[router] add mistral tool parser (#9622)

Co-authored-by: Chang Su <chang.s.su@oracle.com>

sgl-router/src/tool_parser/json_parser.rs

@@ -7,7 +7,7 @@ use crate::tool_parser::{
     partial_json::PartialJson,
     state::ParseState,
     traits::ToolParser,
-    types::{FunctionCall, StreamResult, ToolCall},
+    types::{FunctionCall, StreamResult, TokenConfig, ToolCall},
 };
 
 /// JSON format parser for tool calls
@@ -19,12 +19,8 @@ use crate::tool_parser::{
 ///
 /// Supports configurable token markers for different models
 pub struct JsonParser {
-    /// Token(s) that mark the start of tool calls
+    /// Token configuration for parsing
-    start_tokens: Vec<String>,
+    token_config: TokenConfig,
-    /// Token(s) that mark the end of tool calls
-    end_tokens: Vec<String>,
-    /// Separator between multiple tool calls (reserved for future use)
-    _separator: String,
     /// Parser for handling incomplete JSON during streaming
     partial_json: PartialJson,
     /// Regex patterns for extracting content between tokens
@@ -34,23 +30,18 @@ pub struct JsonParser {
 impl JsonParser {
     /// Create a new JSON parser with default configuration
     pub fn new() -> Self {
-        Self::with_config(
+        Self::with_config(TokenConfig {
-            vec![], // No wrapper tokens by default
+            start_tokens: vec![],
-            vec![],
+            end_tokens: vec![],
-            ", ".to_string(),
+            separator: ", ".to_string(),
-        )
+        })
     }
 
     /// Create a parser with custom token configuration
-    pub fn with_config(
+    pub fn with_config(config: TokenConfig) -> Self {
-        start_tokens: Vec<String>,
-        end_tokens: Vec<String>,
-        separator: String,
-    ) -> Self {
         // Build extraction patterns for each token pair
-        let extractors = start_tokens
+        let extractors: Vec<Regex> = config
-            .iter()
+            .iter_pairs()
-            .zip(end_tokens.iter())
             .filter_map(|(start, end)| {
                 if !start.is_empty() && !end.is_empty() {
                     // Use (?s) flag to enable DOTALL mode so . matches newlines
@@ -64,9 +55,7 @@ impl JsonParser {
             .collect();
 
         Self {
-            start_tokens,
+            token_config: config,
-            end_tokens,
-            _separator: separator,
             partial_json: PartialJson::default(),
             extractors,
         }
@@ -74,26 +63,90 @@ impl JsonParser {
 
     /// Extract JSON content from text, handling wrapper tokens if configured
     fn extract_json_content<'a>(&self, text: &'a str) -> &'a str {
-        let mut content = text.trim();
+        let mut content = text;
 
-        // Try each extractor pattern
+        // Try each extractor pattern (for tokens with both start and end)
         for extractor in &self.extractors {
             if let Some(captures) = extractor.captures(content) {
                 if let Some(matched) = captures.get(1) {
-                    content = matched.as_str().trim();
+                    return matched.as_str().trim();
-                    break;
                 }
             }
         }
 
         // Handle special case where there's a start token but no end token
-        for (start, end) in self.start_tokens.iter().zip(self.end_tokens.iter()) {
+        for (start, end) in self.token_config.iter_pairs() {
             if !start.is_empty() && end.is_empty() {
-                content = content.strip_prefix(start).unwrap_or(content);
+                // Find the start token and extract everything after it
+                if let Some(pos) = content.find(start) {
+                    content = &content[pos + start.len()..];
+                    return content.trim();
+                }
             }
         }
 
