py: Improve handling of memory error in parser.
Parser shouldn't raise exceptions, so needs to check when memory
allocation fails. This patch does that for the initial set up of the
parser state.
Also, we now put the parser object on the stack. It's small enough to
go there instead of on the heap.
This partially addresses issue #558.
diff --git a/py/parse.c b/py/parse.c
index 0ec336c..f5efd7a 100644
--- a/py/parse.c
+++ b/py/parse.c
@@ -344,21 +344,26 @@
mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_parse_error_kind_t *parse_error_kind_out) {
- // allocate memory for the parser and its stacks
+ // initialise parser and allocate memory for its stacks
- parser_t *parser = m_new_obj(parser_t);
+ parser_t parser;
- parser->had_memory_error = false;
+ parser.had_memory_error = false;
- parser->rule_stack_alloc = MP_ALLOC_PARSE_RULE_INIT;
- parser->rule_stack_top = 0;
- parser->rule_stack = m_new(rule_stack_t, parser->rule_stack_alloc);
+ parser.rule_stack_alloc = MP_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 = MP_ALLOC_PARSE_RESULT_INIT;
- parser->result_stack_top = 0;
- parser->result_stack = m_new(mp_parse_node_t, parser->result_stack_alloc);
+ parser.result_stack_alloc = MP_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;
+ 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
int top_level_rule;
@@ -367,7 +372,7 @@
case MP_PARSE_EVAL_INPUT: top_level_rule = RULE_eval_input; break;
default: top_level_rule = RULE_file_input;
}
- push_rule(parser, mp_lexer_cur(lex)->src_line, rules[top_level_rule], 0);
+ push_rule(&parser, mp_lexer_cur(lex)->src_line, rules[top_level_rule], 0);
// parse!
@@ -381,17 +386,17 @@
for (;;) {
next_rule:
- if (parser->rule_stack_top == 0 || parser->had_memory_error) {
+ if (parser.rule_stack_top == 0 || parser.had_memory_error) {
break;
}
- pop_rule(parser, &rule, &i, &rule_src_line);
+ 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("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);
@@ -408,14 +413,14 @@
switch (rule->arg[i] & RULE_ARG_KIND_MASK) {
case RULE_ARG_TOK:
if (mp_lexer_is_kind(lex, rule->arg[i] & RULE_ARG_ARG_MASK)) {
- push_result_token(parser, lex);
+ push_result_token(&parser, lex);
mp_lexer_to_next(lex);
goto next_rule;
}
break;
case RULE_ARG_RULE:
- 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
+ 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;
default:
assert(0);
@@ -423,14 +428,14 @@
}
if ((rule->arg[i] & RULE_ARG_KIND_MASK) == RULE_ARG_TOK) {
if (mp_lexer_is_kind(lex, rule->arg[i] & RULE_ARG_ARG_MASK)) {
- push_result_token(parser, lex);
+ push_result_token(&parser, lex);
mp_lexer_to_next(lex);
} else {
backtrack = true;
goto next_rule;
}
} else {
- push_rule_from_arg(parser, rule->arg[i]);
+ push_rule_from_arg(&parser, rule->arg[i]);
}
break;
@@ -441,7 +446,7 @@
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);
+ push_result_node(&parser, MP_PARSE_NODE_NULL);
backtrack = false;
} else {
// a mandatory rule that failed, so propagate backtrack
@@ -463,7 +468,7 @@
if (mp_lexer_is_kind(lex, tok_kind)) {
// matched token
if (tok_kind == MP_TOKEN_NAME) {
- push_result_token(parser, lex);
+ push_result_token(&parser, lex);
}
mp_lexer_to_next(lex);
} else {
@@ -480,8 +485,8 @@
break;
case RULE_ARG_RULE:
case RULE_ARG_OPT_RULE:
- 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
+ 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);
@@ -514,12 +519,12 @@
#if 0 && !MICROPY_ENABLE_DOC_STRING
// this code discards lonely statement, such as doc strings
// problem is that doc strings have already been interned, so this doesn't really help reduce RAM usage
- 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 (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)) {
pop_result(parser);
pop_result(parser);
- push_result_rule(parser, rule_src_line, rules[RULE_pass_stmt], 0);
+ push_result_rule(&parser, rule_src_line, rules[RULE_pass_stmt], 0);
break;
}
}
@@ -540,35 +545,35 @@
// 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->rule_id)) {
emit_rule = true;
- push_result_node(parser, MP_PARSE_NODE_NULL);
+ push_result_node(&parser, MP_PARSE_NODE_NULL);
i += 1;
}
int num_not_nil = 0;
for (int x = 0; x < i; ++x) {
- if (peek_result(parser, x) != MP_PARSE_NODE_NULL) {
+ if (peek_result(&parser, x) != MP_PARSE_NODE_NULL) {
num_not_nil += 1;
}
}
//printf("done and %s n=%d i=%d notnil=%d\n", rule->rule_name, n, i, num_not_nil);
if (emit_rule) {
- push_result_rule(parser, rule_src_line, rule, i);
+ 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
+ push_result_rule(&parser, rule_src_line, rule, i); // needed for, eg, atom_paren, testlist_comp_3b
//result_stack_show(parser);
//assert(0);
} else if (num_not_nil == 1) {
// single result, leave it on stack
mp_parse_node_t pn = MP_PARSE_NODE_NULL;
for (int x = 0; x < i; ++x) {
- mp_parse_node_t pn2 = pop_result(parser);
+ mp_parse_node_t pn2 = pop_result(&parser);
if (pn2 != MP_PARSE_NODE_NULL) {
pn = pn2;
}
}
- push_result_node(parser, pn);
+ push_result_node(&parser, pn);
} else {
- push_result_rule(parser, rule_src_line, rule, i);
+ push_result_rule(&parser, rule_src_line, rule, i);
}
break;
@@ -615,7 +620,7 @@
if (i & 1 & n) {
// separators which are tokens are not pushed to result stack
} else {
- push_result_token(parser, lex);
+ push_result_token(&parser, lex);
}
mp_lexer_to_next(lex);
// got element of list, so continue parsing list
@@ -628,8 +633,8 @@
}
break;
case RULE_ARG_RULE:
- push_rule(parser, rule_src_line, rule, i + 1); // save this list-rule
- push_rule_from_arg(parser, arg); // push child of list-rule
+ 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);
@@ -649,13 +654,13 @@
// 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);
+ push_result_rule(&parser, rule_src_line, rule, i);
} else {
// just leave single item on stack (ie don't wrap in a list)
}
} else {
//printf("done list %s %d %d\n", rule->rule_name, n, i);
- push_result_rule(parser, rule_src_line, rule, i);
+ push_result_rule(&parser, rule_src_line, rule, i);
}
break;
@@ -667,7 +672,8 @@
mp_parse_node_t result;
// check if we had a memory error
- if (parser->had_memory_error) {
+ if (parser.had_memory_error) {
+memory_error:
*parse_error_kind_out = MP_PARSE_ERROR_MEMORY;
result = MP_PARSE_NODE_NULL;
goto finished;
@@ -681,19 +687,18 @@
//printf("--------------\n");
//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("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);
- result = parser->result_stack[0];
+ assert(parser.result_stack_top == 1);
+ 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);
- m_del_obj(parser_t, parser);
+ 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);
// return the result
return result;