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Record in parse table which actions can hide splits

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Suppose a parse state S has multiple actions for a terminal lookahead symbol A.
Then during incremental parsing, while in state S, the parser should not
reuse a non-terminal lookahead B where FIRST(B) contains A, because reusing B
might prematurely discard one of the possible actions that a batch parser
would have attempted in state S, upon seeing A as a lookahead.
This commit is contained in:
Max Brunsfeld 2015-12-17 12:48:55 -08:00
parent 7fbb628c78
commit c495076adb
19 changed files with 58613 additions and 60661 deletions
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49
src/compiler/parse_table.cc
View file

@ -17,6 +17,9 @@ ParseAction::ParseAction(ParseActionType type, ParseStateId state_index,
rules::Associativity associativity,
const Production *production)
: type(type),
extra(false),
fragile(false),
can_hide_split(false),
symbol(symbol),
state_index(state_index),
consumed_symbol_count(consumed_symbol_count),
@ -26,6 +29,9 @@ ParseAction::ParseAction(ParseActionType type, ParseStateId state_index,
ParseAction::ParseAction()
: type(ParseActionTypeError),
extra(false),
fragile(false),
can_hide_split(false),
symbol(Symbol(-1)),
state_index(-1),
consumed_symbol_count(0),
@ -49,14 +55,17 @@ ParseAction ParseAction::Shift(ParseStateId state_index,
ParseAction ParseAction::ShiftExtra() {
ParseAction action;
action.type = ParseActionTypeShiftExtra;
action.type = ParseActionTypeShift;
action.extra = true;
return action;
}
ParseAction ParseAction::ReduceExtra(Symbol symbol) {
ParseAction action;
action.type = ParseActionTypeReduceExtra;
action.type = ParseActionTypeReduce;
action.extra = true;
action.symbol = symbol;
action.consumed_symbol_count = 1;
return action;
}
@ -69,13 +78,11 @@ ParseAction ParseAction::Reduce(Symbol symbol, size_t consumed_symbol_count,
}
bool ParseAction::operator==(const ParseAction &other) const {
return (
type == other.type &&
symbol == other.symbol &&
state_index == other.state_index &&
production == other.production &&
consumed_symbol_count == other.consumed_symbol_count
);
return (type == other.type && extra == other.extra &&
fragile == other.fragile && can_hide_split == other.can_hide_split &&
symbol == other.symbol && state_index == other.state_index &&
production == other.production &&
consumed_symbol_count == other.consumed_symbol_count);
}
bool ParseAction::operator<(const ParseAction &other) const {
@ -83,6 +90,18 @@ bool ParseAction::operator<(const ParseAction &other) const {
return true;
if (other.type < type)
return false;
if (extra && !other.extra)
return true;
if (other.extra && !extra)
return false;
if (fragile && !other.fragile)
return true;
if (other.fragile && !fragile)
return false;
if (can_hide_split && !other.can_hide_split)
return true;
if (other.can_hide_split && !can_hide_split)
return false;
if (symbol < other.symbol)
return true;
if (other.symbol < symbol)
@ -121,16 +140,20 @@ ParseStateId ParseTable::add_state() {
ParseAction &ParseTable::set_action(ParseStateId id, Symbol symbol,
ParseAction action) {
bool structural = action.type != ParseActionTypeShiftExtra;
symbols[symbol].structural += structural;
if (action.extra)
symbols[symbol];
else
symbols[symbol].structural = true;
states[id].actions[symbol] = vector<ParseAction>({ action });
return *states[id].actions[symbol].begin();
}
ParseAction &ParseTable::add_action(ParseStateId id, Symbol symbol,
ParseAction action) {
bool structural = action.type != ParseActionTypeShiftExtra;
symbols[symbol].structural += structural;
if (action.extra)
symbols[symbol];
else
symbols[symbol].structural = true;
states[id].actions[symbol].push_back(action);
return *states[id].actions[symbol].rbegin();
}