Java 类org.objectweb.asm.commons.TableSwitchGenerator 实例源码

/** See {@link GeneratorAdapter#tableSwitch(int[], TableSwitchGenerator)} */
public void tableSwitch(int[] keys, TableSwitchGenerator generator) {
  adapter.tableSwitch(keys, generator);
}

/** See {@link GeneratorAdapter#tableSwitch(int[], TableSwitchGenerator, boolean)} */
public void tableSwitch(int[] keys, TableSwitchGenerator generator, boolean useTable) {
  adapter.tableSwitch(keys, generator, useTable);
}

/**
 * Returns a statement that generates the reattach jump table.
 *
 * <p>Note: This statement should be the <em>first</em> statement in any detachable method.
 */
Statement generateReattachTable() {
  final Expression readField = stateField.accessor(thisExpr);
  final Statement defaultCase =
      Statement.throwExpression(MethodRef.RUNTIME_UNEXPECTED_STATE_ERROR.invoke(readField));
  return new Statement() {
    @Override
    protected void doGen(final CodeBuilder adapter) {
      int[] keys = new int[reattaches.size()];
      for (int i = 0; i < keys.length; i++) {
        keys[i] = i;
      }
      readField.gen(adapter);
      // Generate a switch table.  Note, while it might be preferable to just 'goto state', Java
      // doesn't allow computable gotos (probably because it makes verification impossible).  So
      // instead we emulate that with a jump table.  And anyway we still need to execute 'restore'
      // logic to repopulate the local variable tables, so the 'case' statements are a natural
      // place for that logic to live.
      adapter.tableSwitch(
          keys,
          new TableSwitchGenerator() {
            @Override
            public void generateCase(int key, Label end) {
              if (key == 0) {
                // State 0 is special, it means initial state, so we just jump to the very end
                adapter.goTo(end);
                return;
              }
              ReattachState reattachState = reattaches.get(key);
              // restore and jump!
              reattachState.restoreStatement().gen(adapter);
              adapter.goTo(reattachState.reattachPoint());
            }

            @Override
            public void generateDefault() {
              defaultCase.gen(adapter);
            }
          },
          // Use tableswitch instead of lookupswitch.  TableSwitch is appropriate because our case
          // labels are sequential integers in the range [0, N).  This means that switch is O(1)
          // and
          // there are no 'holes' meaning that it is compact in the bytecode.
          true);
    }
  };
}