small diffs

Author: mattn

autoload/lsp.vim

@@ -399,6 +399,22 @@ function! s:ensure_conf(buf, server_name, cb) abort
     call a:cb(l:msg)
 endfunction
 
+let s:file_content = {}
+
+function! s:text_changes(buf) abort
+  if has_key(s:file_content, a:buf)
+    let l:old_content = get(s:file_content, a:buf, [])
+    let l:new_content = getline(1, '$')
+    let l:changes = lsp#utils#diff#compute(l:old_content, l:new_content)
+    let s:file_content[a:buf] = l:new_content
+  else
+    let l:new_content = getline(1, '$')
+    let l:changes = {'text': l:new_content}
+    let s:file_content[a:buf] = l:new_content
+  endif
+  return [l:changes]
+endfunction
+
 function! s:ensure_changed(buf, server_name, cb) abort
     let l:server = s:servers[a:server_name]
     let l:path = lsp#utils#get_buffer_uri(a:buf)
@@ -424,9 +440,7 @@ function! s:ensure_changed(buf, server_name, cb) abort
         \ 'method': 'textDocument/didChange',
         \ 'params': {
         \   'textDocument': s:get_text_document_identifier(a:buf, l:buffer_info),
-        \   'contentChanges': [
-        \       { 'text': s:get_text_document_text(a:buf) },
-        \   ],
+        \   'contentChanges': s:text_changes(a:buf),
         \ }
         \ })
 

autoload/lsp/utils/diff.vim

@@ -0,0 +1,113 @@
+" Computes a simplistic diff between [old] and [new].
+"
+" Returns a dict with keys `range`, `rangeLength`, and `text` matching the LSP
+" definition of `TextDocumentContentChangeEvent`.
+"
+" Finds a single change between the common prefix, and common postfix.
+function! lsp#utils#diff#compute(old, new) abort
+  let [start_line, start_char] = s:FirstDifference(a:old, a:new)
+  let [end_line, end_char] =
+      \ s:LastDifference(a:old[start_line:], a:new[start_line:], start_char)
+
+  let text = s:ExtractText(a:new, start_line, start_char, end_line, end_char)
+  let length = s:Length(a:old, start_line, start_char, end_line, end_char)
+
+  let adj_end_line = len(a:old) + end_line
+  let adj_end_char = end_line == 0 ? 0 : strlen(a:old[end_line]) + end_char + 1
+
+  let result = { 'range': {'start': {'line': start_line, 'character': start_char},
+      \  'end': {'line': adj_end_line, 'character': adj_end_char}},
+      \ 'text': text,
+      \ 'rangeLength': length,
+      \}
+
+  return result
+endfunction
+
+" Finds the line and character of the first different character between two
+" list of Strings.
+function! s:FirstDifference(old, new) abort
+  let line_count = min([len(a:old), len(a:new)])
+  let i = 0
+  while i < line_count
+    if a:old[i] !=# a:new[i] | break | endif
+    let i += 1
+  endwhile
+  if i >= line_count
+    return [line_count - 1, strlen(a:old[line_count - 1])]
+  endif
+  let old_line = a:old[i]
+  let new_line = a:new[i]
+  let length = min([strlen(old_line), strlen(new_line)])
+  let j = 0
+  while j < length
+    if old_line[j:j] !=# new_line[j:j] | break | endif
+    let j += 1
+  endwhile
+  return [i, j]
+endfunction
+
+function! s:LastDifference(old, new, start_char) abort
+  let line_count = min([len(a:old), len(a:new)])
+  if line_count == 0 | return [0, 0] | endif
+  let i = -1
+  while i >= -1 * line_count
+    if a:old[i] !=# a:new[i] | break | endif
+    let i -= 1
+  endwhile
+  if i <= -1 * line_count
+    let i = -1 * line_count
+    let old_line = a:old[i][a:start_char:]
+    let new_line = a:new[i][a:start_char:]
+  else
+    let old_line = a:old[i]
+    let new_line = a:new[i]
+  endif
+  let length = min([strlen(old_line), strlen(new_line)])
+  let j = -1
+  while j >= -1 * length
+    if old_line[j:j] !=# new_line[j:j] | break | endif
+    let j -= 1
+  endwhile
+  return [i, j]
+endfunction
+
+function! s:ExtractText(lines, start_line, start_char, end_line, end_char) abort
+  if a:start_line == len(a:lines) + a:end_line
+    if a:end_line == 0 | return '' | endif
+    let result = a:lines[a:start_line][a:start_char:a:end_char]
+    " json_encode treats empty string computed this was as 'null'
+    if strlen(result) == 0 | let result = '' | endif
+    return result
+  endif
+  let result = a:lines[a:start_line][a:start_char:]."\n"
+  let adj_end_line = len(a:lines) + a:end_line
+  for line in a:lines[a:start_line + 1:a:end_line - 1]
+    let result .= line."\n"
+  endfor
+  if a:end_line != 0
+    let result .= a:lines[a:end_line][:a:end_char]
+  endif
+  return result
+endfunction
+
+function! s:Length(lines, start_line, start_char, end_line, end_char)
+    \ abort
+  let adj_end_line = len(a:lines) + a:end_line
+  if adj_end_line >= len(a:lines)
+    let adj_end_char = a:end_char - 1
+  else
+    let adj_end_char = strlen(a:lines[adj_end_line]) + a:end_char
+  endif
+  if a:start_line == adj_end_line
+    return adj_end_char - a:start_char + 1
+  endif
+  let result = strlen(a:lines[a:start_line]) - a:start_char + 1
+  let line = a:start_line + 1
+  while line < adj_end_line
+    let result += strlen(a:lines[line]) + 1
+    let line += 1
+  endwhile
+  let result += adj_end_char + 1
+  return result
+endfunction