feat: simplify prepare_chat_input logic and adjust start stop chars

router/src/server.rs

@@ -23,7 +23,7 @@ use crate::{
     CompletionRequest, CompletionType, DeltaToolCall, Function, Prompt, Tool, VertexRequest,
     VertexResponse,
 };
-use crate::{FunctionDefinition, HubPreprocessorConfig, ToolCall, ToolChoice, ToolType};
+use crate::{FunctionDefinition, HubPreprocessorConfig, ToolCall, ToolChoice, ToolType, Tools};
 use async_stream::__private::AsyncStream;
 use axum::extract::Extension;
 use axum::http::{HeaderMap, HeaderValue, Method, StatusCode};
@@ -144,61 +144,15 @@ async fn get_chat_tokenize(
         ..
     } = req;
 
-    if response_format.is_some() && tools.is_some() {
-        return Err((
-            StatusCode::UNPROCESSABLE_ENTITY,
-            Json(ErrorResponse {
-                error: "Grammar and tools are mutually exclusive".to_string(),
-                error_type: "validation".to_string(),
-            }),
-        ));
-    }
-
-    let tool_grammar = match ToolGrammar::apply(tools, tool_choice) {
-        Ok(grammar) => grammar,
-        Err(err) => {
-            metrics::counter!("tgi_request_failure", "err" => "validation").increment(1);
-            tracing::error!("{}", err);
-            return Err((
-                StatusCode::UNPROCESSABLE_ENTITY,
-                Json(ErrorResponse {
-                    error: err.to_string(),
-                    error_type: err.error_type().to_string(),
-                }),
-            ));
-        }
-    };
-
-    let tools_grammar_prompt = tool_grammar.as_ref().map(|t| {
-        (
-            GrammarType::Json(serde_json::json!(t)),
-            tool_prompt.unwrap_or_default(),
-        )
-    });
-
-    let (tools_grammar_prompt, _grammar) = response_format
-        .map(|rf| (None, Some(rf)))
-        .unwrap_or_else(|| {
-            (
-                tools_grammar_prompt.clone(),
-                tools_grammar_prompt.map(|(g, _)| g),
-            )
-        });
-
-    let inputs = match infer.apply_chat_template(messages, tools_grammar_prompt) {
-        Ok(inputs) => inputs,
-        Err(err) => {
-            metrics::counter!("tgi_request_failure", "err" => "validation").increment(1);
-            tracing::error!("{}", err);
-            return Err((
-                StatusCode::UNPROCESSABLE_ENTITY,
-                Json(ErrorResponse {
-                    error: err.to_string(),
-                    error_type: err.error_type().to_string(),
-                }),
-            ));
-        }
-    };
+    let tool_prompt = tool_prompt.unwrap_or_default();
+    let (inputs, _grammar, _tool_grammar) = prepare_chat_input(
+        &infer,
+        response_format,
+        tools,
+        tool_choice,
+        &tool_prompt,
+        messages,
+    )?;
 
