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circuitpython/py/parse.c

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/*
* This file is part of the Micro Python project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2013-2015 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <assert.h>
#include <string.h>
#include "py/nlr.h"
#include "py/lexer.h"
#include "py/parse.h"
#include "py/parsenum.h"
#include "py/smallint.h"
#define RULE_ACT_ARG_MASK (0x0f)
#define RULE_ACT_KIND_MASK (0x30)
#define RULE_ACT_ALLOW_IDENT (0x40)
#define RULE_ACT_ADD_BLANK (0x80)
#define RULE_ACT_OR (0x10)
#define RULE_ACT_AND (0x20)
#define RULE_ACT_LIST (0x30)
#define RULE_ARG_KIND_MASK (0xf000)
#define RULE_ARG_ARG_MASK (0x0fff)
#define RULE_ARG_TOK (0x1000)
#define RULE_ARG_RULE (0x2000)
#define RULE_ARG_OPT_RULE (0x3000)
#define ADD_BLANK_NODE(rule) ((rule->act & RULE_ACT_ADD_BLANK) != 0)
// (un)comment to use rule names; for debugging
//#define USE_RULE_NAME (1)
typedef struct _rule_t {
byte rule_id;
byte act;
#ifdef USE_RULE_NAME
const char *rule_name;
#endif
uint16_t arg[];
} rule_t;
enum {
#define DEF_RULE(rule, comp, kind, ...) RULE_##rule,
#include "py/grammar.h"
#undef DEF_RULE
RULE_maximum_number_of,
RULE_string, // special node for non-interned string
RULE_bytes, // special node for non-interned bytes
RULE_const_object, // special node for a constant, generic Python object
};
#define ident (RULE_ACT_ALLOW_IDENT)
#define blank (RULE_ACT_ADD_BLANK)
#define or(n) (RULE_ACT_OR | n)
#define and(n) (RULE_ACT_AND | n)
#define one_or_more (RULE_ACT_LIST | 2)
#define list (RULE_ACT_LIST | 1)
#define list_with_end (RULE_ACT_LIST | 3)
#define tok(t) (RULE_ARG_TOK | MP_TOKEN_##t)
#define rule(r) (RULE_ARG_RULE | RULE_##r)
#define opt_rule(r) (RULE_ARG_OPT_RULE | RULE_##r)
#ifdef USE_RULE_NAME
#define DEF_RULE(rule, comp, kind, ...) static const rule_t rule_##rule = { RULE_##rule, kind, #rule, { __VA_ARGS__ } };
#else
#define DEF_RULE(rule, comp, kind, ...) static const rule_t rule_##rule = { RULE_##rule, kind, { __VA_ARGS__ } };
#endif
#include "py/grammar.h"
#undef or
#undef and
#undef list
#undef list_with_end
#undef tok
#undef rule
#undef opt_rule
#undef one_or_more
#undef DEF_RULE
STATIC const rule_t *rules[] = {
#define DEF_RULE(rule, comp, kind, ...) &rule_##rule,
#include "py/grammar.h"
#undef DEF_RULE
};
typedef struct _rule_stack_t {
mp_uint_t src_line : BITS_PER_WORD - 8; // maximum bits storing source line number
mp_uint_t rule_id : 8; // this must be large enough to fit largest rule number
mp_uint_t arg_i; // this dictates the maximum nodes in a "list" of things
} rule_stack_t;
typedef struct _parser_t {
bool had_memory_error;
mp_uint_t rule_stack_alloc;
mp_uint_t rule_stack_top;
rule_stack_t *rule_stack;
mp_uint_t result_stack_alloc;
mp_uint_t result_stack_top;
mp_parse_node_t *result_stack;
mp_lexer_t *lexer;
} parser_t;
STATIC inline void memory_error(parser_t *parser) {
parser->had_memory_error = true;
}
STATIC void push_rule(parser_t *parser, mp_uint_t src_line, const rule_t *rule, mp_uint_t arg_i) {
if (parser->had_memory_error) {
return;
}
if (parser->rule_stack_top >= parser->rule_stack_alloc) {
