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103 líneas
1.9 KiB
103 líneas
1.9 KiB
#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <sysexits.h>
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#include <gc.h> // NEVER, EVER HAVE TO CALL FREE (EVER) AGAIN (YES, REALLY)
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#define malloc(n) GC_MALLOC(n)
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typedef enum { Undefined, Integer, Symbol } type_t;
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union object;
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typedef union object *oop;
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struct Undefined {
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type_t type;
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};
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struct Integer {
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type_t type;
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int value;
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};
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struct Symbol {
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type_t type;
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char *name;
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int defined;
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oop value; // NULL
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};
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union object {
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type_t type;
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struct Undefined Undefined;
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struct Integer Integer;
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struct Symbol Symbol;
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};
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union object _null = { .Undefined = { Undefined } };
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oop null = &_null;
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oop _checkType(oop ptr, type_t type) {
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assert(ptr->type == type);
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return ptr;
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}
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#define get(PTR, TYPE, FIELD) _checkType(PTR, TYPE)->TYPE.FIELD
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#define set(PTR, TYPE, FIELD, VALUE) _checkType(PTR, TYPE)->TYPE.FIELD = VALUE
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void *memcheck(void *ptr)
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{
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if (NULL == ptr) {
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fprintf(stderr, "Error: out of memory\n");
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exit(EX_OSERR);
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}
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return ptr;
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}
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oop makeInteger(int value) {
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oop newInt = memcheck(malloc(sizeof(union object)));
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newInt->type = Integer;
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newInt->Integer.value = value;
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return newInt;
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}
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oop makeSymbol(char *name) {
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oop newSymb = memcheck(calloc(1, sizeof(union object)));
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newSymb->type = Symbol;
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newSymb->Symbol.name = name;
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newSymb->Symbol.defined = 0;
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newSymb->Symbol.value = null;
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return newSymb;
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}
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void print(oop ast) {
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switch (ast->type) {
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case Undefined:
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printf("null");
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return;
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case Integer:
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printf("%i", get(ast, Integer, value));
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return;
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case Symbol:
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printf("%s=", get(ast, Symbol, name));
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print(get(ast, Symbol, value));
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return;
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}
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assert(0);
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}
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void println(oop ast)
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{
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print(ast);
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printf("\n");
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}
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int main(int argc, char **argv)
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{
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oop i = makeInteger(42);
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oop s = makeSymbol("symbolic");
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println(i);
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println(s);
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return 0;
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}
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