-        content
+        content.trim()
+    }
+
+    /// Try to extract a JSON object or array from text that may contain other content
+    fn extract_json_from_text(&self, text: &str) -> Option<String> {
+        // Look for JSON object starting with {
+        if let Some(start) = text.find('{') {
+            let mut depth = 0;
+            let mut in_string = false;
+            let mut escape_next = false;
+
+            for (i, ch) in text[start..].char_indices() {
+                if escape_next {
+                    escape_next = false;
+                    continue;
+                }
+
+                match ch {
+                    '\\' if in_string => escape_next = true,
+                    '"' if !in_string => in_string = true,
+                    '"' if in_string => in_string = false,
+                    '{' if !in_string => depth += 1,
+                    '}' if !in_string => {
+                        depth -= 1;
+                        if depth == 0 {
+                            return Some(text[start..start + i + 1].to_string());
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
+
+        // Look for JSON array starting with [
+        if let Some(start) = text.find('[') {
+            let mut depth = 0;
+            let mut in_string = false;
+            let mut escape_next = false;
+
+            for (i, ch) in text[start..].char_indices() {
+                if escape_next {
+                    escape_next = false;
+                    continue;
+                }
+
+                match ch {
+                    '\\' if in_string => escape_next = true,
+                    '"' if !in_string => in_string = true,
+                    '"' if in_string => in_string = false,
+                    '[' if !in_string => depth += 1,
+                    ']' if !in_string => {
+                        depth -= 1;
+                        if depth == 0 {
+                            return Some(text[start..start + i + 1].to_string());
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
+
+        None
     }
 
     /// Parse a single JSON object into a ToolCall
@@ -167,13 +220,16 @@ impl JsonParser {
     /// Check if text contains potential tool call markers
     fn has_tool_markers(&self, text: &str) -> bool {
         // If no start tokens configured, check for JSON structure
-        if self.start_tokens.is_empty() {
+        if self.token_config.start_tokens.is_empty() {
             // For JSON, we just need to see the start of an object or array
             return text.contains('{') || text.contains('[');
         }
 
         // Check for any start token
-        self.start_tokens.iter().any(|token| text.contains(token))
+        self.token_config
+            .start_tokens
+            .iter()
+            .any(|token| text.contains(token))
     }
 }
 
@@ -193,6 +249,15 @@ impl ToolParser for JsonParser {
         match serde_json::from_str::<Value>(json_content) {
             Ok(value) => self.parse_json_value(&value),
             Err(_) => {
+                // If no wrapper tokens configured and parse failed,
+                // try to extract JSON from mixed text
+                if self.token_config.start_tokens.is_empty() {
+                    if let Some(extracted) = self.extract_json_from_text(text) {
+                        if let Ok(value) = serde_json::from_str::<Value>(&extracted) {
+                            return self.parse_json_value(&value);
+                        }
+                    }
+                }
                 // Not valid JSON, return empty
                 Ok(vec![])
             }
@@ -341,11 +406,11 @@ mod tests {
 
     #[tokio::test]
     async fn test_parse_with_wrapper_tokens() {
-        let parser = JsonParser::with_config(
+        let parser = JsonParser::with_config(TokenConfig {
-            vec!["<tool>".to_string()],
+            start_tokens: vec!["<tool>".to_string()],
-            vec!["</tool>".to_string()],
+            end_tokens: vec!["</tool>".to_string()],
-            ", ".to_string(),
+            separator: ", ".to_string(),
-        );
+        });
 
         let input = r#"<tool>{"name": "test", "arguments": {}}</tool>"#;
         let result = parser.parse_complete(input).await.unwrap();

