Merge pull request #365 from robertknight/try-slice-with

Add fallible variants of `TensorBase::slice_with`

rten-tensor/src/errors.rs

@@ -3,6 +3,8 @@
 use std::error::Error;
 use std::fmt::{Display, Formatter};
 
+use crate::slice_range::SliceRange;
+
 /// Error in a tensor operation if the dimension count is incorrect.
 #[derive(Debug, PartialEq)]
 pub struct DimensionError {}
@@ -47,28 +49,82 @@ impl Error for FromDataError {}
 #[derive(Clone, Debug, PartialEq)]
 pub enum SliceError {
     /// The slice spec has more dimensions than the tensor being sliced.
-    TooManyDims,
+    TooManyDims {
+        /// Number of axes in the tensor.
+        ndim: usize,
+        /// Number of items in the slice spec.
+        range_ndim: usize,
+    },
 
     /// An index in the slice spec is out of bounds for the corresponding tensor
     /// dimension.
-    InvalidIndex,
+    InvalidIndex {
+        /// Axis that the error applies to.
+        axis: usize,
+        /// Index in the slice range.
+        index: isize,
+        /// Size of the dimension.
+        size: usize,
+    },
 
     /// A range in the slice spec is out of bounds for the corresponding tensor
     /// dimension.
-    InvalidRange,
+    InvalidRange {
+        /// Axis that the error applies to.
+        axis: usize,
+
+        /// The range item.
+        range: SliceRange,
+
+        /// Size of the dimension.
+        size: usize,
+    },
 
     /// The step in a slice range is negative, in a context where this is not
     /// supported.
-    InvalidStep,
+    InvalidStep {
+        /// Axis that the error applies to.
+        axis: usize,
+
+        /// Size of the dimension.
+        step: isize,
+    },
+
+    /// There is a mismatch between the actual and expected number of axes
+    /// in the output slice.
+    OutputDimsMismatch { actual: usize, expected: usize },
 }
 
 impl Display for SliceError {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         match self {
-            SliceError::TooManyDims => write!(f, "slice spec has too many dims"),
-            SliceError::InvalidIndex => write!(f, "slice index is invalid"),
-            SliceError::InvalidRange => write!(f, "slice range is invalid"),
-            SliceError::InvalidStep => write!(f, "slice step is invalid"),
+            SliceError::TooManyDims { ndim, range_ndim } => {
+                write!(
+                    f,
+                    "slice range has {} items but tensor has only {} dims",
+                    range_ndim, ndim
+                )
+            }
+            SliceError::InvalidIndex { axis, index, size } => write!(
+                f,
+                "slice index {} is invalid for axis ({}) of size {}",
+                index, axis, size
+            ),
+            SliceError::InvalidRange { axis, range, size } => write!(
+                f,
+                "slice range {:?} is invalid for axis ({}) of size {}",
+                range, axis, size
+            ),
+            SliceError::InvalidStep { axis, step } => {
+                write!(f, "slice step {} is invalid for axis {}", step, axis)
+            }
+            SliceError::OutputDimsMismatch { actual, expected } => {
+                write!(
+                    f,
+                    "slice output dims {} does not match expected dims {}",
+                    actual, expected
+                )
+            }
         }
     }
 }

rten-tensor/src/iterators.rs

@@ -470,7 +470,7 @@ impl LaneRanges {
                 (0..end).into()
             })
             .collect();
-        let (_range, sliced) = layout.slice_dyn(&slice_starts);
+        let (_range, sliced) = layout.slice_dyn(&slice_starts).unwrap();
         let offsets = Offsets::new(&sliced);
         LaneRanges {
             offsets,