f - Add docs for InvoiceRequestBuilder

Author: jkczyz

lightning/src/offers/invoice_request.rs

@@ -27,7 +27,39 @@ use util::ser::{Readable, WithoutLength, Writeable, Writer};
 ///
 const SIGNATURE_TAG: &'static str = concat!("lightning", "invoice_request", "signature");
 
+/// Builds an [`InvoiceRequest`] from an [`Offer`] for the user-pays-merchant flow.
 ///
+/// ```
+/// extern crate bitcoin;
+/// extern crate lightning;
+///
+/// use bitcoin::network::constants::Network;
+/// use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, SecretKey};
+/// use lightning::ln::features::OfferFeatures;
+/// use lightning::offers::Offer;
+/// use lightning::util::ser::Writeable;
+///
+/// # fn parse() -> Result<(), lightning::offers::ParseError> {
+/// let secp_ctx = Secp256k1::new();
+/// let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32])?);
+/// let pubkey = PublicKey::from(keys);
+/// let mut buffer = Vec::new();
+///
+/// "lno1qcp4256ypq"
+///     .parse::<Offer>()?
+///     .request_invoice(pubkey)
+///     .payer_info(vec![42; 64])
+///     .chain(Network::Testnet)?
+///     .amount_msats(1000)?
+///     .features(OfferFeatures::known())
+///     .quantity(5)?
+///     .payer_note("foo".to_string())
+///     .build_signed(|digest| secp_ctx.sign_schnorr_no_aux_rand(digest, &keys))?
+///     .write(&mut buffer)
+///     .unwrap();
+/// # Ok(())
+/// # }
+/// ```
 pub struct InvoiceRequestBuilder<'a> {
 	offer: &'a Offer,
 	invoice_request: InvoiceRequestContents,