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Simplify inherited attribute handling

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This reduces the difference between inherited and non-inherited
attribute handling to the choice of which env to use (in recs and lets)
by setting the AttrDef::e to a new ExprVar in the parser rather than
carrying a separate AttrDef::v VarRef member.

As an added bonus, this allows inherited attributes that inherit from a
with to delay forcing evaluation of the with's attributes.

Signed-off-by: Shea Levy <shea@shealevy.com>
This commit is contained in:
Shea Levy 2013-07-15 17:10:18 -04:00 • committed by Eelco Dolstra
parent 6cd6ce5608
commit afc6c1bad6
7 changed files with 46 additions and 38 deletions
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40
src/libexpr/eval.cc
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@ -521,23 +521,17 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
environment, while the inherited attributes are evaluated
in the original environment. */
unsigned int displ = 0;
foreach (AttrDefs::iterator, i, attrs)
if (i->second.inherited) {
/* !!! handle overrides? */
Value * vAttr = state.lookupVar(&env, i->second.var);
env2.values[displ++] = vAttr;
v.attrs->push_back(Attr(i->first, vAttr, &i->second.pos));
} else {
Value * vAttr;
if (hasOverrides) {
vAttr = state.allocValue();
mkThunk(*vAttr, env2, i->second.e);
} else
vAttr = i->second.e->maybeThunk(state, env2);
env2.values[displ++] = vAttr;
v.attrs->push_back(Attr(i->first, vAttr, &i->second.pos));
}
foreach (AttrDefs::iterator, i, attrs) {
Value * vAttr;
if (hasOverrides && !i->second.inherited) {
vAttr = state.allocValue();
mkThunk(*vAttr, env2, i->second.e);
} else
vAttr = i->second.e->maybeThunk(state, i->second.inherited ? env : env2);
env2.values[displ++] = vAttr;
v.attrs->push_back(Attr(i->first, vAttr, &i->second.pos));
}
/* If the rec contains an attribute called `__overrides', then
evaluate it, and add the attributes in that set to the rec.
This allows overriding of recursive attributes, which is
@ -563,10 +557,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
else {
foreach (AttrDefs::iterator, i, attrs)
if (i->second.inherited)
v.attrs->push_back(Attr(i->first, state.lookupVar(&env, i->second.var), &i->second.pos));
else
v.attrs->push_back(Attr(i->first, i->second.e->maybeThunk(state, env), &i->second.pos));
v.attrs->push_back(Attr(i->first, i->second.e->maybeThunk(state, env), &i->second.pos));
}
}
@ -583,10 +574,7 @@ void ExprLet::eval(EvalState & state, Env & env, Value & v)
environment. */
unsigned int displ = 0;
foreach (ExprAttrs::AttrDefs::iterator, i, attrs->attrs)
if (i->second.inherited)
env2.values[displ++] = state.lookupVar(&env, i->second.var);
else
env2.values[displ++] = i->second.e->maybeThunk(state, env2);
env2.values[displ++] = i->second.e->maybeThunk(state, i->second.inherited ? env : env2);
body->eval(state, env2, v);
}
@ -602,7 +590,7 @@ void ExprList::eval(EvalState & state, Env & env, Value & v)
void ExprVar::eval(EvalState & state, Env & env, Value & v)
{
Value * v2 = state.lookupVar(&env, info);
Value * v2 = state.lookupVar(&env, info, false);
state.forceValue(*v2);
v = *v2;
}