Merge pull request #13719 from chentau/lua_compl

Add completion to lua

7 files changed, 473 insertions, 8 deletions

diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index ccf7dd0f68..18683c54d3 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -3041,9 +3041,10 @@ const char * set_one_cmd_context(
     p = arg + 1;
     arg = (const char *)skip_cmd_arg((char_u *)arg, false);
 
-    /* Still touching the command after '+'? */
-    if (*arg == NUL)
+    // Still touching the command after '+'?
+    if (*arg == NUL) {
       return p;
+    }
 
     // Skip space(s) after +command to get to the real argument.
     arg = (const char *)skipwhite((const char_u *)arg);
@@ -3680,6 +3681,10 @@ const char * set_one_cmd_context(
     xp->xp_pattern = (char_u *)arg;
     break;
 
+  case CMD_lua:
+    xp->xp_context = EXPAND_LUA;
+    break;
+
   default:
     break;
   }
@@ -3968,7 +3973,7 @@ static linenr_T get_address(exarg_T *eap,
       break;
 
     default:
-      if (ascii_isdigit(*cmd)) {  // absolute line number
+      if (ascii_isdigit(*cmd)) {                // absolute line number
         lnum = getdigits_long(&cmd, false, 0);
       }
     }
@@ -5187,6 +5192,7 @@ static const char *command_complete[] =
 #ifdef HAVE_WORKING_LIBINTL
   [EXPAND_LOCALES] = "locale",
 #endif
+  [EXPAND_LUA] = "lua",
   [EXPAND_MAPCLEAR] = "mapclear",
   [EXPAND_MAPPINGS] = "mapping",
   [EXPAND_MENUS] = "menu",
@@ -5400,8 +5406,8 @@ static int uc_scan_attr(char_u *attr, size_t len, uint32_t *argt, long *def,
     size_t vallen = 0;
     size_t attrlen = len;
 
-    /* Look for the attribute name - which is the part before any '=' */
-    for (i = 0; i < (int)len; ++i) {
+    // Look for the attribute name - which is the part before any '='
+    for (i = 0; i < (int)len; i++) {
       if (attr[i] == '=') {
         val = &attr[i + 1];
         vallen = len - i - 1;
@@ -7503,8 +7509,9 @@ static void ex_read(exarg_T *eap)
     }
 
     if (*eap->arg == NUL) {
-      if (check_fname() == FAIL)        /* check for no file name */
+      if (check_fname() == FAIL) {       // check for no file name
         return;
+      }
       i = readfile(curbuf->b_ffname, curbuf->b_fname,
           eap->line2, (linenr_T)0, (linenr_T)MAXLNUM, eap, 0);
     } else {
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 2aa66f6a8c..8d10e98259 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -69,6 +69,7 @@
 #include "nvim/lib/kvec.h"
 #include "nvim/api/private/helpers.h"
 #include "nvim/highlight_defs.h"
+#include "nvim/lua/executor.h"
 #include "nvim/viml/parser/parser.h"
 #include "nvim/viml/parser/expressions.h"
 
@@ -3945,6 +3946,12 @@ nextwild (
     p2 = ExpandOne(xp, p1, vim_strnsave(&ccline.cmdbuff[i], xp->xp_pattern_len),
                    use_options, type);
     xfree(p1);
+
+    // xp->xp_pattern might have been modified by ExpandOne (for example,
+    // in lua completion), so recompute the pattern index and length
+    i = (int)(xp->xp_pattern - ccline.cmdbuff);
+    xp->xp_pattern_len = (size_t)ccline.cmdpos - (size_t)i;
+
     // Longest match: make sure it is not shorter, happens with :help.
     if (p2 != NULL && type == WILD_LONGEST) {
       for (j = 0; (size_t)j < xp->xp_pattern_len; j++) {
@@ -3960,7 +3967,7 @@ nextwild (
   }
 
