// ASM: a very small and fast Java bytecode manipulation framework
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package org.springframework.asm;

Information about an exception handler. Corresponds to an element of the exception_table array of a Code attribute, as defined in the Java Virtual Machine Specification (JVMS). Handler instances can be chained together, with their nextHandler field, to describe a full JVMS exception_table array.
Author:Eric Bruneton
See Also:
/** * Information about an exception handler. Corresponds to an element of the exception_table array of * a Code attribute, as defined in the Java Virtual Machine Specification (JVMS). Handler instances * can be chained together, with their {@link #nextHandler} field, to describe a full JVMS * exception_table array. * * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.3">JVMS * 4.7.3</a> * @author Eric Bruneton */
final class Handler {
The start_pc field of this JVMS exception_table entry. Corresponds to the beginning of the exception handler's scope (inclusive).
/** * The start_pc field of this JVMS exception_table entry. Corresponds to the beginning of the * exception handler's scope (inclusive). */
final Label startPc;
The end_pc field of this JVMS exception_table entry. Corresponds to the end of the exception handler's scope (exclusive).
/** * The end_pc field of this JVMS exception_table entry. Corresponds to the end of the exception * handler's scope (exclusive). */
final Label endPc;
The handler_pc field of this JVMS exception_table entry. Corresponding to the beginning of the exception handler's code.
/** * The handler_pc field of this JVMS exception_table entry. Corresponding to the beginning of the * exception handler's code. */
final Label handlerPc;
The catch_type field of this JVMS exception_table entry. This is the constant pool index of the internal name of the type of exceptions handled by this handler, or 0 to catch any exceptions.
/** * The catch_type field of this JVMS exception_table entry. This is the constant pool index of the * internal name of the type of exceptions handled by this handler, or 0 to catch any exceptions. */
final int catchType;
The internal name of the type of exceptions handled by this handler, or null to catch any exceptions.
/** * The internal name of the type of exceptions handled by this handler, or {@literal null} to * catch any exceptions. */
final String catchTypeDescriptor;
The next exception handler.
/** The next exception handler. */
Handler nextHandler;
Constructs a new Handler.
Params:
  • startPc – the start_pc field of this JVMS exception_table entry.
  • endPc – the end_pc field of this JVMS exception_table entry.
  • handlerPc – the handler_pc field of this JVMS exception_table entry.
  • catchType – The catch_type field of this JVMS exception_table entry.
  • catchTypeDescriptor – The internal name of the type of exceptions handled by this handler, or null to catch any exceptions.
/** * Constructs a new Handler. * * @param startPc the start_pc field of this JVMS exception_table entry. * @param endPc the end_pc field of this JVMS exception_table entry. * @param handlerPc the handler_pc field of this JVMS exception_table entry. * @param catchType The catch_type field of this JVMS exception_table entry. * @param catchTypeDescriptor The internal name of the type of exceptions handled by this handler, * or {@literal null} to catch any exceptions. */
Handler( final Label startPc, final Label endPc, final Label handlerPc, final int catchType, final String catchTypeDescriptor) { this.startPc = startPc; this.endPc = endPc; this.handlerPc = handlerPc; this.catchType = catchType; this.catchTypeDescriptor = catchTypeDescriptor; }
Constructs a new Handler from the given one, with a different scope.
Params:
  • handler – an existing Handler.
  • startPc – the start_pc field of this JVMS exception_table entry.
  • endPc – the end_pc field of this JVMS exception_table entry.
/** * Constructs a new Handler from the given one, with a different scope. * * @param handler an existing Handler. * @param startPc the start_pc field of this JVMS exception_table entry. * @param endPc the end_pc field of this JVMS exception_table entry. */
Handler(final Handler handler, final Label startPc, final Label endPc) { this(startPc, endPc, handler.handlerPc, handler.catchType, handler.catchTypeDescriptor); this.nextHandler = handler.nextHandler; }
Removes the range between start and end from the Handler list that begins with the given element.
Params:
  • firstHandler – the beginning of a Handler list. May be null.
  • start – the start of the range to be removed.
  • end – the end of the range to be removed. Maybe null.
Returns:the exception handler list with the start-end range removed.
