Struct StructuredOutputParser 

pub struct StructuredOutputParser { /* private fields */ }

Structured output parser

Parses the LLM’s key-value output (one key: value per line) into a HashMap. Suited to scenarios where the LLM emits structured information in a non-JSON format.

Format

The input format should be one key: value per line, e.g.:

姓名: 张三
年龄: 28
城市: 北京

Example

use langchainrust::output_parsers::StructuredOutputParser;

let parser = StructuredOutputParser::new();
let result = parser.parse("姓名: 张三\n年龄: 28").await?;
assert_eq!(result.get("姓名").unwrap(), "张三");

Implementations

impl StructuredOutputParser

pub fn new() -> Self

Creates a structured output parser using the default separator (:).

pub fn with_separator(separator: char) -> Self

Creates a parser using a custom separator

Trait Implementations

impl BaseOutputParser<HashMap<String, String>> for StructuredOutputParser

fn parse<'life0, 'life1, 'async_trait>( &'life0 self, text: &'life1 str, ) -> Pin<Box<dyn Future<Output = OutputParserResult<HashMap<String, String>>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Parses raw LLM output text into the target type

fn get_format_instructions(&self) -> String

Returns format instructions (to prompt the LLM to output in the expected format)

fn parse_with_retry<'life0, 'life1, 'async_trait>( &'life0 self, text: &'life1 str, max_retries: usize, ) -> Pin<Box<dyn Future<Output = OutputParserResult<Output>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Parsing with retry (default: genuinely retries max_retries times)

impl Default for StructuredOutputParser

fn default() -> Self

Returns the “default value” for a type.

impl Runnable<LLMResult, HashMap<String, String>> for StructuredOutputParser

type Error = OutputParserError

Error type.

fn invoke<'life0, 'async_trait>( &'life0 self, input: LLMResult, _config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<HashMap<String, String>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Transforms single input to output.

fn stream<'life0, 'async_trait>( &'life0 self, input: LLMResult, _config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<Pin<Box<dyn Stream<Item = Result<HashMap<String, String>, Self::Error>> + Send>>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Streaming output - for real-time responses (LLM, etc).

fn batch<'life0, 'async_trait>( &'life0 self, inputs: Vec<Input>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<Vec<Output>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Batch processing - transforms multiple inputs to outputs.

fn batch_as_completed<'life0, 'async_trait>( &'life0 self, inputs: Vec<Input>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<Vec<(usize, Output)>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Batch processing that returns results in completion order.

fn transform<'life0, 'async_trait>( &'life0 self, input: Pin<Box<dyn Stream<Item = Result<Input, Self::Error>> + Send>>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<Pin<Box<dyn Stream<Item = Result<Output, Self::Error>> + Send + '_>>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Stream-to-stream transformation - the core of LCEL streaming.