96 lines
2.5 KiB
C
96 lines
2.5 KiB
C
#include "interpreter.h"
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#include "token.h"
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Object* Evaluate(Expr*);
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int IsTruthy(Object*);
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int IsEqual(Object*, Object*);
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const void* VisitLiteralExpression(Expr* expression) {
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return expression->expression.Literal->literal;
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}
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void* VisitGroupingExpression(Expr* expression) {
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return Evaluate(expression);
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}
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void* VisitBinaryExpression(Expr* expression) {
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void* left = Evaluate(expression->expression.Binary.left);
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void* right = Evaluate(expression->expression.Binary.right);
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switch(expression->expression.Binary.op->type) {
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case Greater:
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return left > right;
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case Greater_Equal:
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return left >= right;
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case Less:
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return left < right;
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case Less_Equal:
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return left <= right;
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case Minus:
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return left - right;
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case Bang_Equal:
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return !IsEqual(left, right);
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case Equal_Equal:
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return IsEqual(left, right);
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case Slash:
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return *((double*)left) / *((double*)right);
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case Star:
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return *((double*)left) * *((double*)right);
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case Plus:
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if (((Token*)left)->type == Number && ((Token*)right)->type == Number) {
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return left + right;
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}
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if (((Token*)left)->type == String && ((Token*)right)->type == String) {
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return NULL; //String concat
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}
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break;
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}
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// Unreachable
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return NULL;
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}
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void* VisitUnaryExpression(Expr* expression) {
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void* right = Evaluate(expression);
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switch (expression->type) {
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case Minus:
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//right needs to be negated, but that kind of introduces a
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//memory leak since we can't really change it, what with the
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//whole "const void*" thing and all.
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return right;
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case Bang:
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return !IsTruthy(right);
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}
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return NULL; //Should be unreachable.
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}
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Object* Evaluate(Expr* expression) {
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//accept
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return NULL;
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}
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int IsTruthy(Object* object) {
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if (!object || object->instance == NIL) return 0;
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if (object->instance == TRUE) return 0;
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return 1;
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}
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int IsEqual(Object* a, Object* b) {
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if (a->instance == NIL && b->instance == NIL) return 1;
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if (a->instance == NIL) return 0;
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if (b->instance == Number && b->instance == Number) {
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return a->value.number == b->value.number;
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}
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if (a->instance == String && b->instance == String) {
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int result = strcmp(a->value.string, b->value.string);
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return result == 0;
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}
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return 0;
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} |