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Make SetHash iterators more safe

Currently, deleting a key from a nqp::iterator of an nqp::hash and then
continuing iterating over the hash, may cause segfaults.  Prevent that
situation by letting the SetHash.kv/pairs/values methods run on an iterator
on a pre-made list of keys, rather than directly on the nqp::hash iterator.

Deleting can happen if the value of a key from a SetHash is set to False:

    my %s is SetHash = <a b c d e>;
    dd %s;  # SetHash.new("d","b","e","c","a")
    $_ = False for %s.values;
    dd %s;  # SetHash.new()
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lizmat committed Mar 21, 2019
1 parent a6a6070 commit 1f066d96a28940d3aae812fe5d22cd5bf17522ca
Showing with 31 additions and 15 deletions.
  1. +31 −15 src/core/SetHash.pm6
@@ -76,7 +76,7 @@ my class SetHash does Setty {

#--- iterator methods

sub proxy(Mu \iter,Mu \elems) is raw {
sub proxy(str $key, Mu \elems) is raw {
# We are only sure that the key exists when the Proxy
# is made, but we cannot be sure of its existence when
# either the FETCH or STORE block is executed. So we
@@ -87,18 +87,18 @@ my class SetHash does Setty {
# processing.
nqp::stmts(
# save object for potential recreation
(my $object := nqp::iterval(iter)),
(my $object := nqp::atkey(elems,$key)),

Proxy.new(
FETCH => {
nqp::hllbool(nqp::existskey(elems,nqp::iterkey_s(iter)))
nqp::hllbool(nqp::existskey(elems,$key))
},
STORE => -> $, $value {
nqp::stmts(
nqp::if(
$value,
nqp::bindkey(elems,nqp::iterkey_s(iter),$object),
nqp::deletekey(elems,nqp::iterkey_s(iter))
nqp::bindkey(elems,$key,$object),
nqp::deletekey(elems,$key)
),
$value.Bool
)
@@ -108,12 +108,17 @@ my class SetHash does Setty {
}

my class Iterate does Rakudo::Iterator::Mappy {
method !SET-SELF(\elems) {
nqp::bind($!hash,elems);
nqp::bind($!iter,Rakudo::Internals.ITERATIONSET2LISTITER(elems));
self
}
method pull-one() {
nqp::if(
$!iter,
Pair.new(
nqp::iterval(nqp::shift($!iter)),
proxy($!iter,$!hash)
nqp::atkey($!hash,(my $key := nqp::shift($!iter))),
proxy($key,$!hash)
),
IterationEnd
)
@@ -122,36 +127,47 @@ my class SetHash does Setty {
method iterator(SetHash:D:) { Iterate.new($!elems) }

my class KV does Rakudo::QuantHash::Quanty-kv {
method !SET-SELF(Mu \elems) {
nqp::bind($!elems,elems);
nqp::bind($!iter,Rakudo::Internals.ITERATIONSET2LISTITER(elems));
self
}
method pull-one() is raw {
nqp::if(
$!on,
nqp::stmts(
($!on = 0),
proxy($!iter,$!elems)
(my $proxy := proxy($!on,$!elems)),
($!on = ""),
$proxy
),
nqp::if(
$!iter,
nqp::stmts(
($!on = 1),
nqp::iterval(nqp::shift($!iter))
),
nqp::atkey($!elems,$!on = nqp::shift($!iter)),
IterationEnd
)
)
}
method skip-one() { # the one provided by the role interferes
nqp::not_i(nqp::eqaddr(self.pull-one,IterationEnd))
}
method push-all(\target --> IterationEnd) {
nqp::while(
$!iter,
nqp::stmts( # doesn't sink
target.push(nqp::iterval(nqp::shift($!iter))),
target.push(nqp::atkey($!elems,nqp::shift($!iter))),
target.push(True)
)
)
}
}
multi method kv(SetHash:D:) { Seq.new(KV.new(self)) }
multi method kv(SetHash:D:) { Seq.new(KV.new($!elems)) }

my class Values does Rakudo::Iterator::Mappy {
method !SET-SELF(\elems) {
nqp::bind($!hash,elems);
nqp::bind($!iter,Rakudo::Internals.ITERATIONSET2LISTITER(elems));
self
}
method pull-one() is rw {
nqp::if(
$!iter,

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