" File:   increment.vim
" Author: Srinath Avadhanula  fvw fixed
" Email:  srinath@eecs.berkeley.edu
"
" This script provides a way to quickly create incremented lists (either
" increasing or decreasing) using the visual block mode.
"
" Synopsis:
" =========
" 1. Suppose you have a column of the following form:
"     array(1) = 3;
"     array(1) = 3;
"     array(1) = 3;
"     array(1) = 3;
"     array(1) = 3;
" 2. Choose the column of '1's using Ctrl-V and then run the command Inc (you
"    should see "'<,'>Inc" on the command line at this point)(if you do not
"    have any other user commands starting with 'I', just I will suffice).
"    This will tranform the text as:
"     array(1) = 3;       array(1) = 3;
"     array(1) = 3;       array(2) = 3;
"     array(1) = 3;  -->  array(3) = 3;
"     array(1) = 3;       array(4) = 3;
"     array(1) = 3;       array(5) = 3;
" 3. You can then choose the column of '3's (again using Ctrl-V) and run the
"    command "Inc 3" to generate another incremented list. This will
"    generate:
"     array(1) = 3;        array(1) =  3;
"     array(2) = 3;        array(2) =  6;
"     array(3) = 3;  -->   array(3) =  9;
"     array(4) = 3;        array(4) = 12;
"     array(5) = 3;        array(5) = 15;
"
"   Note: increment.vim automatically pads the numbers in the the column
"   with spaces in order to get them right aligned. This is useful in most
"   cases, but for cases when this might be bad, use IncN which doesnt do
"   any alignment.
"
" Commands:
" =========
" 1. Inc : generates a column of increasing numbers with RIGHT  alignment.
" 2. IncN: generates a column of increasing numbers with NO     alignment.
" 3. IncL: generates a column of increasing numbers with LEFT   alignment
"
" Tip:
" A mapping which goes well with this command is the following:
"
" vnoremap <c-a> :Inc<CR>
"
" With this mapping, select a column of numbers and press Ctrl-A, which will
" get them in increasing order. I use <c-a> because its similar to the <c-a>
" command in normal mode which increments the number under the cursor.
"
" Last Modification: Dec 17 2001 00:59:09


"===========================================================================
"2008-11-16 08:43:11 fvw
com! -ra -nargs=* Inc :call IncrementColumn(1,<f-args>)
com! -ra -nargs=* IncL :call IncrementColumn(2,<f-args>)
com! -ra -nargs=* IncN :call IncrementColumn(0,<f-args>)

"===========================================================================
function! StrRepeat(str, count)
    let i = 1
    let retStr = ""
    while i <= a:count
        let retStr = retStr.a:str
        let i = i + 1
    endwhile
    return retStr
endfunction

" first argument is either 0 or 1 or 2 depending on whether padding with
" spaces is desired (pad = 1,2) or not. the second argument contains the
" counter increment. its optional. if not specified, its assumed to be 1.
function! IncrementColumn(pad, ...)
    "2008-11-16 08:43:11 fvw
    let setNum = 0
    if a:0 == 0
        let incr = 1
    elseif a:0 == 1
        let incr = a:1
    elseif a:0 == 2
        let presNum = a:1
        let incr = a:2
        let setNum = 1
    else
        return
    end

    let c1 = col("'<")
    let c2 = col("'>")
    let c1v = virtcol("'<")
    let c2v = virtcol("'>")
    let clen = c2v - c1v
    if c1 > c2
        let temp = c1
        let c1 = c2
        let c2 = temp
    end

    let r1 = line("'<")
    let r2 = line("'>")
    if r1 > r2
        let temp = r1
        let r1 = r2
        let r2 = temp
    end

    exe r1

    "exe "let presNum = ".strpart(getline('.'), c1-1, clen+1)

    if setNum == 0
        let presNum = strpart(getline('.'), c1-1, clen+1)
    endif

    let lastnum = presNum + incr*(r2-r1)

    " a simple way to find the number of digits in a number (including decimal
    " points, - signs etc).
    let maxstrlen = strlen("".lastnum)

    let r = r1
    exe 'normal! '.c1v.'|'
    while (r <= r2)
        let cnow = col(".")
        let linebef = strpart(getline('.'), 0, cnow-1)
        let lineaft = strpart(getline('.'), cnow+clen, 1000)

        " find the number of padding spaces required for left/rigth alignment
        if a:pad
            let preslen = strlen("".presNum)
            let padspace = StrRepeat(" ", maxstrlen - preslen)
        else
            let padspace = ""
        end

        " the final line is made up of
        " 1. the part of the line before the number
        " 2. the padding spaces.
        " 3. the present number
        " 4. the part of the line after the number
        " the padding spaces are either before or after the current number
        " depending on whether the pad argument is 1 or 2 (respectively).
        if a:pad == 1
            let lineset = linebef.padspace.presNum.lineaft
        elseif a:pad == 2
            let lineset = linebef.presNum.padspace.lineaft
        else
            let lineset = linebef.presNum.lineaft
        end

        call setline('.', lineset)
        let presNum = presNum + incr
        normal! j
        let r = r + 1
    endwhile
    normal! `<
endfunction