rule_stack_t *rs = m_renew_maybe(rule_stack_t, parser->rule_stack, parser->rule_stack_alloc, parser->rule_stack_alloc + MICROPY_ALLOC_PARSE_RULE_INC, true);
if (rs == NULL) {
memory_error(parser);
return;
}
parser->rule_stack = rs;
parser->rule_stack_alloc += MICROPY_ALLOC_PARSE_RULE_INC;
}
rule_stack_t *rs = &parser->rule_stack[parser->rule_stack_top++];
rs->src_line = src_line;
rs->rule_id = rule->rule_id;
rs->arg_i = arg_i;
}
STATIC void push_rule_from_arg(parser_t *parser, mp_uint_t arg) {
assert((arg & RULE_ARG_KIND_MASK) == RULE_ARG_RULE || (arg & RULE_ARG_KIND_MASK) == RULE_ARG_OPT_RULE);
mp_uint_t rule_id = arg & RULE_ARG_ARG_MASK;
assert(rule_id < RULE_maximum_number_of);
push_rule(parser, parser->lexer->tok_line, rules[rule_id], 0);
}
STATIC void pop_rule(parser_t *parser, const rule_t **rule, mp_uint_t *arg_i, mp_uint_t *src_line) {
assert(!parser->had_memory_error);
parser->rule_stack_top -= 1;
*rule = rules[parser->rule_stack[parser->rule_stack_top].rule_id];
*arg_i = parser->rule_stack[parser->rule_stack_top].arg_i;
*src_line = parser->rule_stack[parser->rule_stack_top].src_line;
}
mp_parse_node_t mp_parse_node_new_leaf(mp_int_t kind, mp_int_t arg) {
if (kind == MP_PARSE_NODE_SMALL_INT) {
return (mp_parse_node_t)(kind | (arg << 1));
}
return (mp_parse_node_t)(kind | (arg << 4));
}
void mp_parse_node_free(mp_parse_node_t pn) {
if (MP_PARSE_NODE_IS_STRUCT(pn)) {
mp_parse_node_struct_t *pns = (mp_parse_node_struct_t *)pn;
mp_uint_t n = MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
mp_uint_t rule_id = MP_PARSE_NODE_STRUCT_KIND(pns);
if (rule_id == RULE_string || rule_id == RULE_bytes) {
m_del(char, (char*)pns->nodes[0], (mp_uint_t)pns->nodes[1]);
} else if (rule_id == RULE_const_object) {
// don't free the const object since it's probably used by the compiled code
} else {
bool adjust = ADD_BLANK_NODE(rules[rule_id]);
if (adjust) {
n--;
}
for (mp_uint_t i = 0; i < n; i++) {
mp_parse_node_free(pns->nodes[i]);
}
if (adjust) {
n++;
}
}
m_del_var(mp_parse_node_struct_t, mp_parse_node_t, n, pns);
}
}
int mp_parse_node_extract_list(mp_parse_node_t *pn, mp_uint_t pn_kind, mp_parse_node_t **nodes) {
if (MP_PARSE_NODE_IS_NULL(*pn)) {
*nodes = NULL;
return 0;
} else if (MP_PARSE_NODE_IS_LEAF(*pn)) {
*nodes = pn;
return 1;
} else {
mp_parse_node_struct_t *pns = (mp_parse_node_struct_t*)(*pn);
if (MP_PARSE_NODE_STRUCT_KIND(pns) != pn_kind) {
*nodes = pn;
return 1;
} else {
*nodes = pns->nodes;
return MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
}
}
}
#if MICROPY_DEBUG_PRINTERS
void mp_parse_node_print(mp_parse_node_t pn, mp_uint_t indent) {
if (MP_PARSE_NODE_IS_STRUCT(pn)) {
printf("[% 4d] ", (int)((mp_parse_node_struct_t*)pn)->source_line);
} else {
printf(" ");
}
for (mp_uint_t i = 0; i < indent; i++) {
printf(" ");
}
if (MP_PARSE_NODE_IS_NULL(pn)) {
printf("NULL\n");
} else if (MP_PARSE_NODE_IS_SMALL_INT(pn)) {
mp_int_t arg = MP_PARSE_NODE_LEAF_SMALL_INT(pn);
printf("int(" INT_FMT ")\n", arg);
} else if (MP_PARSE_NODE_IS_LEAF(pn)) {
mp_uint_t arg = MP_PARSE_NODE_LEAF_ARG(pn);
switch (MP_PARSE_NODE_LEAF_KIND(pn)) {
case MP_PARSE_NODE_ID: printf("id(%s)\n", qstr_str(arg)); break;
case MP_PARSE_NODE_STRING: printf("str(%s)\n", qstr_str(arg)); break;
case MP_PARSE_NODE_BYTES: printf("bytes(%s)\n", qstr_str(arg)); break;
