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Merge pull request #11682 from NaN-git/opt-str

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Remove superfluous `std::string` copy operations
This commit is contained in:
Robert Hensing 2024-10-12 10:59:40 +02:00 committed by GitHub
parent dbcd4cd6ba a353a99269
commit 30c4f5eb51
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GPG key ID: B5690EEEBB952194
16 changed files with 72 additions and 54 deletions
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4
src/libcmd/repl.cc
View file

@ -645,7 +645,7 @@ ProcessLineResult NixRepl::processLine(std::string line)
logger->cout(trim(renderMarkdownToTerminal(markdown)));
} else if (fallbackPos) {
std::stringstream ss;
std::ostringstream ss;
ss << "Attribute `" << fallbackName << "`\n\n";
ss << " … defined at " << state->positions[fallbackPos] << "\n\n";
if (fallbackDoc) {
@ -654,7 +654,7 @@ ProcessLineResult NixRepl::processLine(std::string line)
ss << "No documentation found.\n\n";
}
auto markdown = ss.str();
auto markdown = toView(ss);
logger->cout(trim(renderMarkdownToTerminal(markdown)));
} else

17
src/libexpr/eval.cc
View file

@ -539,7 +539,7 @@ std::optional<EvalState::Doc> EvalState::getDoc(Value & v)
if (v.isLambda()) {
auto exprLambda = v.payload.lambda.fun;
std::stringstream s(std::ios_base::out);
std::ostringstream s;
std::string name;
auto pos = positions[exprLambda->getPos()];
std::string docStr;
@ -571,17 +571,12 @@ std::optional<EvalState::Doc> EvalState::getDoc(Value & v)
s << docStr;
s << '\0'; // for making a c string below
std::string ss = s.str();
return Doc {
.pos = pos,
.name = name,
.arity = 0, // FIXME: figure out how deep by syntax only? It's not semantically useful though...
.args = {},
.doc =
// FIXME: this leaks; make the field std::string?
strdup(ss.data()),
.doc = makeImmutableString(toView(s)), // NOTE: memory leak when compiled without GC
};
}
if (isFunctor(v)) {
@ -1805,11 +1800,9 @@ void ExprIf::eval(EvalState & state, Env & env, Value & v)
void ExprAssert::eval(EvalState & state, Env & env, Value & v)
{
if (!state.evalBool(env, cond, pos, "in the condition of the assert statement")) {
auto exprStr = ({
std::ostringstream out;
cond->show(state.symbols, out);
out.str();
});
std::ostringstream out;
cond->show(state.symbols, out);
auto exprStr = toView(out);
if (auto eq = dynamic_cast<ExprOpEq *>(cond)) {
try {

9
src/libexpr/get-drvs.cc
View file

@ -374,11 +374,12 @@ static void getDerivations(EvalState & state, Value & vIn,
bound to the attribute with the "lower" name should take
precedence). */
for (auto & i : v.attrs()->lexicographicOrder(state.symbols)) {
std::string_view symbol{state.symbols[i->name]};
try {
debug("evaluating attribute '%1%'", state.symbols[i->name]);
if (!std::regex_match(std::string(state.symbols[i->name]), attrRegex))
debug("evaluating attribute '%1%'", symbol);
if (!std::regex_match(symbol.begin(), symbol.end(), attrRegex))
continue;
std::string pathPrefix2 = addToPath(pathPrefix, state.symbols[i->name]);
std::string pathPrefix2 = addToPath(pathPrefix, symbol);
if (combineChannels)
getDerivations(state, *i->value, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
else if (getDerivation(state, *i->value, pathPrefix2, drvs, done, ignoreAssertionFailures)) {
@ -392,7 +393,7 @@ static void getDerivations(EvalState & state, Value & vIn,
}
}
} catch (Error & e) {
e.addTrace(state.positions[i->pos], "while evaluating the attribute '%s'", state.symbols[i->name]);
e.addTrace(state.positions[i->pos], "while evaluating the attribute '%s'", symbol);
throw;
}
}

