diff --git a/lua/fittencode/opl.lua b/lua/fittencode/opl.lua
new file mode 100644
index 0000000..1ca2751
--- /dev/null
+++ b/lua/fittencode/opl.lua
@@ -0,0 +1,531 @@
+-- Part 1 - Lexer
+-- Part 2 - Parser
+-- Part 3 - Compiler
+
+local function deepcopy(obj, seen)
+    if type(obj) ~= 'table' then return obj end
+    if seen and seen[obj] then return seen[obj] end
+    local s = seen or {}
+    local res = setmetatable({}, getmetatable(obj))
+    s[obj] = res
+    for k, v in pairs(obj) do res[deepcopy(k, s)] = deepcopy(v, s) end
+    return res
+end
+
+local function bit_and(a, b)
+    local result = 0
+    local shift = 0
+    while a > 0 or b > 0 do
+        local bit_a = a % 2
+        local bit_b = b % 2
+        if bit_a == 1 and bit_b == 1 then
+            result = result + (2 ^ shift)
+        end
+        a = math.floor(a / 2)
+        b = math.floor(b / 2)
+        shift = shift + 1
+    end
+    return result
+end
+
+-- 计算 UTF-8 字符长度
+---@param ch number
+---@return number
+local function utf8_length(ch)
+    if bit_and(ch, 0x80) == 0 then
+        return 1
+    elseif bit_and(ch, 0xE0) == 0xC0 then
+        return 2
+    elseif bit_and(ch, 0xF0) == 0xE0 then
+        return 3
+    elseif bit_and(ch, 0xF8) == 0xF0 then
+        return 4
+    else
+        return 0
+    end
+end
+
+---@param ch string
+---@return boolean
+local function is_newline(ch)
+    return ch == '\n' or ch == '\r'
+end
+
+---@param utf table
+---@return boolean
+local function is_newline_utf8(utf)
+    -- 0xA        换行符（LF，Line Feed）
+    -- 0xD        回车符（CR，Carriage Return）
+    -- E2 80 A8   等于 0x2028，即行分隔符（Line Separator）
+    -- E2 80 A9   等于 0x2029，即段落分隔符（Paragraph Separator）
+    return (utf[1] == 0xA or utf[1] == 0xD or (utf[1] == 0xE2 and (utf[2] == 0x80 and (utf[3] == 0xA8 or utf[3] == 0xA9))))
+end
+
+local EOF = '\0'
+
+-- 定义 Lexer 的状态
+local LexerStateType = {
+    STATE_TEXT = 1,       -- 普通文本状态
+    STATE_EXPRESSION = 2, -- 普通表达式状态: {{...}}
+}
+
+-- 定义 Token 类型
+local TokenType = {
+    TOKEN_TEXT = 0x1000,  -- 普通文本
+    TOKEN_OPEN = 2,       -- {{
+    TOKEN_CLOSE = 3,      -- }}
+    TOKEN_IDENTIFIER = 4, -- 标识符
+    TOKEN_NUMBER = 5,     -- 数字 (如 42, 3.14)
+    TOKEN_STRING = 6,     -- 字符串 (如 "hello")
+    TOKEN_BOOLEAN = 7,    -- 布尔值 (如 #t 和 #f)
+    TOKEN_LPAREN = 8,     -- 左括号 (
+    TOKEN_RPAREN = 9,     -- 右括号 )
+    TOKEN_COMMENT = 10,   -- 注释 {{!-- --}}
+    TOKEN_DATA = 11,      -- 表示 @ 的类型
+    TOKEN_END = 12,       -- 输入结束
+}
+
+---@class Location
+local Location = {}
+Location.__index = Location
+
+---@param sr number|nil
+---@param sc number|nil
+---@param er number|nil
+---@param ec number|nil
+function Location:new(sr, sc, er, ec)
+    local obj = {
+        start_row = sr or 0,
+        start_col = sc or 0,
+        end_row = er or 0,
+        end_col = ec or 0,
+    }
+    setmetatable(obj, Location)
+    return obj
+end
+
+---@param state LexerState
+---@param start_row number
+---@param start_col number
+---@return Location
+function Location.make(state, start_row, start_col)
+    local current_row = state.current_row
+    local current_col = state.current_col > 0 and state.current_col - 1 or 0
+    return Location:new(start_row, start_col, current_row, current_col)
+end
+
+---@class Token
+---@field type number
+---@field text string
+---@field loc Location
+local Token = {}
+Token.__index = Token
+
+function Token:new(t, txt, l)
+    local obj = setmetatable({}, self)  -- 创建一个新的 Token 对象
+    obj.type = t or TokenType.TOKEN_END -- 默认类型为 TOKEN_END
+    obj.text = txt or ''                -- 默认文本为空字符串
+    obj.loc = l or Location:new()       -- 默认位置为 Location 的新实例
+    return obj
+end
+
+---@class LexerState
+---@field engine Lexer
+---@field index number
+---@field length number
+---@field state number
+---@field depth number
+---@field current_row number
+---@field current_col number
+---@field lasttoken Token
