diff options
| -rw-r--r-- | ChangeLog | 32 | ||||
| -rw-r--r-- | eval.c | 47 | ||||
| -rw-r--r-- | signal.h | 23 |
3 files changed, 84 insertions, 18 deletions
@@ -1,3 +1,35 @@ +2014-02-23 Kaz Kylheku <kaz@kylheku.com> + + Introducing some changes for improved handling of special variables. + Saving and restoring of individual variables is very silly + and it's making it difficult to implement function parameters + that are rebindings of special variables. + + Let's have a global pointer to a dynamic environment called dyn_env. + Let's make it part of the extended_jmp_buf structure, so that it's + implicitly saved and restored across exception handling. + + Special variable lookups go through the dyn_env chain, and fall back on + the global bindings. + + To override some specials, we just push a new dynamic environment and + stick them there. (As a bonus, the bindings can even be repeated in the + lexical environment (i.e. the same objects), so they can be found + faster. We have to make sure we remove that environment when we + leave the scope in the normal way. If we unwind out, it is done + automatically by extended_longjmp mechanism. + + * eval.c (dyn_env): New global variable. + (lookup_var, lookup_var_l): If env is nil, look in the dyn_env + first, and only if that fails, look in the global bindings top_vb. + + * signal.h (extended_jmp_buf): New member, de, for saving/restoring + dyn_env. This structure is now used whether or not we have signals. + (extended_setjmp, extended_longjmp): Updated to save and restore + dyn_env, and to do it regardless of whether there is POSIX signal + support. + (dyn_env): Declared here. + 2014-02-22 Kaz Kylheku <kaz@kylheku.com> * eval.c (symbol_function): Retrieve the global macro binding if the @@ -73,6 +73,7 @@ struct c_var { val top_vb, top_fb, top_mb, special; val op_table; +val dyn_env; val eval_error_s; val dwim_s, progn_s, prog1_s, let_s, let_star_s, lambda_s, call_s; @@ -141,14 +142,22 @@ noreturn static val eval_error(val form, val fmt, ...) val lookup_var(val env, val sym) { if (nilp(env)) { - val bind = gethash(top_vb, sym); - if (cobjp(bind)) { - struct c_var *cv = (struct c_var *) cptr_get(bind); - set(cv->bind->c.cdr, *cv->loc); - return cv->bind; + if (dyn_env) { + val binding = assoc(sym, dyn_env->e.vbindings); + if (binding) + return binding; + } + + { + val bind = gethash(top_vb, sym); + if (cobjp(bind)) { + struct c_var *cv = (struct c_var *) cptr_get(bind); + set(cv->bind->c.cdr, *cv->loc); + return cv->bind; + } + return bind; } - return bind; - } else { + } else { type_check(env, ENV); { @@ -163,15 +172,23 @@ val lookup_var(val env, val sym) val *lookup_var_l(val env, val sym) { if (nilp(env)) { - val bind = gethash(top_vb, sym); - if (cobjp(bind)) { - struct c_var *cv = (struct c_var *) cptr_get(bind); - return cv->loc; + if (dyn_env) { + val binding = assoc(sym, dyn_env->e.vbindings); + if (binding) + return cdr_l(binding); } - if (bind) - return cdr_l(bind); - return 0; - } else { + + { + val bind = gethash(top_vb, sym); + if (cobjp(bind)) { + struct c_var *cv = (struct c_var *) cptr_get(bind); + return cv->loc; + } + if (bind) + return cdr_l(bind); + return 0; + } + } else { type_check(env, ENV); { @@ -61,15 +61,18 @@ typedef struct { jmp_buf jb; sig_atomic_t se; sigset_t blocked; + val de; int rv; } extended_jmp_buf; #define extended_setjmp(EJB) \ (setjmp((EJB).jb) \ ? (async_sig_enabled = (EJB).se, \ + dyn_env = (EJB).de, \ sig_mask(SIG_SETMASK, &(EJB).blocked, 0), \ (EJB).rv) \ : ((EJB).se = async_sig_enabled, \ + (EJB).de = dyn_env, \ (EJB).blocked = sig_blocked_cache, 0)) #define extended_longjmp(EJB, ARG) \ @@ -86,13 +89,27 @@ extern volatile sig_atomic_t async_sig_enabled; #define sig_restore_enable do { } while (0); } while (0) #define sig_restore_disable do { } while (0); } while (0) -typedef jmp_buf extended_jmp_buf; -#define extended_setjmp(EJB) setjmp(EJB) -#define extended_longjmp(EJB, ARG) longjmp(EJB, ARG) +typedef struct { + jmp_buf jb; + val de; + int rv; +} extended_jmp_buf; + +#define extended_setjmp(EJB) \ + (setjmp((EJB).jb) \ + ? (dyn_env = (EJB).de, \ + (EJB).rv) \ + : ((EJB).de = dyn_env, 0)) + +#define extended_longjmp(EJB, ARG) \ + ((EJB).rv = (ARG), longjmp((EJB).jb, 1)) + extern int async_sig_enabled; #endif +extern val dyn_env; /* eval.c */ + extern val sig_hup, sig_int, sig_quit, sig_ill, sig_trap, sig_abrt, sig_bus; extern val sig_fpe, sig_kill, sig_usr1, sig_segv, sig_usr2, sig_pipe, sig_alrm; extern val sig_term, sig_chld, sig_cont, sig_stop, sig_tstp, sig_ttin; |