Move stack trace formatting in own class

Summary: Moves stack trace formatting logic into its own class to facilitate reusage from custom exception managers.

Reviewed By: javache

Differential Revision: D5086336

fbshipit-source-id: f434a1621c599c5c49991b3bfe5f66d05f84b5c9

ReactAndroid/src/main/java/com/facebook/react/util/BUCK

@@ -0,0 +1,12 @@
+include_defs("//ReactAndroid/DEFS")
+
+android_library(
+    name = "util",
+    srcs = glob(["**/*.java"]),
+    visibility = [
+        "PUBLIC",
+    ],
+    deps = [
+        react_native_target("java/com/facebook/react/bridge:bridge"),
+    ],
+)

ReactAndroid/src/main/java/com/facebook/react/util/JSStackTrace.java

@@ -0,0 +1,59 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+package com.facebook.react.util;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import com.facebook.react.bridge.ReadableArray;
+import com.facebook.react.bridge.ReadableMap;
+import com.facebook.react.bridge.ReadableType;
+
+public class JSStackTrace {
+
+  final private static Pattern mJsModuleIdPattern = Pattern.compile("(?:^|[/\\\\])(\\d+\\.js)$");
+
+  public static String format(String message, ReadableArray stack) {
+    StringBuilder stringBuilder = new StringBuilder(message).append(", stack:\n");
+    for (int i = 0; i < stack.size(); i++) {
+      ReadableMap frame = stack.getMap(i);
+      stringBuilder
+        .append(frame.getString("methodName"))
+        .append("@")
+        .append(stackFrameToModuleId(frame))
+        .append(frame.getInt("lineNumber"));
+      if (frame.hasKey("column") &&
+        !frame.isNull("column") &&
+        frame.getType("column") == ReadableType.Number) {
+        stringBuilder
+          .append(":")
+          .append(frame.getInt("column"));
+      }
+      stringBuilder.append("\n");
+    }
+    return stringBuilder.toString();
+  }
+
+  // If the file name of a stack frame is numeric (+ ".js"), we assume it's a lazily injected module
+  // coming from a "random access bundle". We are using special source maps for these bundles, so
+  // that we can symbolicate stack traces for multiple injected files with a single source map.
+  // We have to include the module id in the stack for that, though. The ".js" suffix is kept to
+  // avoid ambiguities between "module-id:line" and "line:column".
+  private static String stackFrameToModuleId(ReadableMap frame) {
+    if (frame.hasKey("file") &&
+        !frame.isNull("file") &&
+        frame.getType("file") == ReadableType.String) {
+      final Matcher matcher = mJsModuleIdPattern.matcher(frame.getString("file"));
+      if (matcher.find()) {
+        return matcher.group(1) + ":";
+      }
+    }
+    return "";
+  }
+}