[router] add tool parser base structure and partial json parser (#9482)

sgl-router/src/tool_parser/traits.rs

@@ -0,0 +1,35 @@
+use crate::tool_parser::{
+    errors::ToolParserResult,
+    state::ParseState,
+    types::{StreamResult, ToolCall},
+};
+use async_trait::async_trait;
+
+/// Core trait for all tool parsers
+#[async_trait]
+pub trait ToolParser: Send + Sync {
+    /// Parse complete tool calls from final output
+    async fn parse_complete(&self, output: &str) -> ToolParserResult<Vec<ToolCall>>;
+
+    /// Parse tool calls from model output (streaming)
+    async fn parse_incremental(
+        &self,
+        chunk: &str,
+        state: &mut ParseState,
+    ) -> ToolParserResult<StreamResult>;
+
+    /// Check if text contains tool calls in this parser's format
+    fn detect_format(&self, text: &str) -> bool;
+}
+
+/// Trait for partial JSON parsing
+pub trait PartialJsonParser: Send + Sync {
+    /// Parse potentially incomplete JSON
+    fn parse(&self, input: &str) -> ToolParserResult<(serde_json::Value, usize)>;
+
+    /// Check if JSON is complete
+    fn is_complete(&self, input: &str) -> bool;
+
+    /// Get the maximum parsing depth
+    fn max_depth(&self) -> usize;
+}