libexpr: Remove Bindings::find

A follow-up optimization will make it impossible to make a find function
that returns an iterator in an efficient manner. All consumer code can
easily use the `get` variant.

src/libexpr/eval.cc

@@ -582,7 +582,7 @@ std::optional<EvalState::Doc> EvalState::getDoc(Value & v)
     }
     if (isFunctor(v)) {
         try {
-            Value & functor = *v.attrs()->find(s.functor)->value;
+            Value & functor = *v.attrs()->get(s.functor)->value;
             Value * vp[] = {&v};
             Value partiallyApplied;
             // The first parameter is not user-provided, and may be
@@ -1709,8 +1709,8 @@ void EvalState::autoCallFunction(const Bindings & args, Value & fun, Value & res
     forceValue(fun, pos);
 
     if (fun.type() == nAttrs) {
-        auto found = fun.attrs()->find(s.functor);
-        if (found != fun.attrs()->end()) {
+        auto found = fun.attrs()->get(s.functor);
+        if (found) {
             Value * v = allocValue();
             callFunction(*found->value, fun, *v, pos);
             forceValue(*v, pos);
@@ -2160,10 +2160,10 @@ bool EvalState::forceBool(Value & v, const PosIdx pos, std::string_view errorCtx
     return v.boolean();
 }
 
-Bindings::const_iterator EvalState::getAttr(Symbol attrSym, const Bindings * attrSet, std::string_view errorCtx)
+const Attr * EvalState::getAttr(Symbol attrSym, const Bindings * attrSet, std::string_view errorCtx)
 {
-    auto value = attrSet->find(attrSym);
-    if (value == attrSet->end()) {
+    auto value = attrSet->get(attrSym);
+    if (!value) {
         error<TypeError>("attribute '%s' missing", symbols[attrSym]).withTrace(noPos, errorCtx).debugThrow();
     }
     return value;
@@ -2171,7 +2171,7 @@ Bindings::const_iterator EvalState::getAttr(Symbol attrSym, const Bindings * att
 
 bool EvalState::isFunctor(const Value & fun) const
 {
-    return fun.type() == nAttrs && fun.attrs()->find(s.functor) != fun.attrs()->end();
+    return fun.type() == nAttrs && fun.attrs()->get(s.functor);
 }
 
 void EvalState::forceFunction(Value & v, const PosIdx pos, std::string_view errorCtx)
@@ -2252,8 +2252,8 @@ bool EvalState::isDerivation(Value & v)
 std::optional<std::string>
 EvalState::tryAttrsToString(const PosIdx pos, Value & v, NixStringContext & context, bool coerceMore, bool copyToStore)
 {
-    auto i = v.attrs()->find(s.toString);
-    if (i != v.attrs()->end()) {
+    auto i = v.attrs()->get(s.toString);
+    if (i) {
         Value v1;
         callFunction(*i->value, v, v1, pos);
         return coerceToString(
@@ -2298,8 +2298,8 @@ BackedStringView EvalState::coerceToString(
         auto maybeString = tryAttrsToString(pos, v, context, coerceMore, copyToStore);
         if (maybeString)
             return std::move(*maybeString);
-        auto i = v.attrs()->find(s.outPath);
-        if (i == v.attrs()->end()) {
+        auto i = v.attrs()->get(s.outPath);
+        if (!i) {
             error<TypeError>(
                 "cannot coerce %1% to a string: %2%", showType(v), ValuePrinter(*this, v, errorPrintOptions))
                 .withTrace(pos, errorCtx)
@@ -2403,8 +2403,8 @@ SourcePath EvalState::coerceToPath(const PosIdx pos, Value & v, NixStringContext
     /* Similarly, handle __toString where the result may be a path
        value. */
     if (v.type() == nAttrs) {
-        auto i = v.attrs()->find(s.toString);
-        if (i != v.attrs()->end()) {
+        auto i = v.attrs()->get(s.toString);
+        if (i) {
             Value v1;
             callFunction(*i->value, v, v1, pos);
             return coerceToPath(pos, v1, context, errorCtx);

src/libexpr/get-drvs.cc

@@ -45,8 +45,8 @@ PackageInfo::PackageInfo(EvalState & state, ref<Store> store, const std::string
 std::string PackageInfo::queryName() const
 {
     if (name == "" && attrs) {
-        auto i = attrs->find(state->s.name);
-        if (i == attrs->end())
+        auto i = attrs->get(state->s.name);
+        if (!i)
             state->error<TypeError>("derivation name missing").debugThrow();
         name = state->forceStringNoCtx(*i->value, noPos, "while evaluating the 'name' attribute of a derivation");
     }
@@ -56,11 +56,10 @@ std::string PackageInfo::queryName() const
 std::string PackageInfo::querySystem() const
 {
     if (system == "" && attrs) {
-        auto i = attrs->find(state->s.system);
+        auto i = attrs->get(state->s.system);
         system =
-            i == attrs->end()
-                ? "unknown"
-                : state->forceStringNoCtx(*i->value, i->pos, "while evaluating the 'system' attribute of a derivation");
+            !i ? "unknown"
+               : state->forceStringNoCtx(*i->value, i->pos, "while evaluating the 'system' attribute of a derivation");
     }
     return system;
 }
@@ -95,9 +94,9 @@ StorePath PackageInfo::requireDrvPath() const
 StorePath PackageInfo::queryOutPath() const
 {
     if (!outPath && attrs) {
-        auto i = attrs->find(state->s.outPath);
+        auto i = attrs->get(state->s.outPath);
         NixStringContext context;
-        if (i != attrs->end())
+        if (i)
             outPath = state->coerceToStorePath(
                 i->pos, *i->value, context, "while evaluating the output path of a derivation");
     }

