classlib: implement BufferedReader.lines

classlib/src/main/java/org/teavm/classlib/java/io/TBufferedReader.java

@@ -16,10 +16,14 @@
 package org.teavm.classlib.java.io;
 
 import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.function.Predicate;
 import org.teavm.classlib.java.lang.TIllegalArgumentException;
 import org.teavm.classlib.java.lang.TMath;
 import org.teavm.classlib.java.lang.TStringBuilder;
 import org.teavm.classlib.java.util.TArrays;
+import org.teavm.classlib.java.util.stream.TStream;
+import org.teavm.classlib.java.util.stream.impl.TSimpleStreamImpl;
 
 public class TBufferedReader extends TReader {
     private TReader innerReader;
@@ -111,6 +115,33 @@ public String readLine() throws IOException {
         return line.toString();
     }
 
+    public TStream<String> lines() {
+        return new TSimpleStreamImpl<>() {
+            private boolean done;
+
+            @Override
+            public boolean next(Predicate<? super String> consumer) {
+                if (!done) {
+                    while (true) {
+                        try {
+                            var line = readLine();
+                            if (line == null) {
+                                break;
+                            }
+                            if (!consumer.test(line)) {
+                                return true;
+                            }
+                        } catch (IOException e) {
+                            throw new UncheckedIOException(e);
+                        }
+                    }
+                    done = true;
+                }
+                return false;
+            }
+        };
+    }
+
     @Override
     public long skip(long n) throws IOException {
         requireOpened();

classlib/src/main/java/org/teavm/classlib/java/util/stream/impl/TBufferedReaderLinesStream.java

@@ -0,0 +1,51 @@
+/*
+ *  Copyright 2024 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.classlib.java.util.stream.impl;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.function.Predicate;
+import org.teavm.classlib.java.io.TBufferedReader;
+
+public class TBufferedReaderLinesStream extends TSimpleStreamImpl<String> {
+    private TBufferedReader reader;
+    private boolean done;
+
+    public TBufferedReaderLinesStream(TBufferedReader reader) {
+        this.reader = reader;
+    }
+
+    @Override
+    public boolean next(Predicate<? super String> consumer) {
+        if (!done) {
+            while (true) {
+                try {
+                    var line = reader.readLine();
+                    if (line == null) {
+                        break;
+                    }
+                    if (!consumer.test(line)) {
+                        return true;
+                    }
+                } catch (IOException e) {
+                    throw new UncheckedIOException(e);
+                }
+            }
+            done = true;
+        }
+        return false;
+    }
+}

tests/src/test/java/org/teavm/classlib/java/io/BufferedReaderTest.java

@@ -15,6 +15,7 @@
  */
 package org.teavm.classlib.java.io;
 
+import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import java.io.BufferedReader;
@@ -95,4 +96,15 @@ public void leavesMark() throws IOException {
         assertEquals(51, buffer[1]);
         assertEquals(199, buffer[149]);
     }
+
+    @Test
+    public void lines() {
+        var reader = new BufferedReader(new StringReader("a\nb\n\n"));
+        var lines = reader.lines().toArray(String[]::new);
+        assertArrayEquals(new String[] { "a", "b", "" }, lines);
+
+        reader = new BufferedReader(new StringReader("a\nb\n\n"));
+        lines = reader.lines().filter(s -> !s.isEmpty()).map(s -> "*" + s).toArray(String[]::new);
+        assertArrayEquals(new String[] { "*a", "*b" }, lines);
+    }
 }