   if (p2 != NULL && !got_int) {
-    difflen = (int)STRLEN(p2) - (int)xp->xp_pattern_len;
+    difflen = (int)STRLEN(p2) - (int)(xp->xp_pattern_len);
     if (ccline.cmdlen + difflen + 4 > ccline.cmdbufflen) {
       realloc_cmdbuff(ccline.cmdlen + difflen + 4);
       xp->xp_pattern = ccline.cmdbuff + i;
@@ -5106,6 +5113,10 @@ ExpandFromContext (
   if (xp->xp_context == EXPAND_PACKADD) {
     return ExpandPackAddDir(pat, num_file, file);
   }
+  if (xp->xp_context == EXPAND_LUA) {
+    ILOG("PAT %s", pat);
+    return nlua_expand_pat(xp, pat, num_file, file);
+  }
 
   regmatch.regprog = vim_regcomp(pat, p_magic ? RE_MAGIC : 0);
   if (regmatch.regprog == NULL)
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 3219c02068..310b194c8c 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -1292,6 +1292,80 @@ static void nlua_add_treesitter(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   lua_setfield(lstate, -2, "_ts_parse_query");
 }
 
+int nlua_expand_pat(expand_T *xp,
+                    char_u *pat,
+                    int *num_results,
+                    char_u ***results)
+{
+  lua_State *const lstate = nlua_enter();
+  int ret = OK;
+
+  // [ vim ]
+  lua_getglobal(lstate, "vim");
+
+  // [ vim, vim._expand_pat ]
+  lua_getfield(lstate, -1, "_expand_pat");
+  luaL_checktype(lstate, -1, LUA_TFUNCTION);
+
+  // [ vim, vim._log_keystroke, buf ]
+  lua_pushlstring(lstate, (const char *)pat, STRLEN(pat));
+
+  if (lua_pcall(lstate, 1, 2, 0) != 0) {
+    nlua_error(
+        lstate,
+        _("Error executing vim._expand_pat: %.*s"));
+    return FAIL;
+  }
+
+  Error err = ERROR_INIT;
+
+  *num_results = 0;
+  *results = NULL;
+
+  int prefix_len = (int)nlua_pop_Integer(lstate, &err);
+  if (ERROR_SET(&err)) {
+    ret = FAIL;
+    goto cleanup;
+  }
+
+  Array completions = nlua_pop_Array(lstate, &err);
+  if (ERROR_SET(&err)) {
+    ret = FAIL;
+    goto cleanup_array;
+  }
+
+  garray_T result_array;
+  ga_init(&result_array, (int)sizeof(char *), 80);
+  for (size_t i = 0; i < completions.size; i++) {
+    Object v = completions.items[i];
+
+    if (v.type != kObjectTypeString) {
+      ret = FAIL;
+      goto cleanup_array;
+    }
+
+    GA_APPEND(
+        char_u *,
+        &result_array,
+        vim_strsave((char_u *)v.data.string.data));
+  }
+
+  xp->xp_pattern += prefix_len;
+  *results = result_array.ga_data;
+  *num_results = result_array.ga_len;
+
+cleanup_array:
+  api_free_array(completions);
+
+cleanup:
+
+  if (ret == FAIL) {
+    ga_clear(&result_array);
+  }
+
+  return ret;
+}
+
 static int nlua_regex(lua_State *lstate)
 {
   Error err = ERROR_INIT;
diff --git a/src/nvim/lua/vim.lua b/src/nvim/lua/vim.lua
index 80b311de2c..dbf4f6014c 100644
--- a/src/nvim/lua/vim.lua
+++ b/src/nvim/lua/vim.lua
@@ -534,4 +534,164 @@ function vim._log_keystroke(char)
   end
 end
 
