* An forward non-random access input iterator class for ATermLists.

6 files changed, 68 insertions, 88 deletions

diff --git a/src/fix-ng/eval.cc b/src/fix-ng/eval.cc
index 55cb5fbcff27..57cca4c4a827 100644
--- a/src/fix-ng/eval.cc
+++ b/src/fix-ng/eval.cc
@@ -21,25 +21,21 @@ static Expr substArgs(Expr body, ATermList formals, Expr arg)
     Expr undefined = ATmake("Undefined");
 
     /* Get the formal arguments. */
-    while (!ATisEmpty(formals)) {
-        ATerm t = ATgetFirst(formals);
+    for (ATermIterator i(formals); i; ++i) {
         Expr name, def;
-        if (atMatch(m, t) >> "NoDefFormal" >> name)
+        if (atMatch(m, *i) >> "NoDefFormal" >> name)
             subs.set(name, undefined);
-        else if (atMatch(m, t) >> "DefFormal" >> name >> def)
+        else if (atMatch(m, *i) >> "DefFormal" >> name >> def)
             subs.set(name, def);
         else abort(); /* can't happen */
-        formals = ATgetNext(formals);
     }
 
     /* Get the actual arguments, and check that they match with the
        formals. */
     ATermMap args;
     queryAllAttrs(arg, args);
-    for (ATermList keys = args.keys(); !ATisEmpty(keys); 
-         keys = ATgetNext(keys))
-    {
-        Expr key = ATgetFirst(keys);
+    for (ATermIterator i(args.keys()); i; ++i) {
+        Expr key = *i;
         Expr cur = subs.get(key);
         if (!cur)
             throw badTerm(format("function has no formal argument `%1%'")
@@ -48,14 +44,10 @@ static Expr substArgs(Expr body, ATermList formals, Expr arg)
     }
 
     /* Check that all arguments are defined. */
-    for (ATermList keys = subs.keys(); !ATisEmpty(keys); 
-         keys = ATgetNext(keys))
-    {
-        Expr key = ATgetFirst(keys);
-        if (subs.get(key) == undefined)
+    for (ATermIterator i(subs.keys()); i; ++i)
+        if (subs.get(*i) == undefined)
             throw badTerm(format("formal argument `%1%' missing")
-                % aterm2String(key), arg);
-    }
+                % aterm2String(*i), arg);
     
     return substitute(subs, body);
 }
@@ -72,26 +64,22 @@ ATerm expandRec(ATerm e, ATermList bnds)
 
     /* Create the substitution list. */
     ATermMap subs;
-    ATermList bs = bnds;
-    while (!ATisEmpty(bs)) {
+    for (ATermIterator i(bnds); i; ++i) {
         string s;
         Expr e2;
-        if (!(atMatch(m, ATgetFirst(bs)) >> "Bind" >> s >> e2))
+        if (!(atMatch(m, *i) >> "Bind" >> s >> e2))
             abort(); /* can't happen */
         subs.set(s, ATmake("Select(<term>, <str>)", e, s.c_str()));
-        bs = ATgetNext(bs);
     }
 
     /* Create the non-recursive set. */
     ATermMap as;
-    bs = bnds;
-    while (!ATisEmpty(bs)) {
+    for (ATermIterator i(bnds); i; ++i) {
         string s;
         Expr e2;
-        if (!(atMatch(m, ATgetFirst(bs)) >> "Bind" >> s >> e2))
+        if (!(atMatch(m, *i) >> "Bind" >> s >> e2))
             abort(); /* can't happen */
         as.set(s, substitute(subs, e2));
-        bs = ATgetNext(bs);
     }
 
     return makeAttrs(as);
diff --git a/src/fix-ng/fix-expr.cc b/src/fix-ng/fix-expr.cc
index a3d24ba0e6ab..e9c5a3ba633f 100644
--- a/src/fix-ng/fix-expr.cc
+++ b/src/fix-ng/fix-expr.cc
@@ -18,10 +18,8 @@ ATermMap::ATermMap(const ATermMap & map)
     table = ATtableCreate(ATgetLength(keys), map.maxLoadPct);
     if (!table) throw Error("cannot create ATerm table");
 
-    for (; !ATisEmpty(keys); keys = ATgetNext(keys)) {
-        ATerm key = ATgetFirst(keys);
-        set(key, map.get(key));
-    }
+    for (ATermIterator i(keys); i; ++i)
+        set(*i, map.get(*i));
 }
 
 
@@ -104,10 +102,8 @@ ATerm bottomupRewrite(TermFun & f, ATerm e)
         ATermList in = (ATermList) e;
         ATermList out = ATempty;
 
