From eb97b628a9c0c5c63de5a3d00aa75607c136c8cf Mon Sep 17 00:00:00 2001
From: Henry Schimke <henry@azule.info>
Date: Sat, 13 May 2023 11:03:07 -0500
Subject: [PATCH] fix performance issue in `PatternView`:

Previously converting from a `PatternView` to an array reference required an intermediary step, and the creation of a new array on the stack. The new implementation can pass a reference to the underyling data directly, without that intermediary allocation.
---
 src/common/cpp_essentials/pattern.rs | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/common/cpp_essentials/pattern.rs b/src/common/cpp_essentials/pattern.rs
index d222b2c..2ec70bc 100644
--- a/src/common/cpp_essentials/pattern.rs
+++ b/src/common/cpp_essentials/pattern.rs
@@ -348,6 +348,16 @@ impl<'a, const LEN: usize> From<&PatternView<'a>> for [PatternType; LEN] {
     }
 }
 
+impl<'a> From<&PatternView<'a>> for &'a [PatternType] {
+    fn from(value: &PatternView<'a>) -> Self {
+        if value.data.0.len() == value.count {
+            &value.data.0
+        } else {
+            &value.data.0[value.current + value.start..=value.current + value.start + value.count]
+        }
+    }
+}
+
 /**
  * @brief The BarAndSpace struct is a simple 2 element data structure to hold information about bar(s) and space(s).
  *
@@ -476,8 +486,8 @@ pub fn IsPattern<const E2E: bool, const LEN: usize, const SUM: usize, const SPAR
 
     if E2E {
         //using float_t = double;
-        let v_src: [PatternType; LEN] = view.into();
-        let widths = BarAndSpaceSum::<LEN, PatternType, f64>(&v_src);
+        // let v_src: [PatternType; LEN] = view.into();
+        let widths = BarAndSpaceSum::<LEN, PatternType, f64>(view.into());
         let sums = pattern.sums();
         let modSize: BarAndSpace<f64> = BarAndSpace {
             bar: widths[0] / sums[0] as f64,