Add diagnostics facility

4 files changed, 422 insertions, 1 deletions

diff --git a/bpkg/bpkg.cxx b/bpkg/bpkg.cxx
index 6e35544..3492705 100644
--- a/bpkg/bpkg.cxx
+++ b/bpkg/bpkg.cxx
@@ -5,9 +5,31 @@
 #include <iostream>
 #include <exception>
 
+#include <bpkg/diagnostics>
+
 using namespace std;
+using namespace bpkg;
 
 int
 main ()
 {
+  tracer trace ("main");
+
+  try
+  {
+    // Trace verbosity.
+    //
+    verb = 0;
+  }
+  catch (const failed&)
+  {
+    return 1; // Diagnostics has already been issued.
+  }
+  /*
+  catch (const std::exception& e)
+  {
+    error << e.what ();
+    return 1;
+  }
+  */
 }
diff --git a/bpkg/buildfile b/bpkg/buildfile
index 2c22069..8437c86 100644
--- a/bpkg/buildfile
+++ b/bpkg/buildfile
@@ -5,4 +5,4 @@
 import libs  = libbutl%lib{butl}
 import libs += libbpkg%lib{bpkg}
 
-exe{bpkg}: cxx{bpkg} $libs
+exe{bpkg}: cxx{bpkg diagnostics} $libs
diff --git a/bpkg/diagnostics b/bpkg/diagnostics
new file mode 100644
index 0000000..94cb0ba
--- /dev/null
+++ b/bpkg/diagnostics
@@ -0,0 +1,329 @@
+// file      : bpkg/diagnostics -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef BPKG_DIAGNOSTICS
+#define BPKG_DIAGNOSTICS
+
+#include <string>
+#include <cstdint>
+#include <utility> // move(), forward()
+#include <cassert>
+#include <sstream>
+#include <ostream>
+#include <exception>
+
+namespace bpkg
+{
+  // Throw this exception to terminate the process. The handler should
+  // assume that the diagnostics has already been issued.
+  //
+  class failed: public std::exception {};
+
+  // Trace verbosity level.
+  //
+  // 0 - tracing disabled.
+  // 1 - TODO
+  // 2 - TODO
+  // 3 - TODO
+  // 4 - TODO
+  // 5 - TODO
+  //
+  // While uint8 is more than enough, use uint16 for the ease of printing.
+  //
+  extern std::uint16_t verb;
+
+  template <typename F> inline void level1 (const F& f) {if (verb >= 1) f ();}
+  template <typename F> inline void level2 (const F& f) {if (verb >= 2) f ();}
+  template <typename F> inline void level3 (const F& f) {if (verb >= 3) f ();}
+  template <typename F> inline void level4 (const F& f) {if (verb >= 4) f ();}
+  template <typename F> inline void level5 (const F& f) {if (verb >= 5) f ();}
+
+  // Diagnostic facility, base infrastructure (potentially reusable).
+  //
+  extern std::ostream* diag_stream;
+
+  struct diag_record;
+  template <typename> struct diag_prologue;
+  template <typename> struct diag_mark;
+
+  typedef void (*diag_epilogue) (const diag_record&);
+
+  struct diag_record
+  {
+    template <typename T>
+    friend const diag_record&
+    operator<< (const diag_record& r, const T& x)
+    {
+      r.os_ << x;
+      return r;
+    }
+
+    diag_record (): empty_ (true), epilogue_ (nullptr) {}
+
+    template <typename B>
+    explicit
+    diag_record (const diag_prologue<B>& p)
+        : empty_ (true), epilogue_ (nullptr) {*this << p;}
+
+    template <typename B>
+    explicit
+    diag_record (const diag_mark<B>& m)
+        : empty_ (true), epilogue_ (nullptr) {*this << m;}
+
+    ~diag_record () noexcept(false);
+
+    void
+    append (diag_epilogue e) const
+    {
+      if (e != nullptr)
+      {
+        assert (epilogue_ == nullptr); // No multiple epilogues support.
+        epilogue_ = e;
+      }
+
+      if (empty_)
+        empty_ = false;
+      else
+        os_ << "\n  ";
+    }
+
+    // Move constructible-only type.
+    //
+    /*
+    @@ libstdc++ doesn't yet have the ostringstream move support.
+
+    diag_record (diag_record&& r)