+--- Generate a list of possible completions for the string.
+--- String starts with ^ and then has the pattern.
+---
+---     1. Can we get it to just return things in the global namespace with that name prefix
+---     2. Can we get it to return things from global namespace even with `print(` in front.
+function vim._expand_pat(pat, env)
+  env = env or _G
+
+  pat = string.sub(pat, 2, #pat)
+
+  if pat == '' then
+    local result = vim.tbl_keys(env)
+    table.sort(result)
+    return result, 0
+  end
+
+  -- TODO: We can handle spaces in [] ONLY.
+  --    We should probably do that at some point, just for cooler completion.
+  -- TODO: We can suggest the variable names to go in []
+  --    This would be difficult as well.
+  --    Probably just need to do a smarter match than just `:match`
+
+  -- Get the last part of the pattern
+  local last_part = pat:match("[%w.:_%[%]'\"]+$")
+  if not last_part then return {}, 0 end
+
+  local parts, search_index = vim._expand_pat_get_parts(last_part)
+
+  local match_part = string.sub(last_part, search_index, #last_part)
+  local prefix_match_pat = string.sub(pat, 1, #pat - #match_part) or ''
+
+  local final_env = env
+
+  for _, part in ipairs(parts) do
+    if type(final_env) ~= 'table' then
+      return {}, 0
+    end
+    local key
+
+    -- Normally, we just have a string
+    -- Just attempt to get the string directly from the environment
+    if type(part) == "string" then
+      key = part
+    else
+      -- However, sometimes you want to use a variable, and complete on it
+      --    With this, you have the power.
+
+      -- MY_VAR = "api"
+      -- vim[MY_VAR]
+      -- -> _G[MY_VAR] -> "api"
+      local result_key = part[1]
+      if not result_key then
+        return {}, 0
+      end
+
+      local result = rawget(env, result_key)
+
+      if result == nil then
+        return {}, 0
+      end
+
+      key = result
+    end
+    local field = rawget(final_env, key)
+    if field == nil then
+      local mt = getmetatable(final_env)
+      if mt and type(mt.__index) == "table" then
+        field = rawget(mt.__index, key)
+      end
+    end
+    final_env = field
+
+    if not final_env then
+      return {}, 0
+    end
+  end
+
+  local keys = {}
+  local function insert_keys(obj)
+    for k,_ in pairs(obj) do
+      if type(k) == "string" and string.sub(k,1,string.len(match_part)) == match_part then
+        table.insert(keys,k)
+      end
+    end
+  end
+
+  if type(final_env) == "table" then
+    insert_keys(final_env)
+  end
+  local mt = getmetatable(final_env)
+  if mt and type(mt.__index) == "table" then
+    insert_keys(mt.__index)
+  end
+
+  table.sort(keys)
+
+  return keys, #prefix_match_pat
+end
+
+vim._expand_pat_get_parts = function(lua_string)
+  local parts = {}
+
+  local accumulator, search_index = '', 1
+  local in_brackets, bracket_end = false, -1
+  local string_char = nil
+  for idx = 1, #lua_string do
+    local s = lua_string:sub(idx, idx)
+
+    if not in_brackets and (s == "." or s == ":") then
+      table.insert(parts, accumulator)
+      accumulator = ''
+
+      search_index = idx + 1
+    elseif s == "[" then
+      in_brackets = true
+
+      table.insert(parts, accumulator)
+      accumulator = ''
+
+      search_index = idx + 1
+    elseif in_brackets then
+      if idx == bracket_end then
+        in_brackets = false
+        search_index = idx + 1
+
+        if string_char == "VAR" then
+          table.insert(parts, { accumulator })
+          accumulator = ''
+
+          string_char = nil
+        end
+      elseif not string_char then
+        bracket_end = string.find(lua_string, ']', idx, true)
+
+        if s == '"' or s == "'" then
+          string_char = s
+        elseif s ~= ' ' then
+          string_char = "VAR"
+          accumulator = s
+        end
+      elseif string_char then
+        if string_char ~= s then
+          accumulator = accumulator .. s
+        else
+          table.insert(parts, accumulator)
+          accumulator = ''
+
+          string_char = nil
+        end
+      end
+    else
+      accumulator = accumulator .. s
+    end
+  end
+
+  parts = vim.tbl_filter(function(val) return #val > 0 end, parts)
+
+  return parts, search_index
+end
+
 return module
diff --git a/src/nvim/vim.h b/src/nvim/vim.h
index 01f20cf29a..e70749795b 100644
--- a/src/nvim/vim.h
+++ b/src/nvim/vim.h
@@ -159,6 +159,7 @@ enum {
   EXPAND_MAPCLEAR,
   EXPAND_ARGLIST,
   EXPAND_CHECKHEALTH,
+  EXPAND_LUA,
 };
 
