class Grizzled::Stack

A simple stack wrapper on top of a Ruby array, providing a little more protection that using an array directly.

Attributes

pop_empty_nil[R]

Public Class Methods

new(pop_empty_nil=true) click to toggle source

Initialize a new stack.

Parameters:

#pop_empty_nil: true if popping an empty stack should just return nil, false if it should thrown an exception.

# File lib/grizzled/stack.rb, line 58
def initialize(pop_empty_nil=true)
  @the_stack = []
  @pop_empty_nil = pop_empty_nil
end

Public Instance Methods

<=>(other) click to toggle source

Compare this stack to another element.

# File lib/grizzled/stack.rb, line 149
def <=>(other)
  if other.class == Stack
    other.to_a <=> to_a
  else
    other.to_s <=> this.to_s
  end
end

clear() click to toggle source

Clear the stack. Returns the stack, for chaining.

# File lib/grizzled/stack.rb, line 123
def clear
  @the_stack.clear
  self
end

each() { |element| ... } click to toggle source

Yield each element of the stack, in turn. Unaffected by a change in the stack.

# File lib/grizzled/stack.rb, line 116
def each
  self.to_a.each do |element|
    yield element
  end
end

eql?(other) click to toggle source

Determine if this hash is equal to another one.

# File lib/grizzled/stack.rb, line 144
def eql?(other)
  (other.class == Stack) and (other.to_a == to_a)
end

hash() click to toggle source

Return the stack's hash.

# File lib/grizzled/stack.rb, line 139
def hash
  @the_stack.hash
end

inspect() click to toggle source

Printable version.

# File lib/grizzled/stack.rb, line 129
def inspect
  @the_stack.inspect
end

is_empty?() click to toggle source

Convenience method for +length == 0+.

# File lib/grizzled/stack.rb, line 82
def is_empty?
  length == 0
end

length() click to toggle source

Returns the size of the stack.

# File lib/grizzled/stack.rb, line 110
def length
  @the_stack.length
end

pop() click to toggle source

Pop the top element from the stack. If the stack is empty, this method throws a StackUnderflowException, if pop_empty_nil is false; or returns nil, if pop_empty_nil is true.

# File lib/grizzled/stack.rb, line 66
def pop
  if (@the_stack.length == 0) && (not @pop_empty_nil)
    raise StackUnderflowException.new
  end
  @the_stack.pop
end

pop_all() click to toggle source

Pop every element of the stack, returning the results as an array and clearing the stack.

# File lib/grizzled/stack.rb, line 75
def pop_all
  result = @the_stack.reverse
  @the_stack.clear
  result
end

push(element) click to toggle source

Push an element or an array of elements onto the stack. Returns the stack itself, to allow chaining. Note: If you push an array of elements, the elements end up being reversed on the stack. That is, this:

stack = Stack.new.push([1, 2, 3]) # yields Stack[3, 2, 1]

is equivalent to

stack = Stack.new
[1, 2, 3].each {|i| stack.push i}

Parameters:

element: The object to push onto the stack.

# File lib/grizzled/stack.rb, line 100
def push(element)
  if element.class == Array
    element.each {|e| @the_stack.push e}
  else
    @the_stack.push element
  end
  self
end

to_a() click to toggle source

Return the stack as an array.

# File lib/grizzled/stack.rb, line 134
def to_a
  @the_stack.reverse
end