From b05b98df7544d02387f583ca5434f33f3e9cb471 Mon Sep 17 00:00:00 2001
From: Alexander Ried <ried@mytum.de>
Date: Tue, 18 Oct 2016 20:21:21 +0200
Subject: [PATCH] replace own regex class with std::regex

---
 src/libexpr/names.cc   |  4 ++--
 src/libexpr/names.hh   |  4 ++--
 src/libexpr/primops.cc | 21 +++++++++---------
 src/libutil/regex.cc   | 50 ------------------------------------------
 src/libutil/regex.hh   | 29 ------------------------
 5 files changed, 14 insertions(+), 94 deletions(-)
 delete mode 100644 src/libutil/regex.cc
 delete mode 100644 src/libutil/regex.hh

diff --git a/src/libexpr/names.cc b/src/libexpr/names.cc
index 7bca9b655..6d78d2116 100644
--- a/src/libexpr/names.cc
+++ b/src/libexpr/names.cc
@@ -33,8 +33,8 @@ DrvName::DrvName(const string & s) : hits(0)
 bool DrvName::matches(DrvName & n)
 {
     if (name != "*") {
-        if (!regex) regex = std::shared_ptr<Regex>(new Regex(name));
-        if (!regex->matches(n.name)) return false;
+        if (!regex) regex = std::unique_ptr<std::regex>(new std::regex(name, std::regex::extended));
+        if (!std::regex_match(n.name, *regex)) return false;
     }
     if (version != "" && version != n.version) return false;
     return true;
diff --git a/src/libexpr/names.hh b/src/libexpr/names.hh
index 4b3dcddf7..9667fc96f 100644
--- a/src/libexpr/names.hh
+++ b/src/libexpr/names.hh
@@ -3,7 +3,7 @@
 #include <memory>
 
 #include "types.hh"
-#include "regex.hh"
+#include <regex>
 
 namespace nix {
 
@@ -19,7 +19,7 @@ struct DrvName
     bool matches(DrvName & n);
 
 private:
-    std::shared_ptr<Regex> regex;
+    std::unique_ptr<std::regex> regex;
 };
 
 typedef list<DrvName> DrvNames;
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 377fb8c75..4bf3f5a02 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -18,6 +18,7 @@
 
 #include <algorithm>
 #include <cstring>
+#include <regex>
 #include <dlfcn.h>
 
 
@@ -1618,25 +1619,23 @@ static void prim_hashString(EvalState & state, const Pos & pos, Value * * args,
    ‘null’ or a list containing substring matches. */
 static void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    Regex regex(state.forceStringNoCtx(*args[0], pos), true);
+    std::regex regex(state.forceStringNoCtx(*args[0], pos), std::regex::extended);
 
     PathSet context;
-    string s = state.forceString(*args[1], context, pos);
+    const std::string str = state.forceString(*args[1], context, pos);
 
-    Regex::Subs subs;
-    if (!regex.matches(s, subs)) {
+
+    std::smatch match;
+    if (!std::regex_match(str, match, regex)) {
         mkNull(v);
         return;
     }
 
-    unsigned int len = subs.empty() ? 0 : subs.rbegin()->first + 1;
+    // the first match is the whole string
+    const size_t len = match.size() - 1;
     state.mkList(v, len);
-    for (unsigned int n = 0; n < len; ++n) {
-        auto i = subs.find(n);
-        if (i == subs.end())
-            mkNull(*(v.listElems()[n] = state.allocValue()));
-        else
-            mkString(*(v.listElems()[n] = state.allocValue()), i->second);
+    for (size_t i = 0; i < len; ++i) {
+        mkString(*(v.listElems()[i] = state.allocValue()), match[i + 1].str().c_str());
     }
 }
 
diff --git a/src/libutil/regex.cc b/src/libutil/regex.cc
deleted file mode 100644
index 84274b3e1..000000000
--- a/src/libutil/regex.cc
+++ /dev/null
@@ -1,50 +0,0 @@
-#include "regex.hh"
-#include "types.hh"
-
-#include <algorithm>
-
-namespace nix {
-
-Regex::Regex(const string & pattern, bool subs)
-{
-    /* Patterns must match the entire string. */
-    int err = regcomp(&preg, ("^(" + pattern + ")$").c_str(), (subs ? 0 : REG_NOSUB) | REG_EXTENDED);
-    if (err) throw RegexError(format("compiling pattern ‘%1%’: %2%") % pattern % showError(err));
-    nrParens = subs ? std::count(pattern.begin(), pattern.end(), '(') : 0;
-}
-
-Regex::~Regex()
-{
-    regfree(&preg);
-}
-
-bool Regex::matches(const string & s)
-{
-    int err = regexec(&preg, s.c_str(), 0, 0, 0);
-    if (err == 0) return true;
-    else if (err == REG_NOMATCH) return false;
-    throw Error(format("matching string ‘%1%’: %2%") % s % showError(err));
-}
-
-bool Regex::matches(const string & s, Subs & subs)
-{
-    regmatch_t pmatch[nrParens + 2];
-    int err = regexec(&preg, s.c_str(), nrParens + 2, pmatch, 0);
-    if (err == 0) {
-        for (unsigned int n = 2; n < nrParens + 2; ++n)
-            if (pmatch[n].rm_eo != -1)
-                subs[n - 2] = string(s, pmatch[n].rm_so, pmatch[n].rm_eo - pmatch[n].rm_so);
-        return true;
-    }
-    else if (err == REG_NOMATCH) return false;
-    throw Error(format("matching string ‘%1%’: %2%") % s % showError(err));
-}
-
-string Regex::showError(int err)
-{
-    char buf[256];
-    regerror(err, &preg, buf, sizeof(buf));
-    return string(buf);
-}
-
-}
diff --git a/src/libutil/regex.hh b/src/libutil/regex.hh
deleted file mode 100644
index 53e31f4ed..000000000
--- a/src/libutil/regex.hh
+++ /dev/null
@@ -1,29 +0,0 @@
-#pragma once
-
-#include "types.hh"
-
-#include <sys/types.h>
-#include <regex.h>
-
-#include <map>
-
-namespace nix {
-
-MakeError(RegexError, Error)
-
-class Regex
-{
-public:
-    Regex(const string & pattern, bool subs = false);
-    ~Regex();
-    bool matches(const string & s);
-    typedef std::map<unsigned int, string> Subs;
-    bool matches(const string & s, Subs & subs);
-
-private:
-    unsigned nrParens;
-    regex_t preg;
-    string showError(int err);
-};
-
-}