19
src/libexpr/primops.cc
View file

@ -40,6 +40,13 @@ namespace nix {
* Miscellaneous
*************************************************************/
static inline Value * mkString(EvalState & state, const std::csub_match & match)
{
Value * v = state.allocValue();
v->mkString({match.first, match.second});
return v;
}
StringMap EvalState::realiseContext(const NixStringContext & context, StorePathSet * maybePathsOut, bool isIFD)
{
std::vector<DerivedPath::Built> drvs;
@ -2129,7 +2136,7 @@ static void prim_toXML(EvalState & state, const PosIdx pos, Value * * args, Valu
std::ostringstream out;
NixStringContext context;
printValueAsXML(state, true, false, *args[0], out, context, pos);
v.mkString(out.str(), context);
v.mkString(toView(out), context);
}
static RegisterPrimOp primop_toXML({
@ -2237,7 +2244,7 @@ static void prim_toJSON(EvalState & state, const PosIdx pos, Value * * args, Val
std::ostringstream out;
NixStringContext context;
printValueAsJSON(state, true, *args[0], pos, out, context);
v.mkString(out.str(), context);
v.mkString(toView(out), context);
}
static RegisterPrimOp primop_toJSON({
@ -4268,7 +4275,7 @@ void prim_match(EvalState & state, const PosIdx pos, Value * * args, Value & v)
if (!match[i + 1].matched)
v2 = &state.vNull;
else
(v2 = state.allocValue())->mkString(match[i + 1].str());
v2 = mkString(state, match[i + 1]);
v.mkList(list);
} catch (std::regex_error & e) {
@ -4352,7 +4359,7 @@ void prim_split(EvalState & state, const PosIdx pos, Value * * args, Value & v)
auto match = *i;
// Add a string for non-matched characters.
(list[idx++] = state.allocValue())->mkString(match.prefix().str());
list[idx++] = mkString(state, match.prefix());
// Add a list for matched substrings.
const size_t slen = match.size() - 1;
@ -4363,14 +4370,14 @@ void prim_split(EvalState & state, const PosIdx pos, Value * * args, Value & v)
if (!match[si + 1].matched)
v2 = &state.vNull;
else
(v2 = state.allocValue())->mkString(match[si + 1].str());
v2 = mkString(state, match[si + 1]);
}
(list[idx++] = state.allocValue())->mkList(list2);
// Add a string for non-matched suffix characters.
if (idx == 2 * len)
(list[idx++] = state.allocValue())->mkString(match.suffix().str());
list[idx++] = mkString(state, match.suffix());
}
assert(idx == 2 * len + 1);

2
src/libexpr/primops/fromTOML.cc
View file

@ -66,7 +66,7 @@ static void prim_fromTOML(EvalState & state, const PosIdx pos, Value * * args, V
attrs.alloc("_type").mkString("timestamp");
std::ostringstream s;
s << t;
attrs.alloc("value").mkString(s.str());
attrs.alloc("value").mkString(toView(s));
v.mkAttrs(attrs);
} else {
throw std::runtime_error("Dates and times are not supported");

2
src/libexpr/print.cc
View file

@ -460,7 +460,7 @@ private:
std::ostringstream s;
s << state.positions[v.payload.lambda.fun->pos];
output << " @ " << filterANSIEscapes(s.str());
output << " @ " << filterANSIEscapes(toView(s));
}
} else if (v.isPrimOp()) {
if (v.primOp())

4
src/libmain/progress-bar.cc
View file

@ -158,10 +158,10 @@ public:
{
auto state(state_.lock());
std::stringstream oss;
std::ostringstream oss;
showErrorInfo(oss, ei, loggerSettings.showTrace.get());
log(*state, ei.level, oss.str());
log(*state, ei.level, toView(oss));
}
void log(State & state, Verbosity lvl, std::string_view s)

4
src/libstore/daemon.cc
View file

@ -90,11 +90,11 @@ struct TunnelLogger : public Logger
{
if (ei.level > verbosity) return;
std::stringstream oss;
std::ostringstream oss;
showErrorInfo(oss, ei, false);
StringSink buf;
buf << STDERR_NEXT << oss.str();
buf << STDERR_NEXT << toView(oss);
enqueueMsg(buf.s);
}