/** * Removes the range between start and end from the Handler list that begins with the given * element. * * @param firstHandler the beginning of a Handler list. May be {@literal null}. * @param start the start of the range to be removed. * @param end the end of the range to be removed. Maybe {@literal null}. * @return the exception handler list with the start-end range removed. */
static Handler removeRange(final Handler firstHandler, final Label start, final Label end) { if (firstHandler == null) { return null; } else { firstHandler.nextHandler = removeRange(firstHandler.nextHandler, start, end); } int handlerStart = firstHandler.startPc.bytecodeOffset; int handlerEnd = firstHandler.endPc.bytecodeOffset; int rangeStart = start.bytecodeOffset; int rangeEnd = end == null ? Integer.MAX_VALUE : end.bytecodeOffset; // Return early if [handlerStart,handlerEnd[ and [rangeStart,rangeEnd[ don't intersect. if (rangeStart >= handlerEnd || rangeEnd <= handlerStart) { return firstHandler; } if (rangeStart <= handlerStart) { if (rangeEnd >= handlerEnd) { // If [handlerStart,handlerEnd[ is included in [rangeStart,rangeEnd[, remove firstHandler. return firstHandler.nextHandler; } else { // [handlerStart,handlerEnd[ - [rangeStart,rangeEnd[ = [rangeEnd,handlerEnd[ return new Handler(firstHandler, end, firstHandler.endPc); } } else if (rangeEnd >= handlerEnd) { // [handlerStart,handlerEnd[ - [rangeStart,rangeEnd[ = [handlerStart,rangeStart[ return new Handler(firstHandler, firstHandler.startPc, start); } else { // [handlerStart,handlerEnd[ - [rangeStart,rangeEnd[ = // [handlerStart,rangeStart[ + [rangeEnd,handerEnd[ firstHandler.nextHandler = new Handler(firstHandler, end, firstHandler.endPc); return new Handler(firstHandler, firstHandler.startPc, start); } }
Returns the number of elements of the Handler list that begins with the given element.
Params:
  • firstHandler – the beginning of a Handler list. May be null.
Returns:the number of elements of the Handler list that begins with 'handler'.
/** * Returns the number of elements of the Handler list that begins with the given element. * * @param firstHandler the beginning of a Handler list. May be {@literal null}. * @return the number of elements of the Handler list that begins with 'handler'. */
static int getExceptionTableLength(final Handler firstHandler) { int length = 0; Handler handler = firstHandler; while (handler != null) { length++; handler = handler.nextHandler; } return length; }
Returns the size in bytes of the JVMS exception_table corresponding to the Handler list that begins with the given element. This includes the exception_table_length field.
Params:
  • firstHandler – the beginning of a Handler list. May be null.
Returns:the size in bytes of the exception_table_length and exception_table structures.
/** * Returns the size in bytes of the JVMS exception_table corresponding to the Handler list that * begins with the given element. <i>This includes the exception_table_length field.</i> * * @param firstHandler the beginning of a Handler list. May be {@literal null}. * @return the size in bytes of the exception_table_length and exception_table structures. */
static int getExceptionTableSize(final Handler firstHandler) { return 2 + 8 * getExceptionTableLength(firstHandler); }
Puts the JVMS exception_table corresponding to the Handler list that begins with the given element. This includes the exception_table_length field.
Params:
  • firstHandler – the beginning of a Handler list. May be null.
  • output – where the exception_table_length and exception_table structures must be put.
/** * Puts the JVMS exception_table corresponding to the Handler list that begins with the given * element. <i>This includes the exception_table_length field.</i> * * @param firstHandler the beginning of a Handler list. May be {@literal null}. * @param output where the exception_table_length and exception_table structures must be put. */
static void putExceptionTable(final Handler firstHandler, final ByteVector output) { output.putShort(getExceptionTableLength(firstHandler)); Handler handler = firstHandler; while (handler != null) { output .putShort(handler.startPc.bytecodeOffset) .putShort(handler.endPc.bytecodeOffset) .putShort(handler.handlerPc.bytecodeOffset) .putShort(handler.catchType); handler = handler.nextHandler; } } }