Support expansion flags

autoload/fugitive.vim

@@ -53,11 +53,12 @@ function! s:shellesc(arg) abort
   endif
 endfunction
 
+let s:fnameescape = " \t\n*?[{`$\\%#'\"|!<"
 function! s:fnameescape(file) abort
   if exists('*fnameescape')
     return fnameescape(a:file)
   else
-    return escape(a:file," \t\n*?[{`$\\%#'\"|!<")
+    return escape(a:file, s:fnameescape)
   endif
 endfunction
 
@@ -641,18 +642,13 @@ function! s:Generate(rev, ...) abort
   return fugitive#Route(object, dir)
 endfunction
 
-function! s:RemoveDot(path, ...) abort
-  if a:path !~# '^\./'
-    return a:path
+function! s:DotRelative(path) abort
+  let cwd = getcwd()
+  let path = substitute(a:path, '^[~$]\i*', '\=expand(submatch(0))', '')
+  if s:cpath(cwd . '/', (path . '/')[0 : len(cwd)])
+    return '.' . strpart(path, len(cwd))
   endif
-  let dir = a:0 ? a:1 : get(b:, 'git_dir', '')
-  let cdir = fugitive#CommonDir(dir)
-  if len(filter(['', '/tags', '/heads', '/remotes'], 'getftime(cdir . "/refs" . v:val . a:path[1:-1]) >= 0')) ||
-        \ a:path =~# 'HEAD$' && filereadable(dir . a:path[1:-1]) ||
-        \ a:path =~# '^\./refs/' && filereadable(cdir . a:path[1:-1])
   return a:path
-  endif
-  return a:path[2:-1]
 endfunction
 
 function! fugitive#Object(...) abort
@@ -681,6 +677,44 @@ function! fugitive#Object(...) abort
   endif
 endfunction
 
+let s:var = '\%(%\|#<\=\d\+\|##\=\)'
+let s:flag = '\%(:[p8~.htre]\|:g\=s\(.\).\{-\}\1.\{-\}\1\)'
+let s:expand = '\%(\(' . s:var . '\)\(' . s:flag . '*\)\(:S\)\=\)'
+
+function! s:BufName(var) abort
+  if a:var ==# '%'
+    return bufname(get(b:, 'fugitive_blamed_bufnr', ''))
+  elseif a:var =~# '^#\d*$'
+    let nr = getbufvar(+a:var[1:-1], 'fugitive_blamed_bufnr', '')
+    return bufname(nr ? nr : +a:var[1:-1])
+  else
+    return expand(a:var)
+  endif
+endfunction
+
+function! s:ExpandVar(other, var, flags, esc) abort
+  if a:other =~# '^\'
+    return a:other[1:-1]
+  elseif a:other =~# '^!'
+    let buffer = s:BufName(len(a:other) > 1 ? '#'. a:other[1:-1] : '%')
+    let owner = s:Owner(buffer)
+    return len(owner) ? owner : '@'
+  endif
+  let flags = a:flags
+  let file = s:DotRelative(fugitive#Real(s:BufName(a:var)))
+  while len(flags)
+    let flag = matchstr(flags, s:flag)
+    let flags = strpart(flags, len(flag))
+    if flag ==# ':.'
+      let file = s:DotRelative(file)
+    else
+      let file = fnamemodify(file, flag)
+    endif
+  endwhile
+  let file = s:Slash(file)
+  return (len(a:esc) ? shellescape(file) : file)
+endfunction
+
 function! s:Expand(rev) abort
   if a:rev =~# '^:[0-3]$'
     let file = a:rev . s:Relative(':')
@@ -688,19 +722,26 @@ function! s:Expand(rev) abort
     let file = 'HEAD^{}' . a:rev[1:-1] . s:Relative(':')
   elseif a:rev =~# '^@{'
     let file = 'HEAD' . a:rev. s:Relative(':')
-  elseif a:rev =~# '^[~^]/\@!'
+  elseif a:rev =~# '^\^[0-9~^{]\|^\~[0-9~^]'
     let commit = substitute(s:DirCommitFile(@%)[1], '^\d\=$', 'HEAD', '')
     let file = commit . a:rev . s:Relative(':')
   else
     let file = a:rev
   endif
-  return s:sub(substitute(file,
-        \ '\([%#]\)$\|\\\([[:punct:]]\)','\=len(submatch(2)) ? submatch(2) : fugitive#Path(expand(submatch(1)))','g'),
-        \ '\.\@<=/$','')
+  return substitute(file,
+        \ '\(\\[' . s:fnameescape . ']\|^\\[>+-]\|!\d*\)\|' . s:expand,
+        \ '\=s:ExpandVar(submatch(1),submatch(2),submatch(3),"")', 'g')
+endfunction
+
+function! fugitive#Expand(object) abort
+  return substitute(a:object,
+        \ '\(\\[' . s:fnameescape . ']\|^\\[>+-]\|!\d*\)\|' . s:expand,
+        \ '\=s:ExpandVar(submatch(1),submatch(2),submatch(3),submatch(5))', 'g')
 endfunction
 
 function! s:ShellExpand(cmd) abort
-  return substitute(a:cmd, '\\\@<![%#]:\@!', '\=s:RemoveDot(fugitive#Path(expand(submatch(0)), "./"))', 'g')
+  return substitute(a:cmd, '\(\\[!#%]\|!\d*\)\|' . s:expand,
+        \ '\=s:ExpandVar(submatch(1),submatch(2),submatch(3),submatch(5))', 'g')
 endfunction
 
 let s:trees = {}

doc/fugitive.txt

@@ -312,14 +312,14 @@ a                       Show the current tag, commit, or tree in an alternate
 SPECIFYING OBJECTS                      *fugitive-object* *fugitive-revision*
 
 Fugitive objects are either work tree files or Git revisions as defined in the
-"SPECIFYING REVISIONS" section in the git-rev-parse man page, with a few
-convenience notations thrown in for good measure.  For commands that accept an
+"SPECIFYING REVISIONS" section in the git-rev-parse man page, with expansions
+inspired by |cmdline-special| layered on top.  For commands that accept an
 optional object, the default is the file in the index for work tree files and
 the work tree file for everything else.  Example objects follow.
 
 Object          Meaning ~
 HEAD            .git/HEAD
-refs/heads/x    .git/refs/heads/x
+refs/heads/x    .git/refs/heads/x (in "common dir" if present)
 @               The commit referenced by @ aka HEAD
 master^         The parent of the commit referenced by master
 master:         The tree referenced by master
@@ -327,15 +327,16 @@ master:         The tree referenced by master
 Makefile        The file named Makefile in the work tree
 @^:Makefile     The file named Makefile in the parent of HEAD
 :Makefile       The file named Makefile in the index (writable)
-@:%             The current file in HEAD
--               The current file in HEAD
--^              The current file in the previous commit
--~3             The current file 3 commits ago
-:               .git/index (Same as |:Gstatus|)
+@~2:%           The current file in the grandparent of HEAD
 :%              The current file in the index
 :1:%            The current file's common ancestor during a conflict
-:2:%            The current file in the target branch during a conflict
-:3:%            The current file in the merged branch during a conflict
+:2:#            The alternate file in the target branch during a conflict
+:3:#5           The file from buffer #5 in the merged branch during a conflict
+!               The commit owning the current file
+!:Makefile      The file named Makefile in the commit owning the current file
+!3^2            The second parent of the commit owning buffer #3
+.git/config     The repo config file
+:               Same as |:Gstatus|
 
 STATUSLINE                                      *fugitive-statusline*