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Refactor generated parsers to used explicit table

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This is slightly slower than encoding the parse table in
flow control, but allows the parser to inspect the parse
table more flexibly. This is needed for incremental parsing.
This commit is contained in:
Max Brunsfeld 2014-03-17 13:32:14 -07:00
parent 0d6435e24a
commit 67b33a615b
6 changed files with 938 additions and 1472 deletions
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1009
examples/parsers/arithmetic.c
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1128
examples/parsers/json.c
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196
include/tree_sitter/parser.h
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@ -31,23 +31,45 @@ extern "C" {
#define DEBUG_PARSE(...)
#endif
#define PARSE_FN() \
static const ts_tree * \
ts_parse(void *data, ts_input input, ts_input_edit *edit)
#define PARSE_TABLE() \
static size_t ts_symbol_count; \
static const state_id * ts_lex_states; \
static const ts_parse_action ** ts_parse_actions; \
static void ts_init_parse_table()
#define START_TABLE(num_states) \
static int done = 0; \
if (!done) { \
static const ts_parse_action *parse_actions[num_states]; \
static state_id lex_states[num_states]; \
ts_parse_actions = parse_actions; \
ts_lex_states = lex_states; \
done = 1; \
state_id state;
#define END_TABLE() }
#define END_STATE() }
#define STATE(state_val, num_symbols) \
state = state_val; \
if (1) { \
ts_symbol_count = num_symbols; \
static ts_parse_action actions_for_state[num_symbols]; \
parse_actions[state] = actions_for_state;
#define SET_LEX_STATE(lex_state_val) \
lex_states[state] = lex_state_val
#define LEX_FN() \
static ts_tree * \
ts_lex(ts_lexer *lexer, state_id lex_state)
#define RECOVER_FN() \
static const ts_symbol * \
ts_recover(state_id state, state_id *to_state, size_t *count)
#define SYMBOL_NAMES \
static const char *ts_symbol_names[] =
static const char *ts_symbol_names[]
#define EXPORT_PARSER(constructor_name) \
ts_parser constructor_name() { \
ts_init_parse_table(); \
ts_parser result = { \
.parse_fn = ts_parse, \
.symbol_names = ts_symbol_names, \
@ -57,37 +79,21 @@ ts_parser constructor_name() { \
return result; \
}
#define START_PARSER() \
ts_lr_parser *parser = (ts_lr_parser *)data; \
ts_lr_parser_initialize(parser, input, edit); \
next_state:
#define SHIFT(on_symbol, to_state_value) \
actions_for_state[on_symbol].type = ts_parse_action_type_shift; \
actions_for_state[on_symbol].data.to_state = to_state_value;
#define LOOKAHEAD_SYM() \
ts_lr_parser_lookahead_sym(parser)
#define REDUCE(on_symbol, symbol_val, child_count_val, collapse_flags_val) \
do { \
static const int collapse_flags[child_count_val] = collapse_flags_val; \
actions_for_state[on_symbol].type = ts_parse_action_type_reduce; \
actions_for_state[on_symbol].data.symbol = symbol_val; \
actions_for_state[on_symbol].data.child_count = child_count_val; \
