From 2e7584daaf5d2f06d326c21297a71d02dd275a35 Mon Sep 17 00:00:00 2001
From: Niki Roo <niki@nikiroo.be>
Date: Wed, 24 Apr 2019 09:28:48 +0200
Subject: [PATCH] new: NextableInputStream, step 1

---
 src/be/nikiroo/utils/NextableInputStream.java | 66 +++++++++++++++++++
 .../test_code/NextableInputStreamTest.java    | 33 ++++++++++
 2 files changed, 99 insertions(+)
 create mode 100644 src/be/nikiroo/utils/NextableInputStream.java
 create mode 100644 src/be/nikiroo/utils/test_code/NextableInputStreamTest.java

diff --git a/src/be/nikiroo/utils/NextableInputStream.java b/src/be/nikiroo/utils/NextableInputStream.java
new file mode 100644
index 0000000..0bcbe14
--- /dev/null
+++ b/src/be/nikiroo/utils/NextableInputStream.java
@@ -0,0 +1,66 @@
+package be.nikiroo.utils;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+public class NextableInputStream extends InputStream {
+	private InputStream in;
+	private boolean eof;
+	private int pos = 0;
+	private int len = 0;
+	private byte[] buffer = new byte[4096];
+
+	public NextableInputStream(InputStream in) {
+		this.in = in;
+	}
+
+	@Override
+	public int read() throws IOException {
+		preRead();
+		if (eof) {
+			return -1;
+		}
+
+		return buffer[pos++];
+	}
+
+	@Override
+	public int read(byte[] b) throws IOException {
+		return read(b, 0, b.length);
+	}
+
+	@Override
+	public int read(byte[] b, int boff, int blen) throws IOException {
+		if (b == null) {
+			throw new NullPointerException();
+		} else if (boff < 0 || blen < 0 || blen > b.length - boff) {
+			throw new IndexOutOfBoundsException();
+		} else if (blen == 0) {
+			return 0;
+		}
+
+		int done = 0;
+		while (!eof && done < blen) {
+			preRead();
+			for (int i = pos; i < blen && i < len; i++) {
+				b[boff + done] = buffer[i];
+				pos++;
+				done++;
+			}
+		}
+
+		return done > 0 ? done : -1;
+	}
+
+	private void preRead() throws IOException {
+		if (in != null && !eof && pos >= len) {
+			pos = 0;
+			len = in.read(buffer);
+			// checkNexts();
+		}
+
+		if (pos >= len) {
+			eof = true;
+		}
+	}
+}
diff --git a/src/be/nikiroo/utils/test_code/NextableInputStreamTest.java b/src/be/nikiroo/utils/test_code/NextableInputStreamTest.java
new file mode 100644
index 0000000..1b0064d
--- /dev/null
+++ b/src/be/nikiroo/utils/test_code/NextableInputStreamTest.java
@@ -0,0 +1,33 @@
+package be.nikiroo.utils.test_code;
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+
+import be.nikiroo.utils.IOUtils;
+import be.nikiroo.utils.NextableInputStream;
+import be.nikiroo.utils.test.TestCase;
+import be.nikiroo.utils.test.TestLauncher;
+
+public class NextableInputStreamTest extends TestLauncher {
+	public NextableInputStreamTest(String[] args) {
+		super("NextableInputStream test", args);
+
+		addTest(new TestCase("Simple byte array reading") {
+			@Override
+			public void test() throws Exception {
+				byte[] expected = new byte[] { 42, 12, 0, 127 };
+				InputStream bin = new ByteArrayInputStream(expected);
+				NextableInputStream in = new NextableInputStream(bin);
+				byte[] actual = IOUtils.toByteArray(in);
+
+				assertEquals(
+						"The resulting array has not the same number of items",
+						expected.length, actual.length);
+				for (int i = 0; i < expected.length; i++) {
+					assertEquals("Item " + i + " (0-based) is not the same",
+							expected[i], actual[i]);
+				}
+			}
+		});
+	}
+}
-- 
2.27.0