case MP_PARSE_NODE_TOKEN: printf("tok(" INT_FMT ")\n", arg); break;
default: assert(0);
}
} else {
// node must be a mp_parse_node_struct_t
mp_parse_node_struct_t *pns = (mp_parse_node_struct_t*)pn;
if (MP_PARSE_NODE_STRUCT_KIND(pns) == RULE_string) {
printf("literal str(%.*s)\n", (int)pns->nodes[1], (char*)pns->nodes[0]);
} else if (MP_PARSE_NODE_STRUCT_KIND(pns) == RULE_bytes) {
printf("literal bytes(%.*s)\n", (int)pns->nodes[1], (char*)pns->nodes[0]);
} else if (MP_PARSE_NODE_STRUCT_KIND(pns) == RULE_const_object) {
printf("literal const(%p)\n", (mp_obj_t)pns->nodes[0]);
} else {
mp_uint_t n = MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
#ifdef USE_RULE_NAME
printf("%s(" UINT_FMT ") (n=" UINT_FMT ")\n", rules[MP_PARSE_NODE_STRUCT_KIND(pns)]->rule_name, (mp_uint_t)MP_PARSE_NODE_STRUCT_KIND(pns), n);
#else
printf("rule(" UINT_FMT ") (n=" UINT_FMT ")\n", (mp_uint_t)MP_PARSE_NODE_STRUCT_KIND(pns), n);
#endif
for (mp_uint_t i = 0; i < n; i++) {
mp_parse_node_print(pns->nodes[i], indent + 2);
}
}
}
}
#endif // MICROPY_DEBUG_PRINTERS
/*
STATIC void result_stack_show(parser_t *parser) {
printf("result stack, most recent first\n");
for (mp_int_t i = parser->result_stack_top - 1; i >= 0; i--) {
mp_parse_node_print(parser->result_stack[i], 0);
}
}
*/
STATIC mp_parse_node_t pop_result(parser_t *parser) {
if (parser->had_memory_error) {
return MP_PARSE_NODE_NULL;
}
assert(parser->result_stack_top > 0);
return parser->result_stack[--parser->result_stack_top];
}
STATIC mp_parse_node_t peek_result(parser_t *parser, mp_uint_t pos) {
if (parser->had_memory_error) {
return MP_PARSE_NODE_NULL;
}
assert(parser->result_stack_top > pos);
return parser->result_stack[parser->result_stack_top - 1 - pos];
}
STATIC void push_result_node(parser_t *parser, mp_parse_node_t pn) {
if (parser->had_memory_error) {
return;
}
if (parser->result_stack_top >= parser->result_stack_alloc) {
mp_parse_node_t *stack = m_renew_maybe(mp_parse_node_t, parser->result_stack, parser->result_stack_alloc, parser->result_stack_alloc + MICROPY_ALLOC_PARSE_RESULT_INC, true);
if (stack == NULL) {
memory_error(parser);
return;
}
parser->result_stack = stack;
parser->result_stack_alloc += MICROPY_ALLOC_PARSE_RESULT_INC;
}
parser->result_stack[parser->result_stack_top++] = pn;
}
STATIC mp_parse_node_t make_node_string_bytes(parser_t *parser, mp_uint_t src_line, mp_uint_t rule_kind, const char *str, mp_uint_t len) {
mp_parse_node_struct_t *pn = m_new_obj_var_maybe(mp_parse_node_struct_t, mp_parse_node_t, 2);
if (pn == NULL) {
memory_error(parser);
return MP_PARSE_NODE_NULL;
}
pn->source_line = src_line;
pn->kind_num_nodes = rule_kind | (2 << 8);
char *p = m_new(char, len);
memcpy(p, str, len);
pn->nodes[0] = (mp_int_t)p;
pn->nodes[1] = len;
return (mp_parse_node_t)pn;
}
STATIC mp_parse_node_t make_node_const_object(parser_t *parser, mp_uint_t src_line, mp_obj_t obj) {
mp_parse_node_struct_t *pn = m_new_obj_var_maybe(mp_parse_node_struct_t, mp_parse_node_t, 1);
if (pn == NULL) {
memory_error(parser);
return MP_PARSE_NODE_NULL;
}
pn->source_line = src_line;
pn->kind_num_nodes = RULE_const_object | (1 << 8);
pn->nodes[0] = (mp_uint_t)obj;
return (mp_parse_node_t)pn;
}
