com.github.fge.grappa.stack

Interface ValueStack<V>

Type Parameters:

V - the type of the value objects

All Superinterfaces:

Iterable<V>

All Known Implementing Classes:

DefaultValueStack, ValueStackBase

@ParametersAreNonnullByDefault
public interface ValueStack<V>
extends Iterable<V>

Stack implementation for use in parsers

A stack state can be saved and restored using takeSnapshot() and restoreSnapshot(Object).

Stacks do not accept null values; if a null value is inserted, a NullPointerException will be thrown.

Any attempt to pop/swap values on a stack with not enough elements will throw an IllegalStateException.

You probably want to extend ValueStackBase instead of directly implementing this interface.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Clears all values.
void	dup() Duplicates the top value.
boolean	isEmpty() Determines whether the stack is empty.
V	peek() Returns the value at the top of the stack without removing it.
V	peek(int down) Returns the value the given number of elements below the top of the stack without removing it.
<T extends V> T	peekAs(Class<T> type) Casts and returns the value at the top of the stack without removing it
<T extends V> T	peekAs(Class<T> type, int down) Casts and returns the value at a given index in the stack without removing it
void	poke(int down, V value) Replaces the element the given number of elements below the current top of the stack.
void	poke(V value) Replaces the current top value with the given value.
V	pop() Removes the value at the top of the stack and returns it.
V	pop(int down) Removes the value the given number of elements below the top of the stack.
<T extends V> T	popAs(Class<T> type) Removes and casts the value at the top of the stack, and returns it
<T extends V> T	popAs(Class<T> type, int down) Removes and casts the value at a given index in the stack, and returns it
void	push(int down, V value) Inserts the given value a given number of elements below the current top of the stack.
void	push(V value) Pushes the given value onto the stack.
void	restoreSnapshot(Object snapshot) Restores the stack state as previously returned by takeSnapshot().
int	size() Returns the number of elements currently on the stack.
void	swap() Swaps the top two stack values.
void	swap(int n) Reverses the order of the top n stack values
Object	takeSnapshot() Returns an object representing the current state of the stack.

Methods inherited from interface java.lang.Iterable

iterator

Method Detail

isEmpty

boolean isEmpty()

Determines whether the stack is empty.

Returns:

true if empty

size

int size()

Returns the number of elements currently on the stack.

Returns:

the number of elements

clear

void clear()

Clears all values.

takeSnapshot

@Nonnull
Object takeSnapshot()

Returns an object representing the current state of the stack.

Returns:

an object representing the current state of the stack

restoreSnapshot

void restoreSnapshot(Object snapshot)

Restores the stack state as previously returned by takeSnapshot().

Parameters:

snapshot - a snapshot object previously returned by takeSnapshot()

push

void push(V value)

Pushes the given value onto the stack. Equivalent to push(0, value).

Parameters:

value - the value

push

void push(int down,
        V value)

Inserts the given value a given number of elements below the current top of the stack.

Parameters:

down - the number of elements to skip before inserting the value (0 being equivalent to push(value))

value - the value

pop

@Nonnull
V pop()

Removes the value at the top of the stack and returns it.

Returns:

the current top value

pop

@Nonnull
V pop(int down)

Removes the value the given number of elements below the top of the stack.

Parameters:

down - the number of elements to skip before removing the value (0 being equivalent to pop())

Returns:

the value

popAs

@Nonnull
<T extends V> T popAs(Class<T> type)

Removes and casts the value at the top of the stack, and returns it

Type Parameters:

T - type parameter

Parameters:

type - the type to cast to

Returns:

the value

popAs

@Nonnull
<T extends V> T popAs(Class<T> type,
                            int down)

Removes and casts the value at a given index in the stack, and returns it

Type Parameters:

T - type parameter

Parameters:

type - the type to cast to

down - the index

Returns:

the value

peek

@Nonnull
V peek()

Returns the value at the top of the stack without removing it.

Returns:

the current top value

peek

@Nonnull
V peek(int down)

Returns the value the given number of elements below the top of the stack without removing it.

Parameters:

down - the number of elements to skip (0 being equivalent to peek())

Returns:

the value

peekAs

@Nonnull
<T extends V> T peekAs(Class<T> type)

Casts and returns the value at the top of the stack without removing it

Type Parameters:

T - type parameter

Parameters:

type - the type to cast to

Returns:

the value

peekAs

@Nonnull
<T extends V> T peekAs(Class<T> type,
                             int down)

Casts and returns the value at a given index in the stack without removing it

Type Parameters:

T - type parameter

Parameters:

type - the type to cast to

down - the index in the stack

Returns:

the value

poke

void poke(@Nonnull
        V value)

Replaces the current top value with the given value. Equivalent to poke(0, value).

Parameters:

value - the value

poke

void poke(int down,
        V value)

Replaces the element the given number of elements below the current top of the stack.

Parameters:

down - the number of elements to skip before replacing the value (0 being equivalent to poke(value))

value - the value to replace with

dup

void dup()

Duplicates the top value. Equivalent to push(peek()).

swap

void swap(int n)

Reverses the order of the top n stack values

Parameters:

n - the number of elements to reverse

swap

void swap()

Swaps the top two stack values.