Use locale-independent number parsing functions (#14)

Replace the setlocale workaround (which may break when other libraries
also touch the locale) with a proper fix that replaces the
stoi/stoll/stof functions with std::from_chars.

The behavior may not be 100% equivalent (most notably leading +
characters are no longer accepted) but it should not break any existing
usage.

This code could be cleaned up a lot by using std::string_view instead,
but for now this just does the minimal changes necessary.

An alternative solution would have been to replace stoi/stol/stof with
vendored locale-independent implementations.

Bump minimum macOS version to 26.0 to get support for `std::from_chars()` for floating-point types.

---------

Co-authored-by: sgt0 <140186177+sgt0@users.noreply.github.com>

Author: arch1t3cht

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-24.04, macos-15]
+        os: [ubuntu-24.04, macos-26]
         llvm: [19, 20, 21]
     name: Build os=${{ matrix.os }} llvm=${{ matrix.llvm }}
     runs-on: ${{ matrix.os }}

expr2/exprfilter.cpp

@@ -20,6 +20,7 @@
 #define USE_EXPR_CACHE
 
 #include <algorithm>
+#include <charconv>
 #include <cmath>
 #include <cctype>
 #include <clocale>
@@ -286,11 +287,12 @@ ExprOp decodeToken(const std::string &token, bool extended = false)
         if (name.size() == 1)
             return name[0] >= 'x' ? name[0] - 'x' : name[0] - 'a' + 3;
         int idx = -1;
-        try {
-            idx = std::stoi(name.substr(clipNamePrefix.size()));
-        } catch (...) {
+
+        auto result = std::from_chars(name.c_str() + clipNamePrefix.size(), name.c_str() + name.length(), idx);
+        if (result.ec != std::errc()) {
             throw std::runtime_error("invalid clip name: " + name);
         }
+
         return idx;
     };
 
@@ -305,16 +307,15 @@ ExprOp decodeToken(const std::string &token, bool extended = false)
     } else if ((token.substr(0, 3) == "dup" || token.substr(0, 4) == "swap" ||
                 token.substr(0, 4) == "drop" || token.substr(0, 4) == "sort")) {
         size_t prefix = token[1] == 'u' ? 3 : 4;
-        size_t count = 0;
         int idx = -1;
 
-        try {
-            idx = std::stoi(token.substr(prefix), &count);
-        } catch (...) {
+        auto result = std::from_chars(token.c_str() + prefix, token.c_str() + token.length(), idx);
+        if (result.ec != std::errc()) {
             // ...
         }
+        size_t count = std::distance(token.c_str(), result.ptr);
 
-        if (idx < 0 || prefix + count != token.size())
+        if (idx < 0 || count != token.size())
             throw std::runtime_error("illegal token: " + token);
         if (token[1] == 'u')
             return{ ExprOpType::DUP, idx };
@@ -327,16 +328,15 @@ ExprOp decodeToken(const std::string &token, bool extended = false)
     } else if (extended && (token.substr(0, 6) == "argmin" || token.substr(0, 6) == "argmax" ||
                             token.substr(0, 7) == "argsort")) {
         size_t prefix = token[3] == 's' ? 7 : 6;
-        size_t count = 0;
         int idx = -1;
 
-        try {
-            idx = std::stoi(token.substr(prefix), &count);
-        } catch (...) {
+        auto result = std::from_chars(token.c_str() + prefix, token.c_str() + token.length(), idx);
+        if (result.ec != std::errc()) {
             // ...
         }
+        size_t count = std::distance(token.c_str(), result.ptr);
 
-        if (idx < 0 || prefix + count != token.size())
+        if (idx < 0 || count != token.size())
             throw std::runtime_error("illegal token: " + token);
         if (token[3] == 's')
             return{ ExprOpType::ARGSORT, idx };
@@ -365,21 +365,23 @@ ExprOp decodeToken(const std::string &token, bool extended = false)
         long long l = 0;
         float f = 0;
         const size_t len = token.size();
-        try {
-            l = std::stoll(token, &pos, 0);
-        } catch (...) {
-            pos = 0;
+
+        auto resultl = std::from_chars(token.c_str(), token.c_str() + len, l);
+        if (resultl.ec == std::errc()) {
+            pos = std::distance(token.c_str(), resultl.ptr);
         }
+
         if (pos == len) {
             if ((int32_t)l == l) return { ExprOpType::CONSTANTI, (int32_t)l };
             else if ((uint32_t)l == l) return { ExprOpType::CONSTANTI, (uint32_t)l };
             return { ExprOpType::CONSTANTF, (float)l };
         }
-        try {
-            f = std::stof(token, &pos);
-        } catch (...) {
-            pos = 0;
+
+        auto resultf = std::from_chars(token.c_str(), token.c_str() + len, f);
+        if (resultf.ec == std::errc()) {
+            pos = std::distance(token.c_str(), resultf.ptr);
         }
+
         if (pos == len)
             return { ExprOpType::CONSTANTF, f };
         else if (pos > 0)
@@ -1597,9 +1599,6 @@ static void VS_CC exprCreate(const VSMap *in, VSMap *out, void *userData, VSCore
 }
 
 static void initExpr() {
-#ifndef _WIN32
-    std::setlocale(LC_NUMERIC, "C");
-#endif
     auto cfg = rr::Config::Edit()
         .set(rr::Optimization::Level::Aggressive)
         .set(rr::Optimization::FMF::FastMath)

flake.lock

@@ -1,6 +1,7 @@
 {
   lib,
   stdenv,
+  darwinMinVersionHook,
   meson,
   ninja,
   pkg-config,
@@ -37,11 +38,16 @@ stdenv.mkDerivation (finalAttrs: {
     pkg-config
   ];
 
-  buildInputs = [
-    libllvm
-    libxml2
-    vapoursynth
-  ];
+  buildInputs =
+    [
+      libllvm
+      libxml2
+      vapoursynth
+    ]
+    # `std::to_chars()` for floating-point types was introduced in macOS 13.3.
+    # But then `darwinMinVersionHook "13.0"` yields "error: 'from_chars' is
+    # unavailable: introduced in macOS 26.0".
+    ++ lib.optional stdenv.hostPlatform.isDarwin (darwinMinVersionHook "26.0");
 
   postPatch = ''
     substituteInPlace meson.build \