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Add sort primop

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This commit is contained in:
Eelco Dolstra 2015-07-28 18:39:00 +02:00
parent 50807f3dd5
commit 76cc8e97a2
4 changed files with 68 additions and 1 deletions
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37
src/libexpr/primops.cc
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@ -1364,7 +1364,6 @@ static void prim_all(EvalState & state, const Pos & pos, Value * * args, Value &
}
/* Apply a function to every element of a list. */
static void prim_genList(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
state.forceFunction(*args[0], pos);
@ -1383,6 +1382,41 @@ static void prim_genList(EvalState & state, const Pos & pos, Value * * args, Val
}
static void prim_lessThan(EvalState & state, const Pos & pos, Value * * args, Value & v);
static void prim_sort(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
state.forceFunction(*args[0], pos);
state.forceList(*args[1], pos);
auto len = args[1]->listSize();
state.mkList(v, len);
for (unsigned int n = 0; n < len; ++n) {
state.forceValue(*args[1]->listElems()[n]);
v.listElems()[n] = args[1]->listElems()[n];
}
auto comparator = [&](Value * a, Value * b) {
/* Optimization: if the comparator is lessThan, bypass
callFunction. */
if (args[0]->type == tPrimOp && args[0]->primOp->fun == prim_lessThan)
return CompareValues()(a, b);
Value vTmp1, vTmp2;
state.callFunction(*args[0], *a, vTmp1, pos);
state.callFunction(vTmp1, *b, vTmp2, pos);
return state.forceBool(vTmp2);
};
/* FIXME: std::sort can segfault if the comparator is not a strict
weak ordering. What to do? std::stable_sort() seems more
resilient, but no guarantees... */
std::stable_sort(v.listElems(), v.listElems() + len, comparator);
}
/*************************************************************
* Integer arithmetic
*************************************************************/
@ -1779,6 +1813,7 @@ void EvalState::createBaseEnv()
addPrimOp("__any", 2, prim_any);
addPrimOp("__all", 2, prim_all);
addPrimOp("__genList", 2, prim_genList);
addPrimOp("__sort", 2, prim_sort);
// Integer arithmetic
addPrimOp("__add", 2, prim_add);