====== transformer-token原理 ======

===== tokenization在渲染jinja的模板代码 =====

<code>
{%- if tools %}
    <|im_start|>system
    {%- if messages[0]['role'] == 'system' %}
        {{ messages[0]['content'] }}
    {%- else %}
        You are a helpful assistant.
    {%- endif %}
    
# Tools

You may call one or more functions to assist with the user query.

You are provided with function signatures within <tools></tools> XML tags:
<tools>
{%- for tool in tools %}
    {{ tool | tojson }}
{%- endfor %}
</tools>

For each function call, return a json object with function name and arguments within <tool_call></tool_call> XML tags:
<tool_call>
{"name": <function-name>, "arguments": <args-json-object>}
</tool_call><|im_end|>
{%- else %}
    {%- if messages[0]['role'] == 'system' %}
        <|im_start|>system{{ messages[0]['content'] }}<|im_end|>
    {%- else %}
        <|im_start|>systemYou are a helpful assistant.<|im_end|>
    {%- endif %}
{%- endif %}

{%- for message in messages %}
    {%- if (message.role == "user") or (message.role == "system" and not loop.first) or (message.role == "assistant" and not message.tool_calls) %}
        <|im_start|>{{ message.role }}{{ message.content }}<|im_end|>
    {%- elif message.role == "assistant" %}
        <|im_start|>{{ message.role }}
        {%- if message.content %}
            {{ message.content }}
        {%- endif %}
        {%- for tool_call in message.tool_calls %}
            {%- if tool_call.function is defined %}
                {%- set tool_call = tool_call.function %}
            {%- endif %}
            {{
                '\n<tool_call>\n{"name": "' +
                tool_call.name +
                '", "arguments": ' +
                tool_call.arguments | tojson +
                '}\n</tool_call>'
            }}
        {%- endfor %}
        <|im_end|>
    {%- elif message.role == "tool" %}
        {%- if (loop.index0 == 0) or (messages[loop.index0 - 1].role != "tool") %}
            <|im_start|>user
        {%- endif %}
        {{
            '\n</tool_call>\n' +
            message.content +
            '\n</tool>'
        }}
        {%- if loop.last or (messages[loop.index0 + 1].role != "tool") %}
            <|im_end|>
        {%- endif %}
    {%- endif %}
{%- endfor %}

{%- if add_generation_prompt %}
    <|im_start|>assistant
{%- endif %}
</code>

在系统输入  You are a helpful assistant. 用户输入：你好，请介绍一下你自己。 的情况下，模板渲染的输出是：
<code>
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
你好，请介绍一下你自己。<|im_end|>
<|im_start|>assistant

</code>