+---@field lexchar string
+---@field lexchar_utf8 table
+---@field utf8_length number
+local LexerState = {}
+LexerState.__index = LexerState
+
+function LexerState:new(engine)
+    local obj = {
+        engine = engine,                   -- Engine
+        index = 0,                         -- 当前字符的索引位置
+        length = #engine.source,           -- 模板字符串的长度
+        state = LexerStateType.STATE_TEXT, -- 当前 lexer 的状态
+        depth = 0,                         -- 当前 Scheme 表达式的嵌套深度
+        current_row = 1,                   -- 当前行号
+        current_col = 0,                   -- 当前列号
+        lasttoken = nil,                   -- 记录上一个 Token
+        lexchar = EOF,                     -- 当前字符
+        lexchar_utf8 = {},                 -- 当前字符的 UTF-8 编码
+        utf8_length = 0                    -- 当前字符的 UTF-8 编码长度
+    }
+    setmetatable(obj, LexerState)
+    return obj
+end
+
+---@class LexerImpl
+local y = {}
+
+---@param state LexerState
+function y.init_lex(state)
+    y.next(state)
+end
+
+---@param state LexerState
+function y.next(state)
+    if state.index >= state.length then
+        state.lexchar = EOF
+        return
+    end
+
+    local len = utf8_length(state.engine.source:byte(state.index + 1))
+    if len == 0 then
+        error('Invalid UTF-8 character at index ' .. tostring(state.index))
+    end
+
+    state.lexchar_utf8 = {}
+    for i = 1, len do
+        state.lexchar_utf8[i] = state.engine.source:byte(state.index + i)
+    end
+
+    state.lexchar = string.char(state.lexchar_utf8[1])
+    state.utf8_length = len
+    state.index = state.index + len
+
+    if state.lexchar == 13 and state.engine.source:byte(state.index + 1) == 10 then
+        state.index = state.index + 1
+    end
+
+    if is_newline_utf8(state.lexchar_utf8) then
+        state.current_row = state.current_row + 1
+        state.current_col = 0
+        state.lexchar = '\n'
+    else
+        state.current_col = state.current_col + 1
+    end
+end
+
+---@param state LexerState
+---@param ch string
+---@return boolean
+function y.accept(state, ch)
+    if state.lexchar == ch then
+        y.next(state)
+        return true
+    end
+    return false
+end
+
+---@param state LexerState
+---@param ch string
+function y.expect(state, ch)
+    if not y.accept(state, ch) then
+        error('Expected ' .. ch)
+    end
+end
+
+---@param state LexerState
+---@param str string
+---@return boolean
+function y.peek_next(state, str)
+    if state.index + #str > state.length then
+        return false
+    end
+    return state.engine.source:sub(state.index + 1, state.index + #str) == str
+end
+
+---@param state LexerState
+function y.skip_whitespace(state)
+    while state.lexchar:match('%s') do
+        y.next(state)
+    end
+end
+
+---@param state LexerState
+---@param increment number
+function y.update_index_and_position(state, increment)
+    for i = 1, increment do
+        if state.lexchar == EOF then
+            break
+        end
+        y.next(state)
+    end
+end
+
+---@param state LexerState
+---@return string
+function y.lexchar_utf8(state)
+    if state.utf8_length == 1 then
+        return state.lexchar
+    else
+        local result = ''
+        for i = 1, state.utf8_length do
+            result = result .. string.char(state.lexchar_utf8[i])
+        end
+        return result
+    end
+end
+
+---@param state LexerState
+---@return Token
+function y.lex_text(state)
+    local token = { type = 'TOKEN_TEXT', text = '' }
+    local start_row = state.current_row
+    local start_col = state.current_col
+
+    while state.lexchar ~= EOF do
+        local suffix = y.lexchar_utf8(state)
+        token.text = token.text .. suffix
+
+        if state.lexchar == '\n' then
+            break
+        end
+
+        -- 遇到特殊字符：{{、{{{、{{#、{{( 或 {{/
+        if y.peek_next(state, '{{') then
+            break -- 提前退出，准备解析表达式或注释
+        end