STATIC void push_result_token(parser_t *parser) {
mp_parse_node_t pn;
mp_lexer_t *lex = parser->lexer;
if (lex->tok_kind == MP_TOKEN_NAME) {
pn = mp_parse_node_new_leaf(MP_PARSE_NODE_ID, qstr_from_strn(lex->vstr.buf, lex->vstr.len));
} else if (lex->tok_kind == MP_TOKEN_INTEGER) {
mp_obj_t o = mp_parse_num_integer(lex->vstr.buf, lex->vstr.len, 0, lex);
if (MP_OBJ_IS_SMALL_INT(o)) {
pn = mp_parse_node_new_leaf(MP_PARSE_NODE_SMALL_INT, MP_OBJ_SMALL_INT_VALUE(o));
} else {
pn = make_node_const_object(parser, lex->tok_line, o);
}
} else if (lex->tok_kind == MP_TOKEN_FLOAT_OR_IMAG) {
mp_obj_t o = mp_parse_num_decimal(lex->vstr.buf, lex->vstr.len, true, false, lex);
pn = make_node_const_object(parser, lex->tok_line, o);
} else if (lex->tok_kind == MP_TOKEN_STRING || lex->tok_kind == MP_TOKEN_BYTES) {
// Don't automatically intern all strings/bytes. doc strings (which are usually large)
// will be discarded by the compiler, and so we shouldn't intern them.
qstr qst = MP_QSTR_NULL;
if (lex->vstr.len <= MICROPY_ALLOC_PARSE_INTERN_STRING_LEN) {
// intern short strings
qst = qstr_from_strn(lex->vstr.buf, lex->vstr.len);
} else {
// check if this string is already interned
qst = qstr_find_strn(lex->vstr.buf, lex->vstr.len);
}
if (qst != MP_QSTR_NULL) {
// qstr exists, make a leaf node
pn = mp_parse_node_new_leaf(lex->tok_kind == MP_TOKEN_STRING ? MP_PARSE_NODE_STRING : MP_PARSE_NODE_BYTES, qst);
} else {
// not interned, make a node holding a pointer to the string/bytes data
pn = make_node_string_bytes(parser, lex->tok_line, lex->tok_kind == MP_TOKEN_STRING ? RULE_string : RULE_bytes, lex->vstr.buf, lex->vstr.len);
}
} else {
pn = mp_parse_node_new_leaf(MP_PARSE_NODE_TOKEN, lex->tok_kind);
}
push_result_node(parser, pn);
}
STATIC void push_result_rule(parser_t *parser, mp_uint_t src_line, const rule_t *rule, mp_uint_t num_args) {
mp_parse_node_struct_t *pn = m_new_obj_var_maybe(mp_parse_node_struct_t, mp_parse_node_t, num_args);
if (pn == NULL) {
memory_error(parser);
return;
}
pn->source_line = src_line;
pn->kind_num_nodes = (rule->rule_id & 0xff) | (num_args << 8);
for (mp_uint_t i = num_args; i > 0; i--) {
pn->nodes[i - 1] = pop_result(parser);
}
push_result_node(parser, (mp_parse_node_t)pn);
}
mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind) {
// initialise parser and allocate memory for its stacks
parser_t parser;
parser.had_memory_error = false;
parser.rule_stack_alloc = MICROPY_ALLOC_PARSE_RULE_INIT;
parser.rule_stack_top = 0;
parser.rule_stack = m_new_maybe(rule_stack_t, parser.rule_stack_alloc);
parser.result_stack_alloc = MICROPY_ALLOC_PARSE_RESULT_INIT;
parser.result_stack_top = 0;
parser.result_stack = m_new_maybe(mp_parse_node_t, parser.result_stack_alloc);
parser.lexer = lex;
// check if we could allocate the stacks
if (parser.rule_stack == NULL || parser.result_stack == NULL) {
goto memory_error;
}
// work out the top-level rule to use, and push it on the stack
mp_uint_t top_level_rule;
switch (input_kind) {
case MP_PARSE_SINGLE_INPUT: top_level_rule = RULE_single_input; break;
case MP_PARSE_EVAL_INPUT: top_level_rule = RULE_eval_input; break;
default: top_level_rule = RULE_file_input;
}
push_rule(&parser, lex->tok_line, rules[top_level_rule], 0);
// parse!
