qwen3xml_tool_parser.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import ast
import json
from collections.abc import Sequence
from typing import Any
from xml.parsers.expat import ParserCreate

import regex as re

from vllm.entrypoints.chat_utils import make_tool_call_id
from vllm.entrypoints.openai.chat_completion.protocol import (
    ChatCompletionRequest,
)
from vllm.entrypoints.openai.engine.protocol import (
    DeltaFunctionCall,
    DeltaMessage,
    DeltaToolCall,
    ExtractedToolCallInformation,
    FunctionCall,
    ToolCall,
)
from vllm.logger import init_logger
from vllm.tokenizers import TokenizerLike
from vllm.tool_parsers.abstract_tool_parser import (
    Tool,
    ToolParser,
)

logger = init_logger(__name__)


class StreamingXMLToolCallParser:
    """
    Simplified streaming XML tool call parser
    Supports streaming input, parsing, and output
    """

    def __init__(self):
        self.reset_streaming_state()

        # Tool configuration information
        self.tools: list[Tool] | None = None
        self.tool_call_start_token: str = "<tool_call>"
        self.tool_call_end_token: str = "</tool_call>"
        self.function_start_token: str = "<function="
        self.function_end_token: str = "</function>"
        self.parameter_start_token: str = "<parameter="
        self.parameter_end_token: str = "</parameter>"

    def reset_streaming_state(self):
        """Reset streaming parsing state"""

        self.deltas = []
        # state for streaming
        self.tool_call_index = 0
        self.current_call_id = None
        self.last_completed_call_id = None
        self.current_function_name = None
        self.current_function_open = False
        self.parameters = {}
        self.current_param_name = None
        self.current_param_value = ""
        self.current_param_value_converted = ""
        self.current_param_is_first = False
        self.should_emit_end_newline = False
        self.start_quote_emitted = False

        self.streaming_buffer = ""
        self.last_processed_pos = 0

        self.text_content_buffer = ""

        # state for preprocessing and deferred parsing
        self._pre_inside_parameter = False
        self._pre_param_buffer = ""
        self._pre_current_param_name = None
        self.defer_current_parameter = False
        self.deferred_param_raw_value = ""

        # recreate parser
        self.parser = ParserCreate()
        self.setup_parser()

    def parse_single_streaming_chunks(self, xml_chunk: str) -> DeltaMessage:
        """
        Parse single streaming XML chunk and return Delta response
        This is the actual streaming interface that receives chunks
        one by one and maintains internal state

        Args:
            xml_chunk: Single XML chunk string
        Returns:
            DeltaMessage: Contains delta information generated by this chunk,
            returns empty response if no complete elements
        """
        # Record delta count before processing
        initial_delta_count = len(self.deltas)

        self.streaming_buffer += xml_chunk

        found_elements = self._process_complete_xml_elements()

        if found_elements:
            # If complete elements found, check if end events were missed
            # some tags may not have been triggered
            try:
                new_deltas = self.deltas[initial_delta_count:]
                # If this chunk contains </function>
                # but didn't generate '}', then complete it
                if (
                    self.current_call_id is not None
                    and self.function_end_token in xml_chunk
                ):
                    # - Added '}' (non-empty parameter ending)
                    # - Added '{}' (empty parameter function)
                    has_function_close = any(
                        (
                            td.tool_calls
                            and any(
                                (
                                    tc.function
                                    and tc.id == self.current_call_id
                                    and isinstance(tc.function.arguments, str)
                                    and (tc.function.arguments in ("}", "{}"))
                                )
                                for tc in td.tool_calls
                            )
                        )
                        for td in new_deltas
                    )
                    if not has_function_close:
                        # Close potentially unclosed element
                        if self.current_param_name:
                            self._end_element("parameter")
                        if self.current_function_name:
                            self._end_element("function")
                # If this chunk contains </tool_call>
                # but didn't generate final empty delta, then complete it
                if (
                    self.current_call_id is not None
                    and self.tool_call_end_token in xml_chunk
                ):
                    has_toolcall_close = any(
                        (
                            td.tool_calls
                            and any(
                                (
                                    tc.type == "function"
                                    and tc.function
                                    and tc.function.arguments == ""
                                    and tc.id == self.current_call_id
                                )
                                for tc in td.tool_calls
                            )
                        )
                        for td in new_deltas
                    )
                    if not has_toolcall_close:
                        # Close potentially unclosed element
                        if self.current_param_name:
                            self._end_element("parameter")
                        if self.current_function_name:
                            self._end_element("function")
                        self._end_element("tool_call")
            except Exception as e:
                logger.warning("Error with fallback parsing: %s", e)
            # Merge newly generated deltas into single response
            result_delta = self._merge_new_deltas_to_single_response(
                initial_delta_count
            )
            return result_delta
        else:
            # No complete elements, check if there's unoutput text content
            if self.text_content_buffer and self.tool_call_index == 0:
                # Has text content but no tool_call yet, output text content
                text_delta = DeltaMessage(content=self.text_content_buffer)
                self._emit_delta(text_delta)
                # Clear buffer to avoid duplicate output
                self.text_content_buffer = ""
                return text_delta

