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/*
* Copyright 2009 Google Inc.
*
* 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 com.google.gwt.core.client.impl;
import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.JavaScriptObject;
import com.google.gwt.core.client.JsArray;
import com.google.gwt.core.client.JsArrayString;
import javaemul.internal.ArrayHelper;
/**
* Encapsulates logic to create a stack trace. This class should only be used in
* Production Mode.
*/
public class StackTraceCreator {
/**
* Maximum # of frames to look for {@link Throwable#fillInStackTrace()} in the generated stack
* trace. This is just a safe guard just in case if {@code fillInStackTrace} doesn't show up in
* the stack trace for some reason.
*/
private static final int DROP_FRAME_LIMIT = 5;
/**
* Line number used in a stack trace when it is unknown.
*/
private static final int LINE_NUMBER_UNKNOWN = -1;
/**
* Replacement for function names that cannot be extracted from a stack.
*/
private static final String ANONYMOUS = "anonymous";
/**
* Replacement for class or file names that cannot be extracted from a stack.
*/
private static final String UNKNOWN = "Unknown";
/**
* This class acts as a deferred-binding hook point to allow more optimal versions to be
* substituted.
*/
abstract static class Collector {
public abstract void collect(Object error);
public abstract StackTraceElement[] getStackTrace(Object t);
}
/**
* This legacy {@link Collector} simply crawls arguments.callee.caller for browsers
* that doesn't support {@code Error.stack} property.
*/
static class CollectorLegacy extends Collector {
@Override
public native void collect(Object error) /*-{
var seen = {};
var fnStack = [];
error["fnStack"] = fnStack;
// Ignore the collect() call
var callee = arguments.callee.caller;
while (callee) {
var name = @StackTraceCreator::getFunctionName(*)(callee);
fnStack.push(name);
// Avoid infinite loop by associating names to function objects. We
// record each caller in the withThisName variable to handle functions
// with identical names but separate identity (such as 'anonymous')
var keyName = ':' + name;
var withThisName = seen[keyName];
if (withThisName) {
var i, j;
for (i = 0, j = withThisName.length; i < j; i++) {
if (withThisName[i] === callee) {
return;
}
}
}
(withThisName || (seen[keyName] = [])).push(callee);
callee = callee.caller;
}
}-*/;
@Override
public StackTraceElement[] getStackTrace(Object t) {
JsArrayString stack = getFnStack(t);
int length = stack.length();
StackTraceElement[] stackTrace = new StackTraceElement[length];
for (int i = 0; i < length; i++) {
stackTrace[i] = new StackTraceElement(UNKNOWN, stack.get(i), null, LINE_NUMBER_UNKNOWN);
}
return stackTrace;
}
}
/**
* Collaborates with JsStackEmulator.
*/
static final class CollectorEmulated extends Collector {
@Override
public native void collect(Object error) /*-{
var fnStack = [];
error["fnStack"] = fnStack;
for (var i = 0; i < $stackDepth; i++) {
var location = $location[i];
var fn = $stack[i];
var name = fn ? @StackTraceCreator::getFunctionName(*)(fn) : @StackTraceCreator::ANONYMOUS;
// Reverse the order
fnStack[$stackDepth - i - 1] = [name, location];
}
}-*/;
@Override
public StackTraceElement[] getStackTrace(Object t) {
JsArray stack = getFnStack(t).cast();
StackTraceElement[] stackTrace = new StackTraceElement[stack.length()];
for (int i = 0; i < stackTrace.length; i++) {
JsArrayString frame = stack.get(i);
String name = frame.get(0);
String location = frame.get(1);
String fileName = null;
int lineNumber = LINE_NUMBER_UNKNOWN;
if (location != null) {
int idx = location.indexOf(':');
if (idx != -1) {
fileName = location.substring(0, idx);
lineNumber = parseInt(location.substring(idx + 1));
} else {
lineNumber = parseInt(location);
}
}
stackTrace[i] = new StackTraceElement(UNKNOWN, name, fileName, lineNumber);
}
return stackTrace;
}
}
/**
* Modern browsers provide a stack property in thrown objects.
*/
static class CollectorModern extends Collector {
@Override
public void collect(Object error) {
// No op, already collected by the error itself.
}
@Override
public StackTraceElement[] getStackTrace(Object t) {
JsArrayString stack = split(t);
// We are in script-mode - let the array auto grow.
StackTraceElement[] stackTrace = new StackTraceElement[0];
int addIndex = 0, length = stack.length();
if (length == 0) {
// Nothing to parse...
return stackTrace;
}
// Chrome & IE10+ contains the error msg as the first line of stack (iOS, Firefox doesn't).
StackTraceElement ste = parse(stack.get(0));
if (!ste.getMethodName().equals(ANONYMOUS)) {
stackTrace[addIndex++] = ste;
}
// Parse and put the rest of the elements in to the stack trace.
for (int i = 1; i < length; i++) {
stackTrace[addIndex++] = parse(stack.get(i));
}
return stackTrace;
}
/**
* Parses a stack trace line from the browser and returns a new {@link StackTraceElement}
* constructed with the extracted data.
