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Revert "libexpr: Fix prim_replaceStrings() to work on an empty source string"

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This reverts commit 4ea9707591.

It causes an infinite loop in Nixpkgs evaluation,
e.g. "nix-instantiate -A hello" hung.

PR #1886.
This commit is contained in:
Eelco Dolstra 2018-02-21 15:34:40 +01:00
parent a6c497f526
commit e2d71bd186
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GPG key ID: 8170B4726D7198DE
3 changed files with 4 additions and 11 deletions
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11
src/libexpr/primops.cc
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@ -1913,26 +1913,21 @@ static void prim_replaceStrings(EvalState & state, const Pos & pos, Value * * ar
auto s = state.forceString(*args[2], context, pos); auto s = state.forceString(*args[2], context, pos);
string res; string res;
// Loops one past last character to handle the case where 'from' contains an empty string. for (size_t p = 0; p < s.size(); ) {
for (size_t p = 0; p <= s.size(); ) {
bool found = false; bool found = false;
auto i = from.begin(); auto i = from.begin();
auto j = to.begin(); auto j = to.begin();
for (; i != from.end(); ++i, ++j) for (; i != from.end(); ++i, ++j)
if (s.compare(p, i->size(), *i) == 0) { if (s.compare(p, i->size(), *i) == 0) {
found = true; found = true;
res += j->first;
if (i->empty()) {
res += s[p++];
} else {
p += i->size(); p += i->size();
} res += j->first;
for (auto& path : j->second) for (auto& path : j->second)
context.insert(path); context.insert(path);
j->second.clear(); j->second.clear();
break; break;
} }
if (!found && p < s.size()) res += s[p++]; if (!found) res += s[p++];
} }
mkString(v, res, context); mkString(v, res, context);

2
tests/lang/eval-okay-replacestrings.exp
View file

@ -1 +1 @@
[ "faabar" "fbar" "fubar" "faboor" "fubar" "XaXbXcX" "X" ] [ "faabar" "fbar" "fubar" "faboor" "fubar" ]

2
tests/lang/eval-okay-replacestrings.nix
View file

@ -5,6 +5,4 @@ with builtins;
(replaceStrings ["oo"] ["u"] "foobar") (replaceStrings ["oo"] ["u"] "foobar")
(replaceStrings ["oo" "a"] ["a" "oo"] "foobar") (replaceStrings ["oo" "a"] ["a" "oo"] "foobar")
(replaceStrings ["oo" "oo"] ["u" "i"] "foobar") (replaceStrings ["oo" "oo"] ["u" "i"] "foobar")
(replaceStrings [""] ["X"] "abc")
(replaceStrings [""] ["X"] "")
] ]