4 files changed, 142 insertions, 94 deletions
diff --git a/src/libexpr/attr-set.cc b/src/libexpr/attr-set.cc
new file mode 100644
index 000000000000..9ac5e603199a
--- /dev/null
+++ b/src/libexpr/attr-set.cc
@@ -0,0 +1,59 @@
+#include "attr-set.hh"
+#include "eval.hh"
+
+#include <algorithm>
+
+
+namespace nix {
+
+
+static void * allocBytes(size_t n)
+{
+    void * p;
+#if HAVE_BOEHMGC
+    p = GC_malloc(n);
+#else
+    p = malloc(n);
+#endif
+    if (!p) throw std::bad_alloc();
+    return p;
+}
+
+
+/* Allocate a new array of attributes for an attribute set with a specific
+   capacity. The space is implicitly reserved after the Bindings
+   structure. */
+Bindings * EvalState::allocBindings(Bindings::size_t capacity)
+{
+    return new (allocBytes(sizeof(Bindings) + sizeof(Attr) * capacity)) Bindings(capacity);
+}
+
+
+void EvalState::mkAttrs(Value & v, unsigned int expected)
+{
+    clearValue(v);
+    v.type = tAttrs;
+    v.attrs = allocBindings(expected);
+    nrAttrsets++;
+    nrAttrsInAttrsets += expected;
+}
+
+
+/* Create a new attribute named 'name' on an existing attribute set stored
+   in 'vAttrs' and return the newly allocated Value which is associated with
+   this attribute. */
+Value * EvalState::allocAttr(Value & vAttrs, const Symbol & name)
+{
+    Value * v = allocValue();
+    vAttrs.attrs->push_back(Attr(name, v));
+    return v;
+}
+
+
+void Bindings::sort()
+{
+    std::sort(begin(), end());
+}
+
+
+}
diff --git a/src/libexpr/attr-set.hh b/src/libexpr/attr-set.hh
new file mode 100644
index 000000000000..7cf6a9c58086
--- /dev/null
+++ b/src/libexpr/attr-set.hh
@@ -0,0 +1,82 @@
+#pragma once
+
+#include "nixexpr.hh"
+#include "symbol-table.hh"
+
+#include <algorithm>
+
+namespace nix {
+
+
+class EvalState;
+struct Value;
+
+/* Map one attribute name to its value. */
+struct Attr
+{
+    Symbol name;
+    Value * value;
+    Pos * pos;
+    Attr(Symbol name, Value * value, Pos * pos = &noPos)
+        : name(name), value(value), pos(pos) { };
+    Attr() : pos(&noPos) { };
+    bool operator < (const Attr & a) const
+    {
+        return name < a.name;
+    }
+};
+
+/* Bindings contains all the attributes of an attribute set. It is defined
+   by its size and its capacity, the capacity being the number of Attr
+   elements allocated after this structure, while the size corresponds to
+   the number of elements already inserted in this structure. */
+class Bindings
+{
+public:
+    typedef uint32_t size_t;
+
+private:
+    size_t size_, capacity_;
+    Attr attrs[0];
+
+    Bindings(size_t capacity) : size_(0), capacity_(capacity) { }
+    Bindings(const Bindings & bindings) = delete;
+
+public:
+    size_t size() const { return size_; }
+
+    bool empty() const { return !size_; }
+
+    typedef Attr * iterator;
+
+    void push_back(const Attr & attr)
+    {
+        assert(size_ < capacity_);
+        attrs[size_++] = attr;
+    }
+
+    iterator find(const Symbol & name)
+    {
+        Attr key(name, 0);
+        iterator i = std::lower_bound(begin(), end(), key);
+        if (i != end() && i->name == name) return i;
+        return end();
+    }
+
+    iterator begin() { return &attrs[0]; }
+    iterator end() { return &attrs[size_]; }
+
+    Attr & operator[](size_t pos)
+    {
+        return attrs[pos];
+    }
+
+    void sort();
+
+    size_t capacity() { return capacity_; }
+
+    friend class EvalState;
+};
+
+
+}
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index d61ee7e80795..eab38c9da174 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -55,12 +55,6 @@ static void * allocBytes(size_t n)
 }
 
 
-void Bindings::sort()
-{
-    std::sort(begin(), end());
-}
-
-
 static void printValue(std::ostream & str, std::set<const Value *> & active, const Value & v)
 {
     if (active.find(&v) != active.end()) {
@@ -503,20 +497,6 @@ Env & EvalState::allocEnv(unsigned int size)
 }
 
 
-Value * EvalState::allocAttr(Value & vAttrs, const Symbol & name)
-{
-    Value * v = allocValue();
-    vAttrs.attrs->push_back(Attr(name, v));
-    return v;
-}
-
-
-Bindings * EvalState::allocBindings(Bindings::size_t capacity)
-{
-    return new (allocBytes(sizeof(Bindings) + sizeof(Attr) * capacity)) Bindings(capacity);
-}
-
-
 void EvalState::mkList(Value & v, unsigned int length)
 {
     clearValue(v);
@@ -527,16 +507,6 @@ void EvalState::mkList(Value & v, unsigned int length)
 }
 
 
-void EvalState::mkAttrs(Value & v, unsigned int expected)
-{
-    clearValue(v);
-    v.type = tAttrs;
-    v.attrs = allocBindings(expected);
-    nrAttrsets++;
-    nrAttrsInAttrsets += expected;
-}
-
-
 unsigned long nrThunks = 0;
 
 static inline void mkThunk(Value & v, Env & env, Expr * expr)
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 627fae3ff363..1b546f89c836 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "attr-set.hh"
 #include "value.hh"
 #include "nixexpr.hh"
 #include "symbol-table.hh"
@@ -18,70 +19,6 @@ namespace nix {
 class EvalState;
 
 
-struct Attr
-{
-    Symbol name;
-    Value * value;
-    Pos * pos;
-    Attr(Symbol name, Value * value, Pos * pos = &noPos)
-        : name(name), value(value), pos(pos) { };
-    Attr() : pos(&noPos) { };
-    bool operator < (const Attr & a) const
-    {
-        return name < a.name;
-    }
-};
-
-
-class Bindings
-{
-public:
-    typedef uint32_t size_t;
-
-private:
-    size_t size_, capacity_;
-    Attr attrs[0];
-
-    Bindings(size_t capacity) : size_(0), capacity_(capacity) { }
-    Bindings(const Bindings & bindings) = delete;
-
-public:
-    size_t size() const { return size_; }
-
-    bool empty() const { return !size_; }
-
-    typedef Attr * iterator;
-
-    void push_back(const Attr & attr)
-    {
-        assert(size_ < capacity_);
-        attrs[size_++] = attr;
-    }
-
-    iterator find(const Symbol & name)
-    {
-        Attr key(name, 0);
-        iterator i = std::lower_bound(begin(), end(), key);
-        if (i != end() && i->name == name) return i;
-        return end();
-    }
-
-    iterator begin() { return &attrs[0]; }
-    iterator end() { return &attrs[size_]; }
-
-    Attr & operator[](size_t pos)
-    {
-        return attrs[pos];
-    }
-
-    void sort();
-
-    size_t capacity() { return capacity_; }
-
-    friend class EvalState;
-};
-
-
 typedef void (* PrimOpFun) (EvalState & state, const Pos & pos, Value * * args, Value & v);