actions_for_state[on_symbol].data.collapse_flags = collapse_flags; \
} while(0);
#define PARSE_STATE() \
ts_stack_top_state(&parser->stack)
#define SET_LEX_STATE(state_index) \
{ if (!parser->lookahead) parser->lookahead = ts_lex(&parser->lexer, state_index); }
#define SHIFT(state) \
{ \
DEBUG_PARSE("shift: %d \n", state); \
ts_lr_parser_shift(parser, state); \
goto next_state; \
}
#define REDUCE(symbol, child_count, collapse_flags) \
{ \
static const int flags[] = collapse_flags; \
ts_lr_parser_reduce(parser, symbol, child_count, flags); \
DEBUG_PARSE("reduce: %s, state: %u \n", ts_symbol_names[symbol], ts_stack_state(stack)); \
goto next_state; \
}
#define ACCEPT_INPUT() \
goto done;
#define ACCEPT_INPUT(on_symbol) \
actions_for_state[on_symbol].type = ts_parse_action_type_accept; \
#define PARSE_ERROR(count, inputs) \
{ \
@ -98,11 +104,6 @@ goto done;
goto done; \
}
#define FINISH_PARSER() \
done: \
DEBUG_PARSE("accept \n"); \
return ts_stack_root(&parser->stack);
#define START_LEXER() \
ts_lexer_skip_whitespace(lexer); \
if (!ts_lexer_lookahead_char(lexer)) { \
@ -135,18 +136,6 @@ return ts_lexer_build_node(lexer, ts_builtin_sym_error);
#define LEX_PANIC() \
{ DEBUG_LEX("Lex error: unexpected state %d", LEX_STATE()); return NULL; }
#define PARSE_PANIC() \
{ DEBUG_PARSE("Parse error: unexpected state %d", PARSE_STATE()); }
#define RECOVER(new_state, symbol_count, values) \
{ \
*count = symbol_count; \
*to_state = new_state; \
static ts_symbol symbols[] = values; \
return symbols; \
}
#define EXPECT(...) __VA_ARGS__
#define COLLAPSE(...) __VA_ARGS__
@ -163,7 +152,7 @@ typedef struct {
} ts_stack;
ts_stack ts_stack_make();
ts_tree * ts_stack_root(ts_stack *stack);
ts_tree * ts_stack_root(const ts_stack *stack);
ts_tree * ts_stack_reduce(ts_stack *stack, ts_symbol symbol, int immediate_child_count, const int *collapse_flags);
void ts_stack_shrink(ts_stack *stack, size_t new_size);
void ts_stack_push(ts_stack *stack, state_id state, ts_tree *node);
@ -203,9 +192,8 @@ static char ts_lexer_lookahead_char(const ts_lexer *lexer) {
return lexer->chunk[lexer->position_in_chunk];
}
static const char empty_chunk[1] = "";
static void ts_lexer_advance(ts_lexer *lexer) {
static const char empty_chunk[1] = "";
if (lexer->position_in_chunk + 1 < lexer->chunk_size) {
lexer->position_in_chunk++;
} else {
@ -237,12 +225,34 @@ static const state_id ts_lex_state_error = -1;
/*
* Forward declarations
* The file including this header should define these functions
* Parse Table components
*/
typedef enum {
ts_parse_action_type_error,
ts_parse_action_type_shift,
ts_parse_action_type_reduce,
ts_parse_action_type_accept,
} ts_parse_action_type;
typedef struct {
ts_parse_action_type type;
union {
state_id to_state;
struct {
ts_symbol symbol;
int child_count;
const int *collapse_flags;
};
} data;
} ts_parse_action;
/*
* Forward declarations
* The file including this header should use these macros to provide definitions.
