Add ComponentDescriptorRef to re_sorbet (#9043)

### Related

* Related to #9034
* Required for #9018 

### What

This PR introduce the `ComponentDescriptorRef` type to `re_sorbet`. It's
like `ComponentDescriptor` but:
- It has refs instead of owned copies.
- It has a `RowId` enum (which would be difficult to add to
`ComponentDescriptor` because of the ramifications on the dataframe
API—let's wait for the RowID <-> Index column merge for that).

Author: abey79

crates/store/re_sorbet/src/column_descriptor.rs

@@ -28,6 +28,7 @@ pub enum ColumnError {
 // See:
 // * [`IndexColumnDescriptor`]
 // * [`ComponentColumnDescriptor`]
+//TODO(#9034): This should support RowId as well, but this has ramifications on the dataframe API.
 #[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub enum ColumnDescriptor {
     Time(IndexColumnDescriptor),

crates/store/re_sorbet/src/column_descriptor_ref.rs

@@ -0,0 +1,49 @@
+use crate::{
+    ColumnDescriptor, ComponentColumnDescriptor, IndexColumnDescriptor, RowIdColumnDescriptor,
+};
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum ColumnDescriptorRef<'a> {
+    RowId(&'a RowIdColumnDescriptor),
+    Time(&'a IndexColumnDescriptor),
+    Component(&'a ComponentColumnDescriptor),
+}
+
+impl ColumnDescriptorRef<'_> {
+    /// Human-readable name for the column.
+    #[inline]
+    pub fn name(&self) -> String {
+        match self {
+            Self::RowId(descr) => descr.name().to_owned(),
+            Self::Time(descr) => descr.timeline.name().to_string(),
+            Self::Component(descr) => descr.component_name.short_name().to_owned(),
+        }
+    }
+}
+
+impl<'a> From<&'a ColumnDescriptor> for ColumnDescriptorRef<'a> {
+    fn from(desc: &'a ColumnDescriptor) -> Self {
+        match desc {
+            ColumnDescriptor::Time(desc) => Self::Time(desc),
+            ColumnDescriptor::Component(desc) => Self::Component(desc),
+        }
+    }
+}
+
+impl<'a> From<&'a RowIdColumnDescriptor> for ColumnDescriptorRef<'a> {
+    fn from(desc: &'a RowIdColumnDescriptor) -> Self {
+        Self::RowId(desc)
+    }
+}
+
+impl<'a> From<&'a IndexColumnDescriptor> for ColumnDescriptorRef<'a> {
+    fn from(desc: &'a IndexColumnDescriptor) -> Self {
+        Self::Time(desc)
+    }
+}
+
+impl<'a> From<&'a ComponentColumnDescriptor> for ColumnDescriptorRef<'a> {
+    fn from(desc: &'a ComponentColumnDescriptor) -> Self {
+        Self::Component(desc)
+    }
+}

crates/store/re_sorbet/src/lib.rs

@@ -18,6 +18,7 @@
 mod chunk_batch;
 mod chunk_schema;
 mod column_descriptor;
+mod column_descriptor_ref;
 mod column_kind;
 mod component_column_descriptor;
 mod error;
@@ -33,6 +34,7 @@ pub use self::{
     chunk_batch::{ChunkBatch, MismatchedChunkSchemaError},
     chunk_schema::ChunkSchema,
     column_descriptor::{ColumnDescriptor, ColumnError},
+    column_descriptor_ref::ColumnDescriptorRef,
     column_kind::ColumnKind,
     component_column_descriptor::ComponentColumnDescriptor,
     error::SorbetError,

crates/store/re_sorbet/src/row_id_column_descriptor.rs

@@ -34,6 +34,13 @@ impl RowIdColumnDescriptor {
         Self {}
     }
 
+    /// Human-readable name for this column.
+    #[inline]
+    #[expect(clippy::unused_self)]
+    pub fn name(&self) -> &'static str {
+        "Row ID"
+    }
+
     #[inline]
     pub fn to_arrow_field(&self) -> ArrowField {
         let Self {} = self;

crates/store/re_sorbet/src/sorbet_batch.rs

@@ -10,8 +10,8 @@ use arrow::{
 use re_arrow_util::{into_arrow_ref, ArrowArrayDowncastRef};
 
 use crate::{
-    ArrowBatchMetadata, ComponentColumnDescriptor, IndexColumnDescriptor, RowIdColumnDescriptor,
-    SorbetError, SorbetSchema,
+    ArrowBatchMetadata, ColumnDescriptorRef, ComponentColumnDescriptor, IndexColumnDescriptor,
+    RowIdColumnDescriptor, SorbetError, SorbetSchema,
 };
 
 /// Any rerun-compatible [`ArrowRecordBatch`].
@@ -82,6 +82,11 @@ impl SorbetBatch {
         })
     }
 
+    /// All the columns along with their descriptors.
+    pub fn all_columns(&self) -> impl Iterator<Item = (ColumnDescriptorRef<'_>, &ArrowArrayRef)> {
+        self.schema.columns.descriptors().zip(self.batch.columns())
+    }
+
     /// The columns of the indices (timelines).
     pub fn index_columns(&self) -> impl Iterator<Item = (&IndexColumnDescriptor, &ArrowArrayRef)> {
         let num_row_id_columns = self.schema.columns.row_id.is_some() as usize;

crates/store/re_sorbet/src/sorbet_columns.rs

@@ -4,8 +4,8 @@ use nohash_hasher::IntSet;
 use re_log_types::EntityPath;
 
 use crate::{
-    ColumnDescriptor, ColumnKind, ComponentColumnDescriptor, IndexColumnDescriptor,
-    RowIdColumnDescriptor, SorbetError,
+    ColumnDescriptor, ColumnDescriptorRef, ColumnKind, ComponentColumnDescriptor,
+    IndexColumnDescriptor, RowIdColumnDescriptor, SorbetError,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -51,6 +51,17 @@ impl SorbetColumnDescriptors {
             .collect()
     }
 
+    /// Returns all columns, including the `row_id` column.
+    ///
+    /// See also [`Self::indices_and_components`].
+    pub fn descriptors(&self) -> impl Iterator<Item = ColumnDescriptorRef<'_>> + '_ {
+        self.row_id
+            .iter()
+            .map(ColumnDescriptorRef::from)
+            .chain(self.indices.iter().map(ColumnDescriptorRef::from))
+            .chain(self.components.iter().map(ColumnDescriptorRef::from))
+    }
+
     /// Returns all indices and then all components;
     /// skipping the `row_id` column.
     ///