From 7f6e6a2b11aeeb59a9c468c1a8dbb59e7f4736fa Mon Sep 17 00:00:00 2001
From: "Shane F. Carr" <shane@unicode.org>
Date: Thu, 19 Dec 2024 18:20:26 -0800
Subject: [PATCH] generate-readmes

---
 components/decimal/README.md | 66 ++++++++++++++++++++++++++++++++++--
 1 file changed, 64 insertions(+), 2 deletions(-)

diff --git a/components/decimal/README.md b/components/decimal/README.md
index 1170fb74f83..76ce034c677 100644
--- a/components/decimal/README.md
+++ b/components/decimal/README.md
@@ -54,8 +54,7 @@ assert_writeable_eq!(fdf.format(&fixed_decimal), "2,000.50");
 
 #### Format a number using an alternative numbering system
 
-Numbering systems specified in the `-u-nu` subtag will be followed as long as the locale has
-symbols for that numbering system.
+Numbering systems specified in the `-u-nu` subtag will be followed.
 
 ```rust
 use fixed_decimal::SignedFixedDecimal;
@@ -74,6 +73,69 @@ let fixed_decimal = SignedFixedDecimal::from(1000007);
 assert_writeable_eq!(fdf.format(&fixed_decimal), "๑,๐๐๐,๐๐๗");
 ```
 
+#### Get the resolved numbering system
+
+Inspect the data request to get the resolved numbering system (public but unstable):
+
+```rust
+use icu_provider::prelude::*;
+use icu::decimal::FixedDecimalFormatter;
+use icu::decimal::provider::DecimalDigitsV1Marker;
+use icu::locale::locale;
+use std::any::TypeId;
+use std::cell::RefCell;
+
+struct NumberingSystemInspectionProvider<P> {
+    inner: P,
+    numbering_system: RefCell<Option<Box<DataMarkerAttributes>>>,
+}
+
+impl<M, P> DataProvider<M> for NumberingSystemInspectionProvider<P>
+where
+    M: DataMarker,
+    P: DataProvider<M>,
+{
+    fn load(&self, req: DataRequest) -> Result<DataResponse<M>, DataError> {
+        if TypeId::of::<M>() == TypeId::of::<DecimalDigitsV1Marker>() {
+            *self.numbering_system.try_borrow_mut().unwrap() = Some(req.id.marker_attributes.to_owned());
+        }
+        self.inner.load(req)
+    }
+}
+
+let provider = NumberingSystemInspectionProvider {
+    inner: icu::decimal::provider::Baked,
+    numbering_system: RefCell::new(None),
+};
+
+let fdf = FixedDecimalFormatter::try_new_unstable(
+    &provider,
+    locale!("th").into(),
+    Default::default(),
+)
+.unwrap();
+
+assert_eq!(provider.numbering_system.borrow().as_ref().map(|x| x.as_str()), Some("latn"));
+
+let fdf = FixedDecimalFormatter::try_new_unstable(
+    &provider,
+    locale!("th-u-nu-thai").into(),
+    Default::default(),
+)
+.unwrap();
+
+assert_eq!(provider.numbering_system.borrow().as_ref().map(|x| x.as_str()), Some("thai"));
+
+let fdf = FixedDecimalFormatter::try_new_unstable(
+    &provider,
+    locale!("th-u-nu-adlm").into(),
+    Default::default(),
+)
+.unwrap();
+
+assert_eq!(provider.numbering_system.borrow().as_ref().map(|x| x.as_str()), Some("adlm"));
+```
+
 [`FixedDecimalFormatter`]: FixedDecimalFormatter
 
 <!-- cargo-rdme end -->