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Add paren support to reader

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This commit is contained in:
Camden Dixie O'Brien
2024-10-24 20:46:05 +01:00
parent 7b62b58c4f
commit e0070bfb1e
2 changed files with 49 additions and 8 deletions
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31
lib/reader.c
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@@ -3,11 +3,12 @@
#include <ctype.h>
#include <stddef.h>
static int parse_expression(
memory_pool_t *pool, const char *input, int len, expression_t **out);
static int parse_number(
memory_pool_t *pool, const char *input, int len, expression_t **out)
{
(void)pool;
int value = 0, used = 0;
while (used < len && isdigit(input[used])) {
value *= 10;
@@ -24,13 +25,27 @@ static int parse_number(
return used;
}
static int parse_factor(
memory_pool_t *pool, const char *input, int len, expression_t **out)
{
if (len > 1 && input[0] == '(') {
const int result = parse_expression(pool, input + 1, len - 1, out);
if (0 == result)
return 0;
const int used = result + 1;
return len >= used && input[used] == ')' ? used + 1 : 0;
} else {
return parse_number(pool, input, len, out);
}
}
static int parse_term(
memory_pool_t *pool, const char *input, int len, expression_t **out)
{
int result, used = 0;
expression_t *expr;
result = parse_number(pool, input, len, &expr);
result = parse_factor(pool, input, len, &expr);
if (0 >= result)
return 0;
used += result;
@@ -40,15 +55,15 @@ static int parse_term(
operator_t operator;
if ('*' == input[used])
operator = OPERATOR_MULTIPLY;
operator= OPERATOR_MULTIPLY;
else if ('/' == input[used])
operator = OPERATOR_DIVIDE;
operator= OPERATOR_DIVIDE;
else
break;
++used;
expression_t *term1;
result = parse_number(pool, input + used, len - used, &term1);
result = parse_factor(pool, input + used, len - used, &term1);
if (0 >= result)
return 0;
used += result;
@@ -80,9 +95,9 @@ static int parse_expression(
operator_t operator;
if ('+' == input[used])
operator = OPERATOR_ADD;
operator= OPERATOR_ADD;
else if ('-' == input[used])
operator = OPERATOR_SUBTRACT;
operator= OPERATOR_SUBTRACT;
else
break;
++used;