code refactor: Moved logic of whitelisting to separate function

ocrs/src/recognition.rs

@@ -9,7 +9,7 @@ use rten_imageproc::{
     bounding_rect, BoundingRect, Line, Point, PointF, Polygon, Rect, RotatedRect,
 };
 use rten_tensor::prelude::*;
-use rten_tensor::{NdTensor, NdTensorView, Tensor};
+use rten_tensor::{NdTensor, NdTensorView, NdTensorViewMut, Tensor};
 
 use crate::errors::ModelRunError;
 use crate::geom_util::{downwards_line, leftmost_edge, rightmost_edge};
@@ -519,19 +519,12 @@ impl TextRecognizer {
                             .map(|(group_line_index, line)| {
                                 let decoder = CtcDecoder::new();
                                 // Here mutation is added to allow whitelisting of characters
-                                let mut input_seq = rec_output.slice_mut([group_line_index]);
-                                //whitelisting code
-                                if let Some(ref excluded_char_labels) = excluded_char_labels {
-                                    for row in 0..input_seq.shape()[0] {
-                                        for &column in excluded_char_labels.iter() {
-                                            // Setting the output value of excluded char to -Inf causes the
-                                            // `decode_method` to favour chars other than the excluded char.
-                                            input_seq[[row, column]] = f32::NEG_INFINITY;
-                                        }
-                                    }
-                                }
-                                let input_seq = input_seq.view();
-                                //
+                                let mut input_seq_slice = rec_output.slice_mut([group_line_index]);
+                                let input_seq = Self::filter_excluded_char_labels(
+                                    excluded_char_labels,
+                                    &mut input_seq_slice,
+                                );
+
                                 let ctc_output = match decode_method {
                                     DecodeMethod::Greedy => decoder.decode_greedy(input_seq),
                                     DecodeMethod::BeamSearch { width } => {
@@ -563,6 +556,22 @@ impl TextRecognizer {
 
         Ok(text_lines)
     }
+
+    fn filter_excluded_char_labels<'a>(
+        excluded_char_labels: Option<&[usize]>,
+        input_seq_slice: &'a mut NdTensorViewMut<'_, f32, 2>,
+    ) -> NdTensorView<'a, f32, 2> {
+        if let Some(excluded_char_labels) = excluded_char_labels {
+            for row in 0..input_seq_slice.shape()[0] {
+                for &excluded_char_label in excluded_char_labels.iter() {
+                    // Setting the output value of excluded char to -Inf causes the
+                    // `decode_method` to favour chars other than the excluded char.
+                    (*input_seq_slice)[[row, excluded_char_label]] = f32::NEG_INFINITY;
+                }
+            }
+        }
+        input_seq_slice.view()
+    }
 }
 
 #[cfg(test)]