Struct PromptTemplate 

pub struct PromptTemplate {
    pub name: String,
    pub version: String,
    pub system: Option<String>,
    pub body: String,
    pub variables: HashMap<String, Option<String>>,
    pub tags: Vec<String>,
    pub description: Option<String>,
}

A versioned prompt template with variable placeholders.

Placeholders use {{variable_name}} syntax. Variables are resolved at render time from a caller-supplied map. Missing variables default to the empty string unless a default is configured on the template.

Fields

name: String

Unique template name used as the lookup key.

version: String

Semantic version string (e.g. "v1", "v2.1").

system: Option<String>

Optional system prompt (sent as the first turn or prefixed).

body: String

Template body with {{variable}} placeholders.

variables: HashMap<String, Option<String>>

Variable names declared in this template with optional defaults.

tags: Vec<String>

Arbitrary tags for grouping and filtering.

description: Option<String>

Human-readable description.

Implementations

impl PromptTemplate

pub fn builder(name: impl Into<String>) -> TemplateBuilder

Start building a template with the given name.

pub fn render(&self, vars: &HashMap<&str, &str>) -> String

Render the template body by substituting vars for each {{key}}.

In addition to simple {{variable}} interpolation this method handles:

• Conditional blocks {{#if condition}}...{{/if}} — the block is included if vars contains a key equal to condition whose value is non-empty and not the literal string "false" or "0".

• Loop blocks {{#each items}}...{{/each}} — the block is repeated once for each item in a comma-separated list stored under the key items. Inside the block {{this}} is replaced with the current item and {{@index}} with the zero-based index.

Variables present in the template but absent from vars fall back to the template’s own default value. If no default exists the placeholder is replaced with an empty string.

pub fn render_full( &self, vars: &HashMap<&str, &str>, ) -> (Option<String>, String)

Render both system prompt (if any) and body; returns (system, body).

pub fn declared_variables(&self) -> Vec<String>

Extract variable names declared in the body ({{name}}).

Trait Implementations

impl Clone for PromptTemplate

fn clone(&self) -> PromptTemplate

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PromptTemplate

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

Formats the value using the given formatter.