+        y.next(state)
+    end
+
+    token.loc = Location.make(state, start_row, start_col)
+    y.next(state)
+
+    return token
+end
+
+---@param state LexerState
+---@return Token
+function y.lex_close_expression(state)
+    local token = {}
+    local start_row = state.current_row
+    local start_col = state.current_col
+
+    assert(y.peek_next(state, '}'))
+    token.type = 'TOKEN_CLOSE'
+    state.depth = state.depth - 1
+    assert(state.depth == 0)
+    state.state = LexerStateType.STATE_TEXT
+    y.update_index_and_position(state, 2)
+
+    token.loc = Location.make(state, start_row, start_col)
+    return token
+end
+
+---@param state LexerState
+---@return Token
+function y.lex_open_expression(state)
+    local token = {}
+    local start_row = state.current_row
+    local start_col = state.current_col
+
+    ---@return boolean
+    local function valid_inline_scheme_start()
+        local pattern = '^{[%s}a-zA-Z#/%(]'
+        local msg = state.engine.source:sub(state.index + 1, state.index + 2)
+        return state.engine.source:sub(state.index + 1, state.index + 2):match(pattern) ~= nil
+    end
+
+    if y.peek_next(state, '{!--') then
+        -- 注释解析
+        token.type = 'TOKEN_COMMENT'
+        y.update_index_and_position(state, 5) -- 跳过注释开始符号 `{{!--`
+
+        while state.lexchar ~= EOF do
+            token.text = (token.text or '') .. y.lexchar_utf8(state)
+            if y.peek_next(state, '--}}') then
+                break
+            end
+            y.next(state)
+        end
+
+        if y.peek_next(state, '--}}') then
+            y.update_index_and_position(state, 5) -- 跳过注释结束符号 `--}}`
+        else
+            error('Unterminated comment at index ' .. tostring(state.index))
+        end
+        state.state = LexerStateType.STATE_TEXT -- 继续回到普通状态
+    elseif valid_inline_scheme_start() then
+        token.type = 'TOKEN_OPEN'
+        y.update_index_and_position(state, 2) -- 跳过 `{`
+        state.depth = state.depth + 1         -- 设置 Scheme 的嵌套深度
+        assert(state.depth == 1)
+        state.state = LexerStateType.STATE_EXPRESSION
+    else
+        error(string.format('Open Unexpected token: %s%s', state.lexchar, state.engine.source:sub(state.index + 1, state.index + 10)))
+    end
+
+    token.loc = Location.make(state, start_row, start_col)
+    return token
+end
+
+---@param state LexerState
+---@return Token
+function y.lex_inline_scheme_component(state)
+    local token = {}
+    local start_row = state.current_row
+    local start_col = state.current_col
+
+    y.skip_whitespace(state)
+
+    -- 左括号 -> Scheme 表示的 '('
+    if state.lexchar == '(' then
+        token.type = 'TOKEN_LPAREN'
+        token.text = '('
+        y.update_index_and_position(state, 1)
+        state.depth = state.depth + 1 -- Scheme 嵌套增加
+    elseif state.lexchar == ')' then
+        -- 右括号 -> Scheme 表示的 ')'
+        token.type = 'TOKEN_RPAREN'
+        token.text = ')'
+        y.update_index_and_position(state, 1)
+        state.depth = state.depth - 1 -- 减少嵌套深度
+    elseif state.lexchar:match('%d') then
+        -- 解析数字
+        token.type = 'TOKEN_NUMBER'
+        while state.lexchar:match('%d') or state.lexchar == '.' do
+            token.text = (token.text or '') .. state.lexchar
+            y.next(state)
+        end
+    elseif state.lexchar == '"' then
+        -- 解析字符串
+        token.type = 'TOKEN_STRING'
+        y.next(state)
+        while state.lexchar ~= '"' do
+            if state.lexchar == EOF or state.lexchar == '\n' then
+                error('Unterminated string literal at index ' .. tostring(state.index))
+            end
+            if y.accept(state, '\\') then
+                -- Escape sequence
+                if state.lexchar == 'n' then
+                    token.text = (token.text or '') .. '\n'
+                elseif state.lexchar == 't' then
+                    token.text = (token.text or '') .. '\t'