            # If this chunk contains end tags but wasn't triggered by parser,
            # manually complete end events
            # Only execute when still on the same call as when entered,
            # to prevent accidentally closing new calls
            # in multi <tool_call> scenarios
            if self.current_call_id is not None and (
                self.function_end_token in xml_chunk
                or self.tool_call_end_token in xml_chunk
            ):
                # Close potentially unclosed element
                if self.current_param_name:
                    self._end_element("parameter")
                if self.function_end_token in xml_chunk and self.current_function_name:
                    self._end_element("function")
                if self.tool_call_end_token in xml_chunk:
                    self._end_element("tool_call")
                # Return the merged delta result generated by this fallback
                result_delta = self._merge_new_deltas_to_single_response(
                    initial_delta_count
                )
                return result_delta

            # No complete elements, return empty response
            return DeltaMessage(content=None)

    def _escape_xml_special_chars(self, text: str) -> str:
        """
        Escape XML special characters
        Args:
            text: Original text
        Returns:
            Escaped text
        """
        xml_escapes = {
            "&": "&amp;",
            "<": "&lt;",
            ">": "&gt;",
            '"': "&quot;",
            "'": "&apos;",
        }

        for char, escape in xml_escapes.items():
            text = text.replace(char, escape)

        return text

    def _process_complete_xml_elements(self) -> bool:
        """
        Process complete XML elements in buffer

        Returns:
            bool: Whether complete elements were found and processed
        """
        found_any = False

        while self.last_processed_pos < len(self.streaming_buffer):
            # Find next complete xml element
            element, end_pos = self._find_next_complete_element(self.last_processed_pos)
            if element is None:
                # No complete element found, wait for more data
                break

            # Check if this element should be skipped
            if self._should_skip_element(element):
                self.last_processed_pos = end_pos
                continue

            # Found complete XML element, process it
            try:
                preprocessed_element = self._preprocess_xml_chunk(element)
                # Check if this is the first tool_call start
                if (
                    (
                        preprocessed_element.strip().startswith("<tool_call>")
                        or preprocessed_element.strip().startswith("<function name=")
                    )
                    and self.tool_call_index == 0
                ) and self.text_content_buffer:
                    # First tool_call starts,
                    # output previously collected text content first
                    text_delta = DeltaMessage(content=self.text_content_buffer)
                    self._emit_delta(text_delta)
                    # Clear buffer for potential subsequent text content
                    self.text_content_buffer = ""

                # If a new tool_call starts and
                # there are already completed tool_calls
                if (
                    preprocessed_element.strip().startswith("<tool_call>")
                    and self.tool_call_index > 0
                    and self.current_call_id
                ):
                    # Reset parser state but preserve generated deltas
                    if self.current_param_name:
                        self._end_element("parameter")
                    if self.current_function_open or self.current_function_name:
                        self._end_element("function")
                    # Output final tool_call tail delta
                    final_delta = DeltaMessage(
                        role=None,
                        content=None,
                        reasoning=None,
                        tool_calls=[
                            DeltaToolCall(
                                index=self.tool_call_index - 1,
                                id=self.current_call_id,
                                type="function",
                                function=DeltaFunctionCall(name=None, arguments=""),
                            )
                        ],
                    )
                    self._emit_delta(final_delta)
                    # Reset XML parser and current call state
                    self._reset_xml_parser_after_tool_call()
                # Parse preprocessed element
                self.parser.Parse(preprocessed_element, False)
                found_any = True

            except Exception as e:
                logger.warning("Error when parsing XML elements: %s", e)

            # Update processed position
            self.last_processed_pos = end_pos

        return found_any

    def _should_skip_element(self, element: str) -> bool:
        """
        Determine whether an element should be skipped

        Args:
            element: Element to evaluate

        Returns:
            bool: True means should skip, False means should process
        """

        # If it's a tool_call XML tag, don't skip
        if (
            element.startswith(self.tool_call_start_token)
            or element.startswith(self.function_start_token)
            or element.startswith(self.parameter_start_token)
        ):
            return False

        # If currently not parsing tool calls and not blank,
        # collect this text instead of skipping
        # Only process other XML elements after tool_call appears,
        # otherwise treat as plain text
        if self.current_call_id is None and element:
            # Collect text content to buffer
            self.text_content_buffer += element
            return True  # Still skip, but content has been collected

        # If currently parsing tool calls,
        # this might be parameter value, don't skip
        if self.current_call_id is not None:
            return False

        # Skip blank content
        return not element

    def _find_next_complete_element(self, start_pos: int) -> tuple[str | None, int]:
        """
        Find next complete XML element from specified position

