Collections and enumerators

[Steve Dekorte <steve@...>]

Here's a handy Smalltalk-like Collection object and a NeXT-like 
enumerator object. Let me know if anyone likes this stuff - I'm 
considering putting up some web pages with more Lua objects.

Steve

---------------



Collection = 
{
    clone = clone,
    elements = {},
    count = 0
}

function Collection:empty()
    self.elements = {}
end

function Collection:size()
    return self.count 
end

function Collection:add_(anObject)
    self.elements[self.count] = anObject
    self.count = self.count + 1
    return anObject
end

function Collection:insert_at_(anObject, anIndex)
    local index = self.count
    while ( index > anIndex  ) do
         self.elements[index] = self.elements[index-1]
	index = index - 1
    end
    self.elements[anIndex] = anObject
    self.count = self.count + 1
    return anObject
end

function Collection:removeObjectAt_(anIndex)
    local index = anIndex
    local anObject = self:at_(index)
    self.elements[index] = nil
    while ( index < self.count - 1 ) do
         self.elements[index] = self.elements[index + 1]
	index = index + 1
    end
    self.elements[self.count - 1] = nil
    self.count = self.count - 1
    return anObject
end

function Collection:remove_(anObject)
    local index = self:indexOf_(anObject)
    return self:removeObjectAt_(index)
end

function Collection:addAll_(aCollection)
    local enm = aCollection:enumerator()
    local item = enm:next()
    while ( item ~= nil ) do
	self.add_(item)
	item = enm:next()
    end
    return self
end

function Collection:indexOf_(anObject)
   local i, v = next(self.elements, nil)
   while i do
        if ( v == anObject ) then return i end
        i, v = next(self.elements, i)
    end
    return -1
end

function Collection:at_(index)
     return rawgettable( self.elements, index)
end

function Collection:at_put_(index, anObject)
    local oldObject = self.elements[index] 
    self.elements[index] = anObject
    return oldObject
end

function Collection:contains_(anItem)
   if ( self:indexOf_(anItem) == -1 ) then return 0 end
   return 1
end

function Collection:isEmpty_(anObject)
    if ( self.count == 0 ) then return 1 end
    return 0
end

function Collection:isNotEmpty_(anObject)
    if ( self.count == 0 ) then return 0 end
    return 1
end

function Collection:enumerator()
    local enm =  CollectionEnumerator:clone()
    enm.collection = self
    return enm
end

function Collection:sortBy_(astring) -- unfinished
    local enm =  self:enumerator()
    local c = 1
    local value = enm:next()
    while ( c < count ) do
        local e1 = self.elements[c]
        local d = c + 1
        while ( d < count ) do
            --local e2 = 
           d = d + 1
        end
        c = c + 1
    end
    return enm
end

function Collection:do_(aFunction)
    local enm =  self:enumerator()
    local object = enm:next()
    while ( object ) do
        aFunction(object)
        object = enm:next()
    end
end

function Collection:select_(aFunction) 
    local enm =  self:enumerator()
    local object = enm:next()
    local results = Collection:clone()
    while ( object ) do
        if ( aFunction(object) == 1 ) then results:add_(object) end
        object = enm:next()
    end
    return results
end

function Collection:send_to_(aMessage, aTarget)
    local enm =  self:enumerator()
    local object = enm:next()
    while ( object ) do
        aTarget[aMessage](aTarget, object)
        object = enm:next()
    end
end

function Collection:makeAllPerform_(astring)
    local enm =  self:enumerator()
    local i, v = next(self.elements, nil)
    while ( i ) do
        v[astring](v)
        i, v = next(self.elements, i)
    end
    return 0
end



--- Some tests and examples ---

aCollection = Collection:clone()
aCollection:add_("a")
aCollection:add_("b")
aCollection:add_(123)

NSLog(aCollection:at_(0).."\n")
NSLog(aCollection:at_(1).."\n")
NSLog(aCollection:at_(2).."\n")
NSLog("\n")

--aCollection:removeObjectAt_(1)
aCollection:remove_("b")

NSLog(aCollection:at_(0).."\n")
NSLog(aCollection:at_(1).."\n")
NSLog(tostring(aCollection:at_(2)).."\n")
NSLog("\n")

aCollection:at_put_(1, "x")

NSLog(aCollection:at_(0).."\n")
NSLog(aCollection:at_(1).."\n")
NSLog(tostring(aCollection:at_(2)).."\n")
NSLog("\n")

aCollection:insert_at_("d", 0)

NSLog(aCollection:at_(0).."\n")
NSLog(aCollection:at_(1).."\n")
NSLog(tostring(aCollection:at_(2)).."\n")
NSLog(tostring(aCollection:at_(3)).."\n")
NSLog("\n")

testObj = 
{
    print_ = function (self, string) NSLog(string) end
}

aCollection = Collection:clone()
aCollection:empty()
aCollection:add_(testObj)
aCollection:do_(function (object) object:print_("hi") end)


----------------------

CollectionEnumerator = 
{
    clone = clone,
    collection = nil,
    index = 0
}

function CollectionEnumerator:next()
    if ( self.index > self.collection:size() ) then return nil end
    local result = self.collection:at_(self.index)
    self.index = self.index + 1
    return result
end

function CollectionEnumerator:collection_(aCollection)
    self.collection = aCollection
    self.index = 0
end

function CollectionEnumerator:reset()
    self.index = 0
end