mp_uint_t n, i; // state for the current rule
mp_uint_t rule_src_line; // source line for the first token matched by the current rule
bool backtrack = false;
const rule_t *rule = NULL;
for (;;) {
next_rule:
if (parser.rule_stack_top == 0 || parser.had_memory_error) {
break;
}
pop_rule(&parser, &rule, &i, &rule_src_line);
n = rule->act & RULE_ACT_ARG_MASK;
/*
// debugging
printf("depth=%d ", parser.rule_stack_top);
for (int j = 0; j < parser.rule_stack_top; ++j) {
printf(" ");
}
printf("%s n=%d i=%d bt=%d\n", rule->rule_name, n, i, backtrack);
*/
switch (rule->act & RULE_ACT_KIND_MASK) {
case RULE_ACT_OR:
if (i > 0 && !backtrack) {
goto next_rule;
} else {
backtrack = false;
}
for (; i < n; ++i) {
uint16_t kind = rule->arg[i] & RULE_ARG_KIND_MASK;
if (kind == RULE_ARG_TOK) {
if (lex->tok_kind == (rule->arg[i] & RULE_ARG_ARG_MASK)) {
push_result_token(&parser);
mp_lexer_to_next(lex);
goto next_rule;
}
} else {
assert(kind == RULE_ARG_RULE);
if (i + 1 < n) {
push_rule(&parser, rule_src_line, rule, i + 1); // save this or-rule
}
push_rule_from_arg(&parser, rule->arg[i]); // push child of or-rule
goto next_rule;
}
}
backtrack = true;
break;
case RULE_ACT_AND: {
// failed, backtrack if we can, else syntax error
if (backtrack) {
assert(i > 0);
if ((rule->arg[i - 1] & RULE_ARG_KIND_MASK) == RULE_ARG_OPT_RULE) {
// an optional rule that failed, so continue with next arg
push_result_node(&parser, MP_PARSE_NODE_NULL);
backtrack = false;
} else {
// a mandatory rule that failed, so propagate backtrack
if (i > 1) {
// already eaten tokens so can't backtrack
goto syntax_error;
} else {
goto next_rule;
}
}
}
// progress through the rule
for (; i < n; ++i) {
switch (rule->arg[i] & RULE_ARG_KIND_MASK) {
case RULE_ARG_TOK: {
// need to match a token
mp_token_kind_t tok_kind = rule->arg[i] & RULE_ARG_ARG_MASK;
if (lex->tok_kind == tok_kind) {
// matched token
if (tok_kind == MP_TOKEN_NAME) {
push_result_token(&parser);
}
mp_lexer_to_next(lex);
} else {
// failed to match token
if (i > 0) {
// already eaten tokens so can't backtrack
goto syntax_error;
} else {
// this rule failed, so backtrack
backtrack = true;
goto next_rule;
}
}
break;
}
case RULE_ARG_RULE:
case RULE_ARG_OPT_RULE:
rule_and_no_other_choice:
push_rule(&parser, rule_src_line, rule, i + 1); // save this and-rule
push_rule_from_arg(&parser, rule->arg[i]); // push child of and-rule
goto next_rule;
default:
assert(0);
goto rule_and_no_other_choice; // to help flow control analysis
}
}
assert(i == n);
// matched the rule, so now build the corresponding parse_node
// count number of arguments for the parse_node
i = 0;
bool emit_rule = false;
for (mp_uint_t x = 0; x < n; ++x) {
if ((rule->arg[x] & RULE_ARG_KIND_MASK) == RULE_ARG_TOK) {
mp_token_kind_t tok_kind = rule->arg[x] & RULE_ARG_ARG_MASK;
if (tok_kind >= MP_TOKEN_NAME) {
emit_rule = true;
}
if (tok_kind == MP_TOKEN_NAME) {
// only tokens which were names are pushed to stack
i += 1;
}
} else {
// rules are always pushed
i += 1;
}
}
#if !MICROPY_ENABLE_DOC_STRING
// this code discards lonely statements, such as doc strings