        Args:
            start_pos: Position to start searching

        Returns:
            (Complete element string, element end position),
            returns (None, start_pos) if no complete element found
        """
        buffer = self.streaming_buffer[start_pos:]

        if not buffer:
            return None, start_pos

        if buffer.startswith("<"):
            # Need to ensure no new < appears,
            # find the nearest one between < and >
            tag_end = buffer.find("<", 1)
            tag_end2 = buffer.find(">", 1)
            if tag_end != -1 and tag_end2 != -1:
                # Next nearest is <
                if tag_end < tag_end2:
                    return buffer[:tag_end], start_pos + tag_end
                # Next nearest is >, means found XML element
                else:
                    return buffer[: tag_end2 + 1], start_pos + tag_end2 + 1
            elif tag_end != -1:
                return buffer[:tag_end], start_pos + tag_end
            elif tag_end2 != -1:
                return buffer[: tag_end2 + 1], start_pos + tag_end2 + 1
            else:
                # If currently not parsing tool calls (entering a tool_call),
                # check if starts with <tool_call> or <function=
                if self.current_call_id is None:
                    # Check if might be start of <tool_call>
                    if buffer == "<tool_call>"[: len(buffer)]:
                        # Might be start of <tool_call>, wait for more data
                        return None, start_pos
                    elif (
                        buffer.startswith("<function=")
                        or buffer == "<function="[: len(buffer)]
                    ):
                        # Might be start of <function=, wait for more data
                        # to get the complete function tag
                        return None, start_pos
                    else:
                        # Not start of <tool_call> or <function=, treat as text
                        return buffer, start_pos + len(buffer)
                else:
                    # When parsing tool calls,
                    # wait for more data to get complete tag
                    return None, start_pos
        else:
            # Find text content (until next < or buffer end)
            next_tag_pos = buffer.find("<")
            if next_tag_pos != -1:
                # Found text content
                text_content = buffer[:next_tag_pos]
                return text_content, start_pos + next_tag_pos
            else:
                # Buffer end is all text, process
                # (no longer wait for more data)
                remaining = buffer
                return remaining, start_pos + len(remaining)

    def _merge_new_deltas_to_single_response(self, initial_count: int) -> DeltaMessage:
        """
        Merge newly generated deltas from this processing
        into a single DeltaMessage

        Args:
            initial_count: Delta count before processing

        Returns:
            Merged DeltaMessage containing all newly generated delta information
        """
        if len(self.deltas) <= initial_count:
            return DeltaMessage(content=None)

        # Get newly generated deltas
        new_deltas = self.deltas[initial_count:]

        if len(new_deltas) == 1:
            # Only one new delta, return directly
            return new_deltas[0]

        # Merge multiple new deltas
        merged_tool_calls: list[DeltaToolCall] = []
        merged_content: str = ""

        for delta in new_deltas:
            if delta.content:
                merged_content += delta.content
            if delta.tool_calls:
                # For tool_calls, we need to intelligently merge arguments
                for tool_call in delta.tool_calls:
                    # Find if there's already a tool_call with the same call_id
                    existing_call = None
                    for existing in merged_tool_calls:
                        if existing.id == tool_call.id:
                            existing_call = existing
                            break

                    if existing_call and existing_call.function:
                        # Merge to existing tool_call
                        if tool_call.function and tool_call.function.name:
                            existing_call.function.name = tool_call.function.name
                        if (
                            tool_call.function
                            and tool_call.function.arguments is not None
                        ):
                            if existing_call.function.arguments is None:
                                existing_call.function.arguments = ""

                            # For streaming JSON parameters,
                            # simply concatenate in order
                            new_args = tool_call.function.arguments
                            existing_call.function.arguments += new_args
                        if tool_call.type:
                            existing_call.type = tool_call.type
                    else:
                        # Add new tool_call
                        merged_tool_calls.append(tool_call)

        return DeltaMessage(
            content=merged_content if merged_content else None,
            tool_calls=merged_tool_calls,
        )

    def _preprocess_xml_chunk(self, chunk: str) -> str:
        """
        Preprocess XML chunk, handle non-standard formats,
        and escape special characters

        Args:
            chunk: Original XML chunk

        Returns:
            Processed XML chunk
        """

        # Check if this is a tool_call related element
        is_tool_call = False
        if chunk.startswith(self.tool_call_start_token) or chunk.startswith(
            self.tool_call_end_token
        ):
            is_tool_call = True
        if chunk.startswith(self.function_start_token) or chunk.startswith(
            self.function_end_token
        ):
            is_tool_call = True
        if chunk.startswith(self.parameter_start_token) or chunk.startswith(
            self.parameter_end_token
        ):
            is_tool_call = True
        # Handle <function=name> format -> <function name="name">
        processed = re.sub(r"<function=([^>]+)>", r'<function name="\1">', chunk)
        # Handle <parameter=name> format -> <parameter name="name">
        processed = re.sub(r"<parameter=([^>]+)>", r'<parameter name="\1">', processed)

