Extract 'computeLineStarts' utility.

pkg/analyzer/lib/src/generated/java_engine.dart

 library java.engine;
 
 import 'interner.dart';
 import 'java_core.dart';
 
 /**
  * A predicate is a one-argument function that returns a boolean value.
  */
 typedef bool Predicate<E>(E argument);
 
@@ skipping 103 matching lines @@
     return "";
   }
 }
 
 class StringUtilities {
   static const String EMPTY = '';
   static const List<String> EMPTY_ARRAY = const <String>[];
 
   static Interner INTERNER = new NullInterner();
 
+  /**
+   * Compute line starts for the given [content].
+   * Lines end with `\r`, `\n` or `\r\n`.
+   */
+  static List<int> computeLineStarts(String content) {
+    List<int> lineStarts = <int>[0];
+    int length = content.length;
+    int unit;
+    for (int index = 0; index < length; index++) {
+      unit = content.codeUnitAt(index);
+      // Special-case \r\n.
+      if (unit == 0x0D /* \r */) {
+        // Peek ahead to detect a following \n.
+        if ((index + 1 < length) && content.codeUnitAt(index + 1) == 0x0A) {
+          // Line start will get registered at next index at the \n.
+        } else {
+          lineStarts.add(index + 1);
+        }
+      }
+      // \n
+      if (unit == 0x0A) {
+        lineStarts.add(index + 1);
+      }
+    }
+    return lineStarts;
+  }
+
   static endsWith3(String str, int c1, int c2, int c3) {
     var length = str.length;
     return length >= 3 &&
         str.codeUnitAt(length - 3) == c1 &&
         str.codeUnitAt(length - 2) == c2 &&
         str.codeUnitAt(length - 1) == c3;
   }
 
   static endsWithChar(String str, int c) {
     int length = str.length;
@@ skipping 202 matching lines @@
   }
 }
 
 class UUID {
   static int __nextId = 0;
   final String id;
   UUID(this.id);
   String toString() => id;
   static UUID randomUUID() => new UUID((__nextId).toString());
 }