port nvim-cmp tab handler to zig

.config/nvim/lua/pluginconf/nvim_cmp.lua

@@ -1,11 +1,6 @@
 local cmp = require "cmp"
 local luasnip = require "luasnip"
-
--- checks if the char before the cursor is a whitespace
-local function has_words_before()
-    local line, col = unpack(vim.api.nvim_win_get_cursor(0))
-    return col ~= 0 and vim.api.nvim_buf_get_lines(0, line - 1, line, true)[1]:sub(col, col):match "%s" == nil
-end
+local mztenv = require "mzte_nv"
 
 cmp.setup {
     snippet = {
@@ -18,17 +13,7 @@ cmp.setup {
         ["<C-b>"] = cmp.mapping(cmp.mapping.scroll_docs(-4), { "i", "c" }),
         ["<C-f>"] = cmp.mapping(cmp.mapping.scroll_docs(4), { "i", "c" }),
         ["<C-Space>"] = cmp.mapping(cmp.mapping.complete(), { "i", "c" }),
-        ["<Tab>"] = cmp.mapping(function(fallback)
-            if cmp.visible() then
-                cmp.select_next_item()
-            elseif luasnip.expand_or_jumpable() then
-                luasnip.expand_or_jump()
-            elseif has_words_before() then
-                cmp.complete()
-            else
-                fallback()
-            end
-        end, { "i", "s" }),
+        ["<Tab>"] = cmp.mapping(mztenv.cmp.onTab, { "i", "s" }),
         ["<S-Tab>"] = cmp.mapping(cmp.mapping.select_prev_item()),
         ["<CR>"] = cmp.mapping.confirm { select = true },
     },

mzte-nv/src/main.zig

@@ -6,6 +6,7 @@ const c = ffi.c;
 pub const version = "0.2.0";
 
 const modules = struct {
+    const cmp = @import("modules/cmp.zig");
     const jdtls = @import("modules/jdtls.zig");
 };
 
@@ -13,6 +14,7 @@ export fn luaopen_mzte_nv(l_: ?*c.lua_State) c_int {
     const l = l_.?;
     ser.luaPushAny(l, .{
         .onInit = ffi.luaFunc(lOnInit),
+        .cmp = modules.cmp,
         .jdtls = modules.jdtls,
     });
     return 1;

mzte-nv/src/modules/cmp.zig

@@ -0,0 +1,113 @@
+const std = @import("std");
+const ser = @import("../ser.zig");
+const ffi = @import("../ffi.zig");
+const c = ffi.c;
+
+pub fn luaPush(l: *c.lua_State) void {
+    ser.luaPushAny(l, .{
+        .onTab = ffi.luaFunc(lOnTab),
+    });
+}
+
+fn lOnTab(l: *c.lua_State) !c_int {
+    // param 1 is the fallback function
+    c.luaL_checktype(l, 1, c.LUA_TFUNCTION);
+
+    // vim.api at idx 2
+    c.lua_getglobal(l, "vim");
+    c.lua_getfield(l, -1, "api");
+    c.lua_remove(l, 2);
+
+    // cmp module on stack idx 3
+    c.lua_getglobal(l, "require");
+    c.lua_pushstring(l, "cmp");
+    c.lua_call(l, 1, 1);
+
+    // luasnip module on stack idx 4
+    c.lua_getglobal(l, "require");
+    c.lua_pushstring(l, "luasnip");
+    c.lua_call(l, 1, 1);
+
+    // call cmp.visible()
+    c.lua_getfield(l, 3, "visible");
+    c.lua_call(l, 0, 1);
+    const cmp_visible = c.lua_toboolean(l, -1);
+    c.lua_pop(l, 1);
+
+    if (cmp_visible != 0) {
+        // call cmp.select_next_item()
+        c.lua_getfield(l, 3, "select_next_item");
+        c.lua_call(l, 0, 0);
+    } else if (blk: {
+        // call luasnip.expand_or_jumpable()
+        c.lua_getfield(l, 4, "expand_or_jumpable");
+        c.lua_call(l, 0, 1);
+        const b = c.lua_toboolean(l, -1) != 0;
+        c.lua_pop(l, 1);
+        break :blk b;
+    }) {
+        // call luasnip.expand_or_jump()
+        c.lua_getfield(l, 4, "expand_or_jump");
+        c.lua_call(l, 0, 0);
+    } else if (blk: {
+        // in this if, we check if the char before the cursor is NOT a whitespace,
+        // in which case we have cmp complete.
+
+        // call vim.api.nvim_win_get_cursor(0), returns the cursor position in the current buf
+        // in an array table with 2 values
+        c.lua_getfield(l, 2, "nvim_win_get_cursor");
+        c.lua_pushinteger(l, 0);
+        c.lua_call(l, 1, 1);
+
+        c.lua_rawgeti(l, -1, 1);
+        const cursor_line = c.lua_tointeger(l, -1);
+        c.lua_pop(l, 1);
+
+        c.lua_rawgeti(l, -1, 2);
+        const cursor_col = c.lua_tointeger(l, -1);
+        c.lua_pop(l, 2);
+
+        // If the cursor column is 0, that counts as a whitespace.
+        if (cursor_col == 0) {
+            break :blk false;
+        }
+
+        // call vim.api.nvim_buf_get_lines(0, line - 1, line, true)
+        // returns in array containing the line the cursor is at
+        c.lua_getfield(l, 2, "nvim_buf_get_lines");
+        c.lua_pushinteger(l, 0);
+        c.lua_pushinteger(l, cursor_line - 1);
+        c.lua_pushinteger(l, cursor_line);
+        c.lua_pushboolean(l, 1);
+        c.lua_call(l, 4, 1);
+
+        // get the line
+        c.lua_rawgeti(l, -1, 1);
+        var strlen: usize = 0;
+        const line = c.lua_tolstring(l, -1, &strlen)[0..strlen];
+
+        // char at the cursor is NOT whitespace
+        const b = std.mem.indexOfScalar(
+            u8,
+            " \t\n",
+            line[@intCast(usize, cursor_col) - 1],
+        ) == null;
+
+        // remove the string and the string array from the stack
+        c.lua_pop(l, 2);
+
+        break :blk b;
+    }) {
+        // call cmp.complete()
+        c.lua_getfield(l, 3, "complete");
+        c.lua_call(l, 0, 0);
+    } else {
+        // call fallback function
+        c.lua_pushvalue(l, 1);
+        c.lua_call(l, 0, 0);
+    }
+
+    // clear stack
+    c.lua_settop(l, 0);
+    return 0;
+}