[router] add dsr1, kimi, and qwen reasoning parser (#9353)

sgl-router/src/reasoning_parser/parsers/qwen3.rs

@@ -0,0 +1,178 @@
+// Qwen3 specific reasoning parser.
+// This parser starts with in_reasoning=false, requiring an explicit
+// start token to enter reasoning mode.
+
+use crate::reasoning_parser::parsers::BaseReasoningParser;
+use crate::reasoning_parser::traits::{ParseError, ParserConfig, ParserResult, ReasoningParser};
+
+/// Qwen3 reasoning parser.
+///
+/// This parser requires explicit <think> tokens to enter reasoning mode
+/// (in_reasoning=false initially).
+pub struct Qwen3Parser {
+    base: BaseReasoningParser,
+}
+
+impl Qwen3Parser {
+    /// Create a new Qwen3 parser.
+    pub fn new() -> Self {
+        let config = ParserConfig {
+            think_start_token: "<think>".to_string(),
+            think_end_token: "</think>".to_string(),
+            stream_reasoning: true,
+            max_buffer_size: 65536,
+            initial_in_reasoning: false, // Requires explicit start token
+        };
+
+        Self {
+            base: BaseReasoningParser::new(config).with_model_type("qwen3".to_string()),
+        }
+    }
+}
+
+impl Default for Qwen3Parser {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl ReasoningParser for Qwen3Parser {
+    fn detect_and_parse_reasoning(&mut self, text: &str) -> Result<ParserResult, ParseError> {
+        self.base.detect_and_parse_reasoning(text)
+    }
+
+    fn parse_reasoning_streaming_incremental(
+        &mut self,
+        text: &str,
+    ) -> Result<ParserResult, ParseError> {
+        self.base.parse_reasoning_streaming_incremental(text)
+    }
+
+    fn reset(&mut self) {
+        self.base.reset()
+    }
+
+    fn model_type(&self) -> &str {
+        self.base.model_type()
+    }
+}
+
+/// QwenThinking parser - variant that assumes reasoning from start.
+///
+/// This is for qwen*thinking models that behave like DeepSeek-R1.
+pub struct QwenThinkingParser {
+    base: BaseReasoningParser,
+}
+
+impl QwenThinkingParser {
+    /// Create a new QwenThinking parser.
+    pub fn new() -> Self {
+        let config = ParserConfig {
+            think_start_token: "<think>".to_string(),
+            think_end_token: "</think>".to_string(),
+            stream_reasoning: true,
+            max_buffer_size: 65536,
+            initial_in_reasoning: true, // Assumes reasoning from start
+        };
+
+        Self {
+            base: BaseReasoningParser::new(config).with_model_type("qwen_thinking".to_string()),
+        }
+    }
+}
+
+impl Default for QwenThinkingParser {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl ReasoningParser for QwenThinkingParser {
+    fn detect_and_parse_reasoning(&mut self, text: &str) -> Result<ParserResult, ParseError> {
+        self.base.detect_and_parse_reasoning(text)
+    }
+
+    fn parse_reasoning_streaming_incremental(
+        &mut self,
+        text: &str,
+    ) -> Result<ParserResult, ParseError> {
+        self.base.parse_reasoning_streaming_incremental(text)
+    }
+
+    fn reset(&mut self) {
+        self.base.reset()
+    }
+
+    fn model_type(&self) -> &str {
+        self.base.model_type()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_qwen3_initial_state() {
+        let mut parser = Qwen3Parser::new();
+
+        // Should NOT treat text as reasoning without start token
+        let result = parser
+            .detect_and_parse_reasoning("This is normal content")
+            .unwrap();
+        assert_eq!(result.normal_text, "This is normal content");
+        assert_eq!(result.reasoning_text, "");
+    }
+
+    #[test]
+    fn test_qwen3_with_tokens() {
+        let mut parser = Qwen3Parser::new();
+
+        // Should extract reasoning with proper tokens
+        let result = parser
+            .detect_and_parse_reasoning("<think>reasoning</think>answer")
+            .unwrap();
+        assert_eq!(result.normal_text, "answer");
+        assert_eq!(result.reasoning_text, "reasoning");
+    }
+
+    #[test]
+    fn test_qwen_thinking_initial_state() {
+        let mut parser = QwenThinkingParser::new();
+
+        // Should treat text as reasoning even without start token
+        let result = parser
+            .detect_and_parse_reasoning("This is reasoning content")
+            .unwrap();
+        assert_eq!(result.normal_text, "");
+        assert_eq!(result.reasoning_text, "This is reasoning content");
+    }
+
+    #[test]
+    fn test_qwen3_streaming() {
+        let mut parser = Qwen3Parser::new();
+
+        // First chunk - normal text (no start token yet)
+        let result1 = parser
+            .parse_reasoning_streaming_incremental("normal text ")
+            .unwrap();
+        assert_eq!(result1.normal_text, "normal text ");
+        assert_eq!(result1.reasoning_text, "");
+
+        // Second chunk - enters reasoning
+        let result2 = parser
+            .parse_reasoning_streaming_incremental("<think>reasoning")
+            .unwrap();
+        assert_eq!(result2.normal_text, "");
+        assert_eq!(result2.reasoning_text, "reasoning");
+    }
+
+    #[test]
+    fn test_model_types() {
+        let qwen3 = Qwen3Parser::new();
+        assert_eq!(qwen3.model_type(), "qwen3");
+
+        let qwen_thinking = QwenThinkingParser::new();
+        assert_eq!(qwen_thinking.model_type(), "qwen_thinking");
+    }
+}