Merge branch 'more-stringviews' of https://github.com/pennae/nix

src/libstore/derivations.cc

@@ -699,10 +699,10 @@ void writeDerivation(Sink & out, const Store & store, const BasicDerivation & dr
 }
 
 
-std::string hashPlaceholder(const std::string & outputName)
+std::string hashPlaceholder(const std::string_view outputName)
 {
     // FIXME: memoize?
-    return "/" + hashString(htSHA256, "nix-output:" + outputName).to_string(Base32, false);
+    return "/" + hashString(htSHA256, concatStrings("nix-output:", outputName)).to_string(Base32, false);
 }
 
 std::string downstreamPlaceholder(const Store & store, const StorePath & drvPath, std::string_view outputName)

src/libstore/derivations.hh

@@ -236,7 +236,7 @@ void writeDerivation(Sink & out, const Store & store, const BasicDerivation & dr
    It is used as a placeholder to allow derivations to refer to their
    own outputs without needing to use the hash of a derivation in
    itself, making the hash near-impossible to calculate. */
-std::string hashPlaceholder(const std::string & outputName);
+std::string hashPlaceholder(const std::string_view outputName);
 
 /* This creates an opaque and almost certainly unique string
    deterministically from a derivation path and output name.

src/libstore/names.cc

@@ -56,8 +56,8 @@ bool DrvName::matches(const DrvName & n)
 }
 
 
-string nextComponent(string::const_iterator & p,
-    const string::const_iterator end)
+std::string_view nextComponent(std::string_view::const_iterator & p,
+    const std::string_view::const_iterator end)
 {
     /* Skip any dots and dashes (component separators). */
     while (p != end && (*p == '.' || *p == '-')) ++p;
@@ -67,18 +67,18 @@ string nextComponent(string::const_iterator & p,
     /* If the first character is a digit, consume the longest sequence
        of digits.  Otherwise, consume the longest sequence of
        non-digit, non-separator characters. */
-    string s;
+    auto s = p;
     if (isdigit(*p))
-        while (p != end && isdigit(*p)) s += *p++;
+        while (p != end && isdigit(*p)) p++;
     else
         while (p != end && (!isdigit(*p) && *p != '.' && *p != '-'))
-            s += *p++;
+            p++;
 
-    return s;
+    return {s, size_t(p - s)};
 }
 
 
-static bool componentsLT(const string & c1, const string & c2)
+static bool componentsLT(const std::string_view c1, const std::string_view c2)
 {
     auto n1 = string2Int<int>(c1);
     auto n2 = string2Int<int>(c2);
@@ -94,14 +94,14 @@ static bool componentsLT(const string & c1, const string & c2)
 }
 
 
-int compareVersions(const string & v1, const string & v2)
+int compareVersions(const std::string_view v1, const std::string_view v2)
 {
-    string::const_iterator p1 = v1.begin();
-    string::const_iterator p2 = v2.begin();
+    auto p1 = v1.begin();
+    auto p2 = v2.begin();
 
     while (p1 != v1.end() || p2 != v2.end()) {
-        string c1 = nextComponent(p1, v1.end());
-        string c2 = nextComponent(p2, v2.end());
+        auto c1 = nextComponent(p1, v1.end());
+        auto c2 = nextComponent(p2, v2.end());
         if (componentsLT(c1, c2)) return -1;
         else if (componentsLT(c2, c1)) return 1;
     }

src/libstore/names.hh

@@ -27,9 +27,9 @@ private:
 
 typedef list<DrvName> DrvNames;
 
-string nextComponent(string::const_iterator & p,
-    const string::const_iterator end);
-int compareVersions(const string & v1, const string & v2);
+std::string_view nextComponent(std::string_view::const_iterator & p,
+    const std::string_view::const_iterator end);
+int compareVersions(const std::string_view v1, const std::string_view v2);
 DrvNames drvNamesFromArgs(const Strings & opArgs);
 
 }

src/libstore/optimise-store.cc

@@ -26,7 +26,7 @@ static void makeWritable(const Path & path)
 struct MakeReadOnly
 {
     Path path;
-    MakeReadOnly(const Path & path) : path(path) { }
+    MakeReadOnly(const PathView path) : path(path) { }
     ~MakeReadOnly()
     {
         try {
@@ -205,12 +205,13 @@ void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
     /* Make the containing directory writable, but only if it's not
        the store itself (we don't want or need to mess with its
        permissions). */
-    bool mustToggle = dirOf(path) != realStoreDir.get();
-    if (mustToggle) makeWritable(dirOf(path));
+    const Path dirOfPath(dirOf(path));
+    bool mustToggle = dirOfPath != realStoreDir.get();
+    if (mustToggle) makeWritable(dirOfPath);
 
     /* When we're done, make the directory read-only again and reset
        its timestamp back to 0. */
-    MakeReadOnly makeReadOnly(mustToggle ? dirOf(path) : "");
+    MakeReadOnly makeReadOnly(mustToggle ? dirOfPath : "");
 
     Path tempLink = (format("%1%/.tmp-link-%2%-%3%")
         % realStoreDir % getpid() % random()).str();

src/libstore/parsed-derivations.cc

@@ -170,7 +170,7 @@ std::string writeStructuredAttrsShell(const nlohmann::json & json)
 
     auto handleSimpleType = [](const nlohmann::json & value) -> std::optional<std::string> {
         if (value.is_string())
-            return shellEscape(value);
+            return shellEscape(value.get<std::string_view>());
 
         if (value.is_number()) {
             auto f = value.get<float>();