From 070c5572adb1b54e0826af0ad695f8148d7da57d Mon Sep 17 00:00:00 2001
From: hrsh7th <hrsh7th@gmail.com>
Date: Sun, 13 Feb 2022 14:34:28 +0900
Subject: [PATCH] Implement shell like common string completion. Fix #785

---
 doc/cmp.txt                            | 20 ++++++++
 lua/cmp/config/mapping.lua             |  9 ++++
 lua/cmp/core.lua                       | 27 +++++++++++
 lua/cmp/init.lua                       |  4 ++
 lua/cmp/utils/keymap.lua               |  3 ++
 lua/cmp/utils/str.lua                  | 11 +++++
 lua/cmp/view.lua                       | 11 +++++
 lua/cmp/view/custom_entries_view.lua   | 20 ++++++--
 lua/cmp/view/native_entries_view.lua   | 14 ++++++
 lua/cmp/view/wildmenu_entries_view.lua | 65 +++++++++++++++-----------
 10 files changed, 154 insertions(+), 30 deletions(-)

diff --git a/doc/cmp.txt b/doc/cmp.txt
index 7680a02..90a4d3c 100644
--- a/doc/cmp.txt
+++ b/doc/cmp.txt
@@ -204,6 +204,23 @@ NOTE: You can call these functions in mapping via `<Cmd>lua require('cmp').compl
 <
   NOTE: The `config` means a temporary setting, but the `config.mapping` remains permanent.
 
+*cmp.complete_common_string* ()
+  Complete common string as like as shell completion behavior.
+>
+  cmp.setup {
+    mapping = {
+      ['<C-n>'] = cmp.mapping(function(fallback)
+        if cmp.visible() then
+          if cmp.complete_common_string() then
+            return
+          end
+          return cmp.select_next_item()
+        end
+        fallback()
+      end, { 'i', 'c' }),
+    }
+  }
+<
 *cmp.confirm* (option: cmp.ConfirmOption, callback: function)
   Accept current selected completion item.
   If you didn't select any items and specified the `{ select = true }` for
@@ -279,6 +296,9 @@ You can also use built-in mapping helpers.
   *cmp.mapping.complete* (option: cmp.CompleteParams)
     Same as |cmp.complete|
 
+  *cmp.mapping.complete_common_string* ()
+    Same as |cmp.complete_common_string|
+
   *cmp.mapping.confirm* (option: cmp.ConfirmOption)
     Same as |cmp.confirm|
 
diff --git a/lua/cmp/config/mapping.lua b/lua/cmp/config/mapping.lua
index ec73ed3..0c2e81a 100644
--- a/lua/cmp/config/mapping.lua
+++ b/lua/cmp/config/mapping.lua
@@ -22,6 +22,15 @@ mapping.complete = function(option)
   end
 end
 
+---Complete common string.
+mapping.complete_common_string = function()
+  return function(fallback)
+    if not require('cmp').complete_common_string() then
+      fallback()
+    end
+  end
+end
+
 ---Close current completion menu if it displayed.
 mapping.close = function()
   return function(fallback)
diff --git a/lua/cmp/core.lua b/lua/cmp/core.lua
index 673a5cd..8df922d 100644
--- a/lua/cmp/core.lua
+++ b/lua/cmp/core.lua
@@ -1,4 +1,5 @@
 local debug = require('cmp.utils.debug')
+local str = require('cmp.utils.str')
 local char = require('cmp.utils.char')
 local pattern = require('cmp.utils.pattern')
 local feedkeys = require('cmp.utils.feedkeys')
@@ -217,6 +218,32 @@ core.autoindent = function(self, trigger_event, callback)
   callback()
 end
 
+---Complete common string for current completed entries.
+core.complete_common_string = function(self)
+  if not self.view:visible() then
+    return false
+  end
+
+  self.filter:sync(1000)
+
+  local cursor = api.get_cursor()
+  local offset = self.view:get_offset()
+  local common_string
+  for _, e in ipairs(self.view:get_entries()) do
+    local vim_item = e:get_vim_item(offset)
+    if not common_string then
+      common_string = vim_item.word
+    else
+      common_string = str.get_common_string(common_string, vim_item.word)
+    end
+  end
+  if common_string and #common_string > (1 + cursor[2] - offset) then
+    feedkeys.call(keymap.backspace(string.sub(api.get_current_line(), offset, cursor[2])) .. common_string, 'n')
+    return true
+  end
+  return false
+end
+
 ---Invoke completion
 ---@param ctx cmp.Context
 core.complete = function(self, ctx)
diff --git a/lua/cmp/init.lua b/lua/cmp/init.lua
index decebfd..593a2aa 100644
--- a/lua/cmp/init.lua
+++ b/lua/cmp/init.lua
@@ -75,6 +75,10 @@ cmp.complete = cmp.sync(function(option)
   return true
 end)
 