        original_chunk = chunk
        # If in parameter value accumulation mode
        if self._pre_inside_parameter:
            # Parameter end: output accumulated raw text
            # safely then return </parameter>
            if processed.startswith("</parameter>"):
                body_text = self._pre_param_buffer
                # Trigger deferred parsing mode
                # literal_eval+json output in end_element
                self.defer_current_parameter = True
                self.deferred_param_raw_value = body_text
                # Clean up state
                self._pre_inside_parameter = False
                self._pre_param_buffer = ""
                self._pre_current_param_name = None
                safe_text = self._escape_xml_special_chars(body_text)
                return f"{safe_text}</parameter>"
            else:
                # If this is the first block of content after entering parameter
                # evaluate if deferred parsing is needed;
                # If not needed, exit accumulation mode
                # and pass through directly
                if self._pre_param_buffer == "":
                    # Get current parameter type
                    param_type = (
                        self._get_param_type(self._pre_current_param_name)
                        if self._pre_current_param_name
                        else "string"
                    )
                    # Only these types need deferred parsing to
                    # handle Python literals containing single quotes
                    is_object_type = param_type in ["object"]
                    is_complex_type = (
                        param_type in ["array", "arr", "sequence"]
                        or param_type.startswith("dict")
                        or param_type.startswith("list")
                    )

                    # Only delay when contains container symbols
                    # and has single quotes and is complex type
                    has_container_hint = (
                        ("[" in original_chunk)
                        or ("{" in original_chunk)
                        or ("(" in original_chunk)
                    )

                    # Determine if deferred parsing is needed
                    need_defer = False
                    if is_complex_type:
                        # Complex type, always need deferred parsing
                        need_defer = True
                    elif (
                        is_object_type
                        and has_container_hint
                        and ("'" in original_chunk)
                    ):
                        # Object type with container symbols
                        # and single quotes, need deferred parsing
                        need_defer = True

                    if not need_defer:
                        # No need for deferred parsing,
                        # exit parameter mode directly
                        self._pre_inside_parameter = False
                        return self._escape_xml_special_chars(original_chunk)
                self._pre_param_buffer += original_chunk
                return ""

        # Parameter start: enable accumulation
        if processed.startswith("<parameter name="):
            m = re.match(r'<parameter name="([^"]+)">', processed)
            if m:
                self._pre_current_param_name = m.group(1)
            self._pre_inside_parameter = True
            self._pre_param_buffer = ""
            return processed

        # If processed doesn't contain special_token, escape processed
        # This is because XML parsing encounters special characters
        # and reports errors, so escaping is needed
        if not is_tool_call:
            processed = self._escape_xml_special_chars(processed)
        return processed

    def _emit_delta(self, delta: DeltaMessage):
        """Emit Delta response (streaming output)"""
        self.deltas.append(delta)

    def _auto_close_open_parameter_if_needed(self, incoming_tag: str | None = None):
        """Before starting to process new elements,
        if there are unclosed tags from before,
        automatically complete their endings to the parser.
        - If there are unclosed parameters,
        it's equivalent to feeding `</parameter>`
        - When about to start a new function or tool_call,
        if there are unclosed functions, complete `</function>`.
        - When about to start a new tool_call,
        if there are unclosed tool_calls, complete `</tool_call>`.
        """
        # First close unclosed parameters
        if self.current_param_name:
            self._end_element("parameter")

        # If about to start new function or tool_call,
        # and there are unclosed functions, close function first
        if incoming_tag in ("function", "tool_call") and self.current_function_name:
            self._end_element("function")

        # If about to start new tool_call,
        # and there are unclosed tool_calls, close tool_call first
        if incoming_tag == "tool_call" and self.current_call_id:
            self._end_element("tool_call")

    def _start_element(self, name: str, attrs: dict[str, str]):
        """Handle XML start element events"""

        if name == "root":
            return

        if name == "tool_call":
            # Before opening new tool_call,
            # automatically complete previous unclosed tags
            self._auto_close_open_parameter_if_needed("tool_call")

            self.parameters = {}
            self.current_call_id = make_tool_call_id()
            self.current_param_is_first = True
            self.tool_call_index += 1
        elif name.startswith("function") or (name == "function"):
            # If missing tool_call, manually complete
            if not self.current_call_id:
                self._start_element("tool_call", {})
            # Before opening new function,
            # automatically complete previous unclosed tags (parameter/function)
            self._auto_close_open_parameter_if_needed("function")
            function_name = self._extract_function_name(name, attrs)
            self.current_function_name = function_name
            self.current_function_open = True
            if function_name:
                delta = DeltaMessage(
                    tool_calls=[
                        DeltaToolCall(
                            index=self.tool_call_index - 1,
                            id=self.current_call_id,
                            type="function",
                            function=DeltaFunctionCall(
                                name=function_name, arguments=""
                            ),
                        )
                    ]
                )
                self._emit_delta(delta)
        elif name.startswith("parameter") or (name == "parameter"):
            # If previous parameter hasn't ended normally,
            # complete its end first, then start new parameter
            self._auto_close_open_parameter_if_needed("parameter")
            param_name = self._extract_parameter_name(name, attrs)
            self.current_param_name = param_name
            self.current_param_value = ""
            self.current_param_value_converted = ""
            self.start_quote_emitted = False  # Reset start quote flag

