server: streaming of tool calls and thoughts when --jinja is on (#12379)

* add common_json w/ support for truncated json healing

* add common_chat_msg_diff

* partial common_chat_parse

* refactor parser w/ optionals

* server: wire chat diffs in stream mode

* fix trigger of thinking models (must happen after thoughts are closed)

* fix functionary v3.2 raw python!

* rename: common_chat_syntax (now contains format)

* rm common_regex.at_start

* don't return empty <think></think>

* accommodate yet another deepseek r1 distill fantasy syntax (`<｜tool▁calls｜>`)

* fix QwQ 32B tool call parsing after thoughts (hermes2)

* better logs for grammar triggers

* consume spaces after parse_json_tool_calls

* fix required tool calls w/ thinking models that have pre-opened thinking tags

* fix thinking model's initial trigger + test qwq's template

* run most test_tool_call tests in stream + non-stream modes

* make functionary v3.2 parsing more strict (differentiate first match from others)

* send final diff from server, to close off raw python arguments

* support partial content streaming in Generic mode

* tool-call: allow content prelude before hermes2 tool calls (for Qwen2.5)

* Update function-calling.md

* Update tool_bench.py

* chat-parser: remove input from exception (llm output may contain PII)

---------

Co-authored-by: ochafik <ochafik@google.com>
Co-authored-by: Olivier Chafik <ochafik@users.noreply.github.com>

tests/test-json-partial.cpp

@@ -0,0 +1,237 @@
+#include "common.h"
+#include "json-partial.h"
+#include <exception>
+#include <iostream>
+#include <stdexcept>
+
+template <class T> static void assert_equals(const T & expected, const T & actual) {
+  if (expected != actual) {
+      std::cerr << "Expected: " << expected << std::endl;
+      std::cerr << "Actual: " << actual << std::endl;
+      std::cerr << std::flush;
+      throw std::runtime_error("Test failed");
+  }
+}
+
+static void test_json_healing() {
+  auto parse = [](const std::string & str) {
+      std::cerr << "# Parsing: " << str << '\n';
+      std::string::const_iterator it = str.begin();
+      const auto end = str.end();
+      common_json out;
+      std::string healing_marker = "$llama.cpp.json$";
+      if (common_json_parse(it, end, healing_marker, out)) {
+          auto dump = out.json.dump();
+          std::cerr << "Parsed: " << dump << '\n';
+          std::cerr << "Magic: " << out.healing_marker.json_dump_marker << '\n';
+          std::string result;
+          if (!out.healing_marker.json_dump_marker.empty()) {
+              auto i = dump.find(out.healing_marker.json_dump_marker);
+              if (i == std::string::npos) {
+                  throw std::runtime_error("Failed to find magic in dump " + dump + " (magic: " + out.healing_marker.json_dump_marker + ")");
+              }
+              result = dump.substr(0, i);
+          } else {
+            result = dump;
+          }
+          std::cerr << "Result: " << result << '\n';
+          if (string_starts_with(str, result)) {
+            std::cerr << "Failure!\n";
+          }
+        //   return dump;
+      } else {
+        throw std::runtime_error("Failed to parse: " + str);
+      }
+
+  };
+  auto parse_all = [&](const std::string & str) {
+      for (size_t i = 1; i < str.size(); i++) {
+          parse(str.substr(0, i));
+      }
+  };
+  parse_all("{\"a\": \"b\"}");
+  parse_all("{\"hey\": 1, \"ho\\\"ha\": [1]}");
+
+  parse_all("[{\"a\": \"b\"}]");
+
+  auto test = [&](const std::vector<std::string> & inputs, const std::string & expected, const std::string & expected_marker) {
+      for (const auto & input : inputs) {
+        common_json out;
+        assert_equals(true, common_json_parse(input, "$foo", out));
+        assert_equals<std::string>(expected, out.json.dump());
+        assert_equals<std::string>(expected_marker, out.healing_marker.json_dump_marker);
+      }
+  };
+  // No healing needed:
+  test(
+    {
+      R"([{"a":"b"}, "y"])",
+    },
+    R"([{"a":"b"},"y"])",
+    ""
+  );
+  // Partial literals can't be healed:
+  test(
+    {
+      R"([1)",
+      R"([tru)",
+      R"([n)",
+      R"([nul)",
+      R"([23.2)",
+    },
+    R"(["$foo"])",
+    R"("$foo)"
+  );
+  test(
+    {
+      R"({"a": 1)",
+      R"({"a": tru)",
+      R"({"a": n)",
+      R"({"a": nul)",
+      R"({"a": 23.2)",
+    },
+    R"({"a":"$foo"})",
+    R"("$foo)"
+  );
+  test(
+    {
+      R"({)",
+    },
+    R"({"$foo":1})",
+    R"("$foo)"
+  );
+  test(
+    {
+      R"([)",
+    },
+    R"(["$foo"])",
+    R"("$foo)"
+  );
+  // Healing right after a full literal
+  test(
+    {
+      R"(1 )",
+    },
+    R"(1)",
+    ""
+  );
+  test(
+    {
+      R"(true)",
+      R"(true )",
+    },
+    R"(true)",
+    ""
+  );
+  test(
+    {
+      R"(null)",
+      R"(null )",
+    },
+    R"(null)",
+    ""
+  );
+  test(
+    {
+      R"([1 )",
+    },
+    R"([1,"$foo"])",
+    R"(,"$foo)"
+  );
+  test(
+    {
+      R"([{})",
+      R"([{} )",
+    },
+    R"([{},"$foo"])",
+    R"(,"$foo)"
+  );
+  test(
+    {
+      R"([true)",
+    },
+    // TODO: detect the true/false/null literal was complete
+    R"(["$foo"])",
+    R"("$foo)"
+  );
+  test(
+    {
+      R"([true )",
+    },
+    R"([true,"$foo"])",
+    R"(,"$foo)"
+  );
+  test(
+    {
+      R"([true,)",
+    },
+    R"([true,"$foo"])",
+    R"("$foo)"
+  );
+  // Test nesting
+  test(
+    {
+      R"([{"a": [{"b": [{)",
+    },
+    R"([{"a":[{"b":[{"$foo":1}]}]}])",
+    R"("$foo)"
+  );
+  test(
+    {
+      R"([{"a": [{"b": [)",
+    },
+    R"([{"a":[{"b":["$foo"]}]}])",
+    R"("$foo)"
+  );
+
+  test(
+    {
+      R"([{"a": "b"})",
+      R"([{"a": "b"} )",
+    },
+    R"([{"a":"b"},"$foo"])",
+    R"(,"$foo)"
+  );
+  test(
+    {
+      R"([{"a": "b"},)",
+      R"([{"a": "b"}, )",
+    },
+    R"([{"a":"b"},"$foo"])",
+    R"("$foo)"
+  );
+  test(
+    {
+      R"({ "code)",
+    },
+    R"({"code$foo":1})",
+    R"($foo)"
+  );
+  test(
+    {
+      R"({ "code\)",
+    },
+    R"({"code\\$foo":1})",
+    R"(\$foo)"
+  );
+  test(
+    {
+      R"({ "code")",
+    },
+    R"({"code":"$foo"})",
+    R"(:"$foo)"
+  );
+  test(
+    {
+      R"({ "key")",
+    },
+    R"({"key":"$foo"})",
+    R"(:"$foo)"
+  );
+}
+
+int main() {
+    test_json_healing();
+    std::cerr << "All tests passed.\n";
+    return 0;
+}