libexpr: Switch StaticEnv to LinearMap

Change-Id: If98bfafce9fa5235fe962274c03c619fe965dd60

lix/libcmd/repl.cc

@@ -1056,19 +1056,24 @@ template<typename T, typename NameFn, typename ValueFn>
 void NixRepl::addToScope(T && things, NameFn nameFn, ValueFn valueFn)
 {
     size_t added = 0;
-    for (auto && thing : things) {
-        if (displ + 1 >= envSize)
-            throw Error("environment full; cannot add more variables");
 
-        const auto name = nameFn(thing);
-        staticEnv->vars.emplace_back(name, displ);
-        env->values[displ++] = valueFn(thing);
-        varNames.emplace(evaluator.symbols[name]);
-        added++;
-    }
+    staticEnv->vars.unsafe_insert_bulk([&] (auto & map) {
+        auto oldSize = map.size();
+        for (auto && thing : things) {
+            if (displ + 1 >= envSize)
+                throw Error("environment full; cannot add more variables");
+
+            const auto name = nameFn(thing);
+            map.emplace_back(name, displ);
+            env->values[displ++] = valueFn(thing);
+            varNames.emplace(evaluator.symbols[name]);
+            added++;
+        }
+        // safety: we sort the range that we inserted so that we don't have to push that
+        // invariant up to the caller
+        std::sort(map.begin() + oldSize, map.end());
+    });
 
-    staticEnv->sort();
-    staticEnv->deduplicate();
     if (added > 0) {
         notice("Added %1% variables.", added);
     }
@@ -1093,14 +1098,11 @@ void NixRepl::addVarToScope(const Symbol name, Value & v)
 {
     if (displ >= envSize)
         throw Error("environment full; cannot add more variables");
-    if (auto oldVar = staticEnv->find(name); oldVar != staticEnv->vars.end()) {
-        staticEnv->vars.erase(oldVar);
+    if (staticEnv->vars.insert_or_assign(name, displ).second) {
         notice("Updated %s.", evaluator.symbols[name]);
     } else {
         notice("Added %s.", evaluator.symbols[name]);
     }
-    staticEnv->vars.emplace_back(name, displ);
-    staticEnv->sort();
     env->values[displ++] = &v;
     varNames.emplace(evaluator.symbols[name]);
 }

lix/libexpr/eval.cc

@@ -549,7 +549,7 @@ void EvalBuiltins::addConstant(const std::string & name, Value * v, Constant inf
             assert(info.type == gotType);
 
         /* Install value the base environment. */
-        staticEnv->vars.emplace_back(symbols.create(name), baseEnvDispl);
+        staticEnv->vars.insert_or_assign(symbols.create(name), baseEnvDispl);
         env.values[baseEnvDispl++] = v;
         env.values[0]->attrs->push_back(Attr(symbols.create(name2), v));
     }
@@ -584,7 +584,7 @@ Value * EvalBuiltins::addPrimOp(PrimOp && primOp)
 
     Value * v = mem.allocValue();
     v->mkPrimOp(new PrimOp(primOp));
-    staticEnv->vars.emplace_back(envName, baseEnvDispl);
+    staticEnv->vars.insert_or_assign(auto(envName), baseEnvDispl);
     env.values[baseEnvDispl++] = v;
     env.values[0]->attrs->push_back(Attr(symbols.create(primOp.name), v));
     return v;

lix/libexpr/nixexpr.cc

@@ -465,7 +465,7 @@ void VarBinder::visit(ExprVar & e, std::unique_ptr<Expr> & ptr)
         if (curEnv->isWith) {
             if (withLevel == -1) withLevel = level;
         } else {
-            auto i = curEnv->find(e.name);
+            auto i = curEnv->vars.find(e.name);
             if (i != curEnv->vars.end()) {
                 if (e.needsRoot && !curEnv->isRoot) {
                     throw ParseError({
@@ -523,9 +523,12 @@ std::shared_ptr<const StaticEnv> ExprAttrs::buildRecursiveEnv(const std::shared_
 {
     auto newEnv = std::make_shared<StaticEnv>(nullptr, env.get(), attrs.size());
 
-    Displacement displ = 0;
-    for (auto & i : attrs)
-        newEnv->vars.emplace_back(i.first, i.second.displ = displ++);
+    // safety: the attrs is already sorted
+    newEnv->vars.unsafe_insert_bulk([&] (auto & map) {
+        Displacement displ = 0;
+        for (auto & i : attrs)
+            map.emplace_back(i.first, i.second.displ = displ++);
+    });
     return newEnv;
 }
 