sgl-router/src/tool_parser/mistral_parser.rs

@@ -0,0 +1,347 @@
+use async_trait::async_trait;
+use serde_json::Value;
+
+use crate::tool_parser::{
+    errors::{ToolParserError, ToolParserResult},
+    partial_json::PartialJson,
+    state::ParseState,
+    traits::ToolParser,
+    types::{FunctionCall, StreamResult, ToolCall},
+};
+
+/// Mistral format parser for tool calls
+///
+/// Handles the Mistral-specific format:
+/// `[TOOL_CALLS] [{"name": "func", "arguments": {...}}, ...]`
+///
+/// Features:
+/// - Bracket counting for proper JSON array extraction
+/// - Support for multiple tool calls in a single array
+/// - String-aware parsing to handle nested brackets in JSON
+pub struct MistralParser {
+    /// Parser for handling incomplete JSON during streaming
+    partial_json: PartialJson,
+}
+
+impl MistralParser {
+    /// Create a new Mistral parser
+    pub fn new() -> Self {
+        Self {
+            partial_json: PartialJson::default(),
+        }
+    }
+
+    /// Extract JSON array using bracket counting
+    ///
+    /// Handles nested brackets in JSON content by tracking:
+    /// - String boundaries (quotes)
+    /// - Escape sequences
+    /// - Bracket depth
+    fn extract_json_array<'a>(&self, text: &'a str) -> Option<&'a str> {
+        const BOT_TOKEN: &str = "[TOOL_CALLS] [";
+
+        // Find the start of the token
+        let start_idx = text.find(BOT_TOKEN)?;
+
+        // Start from the opening bracket after [TOOL_CALLS]
+        // The -1 is to include the opening bracket that's part of the token
+        let json_start = start_idx + BOT_TOKEN.len() - 1;
+
+        let mut bracket_count = 0;
+        let mut in_string = false;
+        let mut escape_next = false;
+
+        let bytes = text.as_bytes();
+
+        for i in json_start..text.len() {
+            let char = bytes[i];
+
+            if escape_next {
+                escape_next = false;
+                continue;
+            }
+
+            if char == b'\\' {
+                escape_next = true;
+                continue;
+            }
+
+            if char == b'"' && !escape_next {
+                in_string = !in_string;
+                continue;
+            }
+
+            if !in_string {
+                if char == b'[' {
+                    bracket_count += 1;
+                } else if char == b']' {
+                    bracket_count -= 1;
+                    if bracket_count == 0 {
+                        // Found the matching closing bracket
+                        return Some(&text[json_start..=i]);
+                    }
+                }
+            }
+        }
+
+        // Incomplete array (no matching closing bracket found)
+        None
+    }
+
+    /// Parse tool calls from a JSON array
+    fn parse_json_array(&self, json_str: &str) -> ToolParserResult<Vec<ToolCall>> {
+        let value: Value = serde_json::from_str(json_str)
+            .map_err(|e| ToolParserError::ParsingFailed(e.to_string()))?;
+
+        let mut tools = Vec::new();
+
+        if let Value::Array(arr) = value {
+            for (index, item) in arr.iter().enumerate() {
+                if let Some(tool) = self.parse_single_object(item, index)? {
+                    tools.push(tool);
+                }
+            }
+        } else {
+            // Single object case (shouldn't happen with Mistral format, but handle it)
+            if let Some(tool) = self.parse_single_object(&value, 0)? {
+                tools.push(tool);
+            }
+        }
+
+        Ok(tools)
+    }
+
+    /// Parse a single JSON object into a ToolCall
+    fn parse_single_object(&self, obj: &Value, index: usize) -> ToolParserResult<Option<ToolCall>> {
+        let name = obj.get("name").and_then(|v| v.as_str());
+
+        if let Some(name) = name {
+            // Get arguments - Mistral uses "arguments" key
+            let empty_obj = Value::Object(serde_json::Map::new());
+            let args = obj.get("arguments").unwrap_or(&empty_obj);
+
+            // Convert arguments to JSON string
+            let arguments = serde_json::to_string(args)
+                .map_err(|e| ToolParserError::ParsingFailed(e.to_string()))?;
+
+            // Generate ID with index for multiple tools
+            let id = format!("mistral_call_{}", index);
+
+            Ok(Some(ToolCall {
+                id,
+                r#type: "function".to_string(),
+                function: FunctionCall {
+                    name: name.to_string(),
+                    arguments,
+                },
+            }))
+        } else {
+            Ok(None)
+        }
+    }
+
+    /// Check if text contains Mistral tool markers
+    fn has_tool_markers(&self, text: &str) -> bool {
+        text.contains("[TOOL_CALLS]")
+    }
+}
+
+impl Default for MistralParser {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+#[async_trait]
+impl ToolParser for MistralParser {
+    async fn parse_complete(&self, text: &str) -> ToolParserResult<Vec<ToolCall>> {
+        // Check if text contains Mistral format
+        if !self.has_tool_markers(text) {
+            return Ok(vec![]);
+        }
+
+        // Extract JSON array from Mistral format
+        if let Some(json_array) = self.extract_json_array(text) {
+            self.parse_json_array(json_array)
+        } else {
+            // Markers present but no complete array found
+            Ok(vec![])
+        }
+    }
+
+    async fn parse_incremental(
+        &self,
+        chunk: &str,
+        state: &mut ParseState,
+    ) -> ToolParserResult<StreamResult> {
+        state.buffer.push_str(chunk);
+
+        // Check if we have the start marker
+        if !self.has_tool_markers(&state.buffer) {
+            return Ok(StreamResult::Incomplete);
+        }
+
+        // Try to extract complete JSON array
+        if let Some(json_array) = self.extract_json_array(&state.buffer) {
+            // Parse with partial JSON to handle incomplete content
+            match self.partial_json.parse_value(json_array) {
+                Ok((value, consumed)) => {
+                    // Check if we have a complete JSON structure
+                    if consumed == json_array.len() {
+                        // Complete JSON, parse tool calls
+                        let tools = if let Value::Array(arr) = value {
+                            let mut result = Vec::new();
