Class TruffleStringIterator

java.lang.Object
com.oracle.truffle.api.strings.TruffleStringIterator
public final class TruffleStringIterator extends Object
An iterator object that allows iterating over a TruffleString's codepoints, without having to re-calculate codepoint indices on every access.

Usage Example: 

 
 
 abstract static class SomeNode extends Node {

     @Specialization
     static void someSpecialization(
                     TruffleString string,
                     @Cached TruffleString.CreateCodePointIteratorNode createCodePointIteratorNode,
                     @Cached TruffleStringIterator.NextNode nextNode,
                     @Cached TruffleString.CodePointLengthNode codePointLengthNode,
                     @Cached TruffleString.CodePointAtIndexNode codePointAtIndexNode) {

         // iterating over a string's code points using TruffleStringIterator
         TruffleStringIterator iterator = createCodePointIteratorNode.execute(string, Encoding.UTF_8);
         while (iterator.hasNext()) {
             System.out.printf("%x%n", nextNode.execute(iterator));
         }

         // uncached variant:
         TruffleStringIterator iterator2 = string.createCodePointIteratorUncached(Encoding.UTF_8);
         while (iterator2.hasNext()) {
             System.out.printf("%x%n", iterator2.nextUncached());
         }

         // suboptimal variant: using CodePointAtIndexNode in a loop
         int codePointLength = codePointLengthNode.execute(string, Encoding.UTF_8);
         for (int i = 0; i < codePointLength; i++) {
             // performance problem: codePointAtIndexNode may have to calculate the byte index
             // corresponding
             // to codepoint index i for every loop iteration
             System.out.printf("%x%n", codePointAtIndexNode.execute(string, i, Encoding.UTF_8));
         }
     }
 }
Since:
22.1

  • Method Details