if (input_kind != MP_PARSE_SINGLE_INPUT && rule->rule_id == RULE_expr_stmt && peek_result(&parser, 0) == MP_PARSE_NODE_NULL) {
mp_parse_node_t p = peek_result(&parser, 1);
if ((MP_PARSE_NODE_IS_LEAF(p) && !MP_PARSE_NODE_IS_ID(p)) || MP_PARSE_NODE_IS_STRUCT_KIND(p, RULE_string)) {
pop_result(&parser); // MP_PARSE_NODE_NULL
mp_parse_node_free(pop_result(&parser)); // RULE_string
push_result_rule(&parser, rule_src_line, rules[RULE_pass_stmt], 0);
break;
}
}
#endif
// always emit these rules, even if they have only 1 argument
if (rule->rule_id == RULE_expr_stmt || rule->rule_id == RULE_yield_stmt) {
emit_rule = true;
}
// if a rule has the RULE_ACT_ALLOW_IDENT bit set then this
// rule should not be emitted if it has only 1 argument
// NOTE: can't set this flag for atom_paren because we need it
// to distinguish, for example, [a,b] from [(a,b)]
// TODO possibly set for: varargslist_name, varargslist_equal
if (rule->act & RULE_ACT_ALLOW_IDENT) {
emit_rule = false;
}
// always emit these rules, and add an extra blank node at the end (to be used by the compiler to store data)
if (ADD_BLANK_NODE(rule)) {
emit_rule = true;
push_result_node(&parser, MP_PARSE_NODE_NULL);
i += 1;
}
mp_uint_t num_not_nil = 0;
for (mp_uint_t x = 0; x < i; ++x) {
if (peek_result(&parser, x) != MP_PARSE_NODE_NULL) {
num_not_nil += 1;
}
}
if (emit_rule) {
push_result_rule(&parser, rule_src_line, rule, i);
} else if (num_not_nil == 0) {
push_result_rule(&parser, rule_src_line, rule, i); // needed for, eg, atom_paren, testlist_comp_3b
} else if (num_not_nil == 1) {
// single result, leave it on stack
mp_parse_node_t pn = MP_PARSE_NODE_NULL;
for (mp_uint_t x = 0; x < i; ++x) {
mp_parse_node_t pn2 = pop_result(&parser);
if (pn2 != MP_PARSE_NODE_NULL) {
pn = pn2;
}
}
push_result_node(&parser, pn);
} else {
push_result_rule(&parser, rule_src_line, rule, i);
}
break;
}
case RULE_ACT_LIST: {
// n=2 is: item item*
// n=1 is: item (sep item)*
// n=3 is: item (sep item)* [sep]
bool had_trailing_sep;
if (backtrack) {
list_backtrack:
had_trailing_sep = false;
if (n == 2) {
if (i == 1) {
// fail on item, first time round; propagate backtrack
goto next_rule;
} else {
// fail on item, in later rounds; finish with this rule
backtrack = false;
}
} else {
if (i == 1) {
// fail on item, first time round; propagate backtrack
goto next_rule;
} else if ((i & 1) == 1) {
// fail on item, in later rounds; have eaten tokens so can't backtrack
if (n == 3) {
// list allows trailing separator; finish parsing list
had_trailing_sep = true;
backtrack = false;
} else {
// list doesn't allowing trailing separator; fail
goto syntax_error;
}
} else {
// fail on separator; finish parsing list
backtrack = false;
}
}
} else {
for (;;) {
mp_uint_t arg = rule->arg[i & 1 & n];
switch (arg & RULE_ARG_KIND_MASK) {
case RULE_ARG_TOK:
if (lex->tok_kind == (arg & RULE_ARG_ARG_MASK)) {
if (i & 1 & n) {
// separators which are tokens are not pushed to result stack
} else {
push_result_token(&parser);
}
mp_lexer_to_next(lex);
// got element of list, so continue parsing list
i += 1;
} else {
