" File: gtags.vim
" Author: Tama Communications Corporation
" Version: 0.1
" Last Modified: Jan 19, 2004
" 
" Overview
" --------
" The gtags.vim plugin script integrates the GNU GLOBAL source code tag system
" with Vim. About the details, see http://www.gnu.org/software/global/.
"
" Installation
" ------------
" Drop the file in your plugin directory or source it from your vimrc.
" To use this script, you need the GNU GLOBAL installed in your machine.
"
" Usage
" -----
" First of all, you must execute gtags(1) at the root of source directory
" to make tag files.
" Almost global(1)'s command character is available as a command.
"
" To go to func, you can say
"
"       :Gtags func
"
" Special charactor '%', '#' and input completion are available.
"
" If you omitted argument, vim ask it like this:
"
"       Gtags for pattern: <current token>
"
" You can use all the regular quickfix commands to traverse from one hit to
" another.
"
"       :h quickfix 
"
" Suggested map:
"       map <C-n> :cn<CR>
"       map <C-p> :cp<CR>
"
" You can use regular expression too. It requires more execution time though.
"
"       :Gtags ^[sg]et_
"
" It will match to both of 'set_value' and 'get_value'.
"
" To go to the referenced point of func, add -r option.
"
"       :Gtags -r func
"
" To go to any symbols which are not defined in GTAGS, try this.
"
"       :Gtags -s func
"
" To go to any strings other than symbols, try this.
"
"       :Gtags -g ^[sg]et_
"
" This facility utilize grep(1).
"
" To get list of objects in a file 'main.c', use -f command.
"
"       :Gtags -f main.c
"
" You can browse project files whose path includs specified pattern.
" By the way, you can browse under 'vm/' directory by this:
"
"       :Gtags -P /vm/
"
" If you omitted the argument and input only 'ENTER' to prompt, vim
" shows list of all files in your project.
"
" You can use all options of global(1) except for the -c, -p, -u and
" all long name options. They are sent to global(1) as is.
" For example, if you want to ignore case distinctions in pattern.
"
"       :Gtags -gi paTtern
"
" It will match to both of 'PATTERN' and 'pattern'.
" See global(1) for other options.
"
" The GtagsCursor command brings you to the definition or reference of
" the current token in C language.
"
"       :GtagsCursor
"
" The GtagsCursor is not perfect though is considerably wise.
"
" Suggested map:
"       map <C-]> :GtagsCursor<CR>
"
" If you have the hypertext generated by htags(1) then you can display
" the same place on mozilla browser. Let's load mozilla and try this:
"
"       :Gozilla
"
" Suggested map:
"       map <C-g> :Gozilla<CR>
"
" If you want to load vim with all main()s then following command line is useful.
"
"	% vim '+Gtags main'
"
" Also see the chapter of 'vim editor' of the online manual of GLOBAL.
"
"	% info global
"
if exists("loaded_gtags") || &cp
    finish
endif
let loaded_gtags = 1

" Open the Gtags output window.  Set this variable to zero, to not open
" the Gtags output window by default.  You can open it manually by using
" the :cwindow command.
" (This code was drived from 'grep.vim'.)
if !exists("Gtags_OpenQuickfixWindow")
    let Gtags_OpenQuickfixWindow = 1
endif

" Character to use to quote patterns and filenames before passing to global.
" (This code was drived from 'grep.vim'.)
if !exists("Gtags_Shell_Quote_Char")
    if has("win32") || has("win16") || has("win95")
        let Gtags_Shell_Quote_Char = ''
    else
        let Gtags_Shell_Quote_Char = "'"
    endif
endif

"
" Display error message.
"
function s:Error(msg)
    echohl WarningMsg |
           \ echomsg 'Error: ' . a:msg |
           \ echohl None
endfunction
"
" Extract pattern or option string.
"
"
function s:Extract(str, target)
    let out = ''
    let mode = ''
    let length = strlen(a:str)
    let i = 0
    while i < length
        let c = a:str[i]
        " Decide mode.
        if c == ' '
            let mode = ''
        elseif mode == ''
            if c == '-'
                " Ignore long name option like --help.
                if i + 1 < length && a:str[i + 1] == '-'
                    let mode = 'ignore'
                else
                    let mode = 'option'
                endif
            else
                let mode = 'pattern'
                if a:target == 'pattern'
                    let out = ''
                endif
            endif
        endif
        if a:target == mode
            if mode == 'pattern'
                if c != ' '
                    let out = out . c
                endif
            elseif mode == 'option'
                if c !~ '[- cpu]'
                    let out = out . c
                endif
            endif
        endif
        let i = i + 1
    endwhile
    return out
endfunction