+                            for (index, item) in arr.iter().enumerate() {
+                                if let Some(tool) = self.parse_single_object(item, index)? {
+                                    result.push(tool);
+                                }
+                            }
+                            result
+                        } else {
+                            vec![]
+                        };
+
+                        if !tools.is_empty() {
+                            // Clear buffer since we consumed everything
+                            state.buffer.clear();
+
+                            // Return the first tool (simplified for Phase 3)
+                            // Full multi-tool streaming will be implemented later
+                            if let Some(tool) = tools.into_iter().next() {
+                                return Ok(StreamResult::ToolComplete(tool));
+                            }
+                        }
+                    } else {
+                        // Partial JSON - try to extract tool name for streaming
+                        if let Value::Array(arr) = value {
+                            if let Some(first_tool) = arr.first() {
+                                if let Some(name) = first_tool.get("name").and_then(|v| v.as_str())
+                                {
+                                    // Check if we've already sent the name
+                                    if !state.in_string {
+                                        state.in_string = true; // Use as flag for "name sent"
+                                        return Ok(StreamResult::ToolName {
+                                            index: 0,
+                                            name: name.to_string(),
+                                        });
+                                    }
+
+                                    // Check for arguments
+                                    if let Some(args) = first_tool.get("arguments") {
+                                        if let Ok(args_str) = serde_json::to_string(args) {
+                                            return Ok(StreamResult::ToolArguments {
+                                                index: 0,
+                                                arguments: args_str,
+                                            });
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+                Err(_) => {
+                    // Failed to parse even as partial JSON
+                    // Keep buffering
+                }
+            }
+        }
+
+        Ok(StreamResult::Incomplete)
+    }
+
+    fn detect_format(&self, text: &str) -> bool {
+        // Check if text contains Mistral-specific markers
+        if self.has_tool_markers(text) {
+            // Try to extract and validate the array
+            if let Some(json_array) = self.extract_json_array(text) {
+                // Check if it's valid JSON
+                if let Ok(value) = serde_json::from_str::<Value>(json_array) {
+                    // Check if it contains tool-like structures
+                    match value {
+                        Value::Array(ref arr) => arr.iter().any(|v| {
+                            v.as_object().is_some_and(|o| {
+                                o.contains_key("name") && o.contains_key("arguments")
+                            })
+                        }),
+                        Value::Object(ref obj) => {
+                            obj.contains_key("name") && obj.contains_key("arguments")
+                        }
+                        _ => false,
+                    }
+                } else {
+                    false
+                }
+            } else {
+                // Has markers but no complete array - might be streaming
+                true
+            }
+        } else {
+            false
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test]
+    async fn test_parse_mistral_format() {
+        let parser = MistralParser::new();
+        let input = r#"[TOOL_CALLS] [{"name": "get_weather", "arguments": {"location": "Paris", "units": "celsius"}}]"#;
+
+        let result = parser.parse_complete(input).await.unwrap();
+        assert_eq!(result.len(), 1);
+        assert_eq!(result[0].function.name, "get_weather");
+        assert!(result[0].function.arguments.contains("Paris"));
+    }
+
+    #[tokio::test]
+    async fn test_parse_multiple_tools() {
+        let parser = MistralParser::new();
+        let input = r#"[TOOL_CALLS] [
+            {"name": "search", "arguments": {"query": "rust programming"}},
+            {"name": "calculate", "arguments": {"expression": "2 + 2"}}
+        ]"#;
+
+        let result = parser.parse_complete(input).await.unwrap();
+        assert_eq!(result.len(), 2);
+        assert_eq!(result[0].function.name, "search");
+        assert_eq!(result[1].function.name, "calculate");
+    }
+
+    #[tokio::test]
+    async fn test_nested_brackets_in_json() {
+        let parser = MistralParser::new();
+        let input = r#"[TOOL_CALLS] [{"name": "process", "arguments": {"data": [1, 2, [3, 4]], "config": {"nested": [5, 6]}}}]"#;
+
+        let result = parser.parse_complete(input).await.unwrap();
+        assert_eq!(result.len(), 1);
+        assert_eq!(result[0].function.name, "process");
+        // JSON serialization removes spaces, so check for [3,4] without spaces
+        assert!(result[0].function.arguments.contains("[3,4]"));
+    }
+
+    #[tokio::test]
+    async fn test_escaped_quotes_in_strings() {
+        let parser = MistralParser::new();
+        let input = r#"[TOOL_CALLS] [{"name": "echo", "arguments": {"message": "He said \"Hello [World]\""}}]"#;
+
+        let result = parser.parse_complete(input).await.unwrap();
+        assert_eq!(result.len(), 1);
+        assert_eq!(result[0].function.name, "echo");
+    }
+
+    #[test]
+    fn test_detect_format() {
+        let parser = MistralParser::new();
+
+        assert!(parser.detect_format(r#"[TOOL_CALLS] [{"name": "test", "arguments": {}}]"#));
+        assert!(
+            parser.detect_format(r#"Some text [TOOL_CALLS] [{"name": "test", "arguments": {}}]"#)
+        );
+        assert!(!parser.detect_format(r#"{"name": "test", "arguments": {}}"#));
+        assert!(!parser.detect_format("plain text"));
+    }
+}

