initial commit

java/base/Log.java

@@ -0,0 +1,56 @@
+package base;
+
+import java.util.function.Supplier;
+import java.util.regex.Pattern;
+
+/**
+ * @author Georgiy Korneev (kgeorgiy@kgeorgiy.info)
+ */
+public class Log {
+    private final Pattern LINES = Pattern.compile("\n");
+    private int indent;
+
+    public static Supplier<Void> action(final Runnable action) {
+        return () -> {
+            action.run();
+            return null;
+        };
+    }
+
+    public void scope(final String name, final Runnable action) {
+        scope(name, action(action));
+    }
+
+    public <T> T scope(final String name, final Supplier<T> action) {
+        println(name);
+        indent++;
+        try {
+            return silentScope(name, action);
+        } finally {
+            indent--;
+        }
+    }
+
+    public <T> T silentScope(final String ignoredName, final Supplier<T> action) {
+        return action.get();
+    }
+
+    @SuppressWarnings("UseOfSystemOutOrSystemErr")
+    public void println(final Object value) {
+        for (final String line : LINES.split(String.valueOf(value))) {
+            System.out.println(indent() + line);
+        }
+    }
+
+    public void format(final String format, final Object... args) {
+        println(String.format(format,args));
+    }
+
+    private String indent() {
+        return "    ".repeat(indent);
+    }
+
+    protected int getIndent() {
+        return indent;
+    }
+}