+cmp.complete_common_string = cmp.sync(function()
+  return cmp.core:complete_common_string()
+end)
+
 ---Return view is visible or not.
 cmp.visible = cmp.sync(function()
   return cmp.core.view:visible() or vim.fn.pumvisible() == 1
diff --git a/lua/cmp/utils/keymap.lua b/lua/cmp/utils/keymap.lua
index 5f78285..67bec80 100644
--- a/lua/cmp/utils/keymap.lua
+++ b/lua/cmp/utils/keymap.lua
@@ -67,6 +67,9 @@ end
 ---@param count number
 ---@return string
 keymap.backspace = function(count)
+  if type(count) == 'string'  then
+    count = vim.fn.strchars(count, true)
+  end
   if count <= 0 then
     return ''
   end
diff --git a/lua/cmp/utils/str.lua b/lua/cmp/utils/str.lua
index cbdcbf4..450c991 100644
--- a/lua/cmp/utils/str.lua
+++ b/lua/cmp/utils/str.lua
@@ -43,6 +43,17 @@ str.has_prefix = function(text, prefix)
   return true
 end
 
+---get_common_string
+str.get_common_string = function(text1, text2)
+  local min = math.min(#text1, #text2)
+  for i = 1, min do
+    if not char.match(string.byte(text1, i), string.byte(text2, i)) then
+      return string.sub(text1, 1, i - 1)
+    end
+  end
+  return string.sub(text1, 1, min)
+end
+
 ---Remove suffix
 ---@param text string
 ---@param suffix string
diff --git a/lua/cmp/view.lua b/lua/cmp/view.lua
index 129f979..4c2d03f 100644
--- a/lua/cmp/view.lua
+++ b/lua/cmp/view.lua
@@ -161,6 +161,17 @@ view.select_prev_item = function(self, option)
   self:_get_entries_view():select_prev_item(option)
 end
 
+---Get offset.
+view.get_offset = function(self)
+  return self:_get_entries_view():get_offset()
+end
+
+---Get entries.
+---@return cmp.Entry[]
+view.get_entries = function(self)
+  return self:_get_entries_view():get_entries()
+end
+
 ---Get first entry
 ---@param self cmp.Entry|nil
 view.get_first_entry = function(self)
diff --git a/lua/cmp/view/custom_entries_view.lua b/lua/cmp/view/custom_entries_view.lua
index a6b60c8..84adbd5 100644
--- a/lua/cmp/view/custom_entries_view.lua
+++ b/lua/cmp/view/custom_entries_view.lua
@@ -257,6 +257,20 @@ custom_entries_view.select_prev_item = function(self, option)
   end
 end
 
+custom_entries_view.get_offset = function(self)
+  if self:visible() then
+    return self.offset
+  end
+  return nil
+end
+
+custom_entries_view.get_entries = function(self)
+  if self:visible() then
+    return self.entries
+  end
+  return {}
+end
+
 custom_entries_view.get_first_entry = function(self)
   if self:visible() then
     return self.entries[1]
@@ -301,8 +315,7 @@ custom_entries_view._insert = setmetatable({
     word = word or ''
     if api.is_cmdline_mode() then
       local cursor = api.get_cursor()
-      local length = vim.fn.strchars(string.sub(api.get_current_line(), self.offset, cursor[2]), true)
-      vim.api.nvim_feedkeys(keymap.backspace(length) .. word, 'int', true)
+      vim.api.nvim_feedkeys(keymap.backspace(string.sub(api.get_current_line(), self.offset, cursor[2])) .. word, 'int', true)
     else
       if this.pending then
         return
@@ -312,10 +325,9 @@ custom_entries_view._insert = setmetatable({
       local release = require('cmp').suspend()
       feedkeys.call('', '', function()
         local cursor = api.get_cursor()
-        local length = vim.fn.strchars(string.sub(api.get_current_line(), self.offset, cursor[2]), true)
         local keys = {}
         table.insert(keys, keymap.indentkeys())
-        table.insert(keys, keymap.backspace(length))
+        table.insert(keys, keymap.backspace(string.sub(api.get_current_line(), self.offset, cursor[2])))
         table.insert(keys, word)
         table.insert(keys, keymap.indentkeys(vim.bo.indentkeys))
         feedkeys.call(
diff --git a/lua/cmp/view/native_entries_view.lua b/lua/cmp/view/native_entries_view.lua
index a74f697..d1dc8de 100644
--- a/lua/cmp/view/native_entries_view.lua
+++ b/lua/cmp/view/native_entries_view.lua
@@ -143,6 +143,20 @@ native_entries_view.select_prev_item = function(self, option)
   end
 end
 