7
src/libstore/outputs-spec.cc
View file

@ -30,16 +30,15 @@ std::optional<OutputsSpec> OutputsSpec::parseOpt(std::string_view s)
{
static std::regex regex(std::string { outputSpecRegexStr });
std::smatch match;
std::string s2 { s }; // until some improves std::regex
if (!std::regex_match(s2, match, regex))
std::cmatch match;
if (!std::regex_match(s.cbegin(), s.cend(), match, regex))
return std::nullopt;
if (match[1].matched)
return { OutputsSpec::All {} };
if (match[2].matched)
return OutputsSpec::Names { tokenizeString<StringSet>(match[2].str(), ",") };
return OutputsSpec::Names { tokenizeString<StringSet>({match[2].first, match[2].second}, ",") };
assert(false);
}

2
src/libutil/args.cc
View file

@ -293,7 +293,7 @@ void RootArgs::parseCmdline(const Strings & _cmdline, bool allowShebang)
// We match one space after `nix` so that we preserve indentation.
// No space is necessary for an empty line. An empty line has basically no effect.
if (std::regex_match(line, match, std::regex("^#!\\s*nix(:? |$)(.*)$")))
shebangContent += match[2].str() + "\n";
shebangContent += std::string_view{match[2].first, match[2].second} + "\n";
}
for (const auto & word : parseShebangContent(shebangContent)) {
cmdline.push_back(word);

4
src/libutil/logging.cc
View file

@ -85,10 +85,10 @@ public:
void logEI(const ErrorInfo & ei) override
{
std::stringstream oss;
std::ostringstream oss;
showErrorInfo(oss, ei, loggerSettings.showTrace.get());
log(ei.level, oss.str());
log(ei.level, toView(oss));
}
void startActivity(ActivityId act, Verbosity lvl, ActivityType type,

15
src/libutil/strings.cc
View file

@ -6,6 +6,21 @@
namespace nix {
struct view_stringbuf : public std::stringbuf
{
inline std::string_view toView()
{
auto begin = pbase();
return {begin, begin + pubseekoff(0, std::ios_base::cur, std::ios_base::out)};
}
};
std::string_view toView(const std::ostringstream & os)
{
auto buf = static_cast<view_stringbuf *>(os.rdbuf());
return buf->toView();
}
template std::list<std::string> tokenizeString(std::string_view s, std::string_view separators);
template std::set<std::string> tokenizeString(std::string_view s, std::string_view separators);
template std::vector<std::string> tokenizeString(std::string_view s, std::string_view separators);

5
src/libutil/strings.hh
View file

@ -8,6 +8,11 @@
namespace nix {
/*
* workaround for unavailable view() method (C++20) of std::ostringstream under MacOS with clang-16
*/
std::string_view toView(const std::ostringstream & os);
/**
* String tokenizer.
*

