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#include <assert.h>
#include <inttypes.h>
#include <stdio.h>
#include "eval.h"
static int evaluate_value(const struct Node* node, int64_t* out);
static int complain(const struct Node* node, const char* message)
{
(void)fprintf(stderr, "line %d: %s\n", node->line, message);
return 1;
}
static int evaluate_operands(const struct Node* node, int64_t* left, int64_t* right)
{
if (evaluate_value(node->first, left))
return 1;
return evaluate_value(node->second, right);
}
static int evaluate_value(const struct Node* node, int64_t* out)
{
int64_t left = 0;
int64_t right = 0;
switch (node->kind)
{
case VALUE_DIFFERENCE:
*out = (int64_t)node->first->character - (int64_t)node->second->character;
return 0;
case VALUE_SUM:
if (evaluate_operands(node, &left, &right))
return 1;
*out = left + right;
return 0;
case VALUE_PRODUCT:
if (evaluate_operands(node, &left, &right))
return 1;
*out = left * right;
return 0;
case VALUE_QUOTIENT:
if (evaluate_operands(node, &left, &right))
return 1;
if (right == 0)
return complain(node, "division by zero");
*out = left / right;
return 0;
default: break;
}
assert(!"the parser handed a non-value where a value goes");
return 1;
}
static int evaluate_type(const struct Node* node, struct Type* out)
{
out->kind = KIND_VOID;
out->number = 0;
switch (node->kind)
{
case TYPE_DECLTYPE:
if (evaluate_value(node->first, &out->number))
return 1;
out->kind = KIND_VALUE;
return 0;
default: break;
}
assert(!"the parser handed a non-type where a type goes");
return 1;
}
static enum RunStatus emit(const struct Node* node)
{
struct Type type;
if (evaluate_type(node->first, &type))
return RUN_FAILED;
if (type.kind == KIND_VALUE)
(void)printf("%" PRId64 "\n", type.number);
return RUN_DONE;
}
static enum RunStatus execute_one(const struct Node* node)
{
switch (node->kind)
{
case STMT_EMIT: return emit(node);
default: break;
}
assert(!"the parser handed a non-statement where a statement goes");
return RUN_FAILED;
}
enum RunStatus execute(const struct Node* statement)
{
while (statement != NULL)
{
enum RunStatus status = execute_one(statement);
if (status != RUN_DONE)
return status;
statement = statement->next;
}
return RUN_DONE;
}
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