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Start work on error recovery

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- In runtime, make parse errors part of the parse tree
- Add error state to lexers in which they can accept any token
This commit is contained in:
Max Brunsfeld 2014-02-24 18:42:54 -08:00
parent 4520d6e1a2
commit e58a6d8ba7
18 changed files with 622 additions and 528 deletions
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93
src/compiler/build_tables/perform.cpp
View file

@ -14,105 +14,111 @@ namespace tree_sitter {
using rules::CharacterSet;
namespace build_tables {
static int NOT_FOUND = -1;
static int NOT_FOUND = -2;
static Symbol START("start", rules::SymbolTypeAuxiliary);
static Symbol END_OF_INPUT("end", rules::SymbolTypeAuxiliary);
class TableBuilder {
const PreparedGrammar grammar;
const PreparedGrammar lex_grammar;
map<const ParseItemSet, size_t> parse_state_indices;
map<const LexItemSet, size_t> lex_state_indices;
map<const ParseItemSet, ParseStateId> parse_state_ids;
map<const LexItemSet, LexStateId> lex_state_ids;
ParseTable parse_table;
LexTable lex_table;
long parse_state_index_for_item_set(const ParseItemSet &item_set) const {
auto entry = parse_state_indices.find(item_set);
return (entry == parse_state_indices.end()) ? NOT_FOUND : entry->second;
long parse_state_id_for_item_set(const ParseItemSet &item_set) const {
auto entry = parse_state_ids.find(item_set);
return (entry == parse_state_ids.end()) ? NOT_FOUND : entry->second;
}
long lex_state_index_for_item_set(const LexItemSet &item_set) const {
auto entry = lex_state_indices.find(item_set);
return (entry == lex_state_indices.end()) ? NOT_FOUND : entry->second;
long lex_state_id_for_item_set(const LexItemSet &item_set) const {
auto entry = lex_state_ids.find(item_set);
return (entry == lex_state_ids.end()) ? NOT_FOUND : entry->second;
}
void add_shift_actions(const ParseItemSet &item_set, size_t state_index) {
void add_shift_actions(const ParseItemSet &item_set, ParseStateId state_id) {
for (auto transition : sym_transitions(item_set, grammar)) {
Symbol symbol = transition.first;
ParseItemSet item_set = transition.second;
size_t new_state_index = add_parse_state(item_set);
parse_table.add_action(state_index, symbol, ParseAction::Shift(new_state_index));
ParseStateId new_state_id = add_parse_state(item_set);
parse_table.add_action(state_id, symbol, ParseAction::Shift(new_state_id));
}
}
void add_advance_actions(const LexItemSet &item_set, size_t state_index) {
void add_advance_actions(const LexItemSet &item_set, LexStateId state_id) {
for (auto transition : char_transitions(item_set, grammar)) {
CharacterSet rule = transition.first;
LexItemSet item_set = transition.second;
size_t new_state_index = add_lex_state(item_set);
lex_table.add_action(state_index, rule, LexAction::Advance(new_state_index));
LexStateId new_state_id = add_lex_state(item_set);
lex_table.add_action(state_id, rule, LexAction::Advance(new_state_id));
}
}
void add_accept_token_actions(const LexItemSet &item_set, size_t state_index) {
void add_accept_token_actions(const LexItemSet &item_set, LexStateId state_id) {
for (LexItem item : item_set) {
if (item.is_done()) {
lex_table.add_default_action(state_index, LexAction::Accept(item.lhs));
lex_table.add_default_action(state_id, LexAction::Accept(item.lhs));
}
}
}
void add_reduce_actions(const ParseItemSet &item_set, size_t state_index) {
void add_reduce_actions(const ParseItemSet &item_set, ParseStateId state_id) {
for (ParseItem item : item_set) {
if (item.is_done()) {
ParseAction action = (item.lhs == START) ?
ParseAction::Accept() :
ParseAction::Reduce(item.lhs, item.consumed_symbols);
parse_table.add_action(state_index, item.lookahead_sym, action);
parse_table.add_action(state_id, item.lookahead_sym, action);
}
}
}
void assign_lex_state(size_t state_index) {
ParseState &state = parse_table.states[state_index];
void assign_lex_state(ParseStateId state_id) {
ParseState &state = parse_table.states[state_id];
LexItemSet item_set;
for (auto &symbol : state.expected_inputs()) {
if (symbol == END_OF_INPUT)
item_set.insert(LexItem(symbol, make_shared<CharacterSet>(std::set<rules::CharacterRange>{ '\0' })));
if (lex_grammar.has_definition(symbol))
item_set.insert(LexItem(symbol, lex_grammar.rule(symbol)));
}
state.lex_state_index = add_lex_state(item_set);
state.lex_state_id = add_lex_state(item_set);
}
size_t add_lex_state(const LexItemSet &item_set) {
auto state_index = lex_state_index_for_item_set(item_set);
if (state_index == NOT_FOUND) {
state_index = lex_table.add_state();
lex_state_indices[item_set] = state_index;
add_advance_actions(item_set, state_index);
add_accept_token_actions(item_set, state_index);
LexStateId add_lex_state(const LexItemSet &item_set) {
auto state_id = lex_state_id_for_item_set(item_set);
if (state_id == NOT_FOUND) {
state_id = lex_table.add_state();
lex_state_ids[item_set] = state_id;
add_advance_actions(item_set, state_id);
add_accept_token_actions(item_set, state_id);
}
return state_index;
return state_id;
}
size_t add_parse_state(const ParseItemSet &item_set) {
auto state_index = parse_state_index_for_item_set(item_set);
if (state_index == NOT_FOUND) {
state_index = parse_table.add_state();
parse_state_indices[item_set] = state_index;
ParseStateId add_parse_state(const ParseItemSet &item_set) {
auto state_id = parse_state_id_for_item_set(item_set);
if (state_id == NOT_FOUND) {
state_id = parse_table.add_state();
parse_state_ids[item_set] = state_id;
add_shift_actions(item_set, state_index);
add_reduce_actions(item_set, state_index);
assign_lex_state(state_index);
add_shift_actions(item_set, state_id);
add_reduce_actions(item_set, state_id);
assign_lex_state(state_id);
}
return state_index;
return state_id;
}
void add_error_lex_state() {
LexItemSet error_item_set;
for (auto &pair : lex_grammar.rules)
error_item_set.insert(LexItem(pair.first, pair.second));
add_advance_actions(error_item_set, LexTable::ERROR_STATE_ID);
add_accept_token_actions(error_item_set, LexTable::ERROR_STATE_ID);
}
// void dump_item_sets() {
// std::vector<const ParseItemSet *> item_sets(parse_state_indices.size());
// for (auto &pair : parse_state_indices)
// std::vector<const ParseItemSet *> item_sets(parse_state_ids.size());
// for (auto &pair : parse_state_ids)
// item_sets[pair.second] = &pair.first;
//
// for (int i = 0; i < item_sets.size(); i++) {
@ -135,6 +141,7 @@ namespace tree_sitter {
auto item = ParseItem(START, make_shared<Symbol>(grammar.start_rule_name), {}, END_OF_INPUT);
ParseItemSet item_set = item_set_closure(ParseItemSet({ item }), grammar);
add_parse_state(item_set);
add_error_lex_state();
return pair<ParseTable, LexTable>(parse_table, lex_table);
}
};

