copy of them, with its maximum depth set to their count

      • push

        public StackState push​(SimValue value)
        Adds a value on top of the stack.
        Parameters:
        value - the value to push
        Returns:
        the resulting stack, one slot deeper

      • pushWide

        public StackState pushWide​(SimValue value)
        Pushes a long or double, adding the filler second slot after it.
        Parameters:
        value - the wide value to push
        Returns:
        the resulting stack, two slots deeper

      • pop

        public StackState pop​(int count)
        Removes several slots at once.
        Parameters:
        count - how many slots to drop; zero leaves the stack unchanged
        Returns:
        the resulting stack
        Throws:
        IllegalStateException - if the stack holds fewer than count slots

      • popWide

        public StackState popWide()
        Removes the two slots holding a long or double.
        Returns:
        the resulting stack
        Throws:
        IllegalStateException - if fewer than two slots are on the stack

      • peek

        public SimValue peek()
        Reads the top slot without removing it.
        Returns:
        the value in the top slot
        Throws:
        IllegalStateException - if the stack is empty

      • peek

        public SimValue peek​(int depth)
        Reads a slot without removing it.
        Parameters:
        depth - the slot offset from the top, 0 being the topmost slot
        Returns:
        the value in that slot
        Throws:
        IllegalStateException - if the depth is outside the stack

      • peekValue

        public SimValue peekValue()
        Reads the topmost value, stepping past a wide second slot to the value it belongs to.
        Returns:
        the value on top of the stack
        Throws:
        IllegalStateException - if the stack is empty, or holds only a wide second slot

      • peekValue

        public SimValue peekValue​(int depth)
        Reads a value at the given depth, stepping past a wide second slot to the value it belongs to.
        Parameters:
        depth - the slot offset from the top, 0 being the topmost slot
        Returns:
        the value occupying that slot
        Throws:
        IllegalStateException - if the slot, or the one below a wide second slot, is out of range

      • depth

        public int depth()
        Returns:
        the number of occupied slots, counting both halves of a wide value

      • maxDepth

        public int maxDepth()
        Returns:
        the greatest slot count reached by any predecessor of this state

      • isEmpty

        public boolean isEmpty()
        Returns:
        true if no slot is occupied

      • getValues

        public List<SimValue> getValues()
        Returns:
        an unmodifiable view of the slots, bottom to top

      • dupX1

        public StackState dupX1()
        Duplicates the top slot and inserts the copy below the second (dup_x1).
        Returns:
        the resulting stack
        Throws:
        IllegalStateException - if fewer than two slots are on the stack

      • dupX2

        public StackState dupX2()
        Duplicates the top slot and inserts the copy below the third (dup_x2).
        Returns:
        the resulting stack
        Throws:
        IllegalStateException - if fewer than three slots are on the stack

      • dup2

        public StackState dup2()
        Pushes a copy of the top two slots (dup2).
        Returns:
        the resulting stack
        Throws:
        IllegalStateException - if fewer than two slots are on the stack

      • dup2X1

        public StackState dup2X1()
        Duplicates the top two slots and inserts the copies below the third (dup2_x1).
        Returns:
        the resulting stack
        Throws:
        IllegalStateException - if fewer than three slots are on the stack

      • dup2X2

        public StackState dup2X2()
        Duplicates the top two slots and inserts the copies below the fourth (dup2_x2).
        Returns:
        the resulting stack
        Throws:
        IllegalStateException - if fewer than four slots are on the stack

      • swap

        public StackState swap()
        Exchanges the top two slots (swap).
        Returns:
        the resulting stack
        Throws:
        IllegalStateException - if fewer than two slots are on the stack

      • merge

        public StackState merge​(StackState other)
        Joins two stacks at a control flow convergence, keeping this stack's values and the larger recorded maximum depth.
        Parameters:
        other - the incoming stack, or null to keep this one unchanged
        Returns:
        the merged stack
        Throws:
        IllegalStateException - if the two stacks hold a different number of slots

      • clear

        public StackState clear()
        Drops every value, as an exception handler entry does.
        Returns:
        an empty stack that keeps the recorded maximum depth

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class Object