From 88c0758ecb26cafc1a243531059fabf26c790639 Mon Sep 17 00:00:00 2001
From: "R. Steve McKown" <rsmckown@gmail.com>
Date: Tue, 21 Jul 2015 14:53:13 -0600
Subject: [PATCH] Add new function mkbuild#SelectXref()

---
 doc/mkbuild.txt    | 16 ++++++++++++++--
 plugin/mkbuild.vim | 26 ++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/doc/mkbuild.txt b/doc/mkbuild.txt
index 4f658ff..c29f711 100644
--- a/doc/mkbuild.txt
+++ b/doc/mkbuild.txt
@@ -8,8 +8,11 @@ This plugin is only available if 'compatible' is not set.
 INTRODUCTION                                    *mkbuild*
 
 This plugin provides features for working with code using the mkbuild build
-system.  The only tool currently available is a method to select files from
-the project using dmenu, which will also work without mkbuild.
+system.
+
+
+The first tool is a method to select files from the project using dmenu, which
+will also work without mkbuild.
 
 Map mkbuild#DmenuOpen(cmd) to some key, such as:
 nnoremap <leader>e :call mkbuild#DmenuOpen('e')<CR>
@@ -37,4 +40,13 @@ following priority order:
 
 3. Perform a 'find . -type f' in the current directory.
 
+
+The second tool is a method to allow switching to a new tags and/or cscope
+database.  This is especially useful for mkbuild, which can build the same
+code for multiple platforms, and each platform build directory contains its
+own tags and cscope database files.
+
+Map mkbuild#SelectXref() to some key, such as:
+nnoremap <leader>x :call mkbuild#SelectXref()<CR>
+
  vim:tw=78:ts=8:ft=help:norl:
diff --git a/plugin/mkbuild.vim b/plugin/mkbuild.vim
index fd92caa..82c03a2 100644
--- a/plugin/mkbuild.vim
+++ b/plugin/mkbuild.vim
@@ -138,3 +138,29 @@ function! mkbuild#DmenuOpen(cmd)
     execute a:cmd . " " . fname
   endif
 endfunction
+
+" Look recursively from the current directory for directories containing a
+" tags files and/or a cscope database.  Allow the user to select one of these
+" directories.  Both its tag file and its associated cscope database, as
+" present, are made active for cross referencing.
+function! mkbuild#SelectXrefs()
+  let cmd = 'find . -type f -name tags -o -name cscope.out | ' .
+    \ 'while read f; do echo $(dirname $f); done | sort -u | sed -e "s|\./||"'
+  let curr = s:chompsys('dirname "' . &tags . '"')
+  let dname = s:chompsys(cmd . ' | dmenu -i -l 20 -p "xref (' . curr . ')"')
+  if empty(dname)
+    return
+  endif
+  let file = dname . "/tags"
+  let &tags=''
+  if filereadable(file)
+    let &tags = file
+  endif
+  if has('cscope')
+    let file = dname . "/cscope.out"
+    exe 'cscope kill -1'
+    if filereadable(file)
+      exe 'cscope add ' . file
+    endif
+  endif
+endfunction
-- 
2.39.2