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also cache split regexes, not just match regexes

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gives about 1% improvement on system eval, a bit less on nix search.

 # before

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      7.419 s ±  0.045 s    [User: 6.362 s, System: 0.794 s]
    Range (min … max):    7.335 s …  7.517 s    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.921 s ±  0.023 s    [User: 2.626 s, System: 0.210 s]
    Range (min … max):    2.883 s …  2.957 s    20 runs

 # after

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      7.370 s ±  0.059 s    [User: 6.333 s, System: 0.791 s]
    Range (min … max):    7.286 s …  7.541 s    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.891 s ±  0.033 s    [User: 2.606 s, System: 0.210 s]
    Range (min … max):    2.823 s …  2.958 s    20 runs
This commit is contained in:
pennae 2022-01-02 00:46:43 +01:00
parent c9fc975259
commit ad60dfde2a
2 changed files with 6 additions and 3 deletions
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1
src/libexpr/eval.hh
View file

@ -400,6 +400,7 @@ private:
friend struct ExprSelect;
friend void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v);
friend void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v);
friend void prim_split(EvalState & state, const Pos & pos, Value * * args, Value & v);
friend struct Value;
};

8
src/libexpr/primops.cc
View file

@ -3528,18 +3528,20 @@ static RegisterPrimOp primop_match({
/* Split a string with a regular expression, and return a list of the
non-matching parts interleaved by the lists of the matching groups. */
static void prim_split(EvalState & state, const Pos & pos, Value * * args, Value & v)
void prim_split(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
auto re = state.forceStringNoCtx(*args[0], pos);
try {
std::regex regex(re, std::regex::extended);
auto regex = state.regexCache->cache.find(re);
if (regex == state.regexCache->cache.end())
regex = state.regexCache->cache.emplace(re, std::regex(re, std::regex::extended)).first;
PathSet context;
const std::string str = state.forceString(*args[1], context, pos);
auto begin = std::sregex_iterator(str.begin(), str.end(), regex);
auto begin = std::sregex_iterator(str.begin(), str.end(), regex->second);
auto end = std::sregex_iterator();
// Any matches results are surrounded by non-matching results.