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The environment chain lookup should ignore undefined cells if there

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are defined cells available.  This avoids previously undefined values
blocking an export-all import.
This commit is contained in:
Alex Shinn 2013-10-14 08:10:34 +09:00
parent 83262a9dfa
commit 156505e798
1 changed files with 26 additions and 5 deletions
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31
eval.c
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@ -78,25 +78,46 @@ sexp sexp_maybe_wrap_error (sexp ctx, sexp obj) {
/********************** environment utilities ***************************/
/* Look for the first defined instance of the variable. If not found, */
/* return the first undefined instance. */
static sexp sexp_env_cell_loc (sexp env, sexp key, int localp, sexp *varenv) {
sexp ls;
sexp ls, undefined = NULL, undefined_env = NULL;
do {
#if SEXP_USE_RENAME_BINDINGS
for (ls=sexp_env_renames(env); sexp_pairp(ls); ls=sexp_env_next_cell(ls))
if (sexp_car(ls) == key) {
if (varenv) *varenv = env;
return sexp_cdr(ls);
if (sexp_pairp(sexp_cdr(ls)) && sexp_cdr(sexp_cdr(ls)) == SEXP_UNDEF) {
if (!undefined) {
undefined_env = env;
undefined = sexp_cdr(ls);
}
} else {
if (varenv) *varenv = env;
return sexp_cdr(ls);
}
}
#endif
for (ls=sexp_env_bindings(env); sexp_pairp(ls); ls=sexp_env_next_cell(ls))
if (sexp_car(ls) == key) {
if (varenv) *varenv = env;
return ls;
if (sexp_cdr(ls) == SEXP_UNDEF) {
if (!undefined) {
undefined_env = env;
undefined = ls;
}
} else {
if (varenv) *varenv = env;
return ls;
}
}
env = (localp ? NULL : sexp_env_parent(env));
} while (env && sexp_envp(env));
if (undefined) {
if (varenv) *varenv = undefined_env;
return undefined;
}
return NULL;
}