cdo/infix-calculator
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Make + and - left-associative

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This commit is contained in:
Camden Dixie O'Brien 2024-10-24 20:01:45 +01:00
parent b491a1a782
commit 9932aa7ef1
2 changed files with 42 additions and 42 deletions
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60
lib/reader.c
View File

@ -29,40 +29,40 @@ static int parse_expression(
{
int result, used = 0;
expression_t *number;
result = parse_number(pool, input, len, &number);
if (0 >= result)
return 0;
used += result;
if (used >= len) {
*out = number;
return used;
}
operator_t operator;
switch (input[used]) {
case '+':
operator= OPERATOR_ADD;
break;
case '-':
operator= OPERATOR_SUBTRACT;
break;
default:
return 0;
}
++used;
expression_t *subexpr;
result = parse_expression(pool, input + used, len - used, &subexpr);
expression_t *expr;
result = parse_number(pool, input, len, &expr);
if (0 >= result)
return 0;
used += result;
expression_t *expr = allocate_expression(pool);
expr->is_number = false;
expr->application.operator= operator;
expr->application.operands[0] = number;
expr->application.operands[1] = subexpr;
while (len > used) {
const expression_t *term0 = expr;
operator_t operator;
switch (input[used]) {
case '+':
operator= OPERATOR_ADD;
break;
case '-':
operator= OPERATOR_SUBTRACT;
break;
default:
return 0;
}
++used;
expression_t *term1;
result = parse_number(pool, input + used, len - used, &term1);
if (0 >= result)
return 0;
used += result;
expr = allocate_expression(pool);
expr->is_number = false;
expr->application.operator= operator;
expr->application.operands[0] = term0;
expr->application.operands[1] = term1;
}
*out = expr;
return used;

24
tests/reader_tests.c
View File

@ -64,7 +64,7 @@ input_6_minus_2_with_no_spaces_is_read_as_a_subtract_application(void)
}
static void
input_1_plus_2_plus_3_is_parsed_as_a_right_nested_application(void)
input_1_plus_2_plus_3_is_parsed_as_a_left_nested_application(void)
{
init_memory_pool(&pool);
const expression_t *result = read_expression(&pool, "1+2+3", 5);
@ -74,19 +74,19 @@ input_1_plus_2_plus_3_is_parsed_as_a_right_nested_application(void)
const expression_t *operand0 = result->application.operands[0];
ASSERT_NOT_NULL(operand0);
ASSERT_TRUE(operand0->is_number);
ASSERT_EQUAL(1, operand0->number);
ASSERT_FALSE(operand0->is_number);
ASSERT_EQUAL(OPERATOR_ADD, operand0->application.operator);
ASSERT_NOT_NULL(operand0->application.operands[0]);
ASSERT_TRUE(operand0->application.operands[0]->is_number);
ASSERT_EQUAL(1, operand0->application.operands[0]->number);
ASSERT_NOT_NULL(operand0->application.operands[1]);
ASSERT_TRUE(operand0->application.operands[1]->is_number);
ASSERT_EQUAL(2, operand0->application.operands[1]->number);
const expression_t *operand1 = result->application.operands[1];
ASSERT_NOT_NULL(operand1);
ASSERT_FALSE(operand1->is_number);
ASSERT_EQUAL(OPERATOR_ADD, operand1->application.operator);
ASSERT_NOT_NULL(operand1->application.operands[0]);
ASSERT_TRUE(operand1->application.operands[0]->is_number);
ASSERT_EQUAL(2, operand1->application.operands[0]->number);
ASSERT_NOT_NULL(operand1->application.operands[1]);
ASSERT_TRUE(operand1->application.operands[1]->is_number);
ASSERT_EQUAL(3, operand1->application.operands[1]->number);
ASSERT_TRUE(operand1->is_number);
ASSERT_EQUAL(3, operand1->number);
}
int main(void)
@ -99,6 +99,6 @@ int main(void)
RUN_TEST(input_1_plus_2_with_no_spaces_is_read_as_an_add_application);
RUN_TEST(
input_6_minus_2_with_no_spaces_is_read_as_a_subtract_application);
RUN_TEST(input_1_plus_2_plus_3_is_parsed_as_a_right_nested_application);
RUN_TEST(input_1_plus_2_plus_3_is_parsed_as_a_left_nested_application);
TESTING_END();
}