-        while (!ATisEmpty(in)) {
-            out = ATinsert(out, bottomupRewrite(f, ATgetFirst(in)));
-            in = ATgetNext(in);
-        }
+        for (ATermIterator i(in); i; ++i)
+            out = ATinsert(out, bottomupRewrite(f, *i));
 
         e = (ATerm) ATreverse(out);
     }
@@ -123,13 +119,12 @@ void queryAllAttrs(Expr e, ATermMap & attrs)
     if (!(atMatch(m, e) >> "Attrs" >> bnds))
         throw badTerm("expected attribute set", e);
 
-    while (!ATisEmpty(bnds)) {
+    for (ATermIterator i(bnds); i; ++i) {
         string s;
         Expr e;
-        if (!(atMatch(m, ATgetFirst(bnds)) >> "Bind" >> s >> e))
+        if (!(atMatch(m, *i) >> "Bind" >> s >> e))
             abort(); /* can't happen */
         attrs.set(s, e);
-        bnds = ATgetNext(bnds);
     }
 }
 
@@ -144,13 +139,10 @@ Expr queryAttr(Expr e, const string & name)
 
 Expr makeAttrs(const ATermMap & attrs)
 {
-    ATermList bnds = ATempty, keys = attrs.keys();
-    while (!ATisEmpty(keys)) {
-        Expr key = ATgetFirst(keys);
+    ATermList bnds = ATempty;
+    for (ATermIterator i(attrs.keys()); i; ++i)
         bnds = ATinsert(bnds, 
-            ATmake("Bind(<term>, <term>)", key, attrs.get(key)));
-        keys = ATgetNext(keys);
-    }
+            ATmake("Bind(<term>, <term>)", *i, attrs.get(*i)));
     return ATmake("Attrs(<term>)", ATreverse(bnds));
 }
 
@@ -171,14 +163,12 @@ Expr substitute(const ATermMap & subs, Expr e)
     ATerm body;
     if (atMatch(m, e) >> "Function" >> formals >> body) {
         ATermMap subs2(subs);
-        ATermList fs = formals;
-        while (!ATisEmpty(fs)) {
+        for (ATermIterator i(formals); i; ++i) {
             Expr def;
-            if (!(atMatch(m, ATgetFirst(fs)) >> "NoDefFormal" >> s) &&
-                !(atMatch(m, ATgetFirst(fs)) >> "DefFormal" >> s >> def))
+            if (!(atMatch(m, *i) >> "NoDefFormal" >> s) &&
+                !(atMatch(m, *i) >> "DefFormal" >> s >> def))
                 abort();
             subs2.remove(s);
-            fs = ATgetNext(fs);
         }
         return ATmake("Function(<term>, <term>)", formals,
             substitute(subs2, body));
@@ -188,13 +178,11 @@ Expr substitute(const ATermMap & subs, Expr e)
     ATermList bindings;
     if (atMatch(m, e) >> "Rec" >> bindings) {
         ATermMap subs2(subs);
-        ATermList bnds = bindings;
-        while (!ATisEmpty(bnds)) {
+        for (ATermIterator i(bindings); i; ++i) {
             Expr e;
-            if (!(atMatch(m, ATgetFirst(bnds)) >> "Bind" >> s >> e))
+            if (!(atMatch(m, *i) >> "Bind" >> s >> e))
                 abort(); /* can't happen */
             subs2.remove(s);
-            bnds = ATgetNext(bnds);
         }
         return ATmake("Rec(<term>)", substitute(subs2, (ATerm) bindings));
     }
@@ -211,14 +199,9 @@ Expr substitute(const ATermMap & subs, Expr e)
     }
 
     if (ATgetType(e) == AT_LIST) {
-        ATermList in = (ATermList) e;
         ATermList out = ATempty;
-
-        while (!ATisEmpty(in)) {
-            out = ATinsert(out, substitute(subs, ATgetFirst(in)));
-            in = ATgetNext(in);
-        }
-
+        for (ATermIterator i((ATermList) e); i; ++i)
+            out = ATinsert(out, substitute(subs, *i));
         return (ATerm) ATreverse(out);
     }
 
diff --git a/src/fix-ng/fix.cc b/src/fix-ng/fix.cc
index 49f19669a08b..3b7dae38eb77 100644
--- a/src/fix-ng/fix.cc
+++ b/src/fix-ng/fix.cc
@@ -54,10 +54,8 @@ static void printNixExpr(EvalState & state, Expr e)
     }
 
     if (ATgetType(e) == AT_LIST) {
-        while (!ATisEmpty(es)) {
-            printNixExpr(state, evalExpr(state, ATgetFirst(es)));
-            es = ATgetNext(es);
-        }
+        for (ATermIterator i((ATermList) e); i; ++i)
+            printNixExpr(state, evalExpr(state, *i));
         return;
     }
 