22
src/compiler/generate_code/c_code.cpp
View file

@ -164,17 +164,13 @@ namespace tree_sitter {
return input;
}
string lex_error_call(const set<rules::CharacterSet> &expected_inputs) {
rules::CharacterSet expected_set;
for (auto &rule : expected_inputs)
expected_set.add_set(rule);
string result = "LEX_ERROR(" + to_string(expected_set.ranges.size()) + ", EXPECT({";
string parse_error_call(const set<rules::Symbol> &expected_inputs) {
string result = "PARSE_ERROR(" + to_string(expected_inputs.size()) + ", EXPECT({";
bool started = false;
for (auto &range : expected_set.ranges) {
for (auto &symbol : expected_inputs) {
if (started) result += ", ";
started = true;
result += "\"" + escape_string(range.to_string()) + "\"";
result += symbol_id(symbol);
}
result += "}));";
return result;
@ -183,7 +179,7 @@ namespace tree_sitter {
string code_for_lex_actions(const set<LexAction> &actions, const set<rules::CharacterSet> &expected_inputs) {
auto action = actions.begin();
if (action == actions.end()) {
return lex_error_call(expected_inputs);
return "LEX_ERROR();";
} else {
switch (action->type) {
case LexActionTypeAdvance:
@ -198,11 +194,12 @@ namespace tree_sitter {
string code_for_parse_state(const ParseState &parse_state) {
string body = "";
auto expected_inputs = parse_state.expected_inputs();
for (auto pair : parse_state.actions)
body += _case(symbol_id(pair.first), code_for_parse_actions(pair.second, parse_state.expected_inputs()));
body += _default("PARSE_PANIC();");
body += _case(symbol_id(pair.first), code_for_parse_actions(pair.second, expected_inputs));
body += _default(parse_error_call(expected_inputs));
return
string("SET_LEX_STATE(") + to_string(parse_state.lex_state_index) + ");\n" +
string("SET_LEX_STATE(") + to_string(parse_state.lex_state_id) + ");\n" +
_switch("LOOKAHEAD_SYM()", body);
}
@ -227,6 +224,7 @@ namespace tree_sitter {
string body = "";
for (int i = 0; i < lex_table.states.size(); i++)
body += _case(std::to_string(i), switch_on_lookahead_char(lex_table.states[i]));
body += _case("ts_lex_state_error", switch_on_lookahead_char(lex_table.error_state));
body += _default("LEX_PANIC();");
return _switch("LEX_STATE()", body);
}