 
diff --git a/test/functional/lua/command_line_completion_spec.lua b/test/functional/lua/command_line_completion_spec.lua
new file mode 100644
index 0000000000..3ba7e1589f
--- /dev/null
+++ b/test/functional/lua/command_line_completion_spec.lua
@@ -0,0 +1,171 @@
+local helpers = require('test.functional.helpers')(after_each)
+
+local clear = helpers.clear
+local eq = helpers.eq
+local exec_lua = helpers.exec_lua
+
+local get_completions = function(input, env)
+  return exec_lua("return {vim._expand_pat(...)}", '^' .. input, env)
+end
+
+local get_compl_parts = function(parts)
+  return exec_lua("return {vim._expand_pat_get_parts(...)}", parts)
+end
+
+before_each(clear)
+
+describe('nlua_expand_pat', function()
+  it('should complete exact matches', function()
+    eq({{'exact'}, 0}, get_completions('exact', { exact = true }))
+  end)
+
+  it('should return empty table when nothing matches', function()
+    eq({{}, 0}, get_completions('foo', { bar = true }))
+  end)
+
+  it('should return nice completions with function call prefix', function()
+    eq({{'FOO'}, 6}, get_completions('print(F', { FOO = true, bawr = true }))
+  end)
+
+  it('should return keys for nested dictionaries', function()
+    eq(
+      {{
+        'nvim_buf_set_lines',
+        'nvim_buf_set_option'
+       }, 8
+      },
+      get_completions('vim.api.nvim_buf_', {
+        vim = {
+          api = {
+            nvim_buf_set_lines = true,
+            nvim_buf_set_option = true,
+            nvim_win_doesnt_match = true,
+          },
+          other_key = true,
+        }
+      })
+    )
+  end)
+
+  it('it should work with colons', function()
+    eq(
+      {{
+        'bawr',
+        'baz',
+       }, 8
+      },
+      get_completions('MyClass:b', {
+        MyClass = {
+          baz = true,
+          bawr = true,
+          foo = false,
+        }
+      })
+    )
+  end)
+
+  it('should return keys for string reffed dictionaries', function()
+    eq(
+      {{
+        'nvim_buf_set_lines',
+        'nvim_buf_set_option'
+       }, 11
+      },
+      get_completions('vim["api"].nvim_buf_', {
+        vim = {
+          api = {
+            nvim_buf_set_lines = true,
+            nvim_buf_set_option = true,
+            nvim_win_doesnt_match = true,
+          },
+          other_key = true,
+        }
+      })
+    )
+  end)
+
+  it('should return keys for string reffed dictionaries', function()
+    eq(
+      {{
+        'nvim_buf_set_lines',
+        'nvim_buf_set_option'
+       }, 21
+      },
+      get_completions('vim["nested"]["api"].nvim_buf_', {
+        vim = {
+          nested = {
+            api = {
+              nvim_buf_set_lines = true,
+              nvim_buf_set_option = true,
+              nvim_win_doesnt_match = true,
+            },
+          },
+          other_key = true,
+        }
+      })
+    )
+  end)
+
+  it('should be able to interpolate globals', function()
+    eq(
+      {{
+        'nvim_buf_set_lines',
+        'nvim_buf_set_option'
+       }, 12
+      },
+      get_completions('vim[MY_VAR].nvim_buf_', {
+        MY_VAR = "api",
+        vim = {
+          api = {
+            nvim_buf_set_lines = true,
+            nvim_buf_set_option = true,
+            nvim_win_doesnt_match = true,
+          },
+          other_key = true,
+        }
+      })
+    )
+  end)
+
+  it('should return everything if the input is of length 0', function()
+    eq({{"other", "vim"}, 0}, get_completions('', { vim = true, other = true }))
+  end)
+
+  describe('get_parts', function()
+    it('should return an empty list for no separators', function()
+      eq({{}, 1}, get_compl_parts("vim"))
+    end)
+
+    it('just the first item before a period', function()
+      eq({{"vim"}, 5}, get_compl_parts("vim.ap"))
+    end)
+
+    it('should return multiple parts just for period', function()
+      eq({{"vim", "api"}, 9}, get_compl_parts("vim.api.nvim_buf"))
+    end)
+
+    it('should be OK with colons', function()
+      eq({{"vim", "api"}, 9}, get_compl_parts("vim:api.nvim_buf"))
+    end)
+
+    it('should work for just one string ref', function()
+      eq({{"vim", "api"}, 12}, get_compl_parts("vim['api'].nvim_buf"))
+    end)
+
+    it('should work for just one string ref, with double quote', function()
+      eq({{"vim", "api"}, 12}, get_compl_parts('vim["api"].nvim_buf'))
+    end)
+
+    it('should allows back-to-back string ref', function()
+      eq({{"vim", "nested", "api"}, 22}, get_compl_parts('vim["nested"]["api"].nvim_buf'))
+    end)
+
+    it('should allows back-to-back string ref with spaces before and after', function()
+      eq({{"vim", "nested", "api"}, 25}, get_compl_parts('vim[ "nested"  ]["api"].nvim_buf'))
+    end)
+
+    it('should allow VAR style loolup', function()
+      eq({{"vim", {"NESTED"}, "api"}, 20}, get_compl_parts('vim[NESTED]["api"].nvim_buf'))
+    end)
+  end)
+end)
diff --git a/test/functional/viml/completion_spec.lua b/test/functional/viml/completion_spec.lua
index 01fc50289d..a4241fe5aa 100644
--- a/test/functional/viml/completion_spec.lua
+++ b/test/functional/viml/completion_spec.lua
@@ -3,6 +3,7 @@ local Screen = require('test.functional.ui.screen')
 local clear, feed = helpers.clear, helpers.feed
 local eval, eq, neq = helpers.eval, helpers.eq, helpers.neq
 local feed_command, source, expect = helpers.feed_command, helpers.source, helpers.expect
+local funcs = helpers.funcs
 local curbufmeths = helpers.curbufmeths
 local command = helpers.command
 local meths = helpers.meths
@@ -26,6 +27,7 @@ describe('completion', function()
       [7] = {foreground = Screen.colors.White, background = Screen.colors.Red},
       [8] = {reverse = true},
       [9] = {bold = true, reverse = true},
+      [10] = {foreground = Screen.colors.Grey0, background = Screen.colors.Yellow},
     })
   end)
 
