1 files changed, 92 insertions, 0 deletions
diff --git a/third_party/rust/unicode-bidi/src/deprecated.rs b/third_party/rust/unicode-bidi/src/deprecated.rs
new file mode 100644
index 0000000000..ec3b84f67b
--- /dev/null
+++ b/third_party/rust/unicode-bidi/src/deprecated.rs
@@ -0,0 +1,92 @@
+// Copyright 2015 The Servo Project Developers. See the
+// COPYRIGHT file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! This module holds deprecated assets only.
+
+use alloc::vec::Vec;
+
+use super::*;
+
+/// Find the level runs within a line and return them in visual order.
+///
+/// NOTE: This implementation is incomplete. The algorithm needs information about the text,
+/// including original `BidiClass` property of each character, to be able to perform correctly.
+/// Please see [`BidiInfo::visual_runs()`](../struct.BidiInfo.html#method.visual_runs) for the
+/// improved implementation.
+///
+/// `line` is a range of bytes indices within `levels`.
+///
+/// <http://www.unicode.org/reports/tr9/#Reordering_Resolved_Levels>
+#[deprecated(
+    since = "0.3.0",
+    note = "please use `BidiInfo::visual_runs()` instead."
+)]
+pub fn visual_runs(line: Range<usize>, levels: &[Level]) -> Vec<LevelRun> {
+    assert!(line.start <= levels.len());
+    assert!(line.end <= levels.len());
+
+    let mut runs = Vec::new();
+
+    // Find consecutive level runs.
+    let mut start = line.start;
+    let mut run_level = levels[start];
+    let mut min_level = run_level;
+    let mut max_level = run_level;
+
+    for (i, &new_level) in levels.iter().enumerate().take(line.end).skip(start + 1) {
+        if new_level != run_level {
+            // End of the previous run, start of a new one.
+            runs.push(start..i);
+            start = i;
+            run_level = new_level;
+
+            min_level = min(run_level, min_level);
+            max_level = max(run_level, max_level);
+        }
+    }
+    runs.push(start..line.end);
+
+    let run_count = runs.len();
+
+    // Re-order the odd runs.
+    // <http://www.unicode.org/reports/tr9/#L2>
+
+    // Stop at the lowest *odd* level.
+    min_level = min_level.new_lowest_ge_rtl().expect("Level error");
+
+    while max_level >= min_level {
+        // Look for the start of a sequence of consecutive runs of max_level or higher.
+        let mut seq_start = 0;
+        while seq_start < run_count {
+            if levels[runs[seq_start].start] < max_level {
+                seq_start += 1;
+                continue;
+            }
+
+            // Found the start of a sequence. Now find the end.
+            let mut seq_end = seq_start + 1;
+            while seq_end < run_count {
+                if levels[runs[seq_end].start] < max_level {
+                    break;
+                }
+                seq_end += 1;
+            }
+
+            // Reverse the runs within this sequence.
+            runs[seq_start..seq_end].reverse();
+
+            seq_start = seq_end;
+        }
+        max_level
+            .lower(1)
+            .expect("Lowering embedding level below zero");
+    }
+
+    runs
+}