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134 Zeilen
2.8 KiB
134 Zeilen
2.8 KiB
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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struct Symbol {
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char *name;
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int class, selector;
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};
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struct Symbol *newSymbol(char *name)
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{
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struct Symbol *symbol = malloc(sizeof(*symbol));
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symbol->name = strdup(name);
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symbol->class = 0;
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symbol->selector = 0;
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return symbol;
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}
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struct Symbol **symbols = 0;
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int nSymbols = 0;
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struct Symbol *intern(char *name)
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{
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int lo = 0;
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int hi = nSymbols - 1;
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while (lo <= hi ) {
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int mid = (lo+hi)/2;
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int cmp = strcmp(name, symbols[mid]->name);
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if (cmp > 0) lo = mid + 1;
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else if (cmp < 0) hi = mid - 1;
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else return symbols[mid];
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}
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symbols = realloc(symbols, sizeof(*symbols) * ++nSymbols);
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memmove(symbols + lo + 1, symbols + lo, sizeof(*symbols)*(nSymbols - lo - 1));
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return symbols[lo] = newSymbol(name);
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}
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typedef void *(*method_t)();
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void *method_dnu()
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{
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printf("method not found\n");
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exit(1);
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return 0;
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}
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method_t **methods = 0;
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int nClasses = 0;
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int nSelectors = 0;
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int ensureClass(struct Symbol *symbol)
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{
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if (symbol->class == 0) {
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if (nClasses == 0) nClasses++;
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symbol->class = nClasses++;
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methods = realloc(methods, sizeof(*methods)*nClasses);
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methods[symbol->class] = malloc(sizeof(*methods)*nSelectors);
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for (int i = 0; i<nSelectors; ++i)
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methods[symbol->class][i] = method_dnu;
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}
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return symbol->class;
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}
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int ensureSelector(struct Symbol *symbol)
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{
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if (symbol->selector == 0) {
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if (nSelectors == 0) nSelectors++;
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symbol->selector = nSelectors++;
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for (int i = 0; i<nClasses; ++i) {
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methods[i] = realloc(methods[i], sizeof(**methods)*nSelectors);
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methods[i][nSelectors-1] = method_dnu;
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}
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}
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return symbol->selector;
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}
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int findClass(char *class)
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{
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return ensureClass(intern(class));
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}
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int findSelector(char *selector)
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{
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return ensureSelector(intern(selector));
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}
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void addMethod(int class, int selector, method_t method)
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{
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methods[class][selector] = method;
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}
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#define lookup(C, S) (methods[C][S])
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struct Object {
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int class;
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};
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void *Object_print()
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{
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printf("Object\n");
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return 0;
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}
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struct Point {
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int class;
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double x, y;
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};
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void *Point_print(struct Point *self)
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{
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printf("Point(%f, %f)\n", self->x, self->y);
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return 0;
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}
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#define send(R, M, ...) ({ struct Object *__ = (struct Object *)(R); lookup(__->class, _selector_##M)(__, ##__VA_ARGS__); })
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int main()
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{
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int _selector_print = findSelector("print" );
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int _class_object = findClass ("Object" );
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int _class_point = findClass ("Point" );
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addMethod(_class_object, _selector_print, Object_print);
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struct Object *o = calloc(1, sizeof(*o));
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o->class = _class_object;
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send(o, print);
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addMethod(_class_point, _selector_print, Point_print);
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struct Point *p = calloc(1, sizeof(*p));
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p->class = _class_point;
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send(p, print);
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return 0;
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}
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