+        : os_ (std::move (r.os_))
+    {
+      empty_ = r.empty_;
+      r.empty_ = true;
+
+      epilogue_ = r.epilogue_;
+      r.epilogue_ = nullptr;
+    }
+    */
+
+    diag_record (diag_record&& r)
+    {
+      empty_ = r.empty_;
+      epilogue_ = r.epilogue_;
+
+      if (!empty_)
+      {
+        os_ << r.os_.str ();
+        r.empty_ = true;
+        r.epilogue_ = nullptr;
+      }
+    }
+
+    diag_record& operator= (diag_record&&) = delete;
+
+    diag_record (const diag_record&) = delete;
+    diag_record& operator= (const diag_record&) = delete;
+
+  public:
+    mutable std::ostringstream os_;
+
+  private:
+    mutable bool empty_;
+    mutable diag_epilogue epilogue_;
+  };
+
+  template <typename B>
+  struct diag_prologue: B
+  {
+    diag_prologue (diag_epilogue e = nullptr): B (), epilogue_ (e) {}
+
+    template <typename... A>
+    diag_prologue (A&&... a)
+        : B (std::forward<A> (a)...), epilogue_ (nullptr) {}
+
+    template <typename... A>
+    diag_prologue (diag_epilogue e, A&&... a)
+        : B (std::forward<A> (a)...), epilogue_ (e) {}
+
+    template <typename T>
+    diag_record
+    operator<< (const T& x) const
+    {
+      diag_record r;
+      r.append (epilogue_);
+      B::operator() (r);
+      r << x;
+      return r;
+    }
+
+    friend const diag_record&
+    operator<< (const diag_record& r, const diag_prologue& p)
+    {
+      r.append (p.epilogue_);
+      p (r);
+      return r;
+    }
+
+  private:
+    diag_epilogue epilogue_;
+  };
+
+  template <typename B>
+  struct diag_mark: B
+  {
+    diag_mark (): B () {}
+
+    template <typename... A>
+    diag_mark (A&&... a): B (std::forward<A> (a)...) {}
+
+    template <typename T>
+    diag_record
+    operator<< (const T& x) const
+    {
+      return B::operator() () << x;
+    }
+
+    friend const diag_record&
+    operator<< (const diag_record& r, const diag_mark& m)
+    {
+      return r << m ();
+    }
+  };
+
+  // Diagnostic facility, project specifics.
+  //
+  struct simple_prologue_base
+  {
+    explicit
+    simple_prologue_base (const char* type, const char* name)
+        : type_ (type), name_ (name) {}
+
+    void
+    operator() (const diag_record& r) const;
+
+  private:
+    const char* type_;
+    const char* name_;
+  };
+  typedef diag_prologue<simple_prologue_base> simple_prologue;
+
+  class location
+  {
+  public:
+    location () {}
+    location (std::string f, std::uint64_t l, std::uint64_t c)
+        : file (std::move (f)), line (l), column (c) {}
+
+    std::string file;
+    std::uint64_t line;
+    std::uint64_t column;
+  };
+
+  struct location_prologue_base
+  {
+    location_prologue_base (const char* type,
+                            const char* name,
+                            const location& l)
+        : type_ (type), name_ (name), loc_ (l) {}
+
+    void
+    operator() (const diag_record& r) const;
+
+  private:
+    const char* type_;
+    const char* name_;
+    const location loc_;
+  };
+  typedef diag_prologue<location_prologue_base> location_prologue;
+
+  struct basic_mark_base
+  {
+    explicit
+    basic_mark_base (const char* type,
+                     const char* name = nullptr,
+                     const void* data = nullptr)
+        : type_ (type), name_ (name), data_ (data) {}
+
+    simple_prologue
+    operator() () const
+    {
+      return simple_prologue (type_, name_);
+    }
+
+    location_prologue
+    operator() (const location& l) const
+    {
+      return location_prologue (type_, name_, l);
