public ParserState(int startState, TokenStream tokStream) {
reallocateStateStack();
stateStackTop = 0;
stateStack[0] = startState;
//
// The tuple tokens will eventually contain the sequence
// of tokens that resulted in a successful parse. We leave
// it up to the "Stream" implementer to define the predecessor
// of the first token as he sees fit.
//
tokStream.reset(); // Position at first token.
tokens = new IntTuple(tokStream.getStreamLength());
tokens.add(tokStream.getPrevious(tokStream.peek()));
}
private boolean repairable(int error_token) {
//
// Allocate configuration stack.
//
ConfigurationStack configuration_stack = new ConfigurationStack(prs);
//
// Keep parsing until we successfully reach the end of file or
// an error is encountered. The list of actions executed will
// be stored in the "action" tuple.
//
int start_token = tokStream.peek();
int final_token = tokStream.getStreamLength(); // unreachable
int curtok = 0;
int current_kind = ERROR_SYMBOL;
int act = tAction(state.stateStack[state.stateStackTop], current_kind);
for (; ; ) {
if (act <= NUM_RULES) {
state.stateStackTop--;
act = process_repair_reductions(act);
} else if (act > ERROR_ACTION) {
curtok = tokStream.getToken();
if (curtok > final_token) return true;
current_kind = tokStream.getKind(curtok);
act = process_repair_reductions(act - ERROR_ACTION);
} else if (act < ACCEPT_ACTION) {
curtok = tokStream.getToken();
if (curtok > final_token) return true;
current_kind = tokStream.getKind(curtok);
} else if (act == ERROR_ACTION) {
ConfigurationElement configuration = configuration_stack.pop();
if (configuration == null) act = ERROR_ACTION;
else {
state.stateStackTop = configuration.stack_top;
configuration.retrieveStack(state.stateStack);
act = configuration.act;
curtok = configuration.curtok;
if (curtok == 0) {
current_kind = ERROR_SYMBOL;
tokStream.reset(start_token);
} else {
current_kind = tokStream.getKind(curtok);
tokStream.reset(tokStream.getNext(curtok));
}
continue;
}
break;
} else if (act > ACCEPT_ACTION) {
if (configuration_stack.findConfiguration(state.stateStack, state.stateStackTop, curtok))
act = ERROR_ACTION;
else {
configuration_stack.push(state.stateStack, state.stateStackTop, act + 1, curtok, 0);
act = prs.baseAction(act);
}
continue;
} else break; // assert(act == ACCEPT_ACTION);
try {
//
// We consider a configuration to be acceptable for recovery
// if we are able to consume enough symbols in the remaining
// tokens to reach another potential recovery point past the
// original error token.
//
if ((curtok > error_token) && (final_token == tokStream.getStreamLength())) {
//
// If the ERROR_SYMBOL is a valid Action Adjunct in the
// state
// "act" then we set the terminating token as the successor
// of
// the current token. I.e., we have to be able to parse at
// least
// two tokens past the re-synch point before we claim
// victory.
//
if (recoverableState(act)) final_token = skipTokens ? curtok : tokStream.getNext(curtok);
}
state.stateStack[++state.stateStackTop] = act;
} catch (IndexOutOfBoundsException e) {
state.reallocateStateStack();
state.stateStack[state.stateStackTop] = act;
}
act = tAction(act, current_kind);
}
//
// If we can reach the end of the input successfully, we claim victory.
//
return (act == ACCEPT_ACTION);
}
//
// Parse the input until either the parse completes successfully or
// an error is encountered. This function returns an integer that
// represents the last action that was executed by the parser. If
// the parse was succesful, then the tuple "action" contains the
// successful sequence of actions that was executed.
//
private int backtrackParse(int initial_token) {
//
// Allocate configuration stack.
//
state.configurationStack = new ConfigurationStack(prs);
state.trialActionStack = new LinkedList<Integer>();
state.trialActionStack.add(Integer.valueOf(state.trialActionCount));
//
// Keep parsing until we successfully reach the end of file or
// an error is encountered. The list of actions executed will
// be stored in the "action" tuple.
//
int error_token = 0;
int maxStackTop = state.stateStackTop;
int start_token = tokStream.peek();
state.curtok = (initial_token > 0 ? initial_token : tokStream.getToken());
int current_kind = tokStream.getKind(state.curtok);
state.act = tAction(state.stateStack[state.stateStackTop], current_kind);
//
// The main driver loop
//
for (; ; ) {
//
// if the parser needs to stop processing,
// it may do so here.
//
if (monitor != null && monitor.isCancelled()) return 0;
state.parserLocationStack[state.stateStackTop] = state.curtok;
if (state.act <= NUM_RULES) {
state.actionCount++;
state.stateStackTop--;
state.act = process_backtrack_reductions(state.act);
} else if (state.act > ERROR_ACTION) {
state.actionCount++;
state.lastToken = state.curtok;
state.curtok = tokStream.getToken();
current_kind = tokStream.getKind(state.curtok);
state.act = process_backtrack_reductions(state.act - ERROR_ACTION);
} else if (state.act < ACCEPT_ACTION) {
state.actionCount++;
state.lastToken = state.curtok;
state.curtok = tokStream.getToken();
current_kind = tokStream.getKind(state.curtok);
}
if (state.act == ERROR_ACTION) {
error_token = (error_token > state.curtok ? error_token : state.curtok);
ConfigurationElement configuration = state.configurationStack.pop();
if (configuration == null) state.act = ERROR_ACTION;
else {
boolean shouldPop = prs.baseAction(configuration.conflict_index) == 0;
undoActions(shouldPop);
state.actionCount = configuration.action_length;
state.act = configuration.act;
state.curtok = configuration.curtok;
current_kind = tokStream.getKind(state.curtok);
tokStream.reset(
state.curtok == initial_token ? start_token : tokStream.getNext(state.curtok));
state.stateStackTop = configuration.stack_top;
configuration.retrieveStack(state.stateStack);
continue;
}
break;
}
if (state.act > ACCEPT_ACTION && state.act != ERROR_ACTION) {
if (state.configurationStack.findConfiguration(
state.stateStack, state.stateStackTop, state.curtok)) state.act = ERROR_ACTION;
else {
state.configurationStack.push(
state.stateStack,
state.stateStackTop,
state.act + 1,
state.curtok,
state.actionCount);
state.trialActionStack.add(Integer.valueOf(state.trialActionCount));
state.act = prs.baseAction(state.act);
maxStackTop = state.stateStackTop > maxStackTop ? state.stateStackTop : maxStackTop;
}
continue;
} else if (state.act == ACCEPT_ACTION) {
break;
}
try {
state.stateStack[++state.stateStackTop] = state.act;
} catch (IndexOutOfBoundsException e) {
state.reallocateStateStack();
state.stateStack[state.stateStackTop] = state.act;
}
state.act = tAction(state.act, current_kind);
}
// System.out.println("****Number of configurations: " +
// configuration_stack.configurationSize());
// System.out.println("****Number of elements in stack tree: " +
// configuration_stack.numStateElements());
// System.out.println("****Number of elements in stacks: " +
// configuration_stack.stacksSize());
// System.out.println("****Number of actions: " + action.size());
// System.out.println("****Max Stack Size = " + maxStackTop);
// System.out.flush();
return (state.act == ERROR_ACTION ? error_token : 0);
}