Implement tracing support

Also use to-relative path translation in diagnostics.

1 files changed, 36 insertions, 0 deletions

diff --git a/build/context.cxx b/build/context.cxx
index ce80324..fc4ec1c 100644
--- a/build/context.cxx
+++ b/build/context.cxx
@@ -2,6 +2,8 @@
 // copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
 // license   : MIT; see accompanying LICENSE file
 
+#include <ostream>
+
 #include <build/context>
 
 using namespace std;
@@ -16,4 +18,38 @@ namespace build
 
   path src_base;
   path out_base;
+
+  path
+  translate (const path& p)
+  {
+    if (p.sub (work))
+      return p.leaf (work);
+
+    // If work is a sub-path of {src,out}_root and this path is also a
+    // sub-bath of it, then use '..' to form a relative path.
+    //
+    if (work.sub (src_root) && p.sub (src_root) ||
+        work.sub (out_root) && p.sub (out_root)) // @@ cache
+      return p.relative (work);
+
+    return p;
+  }
+
+  std::string
+  diagnostic_string (const path& p)
+  {
+    if (p.absolute ())
+    {
+      path rp (translate (p));
+
+#ifndef _WIN32
+      if (rp.absolute () && rp.sub (home))
+        return "~/" + rp.leaf (home).string ();
+#endif
+
+      return rp.string ();
+    }
+
+    return p.string ();
+  }
 }