feat!: add function calling support to client.chat() & client.chat_async()

BREAKING CHANGE: Too many to count in this version. Check the README examples.

src/v1/chat_stream.rs

@@ -0,0 +1,57 @@
+use serde::{Deserialize, Serialize};
+use serde_json::from_str;
+
+use crate::v1::{chat, common, constants, error};
+
+// -----------------------------------------------------------------------------
+// Response
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct ChatStreamChunk {
+    pub id: String,
+    pub object: String,
+    /// Unix timestamp (in seconds).
+    pub created: u32,
+    pub model: constants::Model,
+    pub choices: Vec<ChatStreamChunkChoice>,
+    pub usage: Option<common::ResponseUsage>,
+    // TODO Check this prop (seen in API responses but undocumented).
+    // pub logprobs: ???,
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct ChatStreamChunkChoice {
+    pub index: u32,
+    pub delta: ChatStreamChunkChoiceDelta,
+    pub finish_reason: Option<String>,
+    // TODO Check this prop (seen in API responses but undocumented).
+    // pub logprobs: ???,
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct ChatStreamChunkChoiceDelta {
+    pub role: Option<chat::ChatMessageRole>,
+    pub content: String,
+}
+
+/// Extracts serialized chunks from a stream message.
+pub fn get_chunk_from_stream_message_line(
+    line: &str,
+) -> Result<Option<Vec<ChatStreamChunk>>, error::ApiError> {
+    if line.trim() == "data: [DONE]" {
+        return Ok(None);
+    }
+
+    let chunk_as_json = line.trim_start_matches("data: ").trim();
+    if chunk_as_json.is_empty() {
+        return Ok(Some(vec![]));
+    }
+
+    // Attempt to deserialize the JSON string into ChatStreamChunk
+    match from_str::<ChatStreamChunk>(chunk_as_json) {
+        Ok(chunk) => Ok(Some(vec![chunk])),
+        Err(e) => Err(error::ApiError {
+            message: e.to_string(),
+        }),
+    }
+}