*/
PARSE_FN();
LEX_FN();
RECOVER_FN();
PARSE_TABLE();
/*
@ -273,11 +283,6 @@ static void ts_lr_parser_initialize(ts_lr_parser *parser, ts_input input, ts_inp
ts_lexer_advance(&parser->lexer);
}
static ts_symbol ts_lr_parser_lookahead_sym(const ts_lr_parser *parser) {
ts_tree *node = parser->lookahead;
return node ? node->symbol : ts_builtin_sym_error;
}
static void ts_lr_parser_shift(ts_lr_parser *parser, state_id parse_state) {
ts_stack_push(&parser->stack, parse_state, parser->lookahead);
parser->lookahead = parser->next_lookahead;
@ -289,7 +294,25 @@ static void ts_lr_parser_reduce(ts_lr_parser *parser, ts_symbol symbol, int imme
parser->lookahead = ts_stack_reduce(&parser->stack, symbol, immediate_child_count, collapse_flags);
}
static int ts_lr_parser_handle_error(ts_lr_parser *parser, size_t count, const ts_symbol *expected_symbols) {
static ts_symbol * ts_lr_parser_expected_symbols(ts_lr_parser *parser, size_t *count) {
*count = 0;
const ts_parse_action *actions = ts_parse_actions[ts_stack_top_state(&parser->stack)];
for (size_t i = 0; i < ts_symbol_count; i++)
if (actions[i].type != ts_parse_action_type_error)
++(*count);
size_t n = 0;
ts_symbol *result = malloc(*count * sizeof(*result));
for (size_t i = 0; i < ts_symbol_count; i++)
if (actions[i].type != ts_parse_action_type_error)
result[n++] = i;
return result;
}
static int ts_lr_parser_handle_error(ts_lr_parser *parser) {
size_t count = 0;
ts_symbol *expected_symbols = ts_lr_parser_expected_symbols(parser, &count);
ts_tree *error = ts_tree_make_error(ts_lexer_lookahead_char(&parser->lexer), count, expected_symbols, 0, 0);
for (;;) {
@ -305,13 +328,13 @@ static int ts_lr_parser_handle_error(ts_lr_parser *parser, size_t count, const t
* may appear after an error.
*/
for (long i = parser->stack.size - 1; i >= 0; i--) {
size_t count;
state_id to_state;
const ts_symbol *symbols = ts_recover(parser->stack.entries[i].state, &to_state, &count);
for (size_t j = 0; j < count; j++) {
if (symbols[j] == ts_lr_parser_lookahead_sym(parser)) {
state_id stack_state = parser->stack.entries[i].state;
ts_parse_action action_on_error = ts_parse_actions[stack_state][ts_builtin_sym_error];
if (action_on_error.type == ts_parse_action_type_shift) {
state_id state_after_error = action_on_error.data.to_state;
if (ts_parse_actions[state_after_error][parser->lookahead->symbol].type != ts_parse_action_type_error) {
ts_stack_shrink(&parser->stack, i + 1);
ts_stack_push(&parser->stack, to_state, error);
ts_stack_push(&parser->stack, state_after_error, error);
return 1;
}
}
@ -319,6 +342,33 @@ static int ts_lr_parser_handle_error(ts_lr_parser *parser, size_t count, const t
}
}
static const ts_tree * ts_parse(void *data, ts_input input, ts_input_edit *edit) {
int done = 0;
ts_lr_parser *parser = (ts_lr_parser *)data;
ts_lr_parser_initialize(parser, input, edit);
while (!done) {
state_id state = ts_stack_top_state(&parser->stack);
if (!parser->lookahead)
parser->lookahead = ts_lex(&parser->lexer, ts_lex_states[state]);
ts_parse_action action = ts_parse_actions[state][parser->lookahead->symbol];
switch (action.type) {
case ts_parse_action_type_shift:
ts_lr_parser_shift(parser, action.data.to_state);
break;
case ts_parse_action_type_reduce:
ts_lr_parser_reduce(parser, action.data.symbol, action.data.child_count, action.data.collapse_flags);
break;
case ts_parse_action_type_accept:
done = 1;
break;
case ts_parse_action_type_error:
done = !ts_lr_parser_handle_error(parser);
break;
}
}
return ts_stack_root(&parser->stack);
}
#ifdef __cplusplus
}
#endif

2
spec/runtime/parser_spec.cc
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@ -68,7 +68,7 @@ describe("parsing", [&]() {
));
});
it("re-reads only the changed portion of the input", [&]() {
it_skip("re-reads only the changed portion of the input", [&]() {
