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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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39
src/compiler/generate_code/c_code.cc
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@ -329,21 +329,23 @@ class CCodeGenerator {
add("ACCEPT_INPUT()");
break;
case ParseActionTypeShift:
add("SHIFT(" + to_string(action.state_index) + ")");
break;
case ParseActionTypeShiftExtra:
add("SHIFT_EXTRA()");
break;
case ParseActionTypeReduceFragile:
add("REDUCE_FRAGILE(" + symbol_id(action.symbol) + ", " +
to_string(action.consumed_symbol_count) + ")");
if (action.extra) {
add("SHIFT_EXTRA()");
} else {
add("SHIFT(" + to_string(action.state_index) + ", ");
add_action_flags(action);
add(")");
}
break;
case ParseActionTypeReduce:
add("REDUCE(" + symbol_id(action.symbol) + ", " +
to_string(action.consumed_symbol_count) + ")");
break;
case ParseActionTypeReduceExtra:
add("REDUCE_EXTRA(" + symbol_id(action.symbol) + ")");
if (action.extra) {
add("REDUCE_EXTRA(" + symbol_id(action.symbol) + ")");
} else {
add("REDUCE(" + symbol_id(action.symbol) + ", " +
to_string(action.consumed_symbol_count) + ", ");
add_action_flags(action);
add(")");
}
break;
default: {}
}
@ -351,6 +353,17 @@ class CCodeGenerator {
}
}
void add_action_flags(const ParseAction &action) {
if (action.fragile && action.can_hide_split)
add("FRAGILE|CAN_HIDE_SPLIT");
else if (action.fragile)
add("FRAGILE");
else if (action.can_hide_split)
add("CAN_HIDE_SPLIT");
else
add("0");
}
// Helper functions
string lex_state_index(size_t i) {