diff --git a/src/fix-ng/primops.cc b/src/fix-ng/primops.cc
index a68352579753..86b364c30f53 100644
--- a/src/fix-ng/primops.cc
+++ b/src/fix-ng/primops.cc
@@ -108,11 +108,10 @@ static string processBinding(EvalState & state, Expr e, NixExpr & ne)
     if (atMatch(m, e) >> "List" >> es) {
 	string s;
 	bool first = true;
-        while (!ATisEmpty(es)) {
+        for (ATermIterator i(es); i; ++i) {
             startNest(nest, lvlVomit, format("processing list element"));
 	    if (!first) s = s + " "; else first = false;
-	    s += processBinding(state, evalExpr(state, ATgetFirst(es)), ne);
-            es = ATgetNext(es);
+	    s += processBinding(state, evalExpr(state, *i), ne);
         }
 	return s;
     }
@@ -140,10 +139,8 @@ Expr primDerivation(EvalState & state, Expr args)
     Hash outHash;
     bool outHashGiven = false;
 
-    for (ATermList keys = attrs.keys(); !ATisEmpty(keys); 
-         keys = ATgetNext(keys))
-    {
-        string key = aterm2String(ATgetFirst(keys));
+    for (ATermIterator i(attrs.keys()); i; ++i) {
+        string key = aterm2String(*i);
         Expr value = attrs.get(key);
         startNest(nest, lvlVomit, format("processing attribute `%1%'") % key);
 
diff --git a/src/libnix/aterm.hh b/src/libnix/aterm.hh
index 1e4ee80eeab5..16d8d6bb6dfd 100644
--- a/src/libnix/aterm.hh
+++ b/src/libnix/aterm.hh
@@ -14,6 +14,28 @@ string atPrint(ATerm t);
 /* Write an ATerm to an output stream. */
 ostream & operator << (ostream & stream, ATerm e);
 
+class ATermIterator
+{
+    ATermList t;
+
+public:
+    ATermIterator(ATermList _t) : t(_t) { }
+    ATermIterator & operator ++ ()
+    {
+        t = ATgetNext(t);
+        return *this;
+    }
+    ATerm operator * ()
+    {
+        return ATgetFirst(t);
+    }
+    operator bool ()
+    {
+        return t != ATempty;
+    }
+};
+
+
 /* Type-safe matching. */
 
 struct ATMatcher 
diff --git a/src/libnix/expr.cc b/src/libnix/expr.cc
index 67fa69f72fab..7bb1f5306129 100644
--- a/src/libnix/expr.cc
+++ b/src/libnix/expr.cc
@@ -43,13 +43,11 @@ Path writeTerm(ATerm t, const string & suffix)
 static void parsePaths(ATermList paths, PathSet & out)
 {
     ATMatcher m;
-    while (!ATisEmpty(paths)) {
+    for (ATermIterator i(paths); i; ++i) {
         string s;
-        ATerm t = ATgetFirst(paths);
-        if (!(atMatch(m, t) >> s))
-            throw badTerm("not a path", t);
+        if (!(atMatch(m, *i) >> s))
+            throw badTerm("not a path", *i);
         out.insert(s);
-        paths = ATgetNext(paths);
     }
 }
 
@@ -91,16 +89,14 @@ static bool parseClosure(ATerm t, Closure & closure)
 
     parsePaths(roots, closure.roots);
 
-    while (!ATisEmpty(elems)) {
+    for (ATermIterator i(elems); i; ++i) {
         string path;
         ATermList refs;
-        ATerm t = ATgetFirst(elems);
-        if (!(atMatch(m, t) >> "" >> path >> refs))
-            throw badTerm("not a closure element", t);
+        if (!(atMatch(m, *i) >> "" >> path >> refs))
+            throw badTerm("not a closure element", *i);
         ClosureElem elem;
         parsePaths(refs, elem.refs);
         closure.elems[path] = elem;
-        elems = ATgetNext(elems);
     }
 
     checkClosure(closure);
@@ -124,22 +120,18 @@ static bool parseDerivation(ATerm t, Derivation & derivation)
     derivation.builder = builder;
     derivation.platform = platform;
     
-    while (!ATisEmpty(args)) {
+    for (ATermIterator i(args); i; ++i) {
         string s;
-        ATerm arg = ATgetFirst(args);
-        if (!(atMatch(m, arg) >> s))
-            throw badTerm("string expected", arg);
+        if (!(atMatch(m, *i) >> s))
+            throw badTerm("string expected", *i);
         derivation.args.push_back(s);
-        args = ATgetNext(args);
     }
 
-    while (!ATisEmpty(bnds)) {
+    for (ATermIterator i(bnds); i; ++i) {
         string s1, s2;
-        ATerm bnd = ATgetFirst(bnds);
-        if (!(atMatch(m, bnd) >> "" >> s1 >> s2))
-            throw badTerm("tuple of strings expected", bnd);
+        if (!(atMatch(m, *i) >> "" >> s1 >> s2))
+            throw badTerm("tuple of strings expected", *i);
         derivation.env[s1] = s2;
-        bnds = ATgetNext(bnds);
     }
 
     return true;