Add hints.vim

Hints work like qutebrowser. <C-f> will enter hint mode, which will
prompt the user to type a two-letter sequence to jump the cursor to a
specific line.

3 files changed, 169 insertions, 0 deletions

diff --git a/autoload/hints.vim b/autoload/hints.vim
new file mode 100644
index 0000000..e7b9a1b
--- /dev/null
+++ b/autoload/hints.vim
@@ -0,0 +1,107 @@
+" Display qutebrowser-like hints.
+
+" Max number of tags is 105, which is LCM(21, 5)
+let s:cons = "bcdfghjklmnpqrstvwxyz" " 21
+let s:vowel = "aeiou" " 5
+
+let s:signs_to_unplace = []
+let s:signs_to_undefine = []
+let s:sign_index = 5555
+
+if !exists('g:hints_ns')
+  let g:hints_ns = nvim_create_namespace("")
+endif
+
+" Generate hints on the current file. This may use specific plugins for each
+" filetype.
+function! s:generate_hints() abort
+  let plugin = hints#plugins#getPluginForFiletype(&ft)
+  call plugin.Before(expand("%"))
+
+  let ci = 0
+  let vi = 0
+
+  let line = line('w0')
+  let endline = line('w$')
+
+  let hints = {}
+
+  while line <= endline
+    if plugin.TagLine(line, getline(line))
+      let tag=printf("%s%s",
+            \ s:cons[ci % len(s:cons)], s:vowel[vi % len(s:vowel)])
+      let hints[tag] = line
+
+      " Advance _both_ the consonants and vowels. We want the tags to generally
+      " have as little in common as possible.
+      let ci += 1
+      let vi += 1
+    endif
+
+    let line += 1
+  endwhile
+
+  return hints
+endfunction
+
+function! s:display_hints(hints) abort
+  let s = s:sign_index
+
+  for [tag, line] in items(a:hints)
+    call add(s:signs_to_undefine, "tag_" . tag)
+    call add(s:signs_to_unplace, s)
+
+    "call nvim_buf_set_virtual_text(
+    "      \ 0, g:hints_ns, line - 1, [[tag, "Number"]], {})
+
+    exec printf("sign define tag_%s text=%s texthl=LineNr", tag, tag)
+    exec printf("sign place %d line=%d name=tag_%s file=%s", s, line, tag, expand('%:p'))
+
+    let s += 1
+  endfor
+endfunction
+
+function! s:cleanup_hints() abort
+  call nvim_buf_clear_namespace(0, g:hints_ns, 0, -1)
+  for s in s:signs_to_unplace
+    try
+      exec printf("sign unplace %d", s)
+    catch
+    endtry
+  endfor
+
+  for s in s:signs_to_undefine
+    try
+      exec printf("sign undefine %s", s)
+    catch
+    endtry
+  endfor
+endfunction
+
+function! hints#runHints(visual) abort
+  let hints = s:generate_hints()
+  call s:display_hints(hints)
+  redraw!
+
+  let c1 = getchar()
+
+  if c1 == 0x1b " Escape
+    call s:cleanup_hints()
+    return
+  endif
+
+  let c2 = getchar()
+
+  call s:cleanup_hints()
+
+  let line = get(hints, nr2char(c1) . nr2char(c2), -1)
+
+  if line >= 0
+    norm m'
+    if len(a:visual)
+      exec "norm " . a:visual
+    endif
+    call cursor(line, 1)
+    norm ^
+  endif
+endfunction
diff --git a/autoload/hints/plugins.vim b/autoload/hints/plugins.vim
new file mode 100644
index 0000000..de8cc6c
--- /dev/null
+++ b/autoload/hints/plugins.vim
@@ -0,0 +1,59 @@
+let s:ftplugins = {}
+let s:default_plugin = {}
+
+let s:vim_plugin = {}
+function! s:vim_plugin.Before(file)
+endfunction
+function! s:vim_plugin.TagLine(linenr, line)
+  return a:line =~ '\<\(if\|function\|return\|end\w*\|while\|for\|let\|else\|try\)\>'
+endfunction
+
+let s:java_plugin = {}
+
+function! s:java_plugin.Before(file) dict
+  let self.last_line = ''
+endfunction
+
+let s:WHITESPACE_OR_COMMENT='\(^\s*$\)\|\(^\s*//\)\|\(^\s*\*/\)'
+function! s:java_plugin.TagLine(linenr, line) dict
+  if self.last_line =~ s:WHITESPACE_OR_COMMENT
+        \ && !(a:line =~ s:WHITESPACE_OR_COMMENT)
+    let self.last_line = a:line
+    return v:true
+  endif
+  let self.last_line = a:line
+
+  return 
+        \ a:line =~ '^\s*}$' ||
+        \ a:line =~ '\<\(public\|private\|protected\|class\|static\|try\|while\|for\|if\|else\|catch\)\>'
+endfunction
+
+call hints#plugins#registerFt("vim", s:vim_plugin)
+call hints#plugins#registerFt("java", s:java_plugin)
+
+function! hints#plugins#registerFt(filetype, plugin) abort
+  let s:ftplugins[a:filetype] = a:plugin
+endfunction
+
+function! hints#plugins#getPluginForFiletype(filetype) abort
+  return get(s:ftplugins, a:filetype, s:default_plugin)
+endfunction
+
+function! hints#plugins#getDefaultPlugin() abort
+  return s:default_plugin
+endfunction
+
+function! s:default_plugin.Before(file)
+  let self.last_line = ''
+endfunction
+
+let s:ISSPACE= '^\s*$'
+function! s:default_plugin.TagLine(linenr, line)
+  if self.last_line =~ s:ISSPACE && !(a:line =~ s:ISSPACE)
+    let self.last_line = a:line
+    return v:true
+  endif
+
+  let self.last_line = a:line
+  return v:false
+endfunction
diff --git a/plugin/hints.vim b/plugin/hints.vim
new file mode 100644
index 0000000..47282ad
--- /dev/null
+++ b/plugin/hints.vim
@@ -0,0 +1,3 @@
+noremap <silent> <C-f> :<C-u>call hints#runHints("")<cr>
+onoremap <silent> <C-f> :<C-u> call hints#runHints("V")<cr>
+vnoremap <silent> <C-f> :<C-u> call hints#runHints("V")<cr>