            # Only output parameter name and colon,
            # don't output quotes
            # decide after parameter value type is determined
            if param_name:
                if not self.parameters:
                    # First parameter
                    # start JSON, only output parameter name and colon
                    json_start = f'{{"{param_name}": '
                    delta = DeltaMessage(
                        tool_calls=[
                            DeltaToolCall(
                                index=self.tool_call_index - 1,
                                id=self.current_call_id,
                                type="function",
                                function=DeltaFunctionCall(
                                    name=None, arguments=json_start
                                ),
                            )
                        ]
                    )
                    self._emit_delta(delta)
                    self.current_param_is_first = True
                else:
                    # Subsequent parameters
                    # add comma and parameter name, no quotes
                    json_continue = f', "{param_name}": '
                    delta = DeltaMessage(
                        tool_calls=[
                            DeltaToolCall(
                                index=self.tool_call_index - 1,
                                id=self.current_call_id,
                                type="function",
                                function=DeltaFunctionCall(
                                    name=None, arguments=json_continue
                                ),
                            )
                        ]
                    )
                    self._emit_delta(delta)
                    self.current_param_is_first = False

    def _char_data(self, data: str):
        """Handle XML character data events"""
        if data and self.current_param_name:
            # If preprocessing stage determines deferred parsing is needed,
            # only cache character data, no streaming output
            if self.defer_current_parameter:
                original_data = data
                if self.should_emit_end_newline:
                    original_data = "\n" + original_data
                    self.should_emit_end_newline = False
                if original_data.endswith("\n"):
                    self.should_emit_end_newline = True
                    original_data = original_data[:-1]
                self.current_param_value += original_data
                return

            param_type = self._get_param_type(self.current_param_name)

            # Check if this is the first time receiving data for this parameter
            # If this is the first packet of data and starts with \n, remove \n
            if not self.current_param_value and data.startswith("\n"):
                data = data[1:]

            # Output start quote for string type (if not already output)
            if (
                param_type in ["string", "str", "text", "varchar", "char", "enum"]
                and not self.start_quote_emitted
            ):
                quote_delta = DeltaMessage(
                    tool_calls=[
                        DeltaToolCall(
                            index=self.tool_call_index - 1,
                            id=self.current_call_id,
                            type="function",
                            function=DeltaFunctionCall(name=None, arguments='"'),
                        )
                    ]
                )
                self._emit_delta(quote_delta)
                self.start_quote_emitted = True

            if not data:
                return

            original_data = data
            # Delay output of trailing newline
            if self.should_emit_end_newline:
                original_data = "\n" + original_data
                self.should_emit_end_newline = False
            if original_data.endswith("\n"):
                self.should_emit_end_newline = True
                original_data = original_data[:-1]
            self.current_param_value += original_data

            # convert parameter value by param_type
            converted_value = self._convert_param_value(
                self.current_param_value, param_type
            )
            output_data = self._convert_for_json_streaming(converted_value, param_type)

            delta_data = output_data[len(self.current_param_value_converted) :]
            self.current_param_value_converted = output_data

            delta = DeltaMessage(
                tool_calls=[
                    DeltaToolCall(
                        index=self.tool_call_index - 1,
                        id=self.current_call_id,
                        type="function",
                        function=DeltaFunctionCall(name=None, arguments=delta_data),
                    )
                ]
            )
            self._emit_delta(delta)

    def _end_element(self, name: str):
        """Handle XML end element events"""

        if name == "root":
            return

        # If function or tool_call ends and there are still unclosed parameters,
        # complete parameter end first
        if (
            name.startswith("function") or name == "function" or name == "tool_call"
        ) and self.current_param_name:
            self._auto_close_open_parameter_if_needed()

        if (
            name.startswith("parameter") or name == "parameter"
        ) and self.current_param_name:
            # End current parameter
            param_name = self.current_param_name
            param_value = self.current_param_value

            # If in deferred parsing mode,
            # perform overall parsing on raw content
            # accumulated in preprocessing stage and output once
            if self.defer_current_parameter:
                raw_text = (
                    self.deferred_param_raw_value
                    if self.deferred_param_raw_value
                    else param_value
                )
                parsed_value = None
                output_arguments = None
                try:
                    # If previously delayed trailing newline,
                    # add it back before parsing
                    if self.should_emit_end_newline:
                        raw_for_parse = raw_text + "\n"
                    else:
                        raw_for_parse = raw_text
                    parsed_value = ast.literal_eval(raw_for_parse)
                    output_arguments = json.dumps(parsed_value, ensure_ascii=False)
                except Exception:
                    # Fallback: output as string as-is
                    output_arguments = json.dumps(raw_text, ensure_ascii=False)
                    parsed_value = raw_text

                delta = DeltaMessage(
                    tool_calls=[
                        DeltaToolCall(
                            index=self.tool_call_index - 1,
                            id=self.current_call_id,
                            type="function",
                            function=DeltaFunctionCall(
                                name=None, arguments=output_arguments
                            ),
                        )
                    ]
                )
                self._emit_delta(delta)

