Module qwen_xml 

Qwen-style XML tool-call parser.

Rewrites <tool_call>...</tool_call> markup — emitted by Qwen 2 / 2.5 / 3 family models in either the text or reasoning channel — into proper ToolCall values. Bytes outside of <tool_call> regions are forwarded verbatim on the channel they arrived on.

Two body dialects are accepted inside the wrapper, tried in order — see finalize_tool_call for the detail:

1. JSON — {"name":"foo","arguments":{...}} (Qwen 2 / 2.5).
2. Inner XML — <function=NAME><parameter=KEY>VALUE</parameter>...</function>, one or more back-to-back inside a single wrapper (Qwen 3 + --jinja, Hermes-style).

Chunk safety

Both the open marker (<tool_call>, 11 bytes) and the close marker (</tool_call>, 12 bytes) may straddle SSE chunk boundaries. The parser holds back at most CLOSE_MARKER.len() - 1 = 11 bytes per channel as a lookahead buffer. The buffered bytes are flushed on the next push or at ToolCallParser::finish.

Cross-channel handling

In practice a Qwen tool call appears entirely on one channel — either text (no reasoning split) or reasoning (when --reasoning-format is on). Each channel therefore maintains its own independent parser state (ChannelState) so that markup never crosses channels. The synthesised tool-call IDs share a single monotonic counter across both channels.

Structs

ChannelState 🔒

Per-channel scanning state. The text and reasoning channels each own one of these; they never share buffers.

QwenXmlParser

Parser for the Qwen XML tool-call dialect. See module docs.

Enums

Channel 🔒

Output channel selector — keeps scan channel-agnostic.

Constants

CLOSE 🔒

Close marker for a Qwen tool call.

OPEN 🔒

Open marker for a Qwen tool call.

Functions

finalize_tool_call 🔒

Parse the accumulated tool-call body and push the resulting ToolCalls (or a NormalizationError) onto out.

find_own_close 🔒

Find this tag’s own closing marker inside rest: the LAST occurrence of close before the next sibling next_open marker (or before the end of rest, if there is no next sibling).

forward 🔒

Append bytes to the channel-appropriate field of out.

parse_function_xml_body 🔒

Try to interpret body as one or more back-to-back Hermes/Qwen3 inner-XML tool calls: <function=NAME><parameter=KEY>VALUE</parameter>...</function>, repeated.

parse_json_body 🔒

Try to interpret body as a Qwen JSON tool call.

parse_param_value 🔒

Best-effort coercion of a <parameter> body to a JSON value. Falls back to a string literal when the body is not valid JSON.

partial_suffix_len 🔒

Largest n in [0, marker.len()) such that the last n bytes of buf are a prefix of marker. Used as the lookahead window for chunk-safe marker detection.