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//! # String Length Node
//!
//! A transform node that returns the length (character count) of a string input.
//!
//! ## Ports
//!
//! - **Input**: `"configuration"` - Receives configuration (currently unused, for consistency)
//! - **Input**: `"in"` - Receives string value
//! - **Output**: `"out"` - Sends the length of the string (usize)
//! - **Output**: `"error"` - Sends errors that occur during processing (e.g., type mismatch)
//!
//! ## Behavior
//!
//! The node returns the character count of a string input. It supports:
//! - String: Returns the number of characters (bytes for ASCII, UTF-8 code units for multi-byte)
//! - Error handling: Non-string inputs result in errors sent to the error port
use crate::node::{InputStreams, Node, NodeExecutionError, OutputStreams};
use crate::nodes::common::BaseNode;
use crate::nodes::string::common::string_length;
use async_trait::async_trait;
use std::any::Any;
use std::collections::HashMap;
use std::pin::Pin;
use std::sync::Arc;
use tokio_stream::{StreamExt, wrappers::ReceiverStream};
/// A node that returns the length of a string input.
///
/// The node receives a string value on the "in" port and outputs
/// its length (as usize) to the "out" port.
pub struct StringLengthNode {
/// Base node functionality.
pub(crate) base: BaseNode,
}
impl StringLengthNode {
/// Creates a new StringLengthNode with the given name.
///
/// # Example
///
/// ```rust,no_run
/// use streamweave::nodes::string::StringLengthNode;
///
/// let node = StringLengthNode::new("length".to_string());
/// // Creates ports: configuration, in → out, error
/// ```
pub fn new(name: String) -> Self {
Self {
base: BaseNode::new(
name,
vec!["configuration".to_string(), "in".to_string()],
vec!["out".to_string(), "error".to_string()],
),
}
}
}
#[async_trait]
impl Node for StringLengthNode {
fn name(&self) -> &str {
self.base.name()
}
fn set_name(&mut self, name: &str) {
self.base.set_name(name);
}
fn input_port_names(&self) -> &[String] {
self.base.input_port_names()
}
fn output_port_names(&self) -> &[String] {
self.base.output_port_names()
}
fn has_input_port(&self, name: &str) -> bool {
self.base.has_input_port(name)
}
fn has_output_port(&self, name: &str) -> bool {
self.base.has_output_port(name)
}
fn execute(
&self,
mut inputs: InputStreams,
) -> Pin<
Box<dyn std::future::Future<Output = Result<OutputStreams, NodeExecutionError>> + Send + '_>,
> {
Box::pin(async move {
// Extract input streams (configuration port is present but unused for now)
let _config_stream = inputs.remove("configuration");
let in_stream = inputs.remove("in").ok_or("Missing 'in' input")?;
// Create output streams
let (out_tx, out_rx) = tokio::sync::mpsc::channel(10);
let (error_tx, error_rx) = tokio::sync::mpsc::channel(10);
// Process the input stream
let out_tx_clone = out_tx.clone();
let error_tx_clone = error_tx.clone();
tokio::spawn(async move {
let mut stream = in_stream;
while let Some(item) = stream.next().await {
match string_length(&item) {
Ok(result) => {
let _ = out_tx_clone.send(result).await;
}
Err(e) => {
let error_arc = Arc::new(e) as Arc<dyn Any + Send + Sync>;
let _ = error_tx_clone.send(error_arc).await;
}
}
}
});
// Convert channels to streams
let mut outputs = HashMap::new();
outputs.insert(
"out".to_string(),
Box::pin(ReceiverStream::new(out_rx))
as Pin<Box<dyn tokio_stream::Stream<Item = Arc<dyn Any + Send + Sync>> + Send>>,
);
outputs.insert(
"error".to_string(),
Box::pin(ReceiverStream::new(error_rx))
as Pin<Box<dyn tokio_stream::Stream<Item = Arc<dyn Any + Send + Sync>> + Send>>,
);
Ok(outputs)
})
}
}