refactor: better source code framework

lua/Trans/util/node.lua

@@ -0,0 +1,73 @@
+local api = vim.api
+local ns = require('Trans').ns
+local add_hl = api.nvim_buf_add_highlight
+
+local item_meta = {
+    load = function(self, bufnr, line, col)
+        if self[2] then
+            add_hl(bufnr, ns, self[2], line, col, col + #self[1])
+        end
+    end,
+}
+
+local text_meta = {
+    load = function(self, bufnr, line, col)
+        local items = self.items
+        local step = self.step or ''
+        local len = #step
+
+        for i = 1, self.size do
+            local item = items[i]
+            item:load(bufnr, line, col)
+            col = col + #item[1] + len
+        end
+    end
+}
+
+item_meta.__index = item_meta
+text_meta.__index = function(self, key)
+    local res = text_meta[key]
+    if res then
+        return res
+    elseif key == 1 then
+        return table.concat(self.strs, self.step)
+    end
+end
+
+return {
+    item = function(text, highlight)
+        return setmetatable({
+            [1] = text,
+            [2] = highlight,
+        }, item_meta)
+    end,
+
+    text = function(items)
+        local strs = {}
+        local size = #items
+        assert(size > 1)
+        for i = 1, size do
+            strs[i] = items[i][1]
+        end
+
+        return setmetatable({
+            strs  = strs,
+            size  = size,
+            items = items,
+        }, text_meta)
+    end,
+
+    format = function(opts)
+        local text  = opts.text
+        local size  = text.size
+        local width = opts.width
+        local spin  = opts.spin or ' '
+
+        local wid   = text[1]:width()
+        local space = math.max(math.floor((width - wid) / (size - 1)), 0)
+        if space > 0 then
+            text.step = spin:rep(space)
+        end
+        return text
+    end,
+}