+                elseif state.lexchar == 'r' then
+                    token.text = (token.text or '') .. '\r'
+                elseif state.lexchar == '"' then
+                    token.text = (token.text or '') .. '"'
+                elseif state.lexchar == '\\' then
+                    token.text = (token.text or '') .. '\\'
+                else
+                    error('Invalid escape sequence at index ' .. tostring(state.index))
+                end
+            else
+                token.text = (token.text or '') .. y.lexchar_utf8(state)
+                y.next(state)
+            end
+        end
+        y.expect(state, '"')
+    elseif (state.lexchar == '#' and (y.peek_next(state, 't ') or y.peek_next(state, 'f '))) then
+        -- 解析布尔值
+        token.type = 'TOKEN_BOOLEAN'
+        token.text = state.lexchar               -- `#`
+        y.update_index_and_position(state, 1)
+        token.text = token.text .. state.lexchar -- `t` 或 `f`
+        y.update_index_and_position(state, 1)
+    elseif state.lexchar == '@' then
+        -- 检查是否为 @ 符号
+        token.type = 'TOKEN_DATA'
+        token.text = '@'
+        y.update_index_and_position(state, 1) -- 跳过 @
+    elseif state.lexchar == '}' and y.peek_next(state, '}') then
+        -- 检查表达式是否结束
+        return y.lex_close_expression(state)
+    else
+        -- 解析标识符或者操作符
+        local function is_identifier_start(ch)
+            return ch:match('%a') or ch:match('%d') or ch:match('[#/]')
+        end
+
+        local function is_identifier_part(ch)
+            return ch:match('%a') or ch:match('%d')
+        end
+
+        if is_identifier_start(state.lexchar) then
+            token.type = 'TOKEN_IDENTIFIER'
+            token.text = state.lexchar -- 第一个字符
+            y.next(state)
+            while is_identifier_part(state.lexchar) do
+                token.text = token.text .. state.lexchar
+                y.next(state)
+            end
+        else
+            error('Inline Unexpected token: ' .. state.engine.source:sub(state.index + 1, state.index + 10))
+        end
+    end
+
+    token.loc = Location.make(state, start_row, start_col)
+    return token
+end
+
+---@param state LexerState
+---@return Token
+function y.lex_expression(state)
+    -- 内联 Scheme 的处理
+    return y.lex_inline_scheme_component(state) -- 解析内联 Scheme 的内容
+end
+
+---@param state LexerState
+---@return Token
+function y.lexx(state)
+    if state.lexchar == EOF then
+        return { type = 'TOKEN_END' }
+    end
+
+    if state.state == LexerStateType.STATE_TEXT then
+        if state.lexchar == '{' then
+            if y.peek_next(state, '{') then
+                return y.lex_open_expression(state)
+            end
+        end
+        return y.lex_text(state) -- 处理普通文本
+    elseif state.state == LexerStateType.STATE_EXPRESSION then
+        return y.lex_expression(state)
+    else
+        return { type = 'TOKEN_END' }
+    end
+end
+
+---@param state LexerState
+---@return Token
+function y.lex(state)
+    state.lasttoken = y.lexx(state)
+    return state.lasttoken
+end
+
+---@param state LexerState
+---@return Token
+function y.lex_peek(state)
+    local s0 = deepcopy(state)
+    local l = y.lexx(s0)
+    return l
+end
+
+---@class Lexer
+---@field source string
+---@field state LexerState
+local Lexer = {}
+Lexer.__index = Lexer
+
+---@param source string
+function Lexer:new(source)
+    local obj = {
+        source = source,
+        state = LexerState:new(self)
+    }
+    setmetatable(obj, Lexer)
+    return obj
+end
+
+function Lexer:init()
+    y.init_lex(self.state)
+end
+
+---@return Token
+function Lexer:lex()
+    return y.lex(self.state)
+end
+
+---@return Token
+function Lexer:lex_peek()
+    return y.lex_peek(self.state)
+end
diff --git a/lua/fittencode/template.lua b/lua/fittencode/template.lua
new file mode 100644
index 0000000..e69de29