* Simplify the implementation of `with'. This gives a 7% speedup in
evaluating the NixOS system configuration.
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@ -246,10 +246,14 @@ Value * EvalState::lookupVar(Env * env, const VarRef & var)
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for (unsigned int l = var.level; l; --l, env = env->up) ;
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for (unsigned int l = var.level; l; --l, env = env->up) ;
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if (var.fromWith) {
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if (var.fromWith) {
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Bindings::iterator j = env->values[0].attrs->find(var.name);
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while (1) {
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if (j == env->values[0].attrs->end())
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Bindings::iterator j = env->values[0].attrs->find(var.name);
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throwEvalError("undefined variable `%1%'", var.name);
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if (j != env->values[0].attrs->end())
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return &j->second;
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return &j->second;
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if (env->prevWith == 0)
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throwEvalError("undefined variable `%1%'", var.name);
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for (unsigned int l = env->prevWith; l; --l, env = env->up) ;
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}
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} else
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} else
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return &env->values[var.displ];
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return &env->values[var.displ];
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}
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}
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@ -656,30 +660,10 @@ void ExprWith::eval(EvalState & state, Env & env, Value & v)
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{
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{
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Env & env2(state.allocEnv(1));
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Env & env2(state.allocEnv(1));
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env2.up = &env;
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env2.up = &env;
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env2.prevWith = prevWith;
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state.evalAttrs(env, attrs, env2.values[0]);
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state.evalAttrs(env, attrs, env2.values[0]);
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/* If there is an enclosing `with', copy all attributes that don't
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appear in this `with'. */
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if (prevWith != -1) {
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Env * env3 = &env;
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for (unsigned int l = prevWith; l; --l, env3 = env3->up) ;
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/* Because the first `with' may be a shallow copy of another
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attribute set (through a tCopy node), we need to clone its
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`attrs' before modifying them. */
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Bindings * old(env2.values[0].attrs);
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state.mkAttrs(env2.values[0]);
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foreach (Bindings::iterator, i, *old)
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mkCopy((*env2.values[0].attrs)[i->first], i->second);
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foreach (Bindings::iterator, i, *env3->values[0].attrs) {
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Bindings::iterator j = env2.values[0].attrs->find(i->first);
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if (j == env2.values[0].attrs->end())
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mkCopy((*env2.values[0].attrs)[i->first], i->second);
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}
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}
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state.eval(env2, body, v);
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state.eval(env2, body, v);
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}
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}
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@ -106,6 +106,7 @@ struct Value
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struct Env
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struct Env
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{
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{
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Env * up;
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Env * up;
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unsigned int prevWith; // nr of levels up to next `with' environment
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Value values[0];
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Value values[0];
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};
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};
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@ -278,12 +278,12 @@ void ExprLet::bindVars(const StaticEnv & env)
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void ExprWith::bindVars(const StaticEnv & env)
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void ExprWith::bindVars(const StaticEnv & env)
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{
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{
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/* Does this `with' have an enclosing `with'? If so, record its
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/* Does this `with' have an enclosing `with'? If so, record its
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level so that we can copy the attributes of the enclosing
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level so that `lookupVar' can look up variables in the previous
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`with'. */
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`with' if this one doesn't contain the desired attribute. */
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const StaticEnv * curEnv;
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const StaticEnv * curEnv;
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unsigned int level;
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unsigned int level;
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prevWith = -1;
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prevWith = 0;
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for (curEnv = &env, level = 0; curEnv; curEnv = curEnv->up, level++)
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for (curEnv = &env, level = 1; curEnv; curEnv = curEnv->up, level++)
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if (curEnv->isWith) {
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if (curEnv->isWith) {
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prevWith = level;
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prevWith = level;
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break;
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break;
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@ -184,7 +184,7 @@ struct ExprWith : Expr
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{
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{
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Pos pos;
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Pos pos;
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Expr * attrs, * body;
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Expr * attrs, * body;
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int prevWith;
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unsigned int prevWith;
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ExprWith(const Pos & pos, Expr * attrs, Expr * body) : pos(pos), attrs(attrs), body(body) { };
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ExprWith(const Pos & pos, Expr * attrs, Expr * body) : pos(pos), attrs(attrs), body(body) { };
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COMMON_METHODS
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COMMON_METHODS
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};
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};
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