19
src/compiler/lex_table.cpp
View file

@ -58,16 +58,25 @@ namespace tree_sitter {
return result;
}
size_t LexTable::add_state() {
LexStateId LexTable::add_state() {
states.push_back(LexState());
return states.size() - 1;
}
void LexTable::add_action(size_t state_index, CharacterSet match, LexAction action) {
states[state_index].actions[match].insert(action);
LexState & state(LexTable *table, LexStateId id) {
if (id < 0)
return table->error_state;
else
return table->states[id];
}
void LexTable::add_default_action(size_t state_index, LexAction action) {
states[state_index].default_actions.insert(action);
void LexTable::add_action(LexStateId id, CharacterSet match, LexAction action) {
state(this, id).actions[match].insert(action);
}
void LexTable::add_default_action(LexStateId id, LexAction action) {
state(this, id).default_actions.insert(action);
}
const LexStateId LexTable::ERROR_STATE_ID = -1;
}

10
src/compiler/lex_table.h
View file

@ -51,13 +51,17 @@ namespace tree_sitter {
std::set<rules::CharacterSet> expected_inputs() const;
};
typedef long int LexStateId;
class LexTable {
public:
size_t add_state();
void add_action(size_t state_index, rules::CharacterSet rule, LexAction action);
void add_default_action(size_t state_index, LexAction action);
static const LexStateId ERROR_STATE_ID;
LexStateId add_state();
void add_action(LexStateId state_id, rules::CharacterSet rule, LexAction action);
void add_default_action(LexStateId state_id, LexAction action);
std::vector<LexState> states;
LexState error_state;
};
}

8
src/compiler/parse_table.cpp
View file

@ -58,7 +58,7 @@ namespace tree_sitter {
}
}
ParseState::ParseState() : lex_state_index(-1) {}
ParseState::ParseState() : lex_state_id(-1) {}
set<Symbol> ParseState::expected_inputs() const {
set<Symbol> result;
@ -86,13 +86,13 @@ namespace tree_sitter {
return stream;
}
size_t ParseTable::add_state() {
ParseStateId ParseTable::add_state() {
states.push_back(ParseState());
return states.size() - 1;
}
void ParseTable::add_action(size_t state_index, Symbol symbol, ParseAction action) {
void ParseTable::add_action(ParseStateId id, Symbol symbol, ParseAction action) {
symbols.insert(symbol);
states[state_index].actions[symbol].insert(action);
states[id].actions[symbol].insert(action);
}
}

7
src/compiler/parse_table.h
View file

@ -5,6 +5,7 @@
#include <vector>
#include <set>
#include "rules/symbol.h"
#include "./lex_table.h"
namespace tree_sitter {
typedef enum {
@ -52,15 +53,17 @@ namespace tree_sitter {
ParseState();
std::map<rules::Symbol, std::set<ParseAction>> actions;
std::set<rules::Symbol> expected_inputs() const;
size_t lex_state_index;
LexStateId lex_state_id;
};
typedef unsigned long int ParseStateId;
std::ostream& operator<<(std::ostream &stream, const ParseState &state);
class ParseTable {
public:
size_t add_state();
void add_action(size_t state_index, rules::Symbol symbol, ParseAction action);
void add_action(ParseStateId state_id, rules::Symbol symbol, ParseAction action);
std::vector<ParseState> states;
std::set<rules::Symbol> symbols;