From 1b82e9af5c9b67cae8f7a35abc2dee3989fbdc06 Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Sat, 10 May 2014 17:36:41 +0100
Subject: [PATCH] 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.
---
py/misc.h | 1 +
py/parse.c | 99 ++++++++++++++++++++++++++++--------------------------
2 files changed, 53 insertions(+), 47 deletions(-)
diff --git a/py/misc.h b/py/misc.h
index 5eb662409..7f3e83d8c 100644
--- a/py/misc.h
+++ b/py/misc.h
@@ -50,6 +50,7 @@ typedef unsigned int uint;
// TODO make a lazy m_renew that can increase by a smaller amount than requested (but by at least 1 more element)
#define m_new(type, num) ((type*)(m_malloc(sizeof(type) * (num))))
+#define m_new_maybe(type, num) ((type*)(m_malloc_maybe(sizeof(type) * (num))))
#define m_new0(type, num) ((type*)(m_malloc0(sizeof(type) * (num))))
#define m_new_obj(type) (m_new(type, 1))
#define m_new_obj_var(obj_type, var_type, var_num) ((obj_type*)m_malloc(sizeof(obj_type) + sizeof(var_type) * (var_num)))
diff --git a/py/parse.c b/py/parse.c
index 0ec336cd1..f5efd7a4f 100644
--- a/py/parse.c
+++ b/py/parse.c
@@ -344,21 +344,26 @@ STATIC void push_result_rule(parser_t *parser, int src_line, const rule_t *rule,
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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
}
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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
#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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
// 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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
}
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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
// 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 mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
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 @@ mp_parse_node_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, mp_p
//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;
--
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