                # Clean up and store
                self.should_emit_end_newline = False
                self.parameters[param_name] = parsed_value
                self.current_param_name = None
                self.current_param_value = ""
                self.current_param_value_converted = ""
                self.start_quote_emitted = False
                self.defer_current_parameter = False
                self.deferred_param_raw_value = ""
                return

            param_type = self._get_param_type(param_name)

            # convert complete parameter value by param_type
            converted_value = self._convert_param_value(param_value, param_type)

            # Decide whether to add end quote based on parameter type
            if param_type in ["string", "str", "text", "varchar", "char", "enum"]:
                # For empty string parameters, need special handling
                if not param_value and not self.start_quote_emitted:
                    # No start quote output,
                    # directly output complete empty string
                    delta = DeltaMessage(
                        tool_calls=[
                            DeltaToolCall(
                                index=self.tool_call_index - 1,
                                id=self.current_call_id,
                                type="function",
                                function=DeltaFunctionCall(name=None, arguments='""'),
                            )
                        ]
                    )
                    self._emit_delta(delta)
                else:
                    # Non-empty parameter value, output end quote
                    delta = DeltaMessage(
                        tool_calls=[
                            DeltaToolCall(
                                index=self.tool_call_index - 1,
                                id=self.current_call_id,
                                type="function",
                                function=DeltaFunctionCall(name=None, arguments='"'),
                            )
                        ]
                    )
                    self._emit_delta(delta)

            self.should_emit_end_newline = False
            # Store converted value
            self.parameters[param_name] = converted_value
            self.current_param_name = None
            self.current_param_value = ""
            self.current_param_value_converted = ""
            self.start_quote_emitted = False

        elif name.startswith("function") or name == "function":
            # if there are parameters, close JSON object
            if self.parameters:
                delta = DeltaMessage(
                    tool_calls=[
                        DeltaToolCall(
                            index=self.tool_call_index - 1,
                            id=self.current_call_id,
                            type="function",
                            function=DeltaFunctionCall(name=None, arguments="}"),
                        )
                    ]
                )
                self._emit_delta(delta)
            # return empty object
            else:
                delta = DeltaMessage(
                    tool_calls=[
                        DeltaToolCall(
                            index=self.tool_call_index - 1,
                            id=self.current_call_id,
                            type="function",
                            function=DeltaFunctionCall(name=None, arguments="{}"),
                        )
                    ]
                )
                self._emit_delta(delta)
            self.current_function_open = False

        elif name == "tool_call":
            # Before ending tool_call,
            # ensure function is closed to complete missing right brace
            if self.current_function_open:
                # If there are still unclosed parameters, close them first
                if self.current_param_name:
                    self._end_element("parameter")
                # Close function, ensure output '}' or '{}'
                self._end_element("function")
            # Final Delta
            delta = DeltaMessage(
                tool_calls=[
                    DeltaToolCall(
                        index=self.tool_call_index - 1,
                        id=self.current_call_id,
                        type="function",
                        function=DeltaFunctionCall(name=None, arguments=""),
                    )
                ]
            )
            self._emit_delta(delta)

            # Check if there's text content to output (between tool_calls)
            if self.text_content_buffer.strip():
                text_delta = DeltaMessage(content=self.text_content_buffer)
                self._emit_delta(text_delta)

            self._reset_xml_parser_after_tool_call()

    def setup_parser(self):
        """Set up XML parser event handlers"""
        self.parser.buffer_text = True
        self.parser.StartElementHandler = self._start_element
        self.parser.EndElementHandler = self._end_element
        self.parser.CharacterDataHandler = self._char_data

    def set_tools(self, tools: list[Tool] | None):
        """Set tool configuration information"""
        self.tools = tools

    def _extract_function_name(self, name: str, attrs: dict[str, str]) -> str | None:
        """Extract function name from various formats"""
        if attrs and "name" in attrs:
            return attrs["name"]

        if "=" in name:
            parts = name.split("=", 1)
            if len(parts) == 2 and parts[0] == "function":
                return parts[1]

        return None

    def _extract_parameter_name(self, name: str, attrs: dict[str, str]) -> str | None:
        """Extract parameter name from various formats"""
        if attrs and "name" in attrs:
            return attrs["name"]

        if "=" in name:
            parts = name.split("=", 1)
            if len(parts) == 2 and parts[0] == "parameter":
                return parts[1]

        return None

    def _get_param_type(self, param_name: str) -> str:
        """Get parameter type based on tool configuration, defaults to string
        Args:
            param_name: Parameter name