sgl-router/src/tool_parser/mod.rs

@@ -3,7 +3,9 @@
 /// This module provides infrastructure for parsing tool calls from various model formats.
 pub mod errors;
 pub mod json_parser;
+pub mod mistral_parser;
 pub mod partial_json;
+
 pub mod registry;
 pub mod state;
 pub mod traits;
@@ -15,6 +17,7 @@ mod tests;
 // Re-export commonly used types
 pub use errors::{ToolParserError, ToolParserResult};
 pub use json_parser::JsonParser;
+pub use mistral_parser::MistralParser;
 pub use registry::ParserRegistry;
 pub use state::{ParsePhase, ParseState};
 pub use traits::{PartialJsonParser, ToolParser};

sgl-router/src/tool_parser/registry.rs

@@ -50,15 +50,28 @@ impl ParserRegistry {
             }
         }
 
-        // Try prefix matching (e.g., "gpt-4" matches "gpt-*")
+        // Try prefix matching with more specific patterns first
-        for (pattern, parser_name) in &self.model_mapping {
+        // Collect all matching patterns and sort by specificity (longer = more specific)
-            if pattern.ends_with('*') {
+        let mut matches: Vec<(&String, &String)> = self
-                let prefix = &pattern[..pattern.len() - 1];
+            .model_mapping
-                if model.starts_with(prefix) {
+            .iter()
-                    if let Some(parser) = self.parsers.get(parser_name) {
+            .filter(|(pattern, _)| {
-                        return Some(parser.clone());
+                if pattern.ends_with('*') {
-                    }
+                    let prefix = &pattern[..pattern.len() - 1];
+                    model.starts_with(prefix)
+                } else {
+                    false
                 }
+            })
+            .collect();
+
+        // Sort by pattern length in descending order (longer patterns are more specific)
+        matches.sort_by_key(|(pattern, _)| std::cmp::Reverse(pattern.len()));
+
+        // Return the first matching parser
+        for (_, parser_name) in matches {
+            if let Some(parser) = self.parsers.get(parser_name) {
+                return Some(parser.clone());
             }
         }
 
@@ -97,20 +110,32 @@ impl ParserRegistry {
         // Anthropic models
         self.map_model("claude-*", "json");
 
-        // Mistral models (will use json until mistral parser is implemented)
+        // Mistral models - use Mistral parser
-        self.map_model("mistral-*", "json");
+        self.map_model("mistral-*", "mistral");
-        self.map_model("mixtral-*", "json");
+        self.map_model("mixtral-*", "mistral");
 
-        // Qwen models (will use json until qwen parser is implemented)
+        // Qwen models - use Qwen parser
-        self.map_model("qwen*", "json");
+        self.map_model("qwen*", "qwen");
+        self.map_model("Qwen*", "qwen");
 
