1 files changed, 124 insertions, 10 deletions

diff --git a/libbutl/utility.ixx b/libbutl/utility.ixx
index fa37a14..fda1ce5 100644
--- a/libbutl/utility.ixx
+++ b/libbutl/utility.ixx
@@ -1,13 +1,10 @@
 // file      : libbutl/utility.ixx -*- C++ -*-
 // license   : MIT; see accompanying LICENSE file
 
-#ifndef __cpp_lib_modules_ts
 #include <cctype>    // toupper(), tolower(), is*()
 #include <cwctype>   // isw*()
-#include <cstdlib>   // getenv()
 #include <algorithm> // for_each()
 #include <stdexcept> // invalid_argument
-#endif
 
 namespace butl
 {
@@ -146,6 +143,12 @@ namespace butl
   }
 
   inline bool
+  wspace (char c)
+  {
+    return std::isspace (c);
+  }
+
+  inline bool
   alpha (wchar_t c)
   {
     return std::iswalpha (c);
@@ -169,6 +172,12 @@ namespace butl
     return std::iswxdigit (c);
   }
 
+  inline bool
+  wspace (wchar_t c)
+  {
+    return std::iswspace (c);
+  }
+
   inline std::size_t
   next_word (const std::string& s, std::size_t& b, std::size_t& e,
              char d1, char d2)
@@ -176,7 +185,7 @@ namespace butl
     return next_word (s, s.size (), b, e, d1, d2);
   }
 
-  inline size_t
+  inline std::size_t
   next_word (const std::string& s,
              std::size_t n, std::size_t& b, std::size_t& e,
              char d1, char d2)
@@ -201,6 +210,66 @@ namespace butl
     return e - b;
   }
 
+  inline std::size_t
+  next_word (const std::string& s,
+             std::size_t n, std::size_t& b, std::size_t& e, std::size_t& m,
+             char d1, char d2)
+  {
+    // An empty word will necessarily be represented as b and e being the
+    // position of a delimiter. Consider these corner cases (in all three we
+    // should produce two words):
+    //
+    // \n
+    // a\n
+    // \na
+    //
+    // It feels sensible to represent an empty word as the position of the
+    // trailing delimiter except if it is the last character (the first two
+    // cases). Thus the additional m state, which, if 0 or 1 indicates the
+    // number of delimiters to skip before parsing the next word and 2 if
+    // this is a trailing delimiter for which we need to fake an empty word
+    // with the leading delimiter.
+
+    if (b != e)
+      b = e;
+
+    if (m > 1)
+    {
+      --m;
+      return 0;
+    }
+
+    // Skip the leading delimiter, if any.
+    //
+    b += m;
+
+    if (b == n)
+    {
+      e = n;
+      return 0;
+    }
+
+    // Find first trailing delimiter.
+    //
+    m = 0;
+    for (e = b; e != n; ++e)
+    {
+      if (s[e] == d1 || s[e] == d2)
+      {
+        m = 1;
+
+        // Handle the special delimiter as the last character case.
+        //
+        if (e + 1 == n)
+          ++m;
+
+        break;
+      }
+    }
+
+    return e - b;
+  }
+
   inline std::string&
   sanitize_identifier (std::string& s)
   {
@@ -228,7 +297,7 @@ namespace butl
   inline void
   sanitize_strlit (const std::string& s, std::string& o)
   {
-    for (size_t i (0), j;; i = j + 1)
+    for (std::size_t i (0), j;; i = j + 1)
     {
       j = s.find_first_of ("\\\"\n", i);
       o.append (s.c_str () + i, (j == std::string::npos ? s.size () : j) - i);
@@ -333,13 +402,58 @@ namespace butl
     return utf8_length_impl (s, nullptr, ts, wl).has_value ();
   }
 
-  inline optional<std::string>
-  getenv (const std::string& name)
+#ifndef _WIN32
+  inline const char* const*
+  thread_env ()
+  {
+    return thread_env_;
+  }
+
+  inline void
+  thread_env (const char* const* v)
+  {
+    thread_env_ = v;
+  }
+#endif
+
+  // auto_thread_env
+  //
+  inline auto_thread_env::
+  auto_thread_env (const char* const* new_env)
   {
-    if (const char* r = std::getenv (name.c_str ()))
-      return std::string (r);
+    const char* const* cur_env (thread_env ());
 
-    return nullopt;
+    if (cur_env != new_env)
+    {
+      prev_env = cur_env;
+      thread_env (new_env);
+    }
+  }
+
+  inline auto_thread_env::
+  auto_thread_env (auto_thread_env&& x) noexcept
+      : prev_env (std::move (x.prev_env))
+  {
+    x.prev_env = nullopt;
+  }
+
+  inline auto_thread_env& auto_thread_env::
+  operator= (auto_thread_env&& x) noexcept
+  {
+    if (this != &x)
+    {
+      prev_env = std::move (x.prev_env);
+      x.prev_env = nullopt;
+    }
+
+    return *this;
+  }
+
+  inline auto_thread_env::
+  ~auto_thread_env ()
+  {
+    if (prev_env)
+      thread_env (*prev_env);
   }
 
   template <typename F, typename P>