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Refactor parsing routines

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Camden Dixie O'Brien 2024-10-24 19:25:58 +01:00
parent bb622a0766
commit 5ea066b75e
1 changed files with 30 additions and 46 deletions
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76
lib/reader.c
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@ -3,46 +3,44 @@
#include <ctype.h> #include <ctype.h>
#include <stddef.h> #include <stddef.h>
static int parse_expression(
memory_pool_t *pool, const char *input, int remaining,
expression_t *out);
static int parse_number( static int parse_number(
memory_pool_t *pool, const char *input, int remaining, expression_t *out) memory_pool_t *pool, const char *input, int len, expression_t **out)
{ {
(void)pool; (void)pool;
int value = 0, used = 0; int value = 0, used = 0;
while (remaining > 0 && isdigit(*input)) { while (used < len && isdigit(input[used])) {
value *= 10; value *= 10;
value += *input - '0'; value += input[used] - '0';
++used; ++used;
--remaining;
++input;
} }
if (0 == used)
return 0;
out->is_number = true; expression_t *number = allocate_expression(pool);
out->number = value; number->is_number = true;
number->number = value;
*out = number;
return used; return used;
} }
static int parse_application( static int parse_expression(
memory_pool_t *pool, const char *input, int remaining, expression_t *out) memory_pool_t *pool, const char *input, int len, expression_t **out)
{ {
int result, used = 0; int result, used = 0;
expression_t *operand0 = allocate_expression(pool); expression_t *number;
result = parse_number(pool, input, remaining, operand0); result = parse_number(pool, input, len, &number);
if (0 == result) if (0 >= result)
return 0; return 0;
used += result; used += result;
remaining -= result; if (used >= len) {
input += result; *out = number;
return used;
}
if (remaining <= 0)
return 0;
operator_t operator; operator_t operator;
switch (*input) { switch (input[used]) {
case '+': case '+':
operator= OPERATOR_ADD; operator= OPERATOR_ADD;
break; break;
@ -53,41 +51,27 @@ static int parse_application(
return 0; return 0;
} }
++used; ++used;
--remaining;
++input;
expression_t *operand1 = allocate_expression(pool); expression_t *subexpr;
result = parse_expression(pool, input, remaining, operand1); result = parse_expression(pool, input + used, len - used, &subexpr);
if (0 == result) if (0 >= result)
return 0; return 0;
used += result; used += result;
remaining -= result;
input += result;
out->is_number = false; expression_t *expr = allocate_expression(pool);
out->application.operator= operator; expr->is_number = false;
out->application.operands[0] = operand0; expr->application.operator= operator;
out->application.operands[1] = operand1; expr->application.operands[0] = number;
expr->application.operands[1] = subexpr;
*out = expr;
return used; return used;
} }
static int parse_expression(
memory_pool_t *pool, const char *input, int remaining, expression_t *out)
{
int result = parse_application(pool, input, remaining, out);
if (0 != result)
return result;
else
return parse_number(pool, input, remaining, out);
}
const expression_t * const expression_t *
read_expression(memory_pool_t *pool, const char *input, int len) read_expression(memory_pool_t *pool, const char *input, int len)
{ {
expression_t *expression = allocate_expression(pool); expression_t *expression;
if (NULL == expression) parse_expression(pool, input, len, &expression);
return NULL;
parse_expression(pool, input, len, expression);
return expression; return expression;
} }