Rework and rename target_triplet

3 files changed, 82 insertions, 33 deletions

diff --git a/butl/buildfile b/butl/buildfile
index 9168774..dd2e6bb 100644
--- a/butl/buildfile
+++ b/butl/buildfile
@@ -24,8 +24,8 @@ lib{butl}:                               \
 {hxx         cxx}{ sha256              } \
 {hxx            }{ small-vector        } \
 {hxx     txx    }{ string-table        } \
+{hxx         cxx}{ target-triplet      } \
 {hxx         cxx}{ timestamp           } \
-{hxx         cxx}{ triplet             } \
 {hxx ixx     cxx}{ utility             } \
 {hxx            }{ vector-view         } \
 {hxx            }{ version             }
diff --git a/butl/triplet b/butl/target-triplet
index 0d1b7f4..d355d75 100644
--- a/butl/triplet
+++ b/butl/target-triplet
@@ -1,11 +1,12 @@
-// file      : butl/triplet -*- C++ -*-
+// file      : butl/target-triplet -*- C++ -*-
 // copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
 // license   : MIT; see accompanying LICENSE file
 
-#ifndef BUTL_TRIPLET
-#define BUTL_TRIPLET
+#ifndef BUTL_TARGET_TRIPLET
+#define BUTL_TARGET_TRIPLET
 
 #include <string>
+#include <ostream>
 
 #include <butl/export>
 
@@ -15,7 +16,7 @@ namespace butl
   // form which, these days, quite often takes the CPU-VENDOR-OS-ABI form. Plus
   // some fields can sometimes be omitted. This looseness makes it hard to base
   // any kind of decisions on the triplet without canonicalizing it and then
-  // splitting it into components. the way we are going to split it is like
+  // splitting it into components. The way we are going to split it is like
   // this:
   //
   // CPU
@@ -95,7 +96,7 @@ namespace butl
   //
   // 2. LLVM has the Triple class with similar goals.
   //
-  struct LIBBUTL_EXPORT triplet
+  struct LIBBUTL_EXPORT target_triplet
   {
     std::string cpu;
     std::string vendor;
@@ -103,14 +104,52 @@ namespace butl
     std::string version;
     std::string class_;
 
-    // Parse the triplet optionally returning the canonicalized string. Throw
-    // std::invalid_argument if the triplet is not recognizable.
+    // Assemble and returning the canonical (i.e., the one we round-trip)
+    // target triplet string.
+    //
+    std::string
+    string () const;
+
+    bool
+    empty () const {return cpu.empty ();}
+
+    int
+    compare (const target_triplet& y) const
+    {
+      int r;
+      return
+        (r =    cpu.compare (y.cpu))    != 0 ? r :
+        (r = vendor.compare (y.vendor)) != 0 ? r :
+        (r = system.compare (y.system)) != 0 ? r :
+        (   version.compare (y.version));
+    }
+
+    // Parse the triplet throw std::invalid_argument if the triplet is not
+    // recognizable.
     //
     explicit
-    triplet (const std::string&, std::string* canon = nullptr);
-    triplet (const std::string& s, std::string& canon): triplet (s, &canon) {}
-    triplet () = default;
+    target_triplet (const std::string&);
+
+    target_triplet () = default;
   };
+
+  inline bool
+  operator== (const target_triplet& x, const target_triplet& y)
+  {
+    return x.compare (y) == 0;
+  }
+
+  inline bool
+  operator!= (const target_triplet& x, const target_triplet& y)
+  {
+    return !(x == y);
+  }
+
+  inline std::ostream&
+  operator<< (std::ostream& o, const target_triplet& x)
+  {
+    return o << x.string ();
+  }
 };
 
-#endif // BUTL_TRIPLET
+#endif // BUTL_TARGET_TRIPLET
diff --git a/butl/triplet.cxx b/butl/target-triplet.cxx
index 2177717..f7da724 100644
--- a/butl/triplet.cxx
+++ b/butl/target-triplet.cxx
@@ -1,8 +1,8 @@
-// file      : butl/triplet.cxx -*- C++ -*-
+// file      : butl/target-triplet.cxx -*- C++ -*-
 // copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
 // license   : MIT; see accompanying LICENSE file
 
-#include <butl/triplet>
+#include <butl/target-triplet>
 
 #include <stdexcept> // invalid_argument
 
@@ -10,9 +10,11 @@ using namespace std;
 
 namespace butl
 {
-  triplet::
-  triplet (const string& s, string* c)
+  target_triplet::
+  target_triplet (const std::string& s)
   {
+    using std::string;
+
     auto bad = [](const char* m) {throw invalid_argument (m);};
 
     // Find the first and the last components. The first is CPU and the last is
@@ -25,9 +27,6 @@ namespace butl
 
     cpu.assign (s, 0, f);
 
-    if (c != nullptr)
-      *c = cpu;
-
     // If we have something in between, then the first component after CPU is
     // VENDOR. Unless it is a first component of two-component system, as in
     // i686-linux-gnu.
@@ -75,15 +74,7 @@ namespace butl
         if (s.compare (f, n, "pc") != 0 &&
             s.compare (f, n, "none") != 0 &&
             s.compare (f, n, "unknown") != 0)
-        {
           vendor.assign (s, f, n);
-
-          if (c != nullptr)
-          {
-            *c += '-';
-            *c += vendor;
-          }
-        }
       }
     }
 
@@ -97,12 +88,6 @@ namespace butl
     if (system.front () == '-' || system.back () == '-')
       bad ("invalid os/kernel/abi");
 
-    if (c != nullptr)
-    {
-      *c += '-';
-      *c += system;
-    }
-
     // Extract VERSION for some recognized systems.
     //
     string::size_type v (0);
@@ -132,4 +117,29 @@ namespace butl
     else
       class_ = "other";
   }
+
+  std::string target_triplet::
+  string () const
+  {
+    std::string r (cpu);
+
+    if (!vendor.empty ())
+    {
+      if (!r.empty ()) r += '-';
+      r += vendor;
+    }
+
+    if (!system.empty ())
+    {
+      if (!r.empty ()) r += '-';
+      r += system;
+    }
+
+    if (!version.empty ())
+    {
+      r += version;
+    }
+
+    return r;
+  }
 }