Add level / displacement types

src/libexpr/eval.cc

@@ -787,7 +787,7 @@ void mkPath(Value & v, const char * s)
 
 inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
 {
- for (size_t l = var.level; l; --l, env = env->up) ;
+ for (auto l = var.level; l; --l, env = env->up) ;
 
  if (!var.fromWith) return env->values[var.displ];
 
@@ -1060,7 +1060,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
  /* The recursive attributes are evaluated in the new
  environment, while the inherited attributes are evaluated
  in the original environment. */
- size_t displ = 0;
+ Displacement displ = 0;
  for (auto & i : attrs) {
  Value * vAttr;
  if (hasOverrides && !i.second.inherited) {
@@ -1136,7 +1136,7 @@ void ExprLet::eval(EvalState & state, Env & env, Value & v)
  /* The recursive attributes are evaluated in the new environment,
  while the inherited attributes are evaluated in the original
  environment. */
- size_t displ = 0;
+ Displacement displ = 0;
  for (auto & i : attrs->attrs)
  env2.values[displ++] = i.second.e->maybeThunk(state, i.second.inherited ? env : env2);
 
@@ -1283,7 +1283,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
  Env & env2(allocEnv(size));
  env2.up = vCur.lambda.env;
 
- size_t displ = 0;
+ Displacement displ = 0;
 
  if (!lambda.hasFormals())
  env2.values[displ++] = args[0];

src/libexpr/nixexpr.cc

@@ -273,7 +273,7 @@ void ExprVar::bindVars(const StaticEnv & env)
  /* Check whether the variable appears in the environment. If so,
  set its level and displacement. */
  const StaticEnv * curEnv;
- unsigned int level;
+ Level level;
  int withLevel = -1;
  for (curEnv = &env, level = 0; curEnv; curEnv = curEnv->up, level++) {
  if (curEnv->isWith) {
@@ -326,7 +326,7 @@ void ExprAttrs::bindVars(const StaticEnv & env)
  if (recursive) {
  dynamicEnv = &newEnv;
 
- unsigned int displ = 0;
+ Displacement displ = 0;
  for (auto & i : attrs)
  newEnv.vars.emplace_back(i.first, i.second.displ = displ++);
 
@@ -359,7 +359,7 @@ void ExprLambda::bindVars(const StaticEnv & env)
  (hasFormals() ? formals->formals.size() : 0) +
  (arg.empty() ? 0 : 1));
 
- unsigned int displ = 0;
+ Displacement displ = 0;
 
  if (!arg.empty()) newEnv.vars.emplace_back(arg, displ++);
 
@@ -387,7 +387,7 @@ void ExprLet::bindVars(const StaticEnv & env)
 {
  StaticEnv newEnv(false, &env, attrs->attrs.size());
 
- unsigned int displ = 0;
+ Displacement displ = 0;
  for (auto & i : attrs->attrs)
  newEnv.vars.emplace_back(i.first, i.second.displ = displ++);
 
@@ -405,7 +405,7 @@ void ExprWith::bindVars(const StaticEnv & env)
  level so that `lookupVar' can look up variables in the previous
  `with' if this one doesn't contain the desired attribute. */
  const StaticEnv * curEnv;
- unsigned int level;
+ Level level;
  prevWith = 0;
  for (curEnv = &env, level = 1; curEnv; curEnv = curEnv->up, level++)
  if (curEnv->isWith) {

src/libexpr/nixexpr.hh

@@ -133,6 +133,9 @@ struct ExprPath : Expr
  Value * maybeThunk(EvalState & state, Env & env);
 };
 
+typedef uint32_t Level;
+typedef uint32_t Displacement;
+
 struct ExprVar : Expr
 {
  Pos pos;
@@ -148,8 +151,8 @@ struct ExprVar : Expr
  value is obtained by getting the attribute named `name' from
  the set stored in the environment that is `level' levels up
  from the current one.*/
- unsigned int level;
- unsigned int displ;
+ Level level;
+ Displacement displ;
 
  ExprVar(const Symbol & name) : name(name) { };
  ExprVar(const Pos & pos, const Symbol & name) : pos(pos), name(name) { };
@@ -183,7 +186,7 @@ struct ExprAttrs : Expr
  bool inherited;
  Expr * e;
  Pos pos;
- unsigned int displ; // displacement
+ Displacement displ; // displacement
  AttrDef(Expr * e, const Pos & pos, bool inherited=false)
  : inherited(inherited), e(e), pos(pos) { };
  AttrDef() { };
@@ -352,7 +355,7 @@ struct StaticEnv
  const StaticEnv * up;
 
  // Note: these must be in sorted order.
- typedef std::vector<std::pair<Symbol, unsigned int>> Vars;
+ typedef std::vector<std::pair<Symbol, Displacement>> Vars;
  Vars vars;
 
  StaticEnv(bool isWith, const StaticEnv * up, size_t expectedSize = 0) : isWith(isWith), up(up) {