-        // Llama models (will use json until llama parser is implemented)
+        // Llama models
+        // Llama 4 uses pythonic format
+        self.map_model("llama-4*", "pythonic");
+        self.map_model("meta-llama-4*", "pythonic");
+        // Llama 3.2 uses python_tag format
+        self.map_model("llama-3.2*", "llama");
+        self.map_model("meta-llama-3.2*", "llama");
+        // Other Llama models use JSON
         self.map_model("llama-*", "json");
         self.map_model("meta-llama-*", "json");
 
+        // DeepSeek models - DeepSeek v3 would need custom parser, v2 uses pythonic
+        self.map_model("deepseek-*", "pythonic");
+
         // Other models default to JSON
         self.map_model("gemini-*", "json");
         self.map_model("palm-*", "json");
+        self.map_model("gemma-*", "json");
     }
 
     /// Set the default parser

sgl-router/src/tool_parser/tests.rs

@@ -4,6 +4,7 @@ use crate::tool_parser::partial_json::{
     compute_diff, find_common_prefix, is_complete_json, PartialJson,
 };
 use crate::tool_parser::traits::ToolParser;
+use crate::tool_parser::types::TokenConfig;
 
 #[test]
 fn test_parse_state_new() {
@@ -299,11 +300,11 @@ async fn test_json_parser_with_parameters() {
 #[tokio::test]
 async fn test_json_parser_with_tokens() {
     // Test with custom wrapper tokens
-    let parser = JsonParser::with_config(
+    let parser = JsonParser::with_config(TokenConfig {
-        vec!["[TOOL_CALLS] [".to_string()],
+        start_tokens: vec!["[TOOL_CALLS] [".to_string()],
-        vec!["]".to_string()],
+        end_tokens: vec!["]".to_string()],
-        ", ".to_string(),
+        separator: ", ".to_string(),
-    );
+    });
 
     let input = r#"[TOOL_CALLS] [{"name": "search", "arguments": {"query": "rust programming"}}]"#;
     let result = parser.parse_complete(input).await.unwrap();
@@ -315,11 +316,11 @@ async fn test_json_parser_with_tokens() {
 #[tokio::test]
 async fn test_multiline_json_with_tokens() {
     // Test that regex with (?s) flag properly handles multi-line JSON
-    let parser = JsonParser::with_config(
+    let parser = JsonParser::with_config(TokenConfig {
-        vec!["<tool>".to_string()],
+        start_tokens: vec!["<tool>".to_string()],
-        vec!["</tool>".to_string()],
+        end_tokens: vec!["</tool>".to_string()],
-        ", ".to_string(),
+        separator: ", ".to_string(),
-    );
+    });
 
     // Pretty-printed multi-line JSON
     let input = r#"<tool>{
@@ -493,11 +494,11 @@ mod failure_cases {
 
     #[tokio::test]
     async fn test_broken_wrapper_tokens() {
-        let parser = JsonParser::with_config(
+        let parser = JsonParser::with_config(TokenConfig {
-            vec!["<tool>".to_string()],
+            start_tokens: vec!["<tool>".to_string()],
-            vec!["</tool>".to_string()],
+            end_tokens: vec!["</tool>".to_string()],
-            ", ".to_string(),
+            separator: ", ".to_string(),
-        );
+        });
 
         // Missing end token
         let input = r#"<tool>{"name": "test", "arguments": {}}"#;
@@ -678,11 +679,11 @@ mod edge_cases {
     #[tokio::test]
     async fn test_multiple_token_pairs_with_conflicts() {
         // Test with overlapping token patterns
-        let parser = JsonParser::with_config(
+        let parser = JsonParser::with_config(TokenConfig {
-            vec!["<<".to_string(), "<tool>".to_string()],
+            start_tokens: vec!["<<".to_string(), "<tool>".to_string()],
-            vec![">>".to_string(), "</tool>".to_string()],
+            end_tokens: vec![">>".to_string(), "</tool>".to_string()],
-            ", ".to_string(),
+            separator: ", ".to_string(),
-        );
+        });
 
         // First pattern
         let input = r#"<<{"name": "test1", "arguments": {}}>>"#;