//
// Parse input allowing up to max_error_count Error token recoveries.
// When max_error_count is 0, no Error token recoveries occur.
// When max_error is > 0, it limits the number of Error token recoveries.
// When max_error is < 0, the number of error token recoveries is unlimited.
// Also, such recoveries only require one token to be parsed beyond the
// recovery point.
// (normally two tokens beyond the recovery point must be parsed)
// Thus, a negative max_error_count should be used when error productions
// are used to
// skip tokens.
//
public Object parse(int max_error_count) throws BadParseException {
state = new ParserState(START_STATE, tokStream);
skipTokens = max_error_count < 0;
state.pendingCommits = new LinkedList();
backtrackRequested = false;
state.trialActionCount = 0;
// Next "start" token
state.repair_token = 0;
int start_token_index = tokStream.peek();
int start_action_index = 0;
// Last commit point
int[] temp_stack = new int[1];
temp_stack[0] = START_STATE;
state.reallocateOtherStacks(start_token_index);
int initial_error_token = backtrackParse(state.repair_token);
for (int error_token = initial_error_token, count = 0;
error_token != 0;
error_token = backtrackParse(state.repair_token), count++) {
if (count == max_error_count) throw new BadParseException(initial_error_token);
state.actionCount = start_action_index;
tokStream.reset(start_token_index);
state.stateStackTop = temp_stack.length - 1;
System.arraycopy(temp_stack, 0, state.stateStack, 0, temp_stack.length);
state.reallocateOtherStacks(start_token_index);
backtrackParseUpToError(state.repair_token, error_token);
for (state.stateStackTop = findRecoveryStateIndex(state.stateStackTop);
state.stateStackTop >= 0;
state.stateStackTop = findRecoveryStateIndex(state.stateStackTop - 1)) {
int recovery_token = state.tokens.get(state.locationStack[state.stateStackTop] - 1);
state.repair_token =
errorRepair(
(recovery_token >= start_token_index ? recovery_token : error_token), error_token);
if (state.repair_token != 0) break;
}
if (state.stateStackTop < 0) throw new BadParseException(initial_error_token);
temp_stack = new int[state.stateStackTop + 1];
System.arraycopy(state.stateStack, 0, temp_stack, 0, temp_stack.length);
start_action_index = state.actionCount;
start_token_index = tokStream.peek();
}
if (state.repair_token != 0) state.tokens.add(state.repair_token);
int t;
for (t = start_token_index; tokStream.getKind(t) != EOFT_SYMBOL; t = tokStream.getNext(t))
state.tokens.add(t);
state.tokens.add(t);
return null;
}
//
// Process reductions and continue...
//
private int process_repair_reductions(int act) {
do {
System.out.println("process_repair_reductions: " + act);
state.stateStackTop -= (prs.rhs(act) - 1);
act = prs.ntAction(state.stateStack[state.stateStackTop], prs.lhs(act));
} while (act <= NUM_RULES);
return act;
}
//
// Process reductions and continue...
//
private int process_backtrack_reductions(int act) {
do {
state.stateStackTop -= (prs.rhs(act) - 1);
trialAction(act);
if (backtrackRequested) {
backtrackRequested = false;
return ERROR_ACTION;
}
act = prs.ntAction(state.stateStack[state.stateStackTop], prs.lhs(act));
} while (act <= NUM_RULES);
return act;
}
private int errorRepair(int recovery_token, int error_token) {
int temp_stack[] = new int[state.stateStackTop + 1];
System.arraycopy(state.stateStack, 0, temp_stack, 0, temp_stack.length);
for (;
tokStream.getKind(recovery_token) != EOFT_SYMBOL;
recovery_token = tokStream.getNext(recovery_token)) {
System.out.println("recovery token: " + tokStream.getKind(recovery_token)); // $NON-NLS-1$
tokStream.reset(recovery_token);
if (repairable(error_token)) break;
state.stateStackTop = temp_stack.length - 1;
System.arraycopy(temp_stack, 0, state.stateStack, 0, temp_stack.length);
}
if (tokStream.getKind(recovery_token) == EOFT_SYMBOL) {
tokStream.reset(recovery_token);
if (!repairable(error_token)) {
state.stateStackTop = temp_stack.length - 1;
System.arraycopy(temp_stack, 0, state.stateStack, 0, temp_stack.length);
return 0;
}
}
state.stateStackTop = temp_stack.length - 1;
System.arraycopy(temp_stack, 0, state.stateStack, 0, temp_stack.length);
undoActions(state.undoStack[state.stateStackTop]);
tokStream.reset(recovery_token);
state.tokens.reset(state.locationStack[state.stateStackTop] - 1);
state.actionCount = state.actionStack[state.stateStackTop];
state.trialActionCount = state.undoStack[state.stateStackTop];
return tokStream.makeErrorToken(
state.tokens.get(state.locationStack[state.stateStackTop] - 1),
tokStream.getPrevious(recovery_token),
error_token,
ERROR_SYMBOL);
}
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);
}
private void backtrackParseUpToError(int initial_token, int error_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.
//
// tokStream.reset(initial_token);
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);
state.tokens.add(state.curtok);
state.locationStack[state.stateStackTop] = state.tokens.size();
state.actionStack[state.stateStackTop] = state.actionCount;
state.undoStack[state.stateStackTop] = state.trialActionCount;
for (; ; ) {
//
// if the parser needs to stop processing,
// it may do so here.
//
if (monitor != null && monitor.isCancelled()) return;
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.tokens.add(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);
state.tokens.add(state.curtok);
} else if (state.act == ERROR_ACTION) {
if (state.curtok != error_token) {
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;
int next_token_index = configuration.curtok;
state.tokens.reset(next_token_index);
state.curtok = state.tokens.get(next_token_index - 1);
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);
state.locationStack[state.stateStackTop] = state.tokens.size();
state.actionStack[state.stateStackTop] = state.actionCount;
state.undoStack[state.stateStackTop] = state.trialActionCount;
continue;
}
}
break;
} else if (state.act > ACCEPT_ACTION) {
if (state.configurationStack.findConfiguration(
state.stateStack, state.stateStackTop, state.tokens.size())) state.act = ERROR_ACTION;
else {
state.configurationStack.push(
state.stateStack,
state.stateStackTop,
state.act + 1,
state.tokens.size(),
state.actionCount);
state.trialActionStack.add(Integer.valueOf(state.trialActionCount));
state.act = prs.baseAction(state.act);
}
continue;
} else break; // assert(act == ACCEPT_ACTION);
state.stateStack[++state.stateStackTop] = state.act; // no need
// to check
// if out of
// bounds
state.locationStack[state.stateStackTop] = state.tokens.size();
state.actionStack[state.stateStackTop] = state.actionCount;
state.undoStack[state.stateStackTop] = state.trialActionCount;
state.act = tAction(state.act, current_kind);
}
// assert(curtok == error_token);
return;
}
//
// 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);
}