10
src/nix-build/nix-build.cc
View file

@ -36,7 +36,7 @@ extern char * * environ __attribute__((weak));
/* Recreate the effect of the perl shellwords function, breaking up a
* string into arguments like a shell word, including escapes
*/
static std::vector<std::string> shellwords(const std::string & s)
static std::vector<std::string> shellwords(std::string_view s)
{
std::regex whitespace("^\\s+");
auto begin = s.cbegin();
@ -51,7 +51,7 @@ static std::vector<std::string> shellwords(const std::string & s)
auto it = begin;
for (; it != s.cend(); ++it) {
if (st == sBegin) {
std::smatch match;
std::cmatch match;
if (regex_search(it, s.cend(), match, whitespace)) {
cur.append(begin, it);
res.push_back(cur);
@ -173,7 +173,7 @@ static void main_nix_build(int argc, char * * argv)
line = chomp(line);
std::smatch match;
if (std::regex_match(line, match, std::regex("^#!\\s*nix-shell\\s+(.*)$")))
for (const auto & word : shellwords(match[1].str()))
for (const auto & word : shellwords({match[1].first, match[1].second}))
args.push_back(word);
}
}
@ -260,9 +260,9 @@ static void main_nix_build(int argc, char * * argv)
// read the shebang to understand which packages to read from. Since
// this is handled via nix-shell -p, we wrap our ruby script execution
// in ruby -e 'load' which ignores the shebangs.
envCommand = fmt("exec %1% %2% -e 'load(ARGV.shift)' -- %3% %4%", execArgs, interpreter, shellEscape(script), joined.str());
envCommand = fmt("exec %1% %2% -e 'load(ARGV.shift)' -- %3% %4%", execArgs, interpreter, shellEscape(script), toView(joined));
} else {
envCommand = fmt("exec %1% %2% %3% %4%", execArgs, interpreter, shellEscape(script), joined.str());
envCommand = fmt("exec %1% %2% %3% %4%", execArgs, interpreter, shellEscape(script), toView(joined));
}
}

4
src/nix-env/user-env.cc
View file

@ -111,9 +111,7 @@ bool createUserEnv(EvalState & state, PackageInfos & elems,
auto manifestFile = ({
std::ostringstream str;
printAmbiguous(manifest, state.symbols, str, nullptr, std::numeric_limits<int>::max());
// TODO with C++20 we can use str.view() instead and avoid copy.
std::string str2 = str.str();
StringSource source { str2 };
StringSource source { toView(str) };
state.store->addToStoreFromDump(
source, "env-manifest.nix", FileSerialisationMethod::Flat, ContentAddressMethod::Raw::Text, HashAlgorithm::SHA256, references);
});

18
src/nix/config-check.cc
View file

@ -26,17 +26,17 @@ std::string formatProtocol(unsigned int proto)
return "unknown";
}
bool checkPass(const std::string & msg) {
bool checkPass(std::string_view msg) {
notice(ANSI_GREEN "[PASS] " ANSI_NORMAL + msg);
return true;
}
bool checkFail(const std::string & msg) {
bool checkFail(std::string_view msg) {
notice(ANSI_RED "[FAIL] " ANSI_NORMAL + msg);
return false;
}
void checkInfo(const std::string & msg) {
void checkInfo(std::string_view msg) {
notice(ANSI_BLUE "[INFO] " ANSI_NORMAL + msg);
}
@ -87,11 +87,11 @@ struct CmdConfigCheck : StoreCommand
}
if (dirs.size() != 1) {
std::stringstream ss;
std::ostringstream ss;
ss << "Multiple versions of nix found in PATH:\n";
for (auto & dir : dirs)
ss << " " << dir << "\n";
return checkFail(ss.str());
return checkFail(toView(ss));
}
return checkPass("PATH contains only one nix version.");
@ -125,14 +125,14 @@ struct CmdConfigCheck : StoreCommand
}
if (!dirs.empty()) {
std::stringstream ss;
std::ostringstream ss;
ss << "Found profiles outside of " << settings.nixStateDir << "/profiles.\n"
<< "The generation this profile points to might not have a gcroot and could be\n"
<< "garbage collected, resulting in broken symlinks.\n\n";
for (auto & dir : dirs)
ss << " " << dir << "\n";
ss << "\n";
return checkFail(ss.str());
return checkFail(toView(ss));
}
return checkPass("All profiles are gcroots.");
@ -145,13 +145,13 @@ struct CmdConfigCheck : StoreCommand
: PROTOCOL_VERSION;
if (clientProto != storeProto) {
std::stringstream ss;
std::ostringstream ss;
ss << "Warning: protocol version of this client does not match the store.\n"
<< "While this is not necessarily a problem it's recommended to keep the client in\n"
<< "sync with the daemon.\n\n"
<< "Client protocol: " << formatProtocol(clientProto) << "\n"
<< "Store protocol: " << formatProtocol(storeProto) << "\n\n";
return checkFail(ss.str());
return checkFail(toView(ss));
}
return checkPass("Client protocol matches store protocol.");