Copy minja from google/minja@58f0ca6

Author: ochafik

common/chat-template.hpp

@@ -0,0 +1,247 @@
+/*
+    Copyright 2024 Google LLC
+
+    Use of this source code is governed by an MIT-style
+    license that can be found in the LICENSE file or at
+    https://opensource.org/licenses/MIT.
+*/
+// SPDX-License-Identifier: MIT
+#pragma once
+
+#include "minja.hpp"
+#include <json.hpp>
+#include <string>
+#include <vector>
+
+using json = nlohmann::ordered_json;
+
+namespace minja {
+
+class chat_template {
+  public:
+
+  private:
+    bool supports_tools_ = true;
+    // Meta-Llama-3.1-8B-Instruct's template expects arguments to be an object.
+    // Most other templates (and OpenAI's API) expect the arguments object to be stringified.
+    bool requires_object_arguments_ = false;
+    bool supports_system_role_ = true;
+    bool supports_parallel_tool_calls_ = false;
+    std::string source_;
+    std::string bos_token_;
+    std::string eos_token_;
+    std::shared_ptr<minja::TemplateNode> template_root_;
+
+    std::string try_render(
+        const nlohmann::ordered_json & messages,
+        const nlohmann::ordered_json & tools,
+        bool add_generation_prompt,
+        const nlohmann::ordered_json & extra_context = nlohmann::ordered_json()) const
+    {
+        try {
+            auto prompt = apply(messages, tools, add_generation_prompt, extra_context);
+            // fprintf(stderr, "Prompt: %s\n", prompt.c_str());
+            return prompt;
+        } catch (const std::exception & e) {
+            // fprintf(stderr, "Error: %s\n", e.what());
+            return "";
+        }
+    }
+
+  public:
+    chat_template(const std::string & source, const std::string & bos_token, const std::string & eos_token)
+        : source_(source), bos_token_(bos_token), eos_token_(eos_token)
+    {
+        template_root_ = minja::Parser::parse(source_, {
+            /* .trim_blocks = */ true,
+            /* .lstrip_blocks = */ true,
+            /* .keep_trailing_newline = */ false,
+        });
+        supports_tools_ = source.find("tools") != std::string::npos;
+
+        auto renders_string_arguments =
+            try_render({
+                {
+                    {"role", "user"},
+                    {"content", "Hey"}
+                },
+                {
+                    {"role", "assistant"},
+                    {"tool_calls", json::array({
+                        {
+                            {"id", "call_1___"},
+                            {"type", "function"},
+                            {"function", {
+                                {"arguments", "{\"code\": \"print('Hello, World!')\"}"},
+                                {"name", "ipython"},
+                            }},
+                        },
+                    })},
+                }
+            }, {}, false).find("{\"code\": \"print") != std::string::npos;
+        if (!renders_string_arguments) {
+            auto renders_object_arguments =
+                try_render({
+                    {
+                        {"role", "user"},
+                        {"content", "Hey"}
+                    },
+                    {
+                        {"role", "assistant"},
+                        {"tool_calls", json::array({
+                            {
+                                {"id", "call_1___"},
+                                {"type", "function"},
+                                {"function", {
+                                    {"arguments", {
+                                        {"code", "print('Hello, World!')"},
+                                    }},
+                                    {"name", "ipython"},
+                                }},
+                            },
+                        })},
+                    }
+                }, {}, false).find("{\"code\": \"print") != std::string::npos;
+            requires_object_arguments_ = renders_object_arguments;
+        }
+        supports_parallel_tool_calls_ = source.find("tool_call_id") != std::string::npos;
+
+        supports_system_role_ = try_render({
+            {{"role", "system"}, {"content", "<System Needle>"}},
+            {{"role", "user"},   {"content", "Hey"}}
+        }, {}, false).find("<System Needle>") != std::string::npos;
+    }
+
+    const std::string & source() const { return source_; }
+    bool supports_tools() const { return supports_tools_; }
+    bool supports_parallel_tool_calls() const { return supports_parallel_tool_calls_; }
+
+    std::string apply(
+        const nlohmann::ordered_json & messages,
+        const nlohmann::ordered_json & tools,
+        bool add_generation_prompt,
+        const nlohmann::ordered_json & extra_context = nlohmann::ordered_json()) const
+    {
+        json actual_messages;
+
+        // First, "fix" messages so they have a chance to be rendered correctly by the template
+
+        if (requires_object_arguments_ || !supports_system_role_ || !supports_tools_) {
+            actual_messages = json::array();
+