"
" RunGlobal()
"
function! s:RunGlobal(...)
    let i = 0
    let sep = ' '
    let line = ''

    while i < a:0
        let i = i + 1
        if line == ''
            let line = a:{i}
        else
            let line = line . ' ' . a:{i}
        endif
    endwhile

    let pattern = s:Extract(line, 'pattern')

    " Replace with path name.
    if pattern == '%'
        let pattern = expand('%')
    elseif pattern == '#'
        let pattern = expand('#')
    endif
    let option = s:Extract(line, 'option')

    " If no pattern supplied then get it from user.
    if pattern == ''
        if option =~ 'P'
            return
        endif
        if option =~ 'f'
            let line = input("Gtags for file: ", expand('%'))
        elseif option =~ 'P'
            let line = input("Gtags for pattern: ", '')
        else
            let line = input("Gtags for pattern: ", expand('<cword>'))
        endif
        let ret = s:Extract(line, 'pattern')
        if ret != ''
            let pattern = ret
        endif
        if option == ''
            let ret = s:Extract(line, 'option')
            if ret != ''
                let option = ret
            endif
        endif
    endif
    if option =~ 's' && option =~ 'r'
        call s:Error('Both of -s and -r are not allowed.')
        return
    endif

    " Execute global(1) command and write the result to a temporary file.
    let tmpfile = tempname()
    let pattern = g:Gtags_Shell_Quote_Char . pattern . g:Gtags_Shell_Quote_Char
    let cmd = 'global' . sep . '-tq' . option . sep . pattern
    let stuff = system(cmd . '>' . tmpfile)

    if getfsize(tmpfile) == 0
        call s:Error('Pattern ' . pattern . ' not found.')
        call delete(tmpfile)
        return
    endif
    if v:shell_error != 0
        call s:Error('Pattern ' . pattern . ' not found.')
        call delete(tmpfile)
        return
    endif

    " Parse the output of 'global -t'.
    let efm_org = &efm
    let &efm="%m%\\t%f%\\t%l"
    execute "silent! cfile " . tmpfile
    let &efm = efm_org

    " Open the quickfix window
    if g:Gtags_OpenQuickfixWindow == 1
"        topleft vertical copen
        botright copen
    endif
    cc
    call delete(tmpfile)
endfunction

"
" Execute RunGlobal() depending on the current position.
"
function! s:GtagsCursor()
    let col = col('.') - 1
    let lnum = line('.')
    let line = getline(lnum)
    let token = expand("<cword>")
    let flag = '-s'

    let pat = '^' . token . '[ \t]*('
    if line =~ pat
        let flag = '-r'
    else
        if matchstr(line, "^[ \t]*[a-zA-Z0-9_][a-zA-Z0-9_]*[ \t]*(", col) != ''
            let pat = '^#[ \t]*define[ \t][ \t]*' . token . '('
            if line =~ pat
                let flag = '-r'
            else
                let flag = '-x'
            endif
        endif
    endif
    call s:RunGlobal(flag, token)
endfunction

"
" Show the current position on mozilla.
" (You need to execute htags(1) in your source direcotry.)
"
function! s:Gozilla()
    let lnum = line('.')
    let fname = expand("%")
    let result = system('gozilla +' . lnum . ' ' . fname)
endfunction
"
" Custom completion.
"
function Candidate(ArgLead, CmdLine, CursorPos)
    let option = s:Extract(a:CmdLine, 'option')
    if option =~ 'P'
        return system('global -P ' . a:ArgLead)
    else
        return system('global -c ' . a:ArgLead)
    endif
endfunction

" Define the set of Gtags commands
command! -nargs=* -complete=custom,Candidate Gtags call s:RunGlobal(<f-args>)
command! -nargs=0 GtagsCursor call s:GtagsCursor()
command! -nargs=0 Gozilla call s:Gozilla()
" Suggested map:
"map <C-]> :GtagsCursor<CR>
"map <C-g> :Gozilla<CR>
"map <C-n> :cn<CR>
"map <C-p> :cp<CR>