+native_entries_view.get_offset = function(self)
+  if self:visible() then
+    return self.offset
+  end
+  return nil
+end
+
+native_entries_view.get_entries = function(self)
+  if self:visible() then
+    return self.entries
+  end
+  return {}
+end
+
 native_entries_view.get_first_entry = function(self)
   if self:visible() then
     return self.entries[1]
diff --git a/lua/cmp/view/wildmenu_entries_view.lua b/lua/cmp/view/wildmenu_entries_view.lua
index 252fb40..9cafb9d 100644
--- a/lua/cmp/view/wildmenu_entries_view.lua
+++ b/lua/cmp/view/wildmenu_entries_view.lua
@@ -14,16 +14,16 @@ local api = require('cmp.utils.api')
 ---@field private active boolean
 ---@field private entries cmp.Entry[]
 ---@field public event cmp.Event
-local statusline_entries_view = {}
+local wildmenu_entries_view = {}
 
 local function get_separator()
   local c = config.get()
   return (c and c.view and c.view.entries and c.view.entries.separator) or '  '
 end
 
-statusline_entries_view.ns = vim.api.nvim_create_namespace('cmp.view.statusline_entries_view')
+wildmenu_entries_view.ns = vim.api.nvim_create_namespace('cmp.view.statusline_entries_view')
 
-statusline_entries_view.init = function(self)
+wildmenu_entries_view.init = function(self)
   self.event = event.new()
   self.offset = -1
   self.active = false
@@ -33,8 +33,8 @@ statusline_entries_view.init = function(self)
   self.moving_forwards = nil
 end
 
-statusline_entries_view.new = function()
-  local self = setmetatable({}, { __index = statusline_entries_view })
+wildmenu_entries_view.new = function()
+  local self = setmetatable({}, { __index = wildmenu_entries_view })
   self:init()
 
   self.entries_win = window.new()
@@ -47,7 +47,7 @@ statusline_entries_view.new = function()
   self.entries_win:option('winhighlight', 'Normal:Pmenu,FloatBorder:Pmenu,CursorLine:PmenuSel,Search:None')
   self.entries_win:buffer_option('tabstop', 1)
 
-  vim.api.nvim_set_decoration_provider(statusline_entries_view.ns, {
+  vim.api.nvim_set_decoration_provider(wildmenu_entries_view.ns, {
     on_win = function(_, win, buf, _, _)
       if win ~= self.entries_win.win or buf ~= self.entries_win:get_buffer() then
         return
@@ -58,7 +58,7 @@ statusline_entries_view.new = function()
         local e = self.entries[i]
         if e then
           local view = e:get_view(self.offset, buf)
-          vim.api.nvim_buf_set_extmark(buf, statusline_entries_view.ns, 0, location, {
+          vim.api.nvim_buf_set_extmark(buf, wildmenu_entries_view.ns, 0, location, {
             end_line = 0,
             end_col = location + view['abbr'].bytes,
             hl_group = view['abbr'].hl_group,
@@ -67,7 +67,7 @@ statusline_entries_view.new = function()
           })
 
           if i == self.selected_index then
-            vim.api.nvim_buf_set_extmark(buf, statusline_entries_view.ns, 0, location, {
+            vim.api.nvim_buf_set_extmark(buf, wildmenu_entries_view.ns, 0, location, {
               end_line = 0,
               end_col = location + view['abbr'].bytes,
               hl_group = 'PmenuSel',
@@ -77,7 +77,7 @@ statusline_entries_view.new = function()
           end
 
           for _, m in ipairs(e.matches or {}) do
-            vim.api.nvim_buf_set_extmark(buf, statusline_entries_view.ns, 0, location + m.word_match_start - 1, {
+            vim.api.nvim_buf_set_extmark(buf, wildmenu_entries_view.ns, 0, location + m.word_match_start - 1, {
               end_line = 0,
               end_col = location + m.word_match_end,
               hl_group = m.fuzzy and 'CmpItemAbbrMatchFuzzy' or 'CmpItemAbbrMatch',
@@ -103,20 +103,20 @@ statusline_entries_view.new = function()
   return self
 end
 