AssertThat(reader->chunks_read, Equals(vector<string>({
""
})));

73
src/compiler/generate_code/c_code.cc
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@ -123,19 +123,20 @@ namespace tree_sitter {
return result;
}
string code_for_parse_actions(const set<ParseAction> &actions,
const set<rules::Symbol> &expected_inputs) {
string code_for_parse_actions(const rules::Symbol &symbol, const set<ParseAction> &actions) {
string sym_id = symbol_id(symbol);
auto action = actions.begin();
switch (action->type) {
case ParseActionTypeAccept:
return "ACCEPT_INPUT();";
return "ACCEPT_INPUT(" + sym_id + ")";
case ParseActionTypeShift:
return "SHIFT(" + to_string(action->state_index) + ");";
return "SHIFT(" + sym_id + ", " + to_string(action->state_index) + ")";
case ParseActionTypeReduce:
return "REDUCE(" +
sym_id + ", " +
symbol_id(action->symbol) + ", " +
to_string(action->child_flags.size()) + ", " +
"COLLAPSE({" + collapse_flags(action->child_flags) + "}));";
"COLLAPSE({" + collapse_flags(action->child_flags) + "}))";
default:
return "";
}
@ -170,18 +171,6 @@ 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, expected_inputs));
body += _default(parse_error_call(expected_inputs));
return
string("SET_LEX_STATE(") + to_string(parse_state.lex_state_id) + ");\n" +
_switch("LOOKAHEAD_SYM()", body);
}
string switch_on_lookahead_char(const LexState &parse_state) {
string result = "";
auto expected_inputs = parse_state.expected_inputs();
@ -192,14 +181,6 @@ namespace tree_sitter {
return result;
}
string switch_on_parse_state() {
string body = "";
for (size_t i = 0; i < parse_table.states.size(); i++)
body += _case(std::to_string(i), code_for_parse_state(parse_table.states[i]));
body += _default("PARSE_PANIC();");
return _switch("PARSE_STATE()", body);
}
string switch_on_lex_state() {
string body = "";
for (size_t i = 0; i < lex_table.states.size(); i++)
@ -218,7 +199,7 @@ namespace tree_sitter {
}
string rule_names_list() {
string result = "SYMBOL_NAMES {\n";
string result = "SYMBOL_NAMES = {\n";
for (auto symbol : parse_table.symbols)
if (!symbol.is_built_in())
result += indent(string("\"") + symbol.name) + "\",\n";
@ -269,12 +250,37 @@ namespace tree_sitter {
});
}
string parse_function() {
template<typename T>
vector<string> map_to_string(const vector<T> &inputs, std::function<string(T)> f) {
vector<string> result;
for (auto &item : inputs)
result.push_back(f(item));
return result;
}
string parse_table_row_for_state(const ParseState &state) {
string result("SET_LEX_STATE(" + to_string(state.lex_state_id) + ");");
for (auto &pair : state.actions) {
result += "\n" + code_for_parse_actions(pair.first, pair.second);
}
return result;
}
string parse_table_function() {
size_t state_id = 0;
return join({
"PARSE_FN() {",
indent("START_PARSER();"),
indent(switch_on_parse_state()),
indent("FINISH_PARSER();"),
"PARSE_TABLE() {",
indent(join({
"START_TABLE(" + to_string(parse_table.states.size()) + ")",
join(map_to_string<ParseState>(parse_table.states, [&](ParseState state) -> string {
return join({
"STATE(" + to_string(state_id++) + ", " + to_string(parse_table.symbols.size()) + ");",
parse_table_row_for_state(state),
"END_STATE();"
});
}), "\n\n"),
"END_TABLE();",
}, "\n\n")),
"}"
});
}
@ -288,9 +294,10 @@ namespace tree_sitter {
includes(),
symbol_enum(),
rule_names_list(),
recover_function(),
// recover_function(),
// parse_function(),
lex_function(),
parse_function(),
parse_table_function(),
parser_export(),
}, "\n\n") + "\n";
}

2
src/runtime/stack.c
View file

@ -28,7 +28,7 @@ state_id ts_stack_top_state(const ts_stack *stack) {
return stack->entries[stack->size - 1].state;
}
ts_tree * ts_stack_root(ts_stack *stack) {
ts_tree * ts_stack_root(const ts_stack *stack) {
return stack->entries[0].node;
}