        Returns:
            Parameter type
        """
        if not self.tools or not self.current_function_name:
            return "string"

        for tool in self.tools:
            if not hasattr(tool, "type") or not (
                hasattr(tool, "function") and hasattr(tool.function, "name")
            ):
                continue
            if (
                tool.type == "function"
                and tool.function.name == self.current_function_name
            ):
                if not hasattr(tool.function, "parameters"):
                    return "string"
                params = tool.function.parameters
                if isinstance(params, dict) and "properties" in params:
                    properties = params["properties"]
                    if param_name in properties and isinstance(
                        properties[param_name], dict
                    ):
                        return self.repair_param_type(
                            str(properties[param_name].get("type", "string"))
                        )
                elif isinstance(params, dict) and param_name in params:
                    param_config = params[param_name]
                    if isinstance(param_config, dict):
                        return self.repair_param_type(
                            str(param_config.get("type", "string"))
                        )
                break
        return "string"

    def repair_param_type(self, param_type: str) -> str:
        """Repair unknown parameter types by treating them as string
        Args:
            param_type: Parameter type

        Returns:
            Repaired parameter type
        """
        if (
            param_type in ["string", "str", "text", "varchar", "char", "enum"]
            or param_type.startswith("int")
            or param_type.startswith("uint")
            or param_type.startswith("long")
            or param_type.startswith("short")
            or param_type.startswith("unsigned")
            or param_type.startswith("num")
            or param_type.startswith("float")
            or param_type in ["boolean", "bool", "binary"]
            or (
                param_type in ["object", "array", "arr", "sequence"]
                or param_type.startswith("dict")
                or param_type.startswith("list")
            )
        ):
            return param_type
        else:
            return "string"

    def _convert_param_value(self, param_value: str, param_type: str) -> Any:
        """Convert value based on parameter type
        Args:
            param_value: Parameter value
            param_type: Parameter type

        Returns:
            Converted value
        """
        if param_value.lower() == "null":
            return None

        param_type = param_type.strip().lower()
        if param_type in ["string", "str", "text", "varchar", "char", "enum"]:
            return param_value
        elif (
            param_type.startswith("int")
            or param_type.startswith("uint")
            or param_type.startswith("long")
            or param_type.startswith("short")
            or param_type.startswith("unsigned")
        ):
            try:
                return int(param_value)
            except (ValueError, TypeError):
                logger.warning(
                    "Parsed value '%s' of parameter '%s' is not an integer "
                    "in tool '%s', degenerating to string.",
                    param_value,
                )
            return param_value
        elif param_type.startswith("num") or param_type.startswith("float"):
            try:
                float_param_value: float = float(param_value)
                return (
                    float_param_value
                    if float_param_value - int(float_param_value) != 0
                    else int(float_param_value)
                )
            except (ValueError, TypeError):
                logger.warning(
                    "Parsed value '%s' of parameter '%s' is not a float "
                    "in tool '%s', degenerating to string.",
                    param_value,
                )
            return param_value
        elif param_type in ["boolean", "bool", "binary"]:
            param_value = param_value.lower()
            return param_value == "true"
        else:
            return param_value

    def _convert_for_json_streaming(self, converted_value: Any, param_type: str) -> str:
        """Convert converted_value based on
        whether it's empty and if type is string
        Args:
            converted_value: Converted value
            param_type: Parameter type

        Returns:
            Converted string for streaming output
        """
        # Check if value is empty, but exclude numeric 0
        if converted_value is None or converted_value == "":
            return ""

        if param_type in ["string", "str", "text", "varchar", "char", "enum"]:
            # String type, remove double quotes
            return json.dumps(converted_value, ensure_ascii=False)[1:-1]
        else:
            # Non-string type, return complete JSON string
            if not isinstance(converted_value, str):
                return json.dumps(converted_value, ensure_ascii=False)
            else:
                return converted_value

    def _reset_xml_parser_after_tool_call(self):
        """
        Each tool_call is treated as a separate XML document,
        so we need to reset the parser after each tool_call.
        """

        # recreate XML parser
        self.parser = ParserCreate()
        self.setup_parser()

        # Reset current tool_call state
        if self.current_call_id:
            self.last_completed_call_id = self.current_call_id
        self.current_call_id = None
        self.current_function_name = None
        self.current_function_open = False
        self.parameters = {}
        self.current_param_name = None
        self.current_param_value = ""
        self.current_param_value_converted = ""
        self.current_param_is_first = False
        self.should_emit_end_newline = False
        self.start_quote_emitted = False
        self.text_content_buffer = ""

