Experiments/libabacus
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Begin the shunting-yard implementation.

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Danila Fedorin 2018-02-17 14:40:43 -08:00
parent 101847e70d
commit bf3c90bed2
1 changed files with 61 additions and 0 deletions
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src/parser.c
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@ -128,8 +128,69 @@ libab_result _parser_pop_brackets(struct parser_state* state, ll* pop_from, ll*
*success = remaining_match && (remaining_match->type == TOKEN_CHAR) && (state->string[remaining_match->from] == bracket);
return result;
}
enum parser_expression_type {
EXPR_NONE,
EXPR_ATOM,
EXPR_OPEN_PARENTH,
EXPR_CLOSE_PARENTH,
EXPR_OP_PREFIX,
EXPR_OP_POSTFIX,
EXPR_OP_INFIX
};
int _parser_can_prefix_follow(enum parser_expression_type type) {
return type == EXPR_OPEN_PARENTH || type == EXPR_OP_PREFIX || type == EXPR_OP_INFIX || type == EXPR_NONE;
}
int _parser_can_postfix_follow(enum parser_expression_type type) {
return type == EXPR_CLOSE_PARENTH || type == EXPR_ATOM || type == EXPR_OP_POSTFIX;
}
libab_result _parse_expression(struct parser_state* state, libab_tree** store_into) {
libab_result result = LIBAB_SUCCESS;
ll out_stack;
ll op_stack;
int pop_success = 0;
enum parser_expression_type last_type = EXPR_NONE;
ll_init(&out_stack);
ll_init(&op_stack);
while(result == LIBAB_SUCCESS && !_parser_eof(state)) {
enum parser_expression_type new_type = EXPR_NONE;
libab_lexer_match* new_token = state->current_match;
if(_parser_is_type(state, TOKEN_CHAR)) {
char current_char = state->string[new_token->from];
if(current_char == '(') {
result = libab_convert_ds_result(ll_append(&op_stack, new_token));
if(result != LIBAB_SUCCESS) break;
_parser_state_step(state);
new_type = EXPR_OPEN_PARENTH;
} else if(current_char == ')') {
result = _parser_pop_brackets(state, &op_stack, &out_stack, '(', &pop_success);
if(result != LIBAB_SUCCESS || !pop_success) break;
free(ll_poptail(&op_stack));
_parser_state_step(state);
new_type = EXPR_CLOSE_PARENTH;
} else {
break;
}
} else if(new_token->type == TOKEN_OP_PREFIX && _parser_can_prefix_follow(last_type)) {
result = libab_convert_ds_result(ll_append(&op_stack, new_token));
if(result != LIBAB_SUCCESS) break;
_parser_state_step(state);
new_type = EXPR_OP_PREFIX;
} else if(new_token->type == TOKEN_OP_POSTFIX && _parser_can_postfix_follow(last_type)) {
result = _parser_append_op_node(state, new_token, &out_stack);
} else if(new_token->type == TOKEN_OP_INFIX) {
} else {
}
last_type = new_type;
}
return result;
}