🔧 Refactor string extension methods for improved performance and consistency. Changes include optimizing character counting, reversing strings, and joining words. Updated tests to cover edge cases and fixed bugs related to character occurrences and string formatting.

Author: esentis

lib/src/nullable_string_extensions.dart

@@ -578,12 +578,14 @@ extension MiscExtensionsNullable on String? {
         count++;
         if (i == letters.length - 1) {
           occurrences.add({checkingLetter: count});
-          checkingLetter = letters[i];
         }
       } else {
         occurrences.add({checkingLetter: count});
         checkingLetter = letters[i];
         count = 1;
+        if (i == letters.length - 1) {
+          occurrences.add({checkingLetter: count});
+        }
       }
     }
     return occurrences;
@@ -662,8 +664,7 @@ extension MiscExtensionsNullable on String? {
       return this;
     }
 
-    var letters = this!.split('').toList().reversed;
-    return letters.reduce((current, next) => current + next);
+    return this!.split('').reversed.join();
   }
 
   /// Returns the first [n] characters of the `String`.
@@ -735,19 +736,11 @@ extension MiscExtensionsNullable on String? {
     }
 
     var words = this!.trim().split(RegExp(r'(\s+)'));
-    var slugWord = '';
 
     if (this!.length == 1) {
       return this;
     }
-    for (var i = 0; i <= words.length - 1; i++) {
-      if (i == words.length - 1) {
-        slugWord += words[i];
-      } else {
-        slugWord += words[i] + '_';
-      }
-    }
-    return slugWord;
+    return words.join('_');
   }
 
   /// Returns the `String` to snake_case.
@@ -763,19 +756,11 @@ extension MiscExtensionsNullable on String? {
     }
 
     var words = this!.toLowerCase().trim().split(RegExp(r'(\s+)'));
-    var snakeWord = '';
 
     if (this!.length == 1) {
       return this;
     }
-    for (var i = 0; i <= words.length - 1; i++) {
-      if (i == words.length - 1) {
-        snakeWord += words[i];
-      } else {
-        snakeWord += words[i] + '_';
-      }
-    }
-    return snakeWord;
+    return words.join('_');
   }
 
   /// Returns the `String` in camelcase.
@@ -944,16 +929,16 @@ extension MiscExtensionsNullable on String? {
   /// ```
   String? get replaceGreek {
     if (this.isBlank) return this;
-    var normalizedWord = '';
+    var sb = StringBuffer();
     for (var i = 0; i < this!.length; i++) {
       var character = this![i];
       if (StringHelpers.greekToLatin.containsKey(character)) {
-        normalizedWord += StringHelpers.greekToLatin[character]!;
+        sb.write(StringHelpers.greekToLatin[character]!);
       } else {
-        normalizedWord += character;
+        sb.write(character);
       }
     }
-    return normalizedWord;
+    return sb.toString();
   }
 
   /// Adds a [replacement] character at [index] of the `String`.
@@ -1088,11 +1073,11 @@ extension MiscExtensionsNullable on String? {
     if (this.isBlank || count <= 0) {
       return this;
     }
-    var repeated = this!;
-    for (var i = 0; i < count - 1; i++) {
-      repeated += this!;
+    var sb = StringBuffer();
+    for (var i = 0; i < count; i++) {
+      sb.write(this!);
     }
-    return repeated;
+    return sb.toString();
   }
 
   /// Squeezes the `String` by removing repeats of a given character.
@@ -1107,15 +1092,15 @@ extension MiscExtensionsNullable on String? {
       return this;
     }
 
-    var sb = '';
+    var sb = StringBuffer();
     for (var i = 0; i < this!.length; i++) {
       if (i == 0 ||
           this![i - 1] != this![i] ||
           (this![i - 1] == this![i] && this![i] != char)) {
-        sb += this![i];
+        sb.write(this![i]);
       }
     }
-    return sb;
+    return sb.toString();
   }
 
   /// Checks if the `String` is consisted of same characters (ignores cases).
@@ -1218,21 +1203,20 @@ extension MiscExtensionsNullable on String? {
       return this;
     }
 
