Implement --buildfile option, overrides default buildfile, supports '-'

8 files changed, 70 insertions, 9 deletions

diff --git a/build2/b-options b/build2/b-options
index 602ea64..b592ece 100644
--- a/build2/b-options
+++ b/build2/b-options
@@ -408,6 +408,12 @@ namespace build2
     verbose_specified () const;
 
     const path&
+    buildfile () const;
+
+    bool
+    buildfile_specified () const;
+
+    const path&
     config_guess () const;
 
     bool
@@ -460,6 +466,8 @@ namespace build2
     bool q_;
     uint16_t verbose_;
     bool verbose_specified_;
+    path buildfile_;
+    bool buildfile_specified_;
     path config_guess_;
     bool config_guess_specified_;
     path config_sub_;
diff --git a/build2/b-options.cxx b/build2/b-options.cxx
index bbdbde9..cf15200 100644
--- a/build2/b-options.cxx
+++ b/build2/b-options.cxx
@@ -573,6 +573,8 @@ namespace build2
     q_ (),
     verbose_ (1),
     verbose_specified_ (false),
+    buildfile_ ("buildfile"),
+    buildfile_specified_ (false),
     config_guess_ (),
     config_guess_specified_ (false),
     config_sub_ (),
@@ -677,6 +679,16 @@ namespace build2
        << "                     6. Even more detailed information, including state dumps." << ::std::endl;
 
     os << std::endl
+       << "\033[1m--buildfile\033[0m \033[4mpath\033[0m     The alternative file to read build information from. The" << ::std::endl
+       << "                     default is \033[1mbuildfile\033[0m. If \033[4mpath\033[0m is '\033[1m-\033[0m', then read from" << ::std::endl
+       << "                     \033[1mSTDIN\033[0m. Note that this option only affects the files read" << ::std::endl
+       << "                     as part of the buildspec processing. Specifically, it has" << ::std::endl
+       << "                     no effect on the \033[1msource\033[0m and \033[1minclude\033[0m directives. As a" << ::std::endl
+       << "                     result, this option is primarily intended for testing" << ::std::endl
+       << "                     rather than changing the build file names in real" << ::std::endl
+       << "                     projects." << ::std::endl;
+
+    os << std::endl
        << "\033[1m--config-guess\033[0m \033[4mpath\033[0m  The path to the \033[1mconfig.guess(1)\033[0m script that should be used" << ::std::endl
        << "                     to guess the host machine triplet. If this option is not" << ::std::endl
        << "                     specified, then \033[1mb\033[0m will fall back on to using the target it" << ::std::endl
@@ -732,6 +744,9 @@ namespace build2
       _cli_options_map_["--verbose"] = 
       &::build2::cl::thunk< options, uint16_t, &options::verbose_,
         &options::verbose_specified_ >;
+      _cli_options_map_["--buildfile"] = 
+      &::build2::cl::thunk< options, path, &options::buildfile_,
+        &options::buildfile_specified_ >;
       _cli_options_map_["--config-guess"] = 
       &::build2::cl::thunk< options, path, &options::config_guess_,
         &options::config_guess_specified_ >;
diff --git a/build2/b-options.ixx b/build2/b-options.ixx
index ed538c9..15329dc 100644
--- a/build2/b-options.ixx
+++ b/build2/b-options.ixx
@@ -241,6 +241,18 @@ namespace build2
   }
 
   inline const path& options::
+  buildfile () const
+  {
+    return this->buildfile_;
+  }
+
+  inline bool options::
+  buildfile_specified () const
+  {
+    return this->buildfile_specified_;
+  }
+
+  inline const path& options::
   config_guess () const
   {
     return this->config_guess_;
diff --git a/build2/b.cli b/build2/b.cli
index 9144acf..013a756 100644
--- a/build2/b.cli
+++ b/build2/b.cli
@@ -220,6 +220,17 @@ namespace build2
        \li|Even more detailed information, including state dumps.||"
     }
 
+    path --buildfile = "buildfile"
+    {
+      "<path>",
+      "The alternative file to read build information from. The default is
+       \cb{buildfile}. If <path> is '\cb{-}', then read from \cb{STDIN}. Note
+       that this option only affects the files read as part of the buildspec
+       processing. Specifically, it has no effect on the \cb{source} and
+       \cb{include} directives. As a result, this option is primarily intended
+       for testing rather than changing the build file names in real projects."
+    }
+
     path --config-guess
     {
       "<path>",
diff --git a/build2/b.cxx b/build2/b.cxx
index f9c3683..313fe95 100644
--- a/build2/b.cxx
+++ b/build2/b.cxx
@@ -786,12 +786,13 @@ main (int argc, char* argv[])
             trace << "  src_root: " << src_root;
           }
 
-          path bf (src_base / path ("buildfile"));
+          const path& bfn (ops.buildfile ());
+          path bf (bfn.string () != "-" ? src_base / bfn : bfn);
 
           // If we were guessing src_base, check that the buildfile
           // exists and if not, issue more detailed diagnostics.
           //
-          if (guessing && !file_exists (bf))
+          if (guessing && bf.string () != "-" && !file_exists (bf))
             fail << bf << " does not exist"
                  << info << "consider explicitly specifying src_base "
                  << "for " << tn;
diff --git a/build2/context.cxx b/build2/context.cxx
index 941f98a..6317476 100644
--- a/build2/context.cxx
+++ b/build2/context.cxx
@@ -406,6 +406,9 @@ namespace build2
   string
   diag_relative (const path& p)
   {
+    if (p.string () == "-")
+      return "<stdin>";
+
     const path& b (*relative_base);
 
     if (p.absolute ())
diff --git a/build2/file b/build2/file
index b198557..00ece85 100644
--- a/build2/file
+++ b/build2/file
@@ -49,11 +49,13 @@ namespace build2
   dir_path
   find_out_root (const dir_path&, bool* src = nullptr);
 
+  // If buildfile is '-', then read from STDIN.
+  //
   void
   source (const path& buildfile, scope& root, scope& base);
 
-  // As above but first check if this buildfile has already been
-  // sourced for the base scope.
+  // As above but first check if this buildfile has already been sourced for
+  // the base scope.
   //
   void
   source_once (const path& buildfile, scope& root, scope& base);
diff --git a/build2/file.cxx b/build2/file.cxx
index 10461c4..b735cab 100644
--- a/build2/file.cxx
+++ b/build2/file.cxx
@@ -5,6 +5,7 @@
 #include <build2/file>
 
 #include <fstream>
+#include <iostream> // cin
 
 #include <butl/filesystem>
 
@@ -80,16 +81,24 @@ namespace build2
 
     try
     {
-      ifstream ifs (bf.string ());
-      if (!ifs.is_open ())
-        fail << "unable to open " << bf;
+      bool sin (bf.string () == "-");
 
-      ifs.exceptions (ifstream::failbit | ifstream::badbit);
+      ifstream ifs;
+      if (!sin)
+      {
+        ifs.open (bf.string ());
+
+        if (!ifs.is_open ())
+          fail << "unable to open " << bf;
+      }
+
+      istream& is (sin ? std::cin : ifs);
+      is.exceptions (ifstream::failbit | ifstream::badbit);
 
       l5 ([&]{trace << "sourcing " << bf;});
 
       parser p (boot);
-      p.parse_buildfile (ifs, bf, root, base);
+      p.parse_buildfile (is, bf, root, base);
     }
     catch (const ifstream::failure&)
     {