+    }
+
+    template <typename L>
+    location_prologue
+    operator() (const L& l) const
+    {
+      return location_prologue (type_, name_, get_location (l, data_));
+    }
+
+  protected:
+    const char* type_;
+    const char* name_;
+    const void* data_;
+  };
+  typedef diag_mark<basic_mark_base> basic_mark;
+
+  extern const basic_mark error;
+  extern const basic_mark warn;
+  extern const basic_mark info;
+  extern const basic_mark text;
+
+  // trace
+  //
+  struct trace_mark_base: basic_mark_base
+  {
+    explicit
+    trace_mark_base (const char* name, const void* data = nullptr)
+        : basic_mark_base ("trace", name, data) {}
+  };
+  typedef diag_mark<trace_mark_base> trace_mark;
+
+  typedef trace_mark tracer;
+
+  // fail
+  //
+  template <typename E>
+  struct fail_mark_base
+  {
+    explicit
+    fail_mark_base (const void* data = nullptr): data_ (data) {}
+
+    simple_prologue
+    operator() () const
+    {
+      return simple_prologue (&epilogue, "error", nullptr);
+    }
+
+    location_prologue
+    operator() (const location& l) const
+    {
+      return location_prologue (&epilogue, "error", nullptr, l);
+    }
+
+    template <typename L>
+    location_prologue
+    operator() (const L& l) const
+    {
+      return location_prologue (
+        &epilogue, "error", nullptr, get_location (l, data_));
+    }
+
+    static void
+    epilogue (const diag_record&) {throw E ();}
+
+  private:
+    const void* data_;
+  };
+
+  template <typename E>
+  using fail_mark = diag_mark<fail_mark_base<E>>;
+
+  extern const fail_mark<failed> fail;
+}
+
+#endif // BPKG_DIAGNOSTICS
diff --git a/bpkg/diagnostics.cxx b/bpkg/diagnostics.cxx
new file mode 100644
index 0000000..2bee18e
--- /dev/null
+++ b/bpkg/diagnostics.cxx
@@ -0,0 +1,70 @@
+// file      : bpkg/diagnostics.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <bpkg/diagnostics>
+
+#include <iostream>
+
+using namespace std;
+
+namespace bpkg
+{
+  // Trace verbosity level.
+  //
+  uint16_t verb;
+
+  // Diagnostic facility, base infrastructure.
+  //
+  ostream* diag_stream = &cerr;
+
+  diag_record::
+  ~diag_record () noexcept(false)
+  {
+    // Don't flush the record if this destructor was called as part of
+    // the stack unwinding. Right now this means we cannot use this
+    // mechanism in destructors, which is not a big deal, except for
+    // one place: exception_guard. So for now we are going to have
+    // this ugly special check which we will be able to get rid of
+    // once C++17 uncaught_exceptions() becomes available.
+    //
+    if (!empty_ && (!uncaught_exception () /*|| exception_unwinding_dtor*/))
+    {
+      *diag_stream << os_.str () << endl;
+
+      if (epilogue_ != nullptr)
+        epilogue_ (*this); // Can throw.
+    }
+  }
+
+  // Diagnostic facility, project specifics.
+  //
+
+  void simple_prologue_base::
+  operator() (const diag_record& r) const
+  {
+    if (type_ != nullptr)
+      r << type_ << ": ";
+
+    if (name_ != nullptr)
+      r << name_ << ": ";
+  }
+
+  void location_prologue_base::
+  operator() (const diag_record& r) const
+  {
+    r << loc_.file << ':' << loc_.line << ':' << loc_.column << ": ";
+
+    if (type_ != nullptr)
+      r << type_ << ": ";
+
+    if (name_ != nullptr)
+      r << name_ << ": ";
+  }
+
+  const basic_mark error ("error");
+  const basic_mark warn ("warning");
+  const basic_mark info ("info");
+  const basic_mark text (nullptr);
+  const fail_mark<failed> fail;
+}