Menu creating API - KaoS

--[[SYNTAX:
apiname.generate(table, separator, x1, y1, x2, y2, delim1, delim2)

an example of its use can be found at http://pastebin.com/LTBY9xcW

table - a table of all the options selectable and what to do if each option is selected
the format of table is:
table[y][x][1]='displayed option'
table[y][x][2]=another table where the first value is the function to call (exclude the brackets after it and do not make it a string, it is a function) and all values after it are passed to the function as arguments

separator - the x distance between the first character of each option (default is 10)

x1,y1,x2 and y2 are used to generate a box in which the menu is generated
x1 and y1 are the co-ordinates of the top left corner
x2 and y2 are the co-ordinates of the bottom right corner

delim1 and 2 are the character to display before and after the selected option (default is '>' and '<')
]]

function generate(input,dist,offsetx,offsety,limx,limy,delim1,delim2)
    --[Required functions]
    local function pullfirst(input)
        local first=input[1]
        local temp={}
        for k,v in pairs(input) do
            if k~=1 then
                temp[#temp+1]=v
            end
        end
        return first,temp
    end

    local function cleararea(...)
        local pos={term.getCursorPos()}
        local args={...}
        for y=args[2], args[2]+args[4]-2 do
            term.setCursorPos(args[1],y)
            write(string.rep(' ',args[3]-args[1]+1))
        end
        term.setCursorPos(pos[1],pos[2])
    end

    --[Gathering initial information and declaring variables]
    local scrolledx=0
    local scrolledy=0
    local selectedx=1
    local selectedy=1
    local lastx=0
    dist=dist or 10
    local columnmaxlen={}
    local maxlen=0
    for b,y in pairs(input) do
        for a,x in pairs(y) do
            if columnmaxlen[a] or 0<string.len(x[1]) then
                columnmaxlen[a]=string.len(x[1])
            end
        end
    end
    for a,b in pairs(columnmaxlen) do
        if string.len(b)>maxlen then
            maxlen=string.len(b)
        end
    end

    while true do
        --[Render the menu]
        cleararea(offsetx,offsety,limx,limy)
        lastx=0
        for b,y in pairs(input) do
            for a,x in pairs(y) do
                currentlen=dist*(a-scrolledx-1)+columnmaxlen[a]

                if b>scrolledy and b<=limy-offsety+scrolledy+1 and a>scrolledx and currentlen<limx-offsetx+1 then
                    lastx=(lastx<=a and a) or lastx
                    if a==selectedx and b==selectedy then
                        term.setCursorPos(offsetx+a*dist-scrolledx*dist-dist,offsety+b-1-scrolledy)
                        write((delim1 or '>')..x[1]..(delim2 or delim1 or '<'))
                    else
                        term.setCursorPos(offsetx+1+a*dist-scrolledx*dist-dist,offsety+b-1-scrolledy)
                        write(x[1])
                    end
                end
            end
        end
        print('')

        --[Detect keypresses for interface and adjust variables accordingly]
        while true do
            local event,key=os.pullEvent('key')
            if key==203 and selectedx>1 then
                selectedx=selectedx-1
                if selectedx<=scrolledx then
                    scrolledx=scrolledx-1
                end
                break
            elseif key==205 and selectedx<#input[selectedy] then
                selectedx=selectedx+1
                if selectedx>lastx then
                    scrolledx=scrolledx+1
                end
                break
            elseif key==200 and selectedy>1 then
                selectedy=selectedy-1
                if selectedy<=scrolledy then
                scrolledy=scrolledy-1
                end
                break
            elseif key==208 and selectedy<#input then
                selectedy=selectedy+1
                if selectedy>limy-offsety+scrolledy+1 then
                    scrolledy=scrolledy+1
                end
                break
            elseif key==28 then
                local cmd={pullfirst(input[selectedy][selectedx][2])}
                return cmd[1](unpack(cmd[2]))
            end
        end
        if selectedx>#input[selectedy] then
            selectedx=#input[selectedy]
        end
    end
end