+            std::string pending_system;
+            auto flush_sys = [&]() {
+                if (!pending_system.empty()) {
+                    actual_messages.push_back({
+                        {"role", "user"},
+                        {"content", pending_system},
+                    });
+                    pending_system.clear();
+                }
+            };
+            for (const auto & message_ : messages) {
+                auto message = message_;
+                if (!message.contains("role") || !message.contains("content")) {
+                    throw std::runtime_error("message must have 'role' and 'content' fields: " + message.dump());
+                }
+                std::string role = message.at("role");
+
+                if (message.contains("tool_calls")) {
+                    if (requires_object_arguments_ || !supports_tools_) {
+                        for (auto & tool_call : message.at("tool_calls")) {
+                            if (tool_call["type"] == "function") {
+                                auto & function = tool_call.at("function");
+                                std::string arguments = function.at("arguments");
+                                function["arguments"] = json::parse(arguments);
+                            }
+                        }
+                    }
+                    if (!supports_tools_) {
+                        auto content = message.at("content");
+                        auto tool_calls = json::array();
+                        for (const auto & tool_call : message.at("tool_calls")) {
+                            if (tool_call.at("type") != "function") {
+                                continue;
+                            }
+                            const auto & function = tool_call.at("function");
+                            auto tc = json {
+                                {"name", function.at("name")},
+                                {"arguments", function.at("arguments")},
+                            };
+                            if (tool_call.contains("id")) {
+                                tc["id"] = tool_call["id"];
+                            }
+                            tool_calls.push_back(tc);
+                        }
+                        auto obj = json {
+                            {"tool_calls", tool_calls},
+                        };
+                        if (!content.is_null() && content != "") {
+                            obj["content"] = content;
+                        }
+                        message["content"] = obj.dump(2);
+                        message.erase("tool_calls");
+                    }
+                }
+                if (!supports_tools_ && role == "tool") {
+                    message["role"] = "user";
+                    auto obj = json {
+                        {"tool_response", {
+                            {"tool", message.at("name")},
+                            {"content", message.at("content")},
+                        }},
+                    };
+                    if (message.contains("tool_call_id")) {
+                        obj["tool_response"]["tool_call_id"] = message.at("tool_call_id");
+                    }
+                    message["content"] = obj.dump(2);
+                    message.erase("name");
+                }
+
+                if (!message["content"].is_null() && !supports_system_role_) {
+                    std::string content = message.at("content");
+                    if (role == "system") {
+                        if (!pending_system.empty()) pending_system += "\n";
+                        pending_system += content;
+                        continue;
+                    } else {
+                        if (role == "user") {
+                            if (!pending_system.empty()) {
+                                message["content"] = pending_system + (content.empty() ? "" : "\n" + content);
+                                pending_system.clear();
+                            }
+                        } else {
+                            flush_sys();
+                        }
+                    }
+                }
+                actual_messages.push_back(message);
+            }
+            flush_sys();
+        } else {
+            actual_messages = messages;
+        }
+
+        auto context = minja::Context::make(json({
+            {"messages", actual_messages},
+            {"add_generation_prompt", add_generation_prompt},
+            {"bos_token", bos_token_},
+            {"eos_token", eos_token_},
+        }));
+
+        if (!tools.is_null()) {
+            auto tools_val = minja::Value(tools);
+            context->set("tools", tools_val);
+        }
+        if (!extra_context.is_null()) {
+            for (auto & kv : extra_context.items()) {
+                minja::Value val(kv.value());
+                context->set(kv.key(), val);
+            }
+        }
+
+        return template_root_->render(context);
+    }
+};
+
+}  // namespace minja