diff options
Diffstat (limited to 'lisp.c')
| -rw-r--r-- | lisp.c | 98 |
1 files changed, 87 insertions, 11 deletions
@@ -48,7 +48,7 @@ value *cons(value *car, value *cdr) { return val; } -void *print_val(value *val){ +void *print_value(value *val){ char *str; switch (val->type) { case VALTYPE_INT: @@ -73,9 +73,9 @@ void *print_val(value *val){ case VALTYPE_PAIR: printf("("); - print_val(val->as.pair.car); + print_value(val->as.pair.car); printf(" . "); - print_val(val->as.pair.cdr); + print_value(val->as.pair.cdr); printf(")"); default: } @@ -83,13 +83,89 @@ void *print_val(value *val){ return val; } +env *env_create(env *parent) { + env *e = malloc(sizeof(env)); + e->symbol = NULL; + e->value = NULL; + e->next = NULL; + e->parent = parent; + return e; +} + +env *env_define(env *e, const char *sym, value *val) { + if (e->next) { + return env_define(e->next, sym, val); + } + env *new = malloc(sizeof(env)); + new->symbol = strdup(sym); + new->value = val; + new->next = NULL; + new->parent = e->parent; + e->next = new; + return new; +} + +value *env_lookup(env *e, const char *sym) { + if (e->symbol && !strcmp(e->symbol, sym)) { + return e->value; + } + if (e->next) { + return env_lookup(e->next, sym); + } + if (e->parent) { + return env_lookup(e->parent, sym); + } + return NULL; +} + int main(void) { - char* line; - while ((line = readline("λ > ")) != NULL) { - if (*line) add_history(line); - yy_scan_string(line); - yyparse(); - free(line); - } - return 0; + /* TEST; DANKE CHATGPT + // create global environment + env *global = env_create(NULL); + // define some variables + env_define(global, "x", make_int(10)); + env_define(global, "y", make_int(42)); + + // lookup variables + value *vx = env_lookup(global, "x"); + value *vy = env_lookup(global, "y"); + value *vz = env_lookup(global, "z"); // undefined + // + if (vx) { + printf("x = "); + print_value(vx); + printf("\n"); + } + if (vx) { + printf("y = "); + print_value(vy); + printf("\n"); + } + if (vz) { + printf("z = "); + print_value(vz); + printf("\n"); + } + + // create nested environment + env *local = env_create(global); + env_define(local, "x", make_int(99)); // shadow global x + + value *lx = env_lookup(local, "x"); // should find local + value *ly = env_lookup(local, "y"); // should find global + + printf("local x = %d\n", lx ? lx->as.i : -1); + printf("local y = %d\n", ly ? ly->as.i : -1); + */ + // START REPL + char* line; + while ((line = readline("λ > ")) != NULL) { + if (*line) { + add_history(line); + } + yy_scan_string(line); + yyparse(); + free(line); + } + return 0; } |