// couldn't get element of list
i += 1;
backtrack = true;
goto list_backtrack;
}
break;
case RULE_ARG_RULE:
rule_list_no_other_choice:
push_rule(&parser, rule_src_line, rule, i + 1); // save this list-rule
push_rule_from_arg(&parser, arg); // push child of list-rule
goto next_rule;
default:
assert(0);
goto rule_list_no_other_choice; // to help flow control analysis
}
}
}
assert(i >= 1);
// compute number of elements in list, result in i
i -= 1;
if ((n & 1) && (rule->arg[1] & RULE_ARG_KIND_MASK) == RULE_ARG_TOK) {
// don't count separators when they are tokens
i = (i + 1) / 2;
}
if (i == 1) {
// list matched single item
if (had_trailing_sep) {
// if there was a trailing separator, make a list of a single item
push_result_rule(&parser, rule_src_line, rule, i);
} else {
// just leave single item on stack (ie don't wrap in a list)
}
} else {
push_result_rule(&parser, rule_src_line, rule, i);
}
break;
}
default:
assert(0);
}
}
mp_obj_t exc;
mp_parse_node_t result;
// check if we had a memory error
if (parser.had_memory_error) {
memory_error:
exc = mp_obj_new_exception_msg(&mp_type_MemoryError,
"parser could not allocate enough memory");
result = MP_PARSE_NODE_NULL;
goto finished;
}
// check we are at the end of the token stream
if (lex->tok_kind != MP_TOKEN_END) {
goto syntax_error;
}
// check that parsing resulted in a parse node (can fail on empty input)
if (parser.result_stack_top == 0) {
goto syntax_error;
}
//result_stack_show(parser);
//printf("rule stack alloc: %d\n", parser.rule_stack_alloc);
//printf("result stack alloc: %d\n", parser.result_stack_alloc);
//printf("number of parse nodes allocated: %d\n", num_parse_nodes_allocated);
// get the root parse node that we created
assert(parser.result_stack_top == 1);
exc = MP_OBJ_NULL;
result = parser.result_stack[0];
finished:
// free the memory that we don't need anymore
m_del(rule_stack_t, parser.rule_stack, parser.rule_stack_alloc);
m_del(mp_parse_node_t, parser.result_stack, parser.result_stack_alloc);
// we also free the lexer on behalf of the caller (see below)
if (exc != MP_OBJ_NULL) {
// had an error so raise the exception
// add traceback to give info about file name and location
// we don't have a 'block' name, so just pass the NULL qstr to indicate this
mp_obj_exception_add_traceback(exc, lex->source_name, lex->tok_line, MP_QSTR_NULL);
mp_lexer_free(lex);
nlr_raise(exc);
} else {
mp_lexer_free(lex);
return result;
}
syntax_error:
if (lex->tok_kind == MP_TOKEN_INDENT) {
exc = mp_obj_new_exception_msg(&mp_type_IndentationError,
"unexpected indent");
} else if (lex->tok_kind == MP_TOKEN_DEDENT_MISMATCH) {
exc = mp_obj_new_exception_msg(&mp_type_IndentationError,
"unindent does not match any outer indentation level");
} else {
exc = mp_obj_new_exception_msg(&mp_type_SyntaxError,
"invalid syntax");
#ifdef USE_RULE_NAME
// debugging: print the rule name that failed and the token
printf("rule: %s\n", rule->rule_name);
#if MICROPY_DEBUG_PRINTERS
mp_lexer_show_token(lex);
#endif
#endif
}
result = MP_PARSE_NODE_NULL;
goto finished;
}
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