Add path::combine(string,separator)

In particular, this can be used to recombine a path during iteration:

  dir_path r;
  for (auto i (d.begin ()); i != d.end (); ++i)
    r.combine (*i, i.separator ());

1 files changed, 36 insertions, 4 deletions

diff --git a/libbutl/path.mxx b/libbutl/path.mxx
index 136f361..1ee2a66 100644
--- a/libbutl/path.mxx
+++ b/libbutl/path.mxx
@@ -72,11 +72,15 @@ LIBBUTL_MODEXPORT namespace butl
   struct invalid_basic_path: invalid_path_base
   {
     using string_type = std::basic_string<C>;
+    using size_type = typename string_type::size_type;
 
     string_type path;
 
-    invalid_basic_path (const C* p): path (p) {}
+    explicit
     invalid_basic_path (const string_type& p): path (p) {}
+    explicit
+    invalid_basic_path (const C* p): path (p) {}
+    invalid_basic_path (const C* p, size_type n): path (p, n) {}
   };
 
   enum class path_abnormality: std::uint16_t
@@ -943,6 +947,16 @@ LIBBUTL_MODEXPORT namespace butl
 
     // Iteration over path components.
     //
+    // Note that for an absolute POSIX path the first component is empty,
+    // not `/`. Which means recombining a path with operator/= is not going
+    // to work. Instead, do something along these lines:
+    //
+    // dir_path r;
+    // for (auto i (d.begin ()); i != d.end (); ++i)
+    //   r.combine (*i, i.separator ());
+    //
+    // @@ TODO: would be nice to skip consecutive separators (foo//bar).
+    //
   public:
     struct iterator
     {
@@ -1022,6 +1036,8 @@ LIBBUTL_MODEXPORT namespace butl
       iterator
       operator-- (int) {iterator r (*this); operator-- (); return r;}
 
+      // @@ TODO: this should return string_view.
+      //
       string_type
       operator* () const
       {
@@ -1137,11 +1153,14 @@ LIBBUTL_MODEXPORT namespace butl
     realize ();
 
   public:
+    // Combine two paths. Note: empty path on RHS has no effect.
+    //
     basic_path&
     operator/= (basic_path const&);
 
     // Combine a single path component (must not contain directory separators)
-    // as a string, without first constructing the path object.
+    // as a string, without first constructing the path object. Note: empty
+    // string has no effect.
     //
     basic_path&
     operator/= (string_type const&);
@@ -1149,6 +1168,19 @@ LIBBUTL_MODEXPORT namespace butl
     basic_path&
     operator/= (const C*);
 
+    // As above but with an optional separator after the component. Note that
+    // if the LHS is empty and the string is empty but the separator is not
+    // '\0', then on POSIX this is treated as a root component.
+    //
+    void
+    combine (string_type const&, C separator);
+
+    void
+    combine (const C*, C separator);
+
+    void
+    combine (const C*, size_type, C separator);
+
     // Append to the end of the path (normally an extension, etc).
     //
     basic_path&
@@ -1240,10 +1272,10 @@ LIBBUTL_MODEXPORT namespace butl
     // Common implementation for operator/=.
     //
     void
-    combine (const C*, size_type, difference_type);
+    combine_impl (const C*, size_type, difference_type);
 
     void
-    combine (const C*, size_type);
+    combine_impl (const C*, size_type);
 
     // Friends.
     //