-statusline_entries_view.close = function(self)
+wildmenu_entries_view.close = function(self)
   self.entries_win:close()
   self:init()
 end
 
-statusline_entries_view.ready = function()
+wildmenu_entries_view.ready = function()
   return vim.fn.pumvisible() == 0
 end
 
-statusline_entries_view.on_change = function(self)
+wildmenu_entries_view.on_change = function(self)
   self.active = false
 end
 
-statusline_entries_view.open = function(self, offset, entries)
+wildmenu_entries_view.open = function(self, offset, entries)
   self.offset = offset
   self.entries = {}
   self.last_displayed_indices = {}
@@ -159,13 +159,13 @@ statusline_entries_view.open = function(self, offset, entries)
   end
 end
 
-statusline_entries_view.abort = function(self)
+wildmenu_entries_view.abort = function(self)
   feedkeys.call('', 'n', function()
     self:close()
   end)
 end
 
-statusline_entries_view.draw = function(self)
+wildmenu_entries_view.draw = function(self)
   local entries_buf = self.entries_win:get_buffer()
   local texts = {}
   local lengths = {}
@@ -235,15 +235,15 @@ statusline_entries_view.draw = function(self)
   end)
 end
 
-statusline_entries_view.visible = function(self)
+wildmenu_entries_view.visible = function(self)
   return self.entries_win:visible()
 end
 
-statusline_entries_view.info = function(self)
+wildmenu_entries_view.info = function(self)
   return self.entries_win:info()
 end
 
-statusline_entries_view.select_next_item = function(self, option)
+wildmenu_entries_view.select_next_item = function(self, option)
   if self:visible() then
     self.moving_forwards = true
     if self.selected_index == nil or self.selected_index == #self.entries then
@@ -254,7 +254,7 @@ statusline_entries_view.select_next_item = function(self, option)
   end
 end
 
-statusline_entries_view.select_prev_item = function(self, option)
+wildmenu_entries_view.select_prev_item = function(self, option)
   if self:visible() then
     self.moving_forwards = false
     if self.selected_index == nil or self.selected_index <= 1 then
@@ -265,33 +265,46 @@ statusline_entries_view.select_prev_item = function(self, option)
   end
 end
 
-statusline_entries_view.get_first_entry = function(self)
+wildmenu_entries_view.get_offset = function(self)
+  if self:visible() then
+    return self.offset
+  end
+  return nil
+end
+
+wildmenu_entries_view.get_entries = function(self)
+  if self:visible() then
+    return self.entries
+  end
+  return {}
+end
+
+wildmenu_entries_view.get_first_entry = function(self)
   if self:visible() then
     return self.entries[1]
   end
 end
 
-statusline_entries_view.get_selected_entry = function(self)
+wildmenu_entries_view.get_selected_entry = function(self)
   if self:visible() and self.active then
     return self.entries[self.selected_index]
   end
 end
 
-statusline_entries_view.get_active_entry = function(self)
+wildmenu_entries_view.get_active_entry = function(self)
   if self:visible() and self.active then
     return self:get_selected_entry()
   end
 end
 
-statusline_entries_view._select = function(self, selected_index, _)
+wildmenu_entries_view._select = function(self, selected_index, _)
   self.selected_index = selected_index
   self.active = (selected_index ~= nil)
 
   if self.active then
     local cursor = api.get_cursor()
     local word = self:get_active_entry():get_vim_item(self.offset).word
-    local length = vim.fn.strchars(string.sub(api.get_current_line(), self.offset, cursor[2]), true)
-    vim.api.nvim_feedkeys(keymap.backspace(length) .. word, 'int', true)
+    vim.api.nvim_feedkeys(keymap.backspace(string.sub(api.get_current_line(), self.offset, cursor[2])) .. word, 'int', true)
   end
 
   self.entries_win:update()
@@ -299,4 +312,4 @@ statusline_entries_view._select = function(self, selected_index, _)
   self.event:emit('change')
 end
 
-return statusline_entries_view
+return wildmenu_entries_view