Add package_manifest::load_files() function loading file-* values

2 files changed, 48 insertions, 3 deletions

diff --git a/libbpkg/manifest.cxx b/libbpkg/manifest.cxx
index 8782409..b94b4da 100644
--- a/libbpkg/manifest.cxx
+++ b/libbpkg/manifest.cxx
@@ -1803,6 +1803,36 @@ namespace bpkg
     parse_package_manifest (p, move (nv), iu, fl, *this);
   }
 
+  static const string description_file ("description-file");
+  static const string changes_file     ("changes-file");
+
+  void package_manifest::
+  load_files (const function<load_function>& loader)
+  {
+    auto load = [&loader] (const string& n, const path& p)
+    {
+      string r (loader (n, p));
+
+      if (r.empty ())
+        throw parsing ("package " + n + " references empty file");
+
+      return r;
+    };
+
+    // Load the description-file manifest value.
+    //
+    if (description && description->file)
+      description = text_file (load (description_file, description->path));
+
+    // Load the changes-file manifest values.
+    //
+    for (text_file& c: changes)
+    {
+      if (c.file)
+        c = text_file (load (changes_file, c.path));
+    }
+  }
+
   static void
   serialize_package_manifest (manifest_serializer& s,
                               const package_manifest& m,
diff --git a/libbpkg/manifest.hxx b/libbpkg/manifest.hxx
index fc61511..3d8f5f5 100644
--- a/libbpkg/manifest.hxx
+++ b/libbpkg/manifest.hxx
@@ -9,10 +9,11 @@
 #include <string>
 #include <vector>
 #include <cassert>
-#include <cstdint>   // uint16_t
+#include <cstdint>    // uint16_t
 #include <ostream>
-#include <utility>   // move()
-#include <stdexcept> // logic_error
+#include <utility>    // move()
+#include <stdexcept>  // logic_error
+#include <functional>
 
 #include <libbutl/url.mxx>
 #include <libbutl/path.mxx>
@@ -634,6 +635,20 @@ namespace bpkg
     //
     void
     serialize_header (butl::manifest_serializer&) const;
+
+    // Load the *-file manifest values using the specified load function that
+    // returns the file contents passing through any exception it may throw.
+    //
+    // Note that if the returned file contents is empty, load_files() makes
+    // sure that this is allowed by the value's semantics throwing
+    // manifest_parsing otherwise. However, the load function may want to
+    // recognize such cases itself in order to issue more precise diagnostics.
+    //
+    using load_function = std::string (const std::string& name,
+                                       const butl::path& value);
+
+    void
+    load_files (const std::function<load_function>&);
   };
 
   // Create individual package manifest.