*/
private StackTraceElement parse(String stString) {
String location = "";
if (stString.isEmpty()) {
return createSte(UNKNOWN, ANONYMOUS, LINE_NUMBER_UNKNOWN, -1);
}
String toReturn = stString.trim();
// Strip the "at " prefix:
if (toReturn.startsWith("at ")) {
toReturn = toReturn.substring(3);
}
toReturn = stripSquareBrackets(toReturn);
int index = toReturn.indexOf("(");
if (index == -1) {
// No bracketed items found, try '@' (used by iOS & Firefox).
index = toReturn.indexOf("@");
if (index == -1) {
// No bracketed items nor '@' found, hence no function name available
location = toReturn;
toReturn = "";
} else {
location = toReturn.substring(index + 1).trim();
toReturn = toReturn.substring(0, index).trim();
}
} else {
// Bracketed items found: strip them off, parse location info
int closeParen = toReturn.indexOf(")", index);
location = toReturn.substring(index + 1, closeParen);
toReturn = toReturn.substring(0, index).trim();
}
// Strip the Type off t
index = toReturn.indexOf('.');
if (index != -1) {
toReturn = toReturn.substring(index + 1);
}
final String ieAnonymousFunctionName = "Anonymous function";
if (toReturn.isEmpty() || toReturn.equals(ieAnonymousFunctionName)) {
toReturn = ANONYMOUS;
}
// colon between line and column
int lastColonIndex = location.lastIndexOf(':');
// colon between file url and line number
int endFileUrlIndex = location.lastIndexOf(':', lastColonIndex - 1);
int line = LINE_NUMBER_UNKNOWN;
int col = -1;
String fileName = UNKNOWN;
if (lastColonIndex != -1 && endFileUrlIndex != -1) {
fileName = location.substring(0, endFileUrlIndex);
line = parseInt(location.substring(endFileUrlIndex + 1, lastColonIndex));
col = parseInt(location.substring(lastColonIndex + 1));
}
return createSte(fileName, toReturn, line, col);
}
protected StackTraceElement createSte(String fileName, String method, int line, int col) {
return new StackTraceElement(UNKNOWN, method, fileName + "@" + col,
line < 0 ? LINE_NUMBER_UNKNOWN : line);
}
private native String stripSquareBrackets(String toReturn) /*-{
return toReturn.replace(/\[.*?\]/g,"")
}-*/;
}
/**
* Subclass that forces reported line numbers to -1 (fetch from symbolMap) if source maps are
* disabled.
*/
static class CollectorModernNoSourceMap extends CollectorModern {
@Override
protected StackTraceElement createSte(String fileName, String method, int line, int col) {
return new StackTraceElement(UNKNOWN, method, fileName, LINE_NUMBER_UNKNOWN);
}
}
private static native int parseInt(String number) /*-{
return parseInt(number) || @StackTraceCreator::LINE_NUMBER_UNKNOWN;
}-*/;
/**
* When compiler.stackMode = strip, we stub out the collector.
*/
static class CollectorNull extends Collector {
@Override
public void collect(Object error) {
// Nothing to do
}
@Override
public StackTraceElement[] getStackTrace(Object ignored) {
return new StackTraceElement[0];
}
}
/**
* Collect necessary information to construct stack trace trace later in time.
*/
public static void captureStackTrace(Object error) {
collector.collect(error);
}
public static StackTraceElement[] constructJavaStackTrace(Throwable thrown) {
StackTraceElement[] stackTrace = collector.getStackTrace(thrown);
return dropInternalFrames(stackTrace);
}
private static StackTraceElement[] dropInternalFrames(StackTraceElement[] stackTrace) {
final String dropFrameUntilFnName =
Impl.getNameOf("@com.google.gwt.core.client.impl.StackTraceCreator::captureStackTrace(*)");
final String dropFrameUntilFnName2 =
Impl.getNameOf("@java.lang.Throwable::initializeBackingError(*)");
int numberOfFramesToSearch = Math.min(stackTrace.length, DROP_FRAME_LIMIT);
for (int i = numberOfFramesToSearch - 1; i >= 0; i--) {
if (stackTrace[i].getMethodName().equals(dropFrameUntilFnName)
|| stackTrace[i].getMethodName().equals(dropFrameUntilFnName2)) {
splice(stackTrace, i + 1);
break;
}
}
return stackTrace;
}
private static void splice(Object[] arr, int length) {
if (arr.length >= length) {
ArrayHelper.removeFrom(arr, 0, length);
}
}
// Visible for testing
static final Collector collector;
static {
// Ensure old Safari falls back to legacy Collector implementation.
boolean enforceLegacy = !supportsErrorStack();
Collector c = GWT.create(Collector.class);
collector = (c instanceof CollectorModern && enforceLegacy) ? new CollectorLegacy() : c;
}
private static native boolean supportsErrorStack() /*-{
// Error.stackTraceLimit is cheaper to check and available in both IE and Chrome
if (Error.stackTraceLimit > 0) {
$wnd.Error.stackTraceLimit = Error.stackTraceLimit = 64;
return true;
}
return "stack" in new Error();
}-*/;
private static native JsArrayString getFnStack(Object e) /*-{
return (e && e["fnStack"]) ? e["fnStack"] : [];
}-*/;
private static native String getFunctionName(JavaScriptObject fn) /*-{
return fn.name || (fn.name = @StackTraceCreator::extractFunctionName(*)(fn.toString()));
}-*/;
// Visible for testing
static native String extractFunctionName(String fnName) /*-{
var fnRE = /function(?:\s+([\w$]+))?\s*\(/;
var match = fnRE.exec(fnName);
return (match && match[1]) || @StackTraceCreator::ANONYMOUS;
}-*/;
private static native JsArrayString split(Object t) /*-{
var e = t.@Throwable::backingJsObject;
return (e && e.stack) ? e.stack.split('\n') : [];
}-*/;
}