        # Reset preprocessing and deferred parsing state
        self._pre_inside_parameter = False
        self._pre_param_buffer = ""
        self._pre_current_param_name = None
        self.defer_current_parameter = False
        self.deferred_param_raw_value = ""


class Qwen3XMLToolParser(ToolParser):
    def __init__(self, tokenizer: TokenizerLike, tools: list[Tool] | None = None):
        super().__init__(tokenizer, tools)
        self.parser = StreamingXMLToolCallParser()

        # Add missing attributes for compatibility with serving_chat.py
        self.prev_tool_call_arr: list[dict] = []
        self.streamed_args_for_tool: list[str] = []

        logger.info(
            "vLLM Successfully import tool parser %s !", self.__class__.__name__
        )

    def extract_tool_calls(
        self,
        model_output: str,
        request: ChatCompletionRequest,
    ) -> ExtractedToolCallInformation:
        self.parser.reset_streaming_state()
        # Reset tool call tracking arrays for new extraction
        self.prev_tool_call_arr = []
        self.streamed_args_for_tool = []
        if request:
            self.parser.set_tools(request.tools)
        result = self.parser.parse_single_streaming_chunks(model_output)
        if not result.tool_calls:
            return ExtractedToolCallInformation(
                tool_calls=[],
                tools_called=False,
                content=result.content,
            )
        else:
            tool_calls = []
            for tool_call in result.tool_calls:
                if tool_call.function and tool_call.function.name:
                    tool_calls.append(
                        ToolCall(
                            id=tool_call.id,
                            type=tool_call.type,
                            function=FunctionCall(
                                name=tool_call.function.name,
                                arguments=tool_call.function.arguments,
                            ),
                        )
                    )

                    # Update tool call tracking arrays for compatibility
                    tool_index = (
                        tool_call.index
                        if tool_call.index is not None
                        else len(self.prev_tool_call_arr) - 1
                    )

                    # Ensure we have enough entries in our tracking arrays
                    while len(self.prev_tool_call_arr) <= tool_index:
                        self.prev_tool_call_arr.append({"name": "", "arguments": ""})
                    while len(self.streamed_args_for_tool) <= tool_index:
                        self.streamed_args_for_tool.append("")

                    # Update tool call information
                    self.prev_tool_call_arr[tool_index]["name"] = (
                        tool_call.function.name
                    )
                    self.prev_tool_call_arr[tool_index]["arguments"] = (
                        tool_call.function.arguments
                    )

                    # Update streamed arguments
                    if tool_call.function.arguments:
                        self.streamed_args_for_tool[tool_index] = (
                            tool_call.function.arguments
                        )

            return ExtractedToolCallInformation(
                tool_calls=tool_calls,
                tools_called=len(tool_calls) > 0,
                content=result.content,
            )

    def extract_tool_calls_streaming(
        self,
        previous_text: str,
        current_text: str,
        delta_text: str,
        previous_token_ids: Sequence[int],
        current_token_ids: Sequence[int],
        delta_token_ids: Sequence[int],
        request: ChatCompletionRequest,
    ) -> DeltaMessage | None:
        if not previous_text:
            self.parser.reset_streaming_state()
            # Reset tool call tracking arrays for new streaming session
            self.prev_tool_call_arr = []
            self.streamed_args_for_tool = []
            if request:
                self.parser.set_tools(request.tools)

        # Model sometimes outputs separately causing delta_text to be empty.
        # If there were tool_calls before and all current tool_calls have ended,
        # return an empty tool_call for outer streaming output
        # to correctly output tool_call field
        if not delta_text and delta_token_ids:
            open_calls = current_text.count(
                self.parser.tool_call_start_token
            ) - current_text.count(self.parser.tool_call_end_token)
            if (
                open_calls == 0
                and self.parser.tool_call_index > 0
                or not self.parser.tool_call_index
                and current_text
            ):
                return DeltaMessage(content="")
            return None

        # Parse the delta text and get the result
        result = self.parser.parse_single_streaming_chunks(delta_text)

        # Update tool call tracking arrays based on incremental parsing results
        if result and result.tool_calls:
            for tool_call in result.tool_calls:
                if tool_call.function:
                    tool_index = (
                        tool_call.index
                        if tool_call.index is not None
                        else len(self.prev_tool_call_arr) - 1
                    )

                    # Ensure we have enough entries in our tracking arrays
                    while len(self.prev_tool_call_arr) <= tool_index:
                        self.prev_tool_call_arr.append({"name": "", "arguments": ""})
                    while len(self.streamed_args_for_tool) <= tool_index:
                        self.streamed_args_for_tool.append("")

                    # Update tool name if provided
                    if tool_call.function.name:
                        self.prev_tool_call_arr[tool_index]["name"] = (
                            tool_call.function.name
                        )

                    # Update arguments incrementally
                    if tool_call.function.arguments is not None:
                        # Concatenate the incremental arguments
                        # to the existing streamed arguments
                        self.prev_tool_call_arr[tool_index]["arguments"] += (
                            tool_call.function.arguments
                        )
                        self.streamed_args_for_tool[tool_index] += (
                            tool_call.function.arguments
                        )
        return result