@@ -662,7 +665,7 @@ void VarBinder::visit(ExprPos & e, std::unique_ptr<Expr> & ptr)
 std::shared_ptr<const StaticEnv> SimplePattern::buildEnv(const StaticEnv * up)
 {
     auto newEnv = std::make_shared<StaticEnv>(nullptr, up, 1);
-    newEnv->vars.emplace_back(name, 0);
+    newEnv->vars.insert_or_assign(name, 0);
     return newEnv;
 }
 
@@ -677,12 +680,14 @@ std::shared_ptr<const StaticEnv> AttrsPattern::buildEnv(const StaticEnv * up)
 
     Displacement displ = 0;
 
-    if (name) newEnv->vars.emplace_back(name, displ++);
+    if (name) newEnv->vars.insert_or_assign(name, displ++);
 
-    for (auto & i : formals)
-        newEnv->vars.emplace_back(i.name, displ++);
+    // safety: The formals are already sorted
+    newEnv->vars.unsafe_insert_bulk([&] (auto & map) {
+        for (auto & i : formals)
+            map.emplace_back(i.name, displ++);
+    });
 
-    newEnv->sort();
     return newEnv;
 }
 

lix/libexpr/nixexpr.hh

@@ -11,6 +11,7 @@
 #include "lix/libexpr/eval-error.hh"
 #include "lix/libexpr/pos-idx.hh"
 #include "lix/libutil/strings.hh"
+#include "lix/libutil/linear-map.hh"
 
 namespace nix {
 
@@ -607,9 +608,7 @@ struct StaticEnv
     ExprWith * isWith;
     const StaticEnv * up;
 
-    // Note: these must be in sorted order.
-    typedef std::vector<std::pair<Symbol, Displacement>> Vars;
-    Vars vars;
+    LinearMap<Symbol, Displacement> vars;
 
     /* See ExprVar::needsRoot */
     bool isRoot = false;
@@ -617,31 +616,6 @@ struct StaticEnv
     StaticEnv(ExprWith * isWith, const StaticEnv * up, size_t expectedSize = 0) : isWith(isWith), up(up) {
         vars.reserve(expectedSize);
     };
-
-    void sort()
-    {
-        std::stable_sort(vars.begin(), vars.end(),
-            [](const Vars::value_type & a, const Vars::value_type & b) { return a.first < b.first; });
-    }
-
-    void deduplicate()
-    {
-        auto it = vars.begin(), jt = it, end = vars.end();
-        while (jt != end) {
-            *it = *jt++;
-            while (jt != end && it->first == jt->first) *it = *jt++;
-            it++;
-        }
-        vars.erase(it, end);
-    }
-
-    Vars::const_iterator find(Symbol name) const
-    {
-        Vars::value_type key(name, 0);
-        auto i = std::lower_bound(vars.begin(), vars.end(), key);
-        if (i != vars.end() && i->first == name) return i;
-        return vars.end();
-    }
 };
 
 

lix/libexpr/primops.cc

@@ -242,14 +242,14 @@ static void import(EvalState & state, Value & vPath, Value * vScope, Value & v)
                 nullptr, state.ctx.builtins.staticEnv.get(), vScope->attrs->size()
             );
 
-            unsigned int displ = 0;
-            for (auto & attr : *vScope->attrs) {
-                staticEnv->vars.emplace_back(attr.name, displ);
-                env->values[displ++] = attr.value;
-            }
-
-            // No need to call staticEnv.sort(), because
-            // args[0]->attrs is already sorted.
+            staticEnv->vars.unsafe_insert_bulk([&] (auto & map) {
+                unsigned int displ = 0;
+                for (auto & attr : *vScope->attrs) {
+                    // safety: args[0]->attrs is already sorted.
+                    map.emplace_back(attr.name, displ);
+                    env->values[displ++] = attr.value;
+                }
+            });
 
             debug("evaluating file '%1%'", path);
             Expr & e = state.ctx.parseExprFromFile(state.ctx.paths.resolveExprPath(path), staticEnv);
@@ -2835,7 +2835,6 @@ void EvalBuiltins::createBaseEnv(const SearchPath & searchPath, const Path & sto
        because attribute lookups expect it to be sorted. */
     env.values[0]->attrs->sort();
 
-    staticEnv->sort();
     staticEnv->isRoot = true;
 }