src/libexpr/include/nix/expr/attr-set.hh

@@ -137,17 +137,6 @@ public:
         attrs[size_++] = attr;
     }
 
-    const_iterator find(Symbol name) const
-    {
-        Attr key(name, 0);
-        auto first = attrs;
-        auto last = attrs + size_;
-        const Attr * i = std::lower_bound(first, last, key);
-        if (i != last && i->name == name)
-            return const_iterator{i};
-        return end();
-    }
-
     const Attr * get(Symbol name) const
     {
         Attr key(name, 0);

src/libexpr/include/nix/expr/eval.hh

@@ -613,7 +613,7 @@ public:
     /**
      * Get attribute from an attribute set and throw an error if it doesn't exist.
      */
-    Bindings::const_iterator getAttr(Symbol attrSym, const Bindings * attrSet, std::string_view errorCtx);
+    const Attr * getAttr(Symbol attrSym, const Bindings * attrSet, std::string_view errorCtx);
 
     template<typename... Args>
     [[gnu::noinline]]

src/libexpr/primops.cc

@@ -1367,8 +1367,8 @@ static void derivationStrictInternal(EvalState & state, std::string_view drvName
     using nlohmann::json;
     std::optional<StructuredAttrs> jsonObject;
     auto pos = v.determinePos(noPos);
-    auto attr = attrs->find(state.s.structuredAttrs);
-    if (attr != attrs->end()
+    auto attr = attrs->get(state.s.structuredAttrs);
+    if (attr
         && state.forceBool(
             *attr->value,
             pos,
@@ -1378,8 +1378,8 @@ static void derivationStrictInternal(EvalState & state, std::string_view drvName
 
     /* Check whether null attributes should be ignored. */
     bool ignoreNulls = false;
-    attr = attrs->find(state.s.ignoreNulls);
-    if (attr != attrs->end())
+    attr = attrs->get(state.s.ignoreNulls);
+    if (attr)
         ignoreNulls = state.forceBool(
             *attr->value,
             pos,
@@ -2040,8 +2040,8 @@ static void prim_findFile(EvalState & state, const PosIdx pos, Value ** args, Va
         state.forceAttrs(*v2, pos, "while evaluating an element of the list passed to builtins.findFile");
 
         std::string prefix;
-        auto i = v2->attrs()->find(state.s.prefix);
-        if (i != v2->attrs()->end())
+        auto i = v2->attrs()->get(state.s.prefix);
+        if (i)
             prefix = state.forceStringNoCtx(
                 *i->value,
                 pos,
@@ -3008,8 +3008,8 @@ static void prim_unsafeGetAttrPos(EvalState & state, const PosIdx pos, Value **
     auto attr = state.forceStringNoCtx(
         *args[0], pos, "while evaluating the first argument passed to builtins.unsafeGetAttrPos");
     state.forceAttrs(*args[1], pos, "while evaluating the second argument passed to builtins.unsafeGetAttrPos");
-    auto i = args[1]->attrs()->find(state.symbols.create(attr));
-    if (i == args[1]->attrs()->end())
+    auto i = args[1]->attrs()->get(state.symbols.create(attr));
+    if (!i)
         v.mkNull();
     else
         state.mkPos(v, i->pos);
@@ -3076,7 +3076,7 @@ static void prim_hasAttr(EvalState & state, const PosIdx pos, Value ** args, Val
 {
     auto attr = state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.hasAttr");
     state.forceAttrs(*args[1], pos, "while evaluating the second argument passed to builtins.hasAttr");
-    v.mkBool(args[1]->attrs()->find(state.symbols.create(attr)) != args[1]->attrs()->end());
+    v.mkBool(args[1]->attrs()->get(state.symbols.create(attr)));
 }
 
 static RegisterPrimOp primop_hasAttr({
@@ -3286,14 +3286,14 @@ static void prim_intersectAttrs(EvalState & state, const PosIdx pos, Value ** ar
 
     if (left.size() < right.size()) {
         for (auto & l : left) {
-            auto r = right.find(l.name);
-            if (r != right.end())
+            auto r = right.get(l.name);
+            if (r)
                 attrs.insert(*r);
         }
     } else {
         for (auto & r : right) {
-            auto l = left.find(r.name);
-            if (l != left.end())
+            auto l = left.get(r.name);
+            if (l)
                 attrs.insert(r);
         }
     }

src/nix/nix-env/user-env.cc

@@ -141,10 +141,10 @@ bool createUserEnv(
     debug("evaluating user environment builder");
     state.forceValue(topLevel, topLevel.determinePos(noPos));
     NixStringContext context;
-    auto & aDrvPath(*topLevel.attrs()->find(state.s.drvPath));
+    auto & aDrvPath(*topLevel.attrs()->get(state.s.drvPath));
     auto topLevelDrv = state.coerceToStorePath(aDrvPath.pos, *aDrvPath.value, context, "");
     topLevelDrv.requireDerivation();
-    auto & aOutPath(*topLevel.attrs()->find(state.s.outPath));
+    auto & aOutPath(*topLevel.attrs()->get(state.s.outPath));
     auto topLevelOut = state.coerceToStorePath(aOutPath.pos, *aOutPath.value, context, "");
 
     /* Realise the resulting store expression. */