Struct Turn 

#[non_exhaustive]
pub struct Turn {
    pub role: Role,
    pub content: String,
    pub parts: Vec<Part>,
    pub tool_calls: Vec<ToolCall>,
    pub tool_results: Vec<ToolResult>,
}

One message of the conversation a Prompt carries.

#[non_exhaustive]: a turn grew its tool fields in issue #665 and its image Parts in issue #628 and will grow again, so it is built with Turn::user, Turn::user_parts, Turn::assistant, Turn::assistant_tool_calls or Turn::tool_results rather than a struct literal.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

role: Role

content: String

parts: Vec<Part>

The turn’s content as ordered Parts, where it carries any (issue #628). When non-empty it is the whole content, in order, and content is empty; a text-only turn keeps it empty so it serialises exactly as before images existed.

tool_calls: Vec<ToolCall>

The calls an assistant turn asked for. Carried on a Role::Assistant turn; empty on every other turn.

tool_results: Vec<ToolResult>

The results a user turn carries back for the previous assistant turn’s calls. Carried on a Role::User turn; empty otherwise.

Implementations

impl Turn

pub fn user(content: impl Into<String>) -> Self

A turn spoken by the Role::User side.

pub fn user_parts(parts: impl IntoIterator<Item = Part>) -> Self

A user turn carrying parts — text and images in order — with an empty content (issue #628). The way a prompt sends an image: providers expect text and image in one message, so the parts travel together rather than across two turns.

pub fn assistant(content: impl Into<String>) -> Self

A turn spoken by the Role::Assistant side — a previous completion, quoted back as context.

pub fn assistant_tool_calls( content: impl Into<String>, calls: Vec<ToolCall>, ) -> Self

An assistant turn that asked to call calls. content is the text the model wrote alongside the calls (often empty).

pub fn tool_results(results: Vec<ToolResult>) -> Self

A user turn carrying the results of the previous assistant turn’s tool calls — the shape a provider expects the tool answers back in.

Trait Implementations

impl Clone for Turn

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Turn

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for Turn

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Turn