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py/parse: Make parser error handling cleaner, less spaghetti-like.

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This commit is contained in:
Damien George 2015-10-12 12:59:18 +01:00
parent 64f2b213bb
commit fdfcee7b1e
1 changed files with 28 additions and 43 deletions
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51
py/parse.c
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@ -1013,18 +1013,24 @@ mp_parse_tree_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind) {
"parser could not allocate enough memory"); "parser could not allocate enough memory");
} }
parser.tree.root = MP_PARSE_NODE_NULL; parser.tree.root = MP_PARSE_NODE_NULL;
goto finished; } else if (
} lex->tok_kind != MP_TOKEN_END // check we are at the end of the token stream
|| parser.result_stack_top == 0 // check that we got a node (can fail on empty input)
// check we are at the end of the token stream ) {
if (lex->tok_kind != MP_TOKEN_END) { syntax_error:
goto syntax_error; if (lex->tok_kind == MP_TOKEN_INDENT) {
} exc = mp_obj_new_exception_msg(&mp_type_IndentationError,
"unexpected indent");
// check that parsing resulted in a parse node (can fail on empty input) } else if (lex->tok_kind == MP_TOKEN_DEDENT_MISMATCH) {
if (parser.result_stack_top == 0) { exc = mp_obj_new_exception_msg(&mp_type_IndentationError,
goto syntax_error; "unindent does not match any outer indentation level");
} else {
exc = mp_obj_new_exception_msg(&mp_type_SyntaxError,
"invalid syntax");
} }
parser.tree.root = MP_PARSE_NODE_NULL;
} else {
// no errors
//result_stack_show(parser); //result_stack_show(parser);
//printf("rule stack alloc: %d\n", parser.rule_stack_alloc); //printf("rule stack alloc: %d\n", parser.rule_stack_alloc);
@ -1035,8 +1041,8 @@ mp_parse_tree_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind) {
assert(parser.result_stack_top == 1); assert(parser.result_stack_top == 1);
exc = MP_OBJ_NULL; exc = MP_OBJ_NULL;
parser.tree.root = parser.result_stack[0]; parser.tree.root = parser.result_stack[0];
}
finished:
// free the memory that we don't need anymore // free the memory that we don't need anymore
m_del(rule_stack_t, parser.rule_stack, parser.rule_stack_alloc); 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(mp_parse_node_t, parser.result_stack, parser.result_stack_alloc);
@ -1053,27 +1059,6 @@ finished:
mp_lexer_free(lex); mp_lexer_free(lex);
return parser.tree; return parser.tree;
} }
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
}
parser.tree.root = MP_PARSE_NODE_NULL;
goto finished;
} }
void mp_parse_tree_clear(mp_parse_tree_t *tree) { void mp_parse_tree_clear(mp_parse_tree_t *tree) {