@@ -895,8 +897,47 @@ describe('completion', function()
     ]])
   end)
 
-  describe('from the commandline window', function()
+  describe('lua completion', function()
+    it('expands when there is only one match', function()
+      feed(':lua CURRENT_TESTING_VAR = 1<CR>')
+      feed(':lua CURRENT_TESTING_<TAB>')
+      screen:expect{grid=[[
+                                                                    |
+        {0:~                                                           }|
+        {0:~                                                           }|
+        {0:~                                                           }|
+        {0:~                                                           }|
+        {0:~                                                           }|
+        {0:~                                                           }|
+        :lua CURRENT_TESTING_VAR^                                    |
+      ]]}
+    end)
 
+    it('expands when there is only one match', function()
+      feed(':lua CURRENT_TESTING_FOO = 1<CR>')
+      feed(':lua CURRENT_TESTING_BAR = 1<CR>')
+      feed(':lua CURRENT_TESTING_<TAB>')
+      screen:expect{ grid = [[
+                                                                    |
+        {0:~                                                           }|
+        {0:~                                                           }|
+        {0:~                                                           }|
+        {0:~                                                           }|
+        {0:~                                                           }|
+        {10:CURRENT_TESTING_BAR}{9:  CURRENT_TESTING_FOO                    }|
+        :lua CURRENT_TESTING_BAR^                                    |
+      ]], unchanged = true }
+    end)
+
+    it('provides completion from `getcompletion()`', function()
+      eq({'vim'}, funcs.getcompletion('vi', 'lua'))
+      eq({'api'}, funcs.getcompletion('vim.ap', 'lua'))
+      eq({'tbl_filter'}, funcs.getcompletion('vim.tbl_fil', 'lua'))
+      eq({'vim'}, funcs.getcompletion('print(vi', 'lua'))
+    end)
+  end)
+
+  describe('from the commandline window', function()
     it('is cleared after CTRL-C', function ()
       feed('q:')
       feed('ifoo faa fee f')