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* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
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package jdk.nashorn.internal.runtime;
import static jdk.nashorn.internal.parser.TokenType.EOF;
import jdk.nashorn.api.scripting.NashornException;
import jdk.nashorn.internal.parser.Lexer;
import jdk.nashorn.internal.parser.Token;
import jdk.nashorn.internal.parser.TokenStream;
import jdk.nashorn.internal.parser.TokenType;
Utilities for debugging Nashorn.
/**
* Utilities for debugging Nashorn.
*
*/
public final class Debug {
private Debug() {
}
Return the topmost JavaScript frame in a stack trace
Params: - t – throwable that contains the stack trace
Returns: line describing the topmost JavaScript frame
/**
* Return the topmost JavaScript frame in a stack trace
* @param t throwable that contains the stack trace
* @return line describing the topmost JavaScript frame
*/
public static String firstJSFrame(final Throwable t) {
for (final StackTraceElement ste : t.getStackTrace()) {
if (ECMAErrors.isScriptFrame(ste)) {
return ste.toString();
}
}
return "<native code>";
}
Return the topmost JavaScript frame from the current
continuation
Returns: line describing the topmost JavaScript frame
/**
* Return the topmost JavaScript frame from the current
* continuation
* @return line describing the topmost JavaScript frame
*/
public static String firstJSFrame() {
return firstJSFrame(new Throwable());
}
Return a formatted script stack trace string with frames information separated by '\n'. This is a shortcut for NashornException.getScriptStackString(new Throwable()). Returns: formatted stack trace string
/**
* Return a formatted script stack trace string with frames information separated by '\n'.
* This is a shortcut for {@code NashornException.getScriptStackString(new Throwable())}.
* @return formatted stack trace string
*/
public static String scriptStack() {
return NashornException.getScriptStackString(new Throwable());
}
Return the system identity hashcode for an object as a human readable
string
Params: - x – object
Returns: system identity hashcode as string
/**
* Return the system identity hashcode for an object as a human readable
* string
*
* @param x object
* @return system identity hashcode as string
*/
public static String id(final Object x) {
return String.format("0x%08x", System.identityHashCode(x));
}
Same as id but returns the identity hashcode as an integer Params: - x – object
Returns: system identity hashcode
/**
* Same as {@link Debug#id} but returns the identity hashcode as
* an integer
*
* @param x object
* @return system identity hashcode
*/
public static int intId(final Object x) {
return System.identityHashCode(x);
}
Return a stack trace element description at a depth from where we are not
Params: - depth – depth
Returns: stack trace element as string
/**
* Return a stack trace element description at a depth from where we are not
*
* @param depth depth
* @return stack trace element as string
*/
public static String stackTraceElementAt(final int depth) {
return new Throwable().getStackTrace()[depth + 1].toString(); // add 1 to compensate for this method
}
Determine caller for tracing purposes.
Params: - depth – depth to trace
- count – max depth
- ignores – elements to ignore in stack trace
Returns: caller
/**
* Determine caller for tracing purposes.
* @param depth depth to trace
* @param count max depth
* @param ignores elements to ignore in stack trace
* @return caller
*/
public static String caller(final int depth, final int count, final String... ignores) {
String result = "";
final StackTraceElement[] callers = Thread.currentThread().getStackTrace();
int c = count;
loop:
for (int i = depth + 1; i < callers.length && c != 0; i++) {
final StackTraceElement element = callers[i];
final String method = element.getMethodName();
for (final String ignore : ignores) {
if (method.compareTo(ignore) == 0) {
continue loop;
}
}
result += (method + ":" + element.getLineNumber() +
" ").substring(0, 30);
c--;
}
return result.isEmpty() ? "<no caller>" : result;
}
Dump a token stream to stdout
TODO: most other bugging goes to stderr, change?
Params: - source – the source
- lexer – the lexer
- stream – the stream to dump
/**
* Dump a token stream to stdout
*
* TODO: most other bugging goes to stderr, change?
*
* @param source the source
* @param lexer the lexer
* @param stream the stream to dump
*/
public static void dumpTokens(final Source source, final Lexer lexer, final TokenStream stream) {
TokenType type;
int k = 0;
do {
while (k > stream.last()) {
// Get more tokens.
lexer.lexify();
}
final long token = stream.get(k);
type = Token.descType(token);
System.out.println("" + k + ": " + Token.toString(source, token, true));
k++;
} while(type != EOF);
}
}