-    //var buffer = StringBuffer();
     var maskChars = mask.toArray;
     var index = 0;
-    var out = '';
+    var sb = StringBuffer();
     for (var m in maskChars) {
       if (m == specialChar) {
         if (index < this!.length) {
-          out += this![index];
+          sb.write(this![index]);
           index++;
         }
       } else {
-        out += m;
+        sb.write(m);
       }
     }
-    return out;
+    return sb.toString();
   }
 
   /// Removes the first [n] characters from the `String`.
@@ -1344,7 +1328,7 @@ extension MiscExtensionsNullable on String? {
     if (index < 0) {
       return null;
     }
-    return this!.split('')[index];
+    return this![index];
   }
 
   /// Appends a [suffix] to the `String`.
@@ -1575,7 +1559,7 @@ extension MiscExtensionsNullable on String? {
 
     int index = this!.indexOf(char);
     if (index == -1) {
-      return null;
+      return '';
     }
 
     return this!.substring(0, index);
@@ -1721,23 +1705,13 @@ extension MiscExtensionsNullable on String? {
       return this;
     }
 
-    if (!this!.contains(pattern)) {
-      return defaultToBlank ? '' : this;
-    }
-
-    List<String> patternWords = pattern.split(' ');
-
-    if (patternWords.isEmpty) {
-      return defaultToBlank ? '' : this;
-    }
-    int indexOfLastPatternWord = this!.indexOf(patternWords.last);
+    int index = this!.indexOf(pattern);
 
-    if (patternWords.last.length == 0) {
+    if (index == -1) {
       return defaultToBlank ? '' : this;
     }
 
-    return this!.substring(
-        indexOfLastPatternWord + patternWords.last.length, this!.length);
+    return this!.substring(index + pattern.length);
   }
 
   /// Returns the `String` before a specific character
@@ -1757,25 +1731,13 @@ extension MiscExtensionsNullable on String? {
       return this;
     }
 
-    if (!this!.contains(pattern)) {
-      return defaultToBlank ? '' : this;
-    }
-
-    List<String> patternWords = pattern.split(' ');
-
-    if (patternWords.isEmpty) {
-      return defaultToBlank ? '' : this;
-    }
-    int indexOfFirstPatternWord = this!.indexOf(patternWords.first);
+    int index = this!.indexOf(pattern);
 
-    if (patternWords.last.length == 0) {
+    if (index == -1) {
       return defaultToBlank ? '' : this;
     }
 
-    return this!.substring(
-      0,
-      indexOfFirstPatternWord,
-    );
+    return this!.substring(0, index);
   }
 
   /// The Jaro distance is a measure of edit distance between two strings
@@ -2090,8 +2052,7 @@ extension MiscExtensionsNullable on String? {
       return '';
     }
 
-    final startIndex = pattern.length == 1 ? index + pattern.length : index;
-    return this!.substring(startIndex);
+    return this!.substring(index);
   }
 
   /// Adds a `String` after the first match of the [pattern]. The [pattern] should not be `null`.
@@ -2223,11 +2184,11 @@ extension MiscExtensionsNullable on String? {
       return this;
     }
 
-    List<String> suffix = ["bytes", "KB", "MB", "GB"];
+    List<String> suffix = ["bytes", "KB", "MB", "GB", "TB"];
 
     int j = 0;
 
-    while (number! >= 1024 && j < 4) {
+    while (number! >= 1024 && j < suffix.length - 1) {
       number = (number / 1024).floor();
       j++;
     }
@@ -2428,18 +2389,16 @@ extension MiscExtensionsNullable on String? {
       return this;
     }
 
-    List<String> letters = this!.toArray;
-
-    String swapped = '';
+    var sb = StringBuffer();
 
-    for (final l in letters) {
+    for (final l in this!.toArray) {
       if (l.isUpperCase) {
-        swapped += l.toLowerCase();
+        sb.write(l.toLowerCase());
       } else {
-        swapped += l.toUpperCase();
+        sb.write(l.toUpperCase());
       }
     }
-    return swapped;
+    return sb.toString();
   }
 
   /// Checks whether the provided `String` is a valid Swift code.