From 9a448b8d4f6f144419e8143873a4a4946681afcc Mon Sep 17 00:00:00 2001
From: "ilya (leo)" <heroesleo65@gmail.com>
Date: Wed, 23 Jun 2021 19:31:31 +0300
Subject: [PATCH] Optimizing StringDisplayUtils.trimDisplayLength

---
 .../progressbar/StringDisplayUtils.java       | 19 ++++++++++---------
 .../progressbar/EastAsianDisplayTest.java     | 19 +++++++++++++++++++
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/src/main/java/me/tongfei/progressbar/StringDisplayUtils.java b/src/main/java/me/tongfei/progressbar/StringDisplayUtils.java
index 9c364b9..f69c633 100644
--- a/src/main/java/me/tongfei/progressbar/StringDisplayUtils.java
+++ b/src/main/java/me/tongfei/progressbar/StringDisplayUtils.java
@@ -29,17 +29,18 @@ static int getStringDisplayLength(String s) {
     }
 
     static String trimDisplayLength(String s, int maxDisplayLength) {
-        StringBuilder sb = new StringBuilder();
-        int i = 0;
+        if (maxDisplayLength <= 0) {
+            return "";
+        }
+
         int totalLength = 0;
-        while (totalLength < maxDisplayLength) {
-            char c = s.charAt(i);
-            totalLength += getCharDisplayLength(c);
-            if (totalLength > maxDisplayLength) break;
-            i++;
-            sb.append(c);
+        for (int i = 0; i < s.length(); i++) {
+            totalLength += getCharDisplayLength(s.charAt(i));
+            if (totalLength > maxDisplayLength) {
+                return s.substring(0, i);
+            }
         }
-        return sb.toString();
+        return s;
     }
 
 }
diff --git a/src/test/java/me/tongfei/progressbar/EastAsianDisplayTest.java b/src/test/java/me/tongfei/progressbar/EastAsianDisplayTest.java
index d1df7ed..626602e 100644
--- a/src/test/java/me/tongfei/progressbar/EastAsianDisplayTest.java
+++ b/src/test/java/me/tongfei/progressbar/EastAsianDisplayTest.java
@@ -17,6 +17,25 @@ void testEastAsianDisplayLength() {
         assertEquals(StringDisplayUtils.getStringDisplayLength("プログレスバー"), 14);
     }
 
+    @Test
+    void testEastAsianTrimDisplayLength() {
+        assertEquals(StringDisplayUtils.trimDisplayLength("Progress bar", 0), "");
+        assertEquals(StringDisplayUtils.trimDisplayLength("Progress bar", 10), "Progress b");
+        assertEquals(StringDisplayUtils.trimDisplayLength("Progress bar", 15), "Progress bar");
+        assertEquals(StringDisplayUtils.trimDisplayLength("进度条", 0), "");
+        assertEquals(StringDisplayUtils.trimDisplayLength("进度条", 4), "进度");
+        assertEquals(StringDisplayUtils.trimDisplayLength("进度条", 8), "进度条");
+        assertEquals(StringDisplayUtils.trimDisplayLength("进度条", 0), "");
+        assertEquals(StringDisplayUtils.trimDisplayLength("進度條", 4), "進度");
+        assertEquals(StringDisplayUtils.trimDisplayLength("進度條", 8), "進度條");
+        assertEquals(StringDisplayUtils.trimDisplayLength("진행 표시줄", 0), "");
+        assertEquals(StringDisplayUtils.trimDisplayLength("진행 표시줄", 8), "진행 표");
+        assertEquals(StringDisplayUtils.trimDisplayLength("진행 표시줄", 15), "진행 표시줄");
+        assertEquals(StringDisplayUtils.trimDisplayLength("プログレスバー", 0), "");
+        assertEquals(StringDisplayUtils.trimDisplayLength("プログレスバー", 11), "プログレス");
+        assertEquals(StringDisplayUtils.trimDisplayLength("プログレスバー", 18), "プログレスバー");
+    }
+
     @Test
     void testProgressBarsWithEastAsianScript() {