     let generate_request = GenerateRequest {
         inputs,
@@ -233,8 +187,11 @@ async fn get_chat_tokenize(
             .iter()
             .zip(encoding.get_offsets())
             .map(|(&id, &(start, stop))| {
-                let text: String =
-                    String::from_utf8_lossy(&input.as_bytes()[start..stop]).to_string();
+                let text = input
+                    .chars()
+                    .skip(start)
+                    .take(stop - start)
+                    .collect::<String>();
                 SimpleToken {
                     id,
                     text,
@@ -1179,63 +1136,14 @@ async fn chat_completions(
         Some(temperature) if temperature == 0.0 => (false, None),
         other => (true, other),
     };
-
-    // response_format and tools are mutually exclusive
-    if response_format.is_some() && tools.as_ref().is_some() {
-        metrics::counter!("tgi_request_failure", "err" => "validation").increment(1);
-        return Err((
-            StatusCode::UNPROCESSABLE_ENTITY,
-            Json(ErrorResponse {
-                error: "Grammar and tools are mutually exclusive".to_string(),
-                error_type: "grammar and tools".to_string(),
-            }),
-        ));
-    }
-
-    // extract tool grammar if present
-    let tool_grammar = match ToolGrammar::apply(tools, tool_choice) {
-        Ok(grammar) => grammar,
-        Err(err) => {
-            metrics::counter!("tgi_request_failure", "err" => "validation").increment(1);
-            tracing::error!("{err}");
-            return Err((
-                StatusCode::UNPROCESSABLE_ENTITY,
-                Json(ErrorResponse {
-                    error: err.to_string(),
-                    error_type: err.error_type().to_string(),
-                }),
-            ));
-        }
-    };
-
-    // determine the appropriate arguments for apply_chat_template
-    let tools_grammar_prompt = tool_grammar
-        .as_ref()
-        .map(|t| (GrammarType::Json(serde_json::json!(t)), tool_prompt));
-
-    let (tools_grammar_prompt, grammar) = match response_format {
-        Some(response_format) => (None, Some(response_format)),
-        None => (
-            tools_grammar_prompt.clone(),
-            tools_grammar_prompt.map(|(grammar, _)| grammar.clone()),
-        ),
-    };
-
-    // apply chat template to flatten the request into a single input
-    let inputs = match infer.apply_chat_template(messages, tools_grammar_prompt) {
-        Ok(inputs) => inputs,
-        Err(err) => {
-            metrics::counter!("tgi_request_failure", "err" => "validation").increment(1);
-            tracing::error!("{err}");
-            return Err((
-                StatusCode::UNPROCESSABLE_ENTITY,
-                Json(ErrorResponse {
-                    error: err.to_string(),
-                    error_type: err.error_type().to_string(),
-                }),
-            ));
-        }
-    };
+    let (inputs, grammar, tool_grammar) = prepare_chat_input(
+        &infer,
+        response_format,
+        tools,
+        tool_choice,
+        &tool_prompt,
+        messages,
+    )?;
 
     // build the request passing some parameters
     let generate_request = GenerateRequest {
@@ -1505,8 +1413,11 @@ async fn tokenize(
             .iter()
             .zip(encoding.get_offsets())
             .map(|(&id, &(start, stop))| {
-                let text: String =
-                    String::from_utf8_lossy(&input.as_bytes()[start..stop]).to_string();
+                let text = input
+                    .chars()
+                    .skip(start)
+                    .take(stop - start)
+                    .collect::<String>();
                 SimpleToken {
                     id,
                     text,
@@ -2478,3 +2389,36 @@ fn create_post_processor(
 
     Ok(post_processor)
 }
+
+type PreparedInput = (String, Option<GrammarType>, Option<Tools>);
+
+fn prepare_chat_input(
+    infer: &Infer,
+    response_format: Option<GrammarType>,
+    tools: Option<Vec<Tool>>,
+    tool_choice: ToolChoice,
+    tool_prompt: &str,
+    messages: Vec<Message>,
+) -> Result<PreparedInput, InferError> {
+    if response_format.is_some() && tools.is_some() {
+        return Err(InferError::ToolError(
+            "Grammar and tools are mutually exclusive".into(),
+        ));
+    }
+
+    if let Some(format) = response_format {
+        let inputs = infer.apply_chat_template(messages, None)?;
+        return Ok((inputs, Some(format), None));
+    }
+
+    // if tools are set, apply the tool grammar and then the chat template
+    let tool_grammar: Option<Tools> = ToolGrammar::apply(tools, tool_choice)?;
+    let grammar = tool_grammar
+        .as_ref()
+        .map(|t| GrammarType::Json(serde_json::json!(t)));
+    let tools_grammar_prompt = tool_grammar
+        .as_ref()
+        .map(|t| (GrammarType::Json(serde_json::json!(t)), tool_prompt.into()));
+    let inputs = infer.apply_chat_template(messages, tools_grammar_prompt)?;
+    Ok((inputs, grammar, tool_grammar))
+}