From 1ff42722ce44f485c7dfabc6bb370494080f2755 Mon Sep 17 00:00:00 2001
From: Ben Burdette <bburdette@gmail.com>
Date: Sun, 26 Apr 2020 14:47:41 -0600
Subject: [PATCH] error.hh

---
 src/libutil/error.hh | 157 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 157 insertions(+)
 create mode 100644 src/libutil/error.hh

diff --git a/src/libutil/error.hh b/src/libutil/error.hh
new file mode 100644
index 000000000..e33b1d3d6
--- /dev/null
+++ b/src/libutil/error.hh
@@ -0,0 +1,157 @@
+#pragma once
+
+
+#include "ref.hh"
+
+#include <list>
+#include <memory>
+#include <map>
+#include <optional>
+
+#include "fmt.hh"
+
+/* Before 4.7, gcc's std::exception uses empty throw() specifiers for
+ * its (virtual) destructor and what() in c++11 mode, in violation of spec
+ */
+#ifdef __GNUC__
+#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
+#define EXCEPTION_NEEDS_THROW_SPEC
+#endif
+#endif
+
+namespace nix {
+
+using std::list;
+using std::vector;
+
+typedef enum {
+    lvlError = 0,
+    lvlWarn,
+    lvlInfo,
+    lvlTalkative,
+    lvlChatty,
+    lvlDebug,
+    lvlVomit
+} Verbosity;
+
+struct ErrPos
+{
+    int line;
+    int column;
+    string file;
+
+    template <class P>
+    ErrPos& operator=(const P &pos)
+    {
+        line = pos.line;
+        column = pos.column;
+        file = pos.file;
+        return *this;
+    }
+
+    template <class P>
+    ErrPos(const P &p)
+    {
+      *this = p;
+    }
+};
+
+struct NixCode
+{
+    ErrPos errPos;
+    std::optional<string> prevLineOfCode;
+    string errLineOfCode;
+    std::optional<string> nextLineOfCode;
+};
+
+// -------------------------------------------------
+// ErrorInfo.
+struct ErrorInfo
+{
+    Verbosity level;
+    string name;
+    string description;
+    std::optional<hintformat> hint;
+    std::optional<NixCode> nixCode;
+
+    static std::optional<string> programName;
+};
+
+std::ostream& operator<<(std::ostream &out, const ErrorInfo &einfo);
+
+/* BaseError should generally not be caught, as it has Interrupted as
+   a subclass. Catch Error instead. */
+class BaseError : public std::exception
+{
+protected:
+    string prefix_; // used for location traces etc.
+    ErrorInfo err;
+    string what_;
+    void initWhat() 
+    {
+        std::ostringstream oss;
+        oss << err;
+        what_ = oss.str();
+    }
+public:
+    unsigned int status = 1; // exit status
+
+    template<typename... Args>
+    BaseError(unsigned int status, const Args & ... args)
+        : err { .level = lvlError,
+                .hint = hintfmt(args...)
+              }
+        , status(status)
+    { initWhat(); }
+
+    template<typename... Args>
+    BaseError(const Args & ... args)
+        : err { .level = lvlError, 
+                .hint = hintfmt(args...)
+              }
+    { initWhat(); }
+
+    BaseError(ErrorInfo e)
+        : err(e)
+    { initWhat(); }
+
+#ifdef EXCEPTION_NEEDS_THROW_SPEC
+    ~BaseError() throw () { };
+    const char * what() const throw () { return what_.c_str(); }
+#else
+    const char * what() const noexcept { return what_.c_str(); }
+#endif
+
+    const string & msg() const { return what_; }
+    const string & prefix() const { return prefix_; }
+    BaseError & addPrefix(const FormatOrString & fs);
+
+    const ErrorInfo & info() const { return err; }
+};
+
+#define MakeError(newClass, superClass) \
+    class newClass : public superClass                  \
+    {                                                   \
+    public:                                             \
+        using superClass::superClass;                   \
+    }
+
+MakeError(Error, BaseError);
+
+class SysError : public Error
+{
+public:
+    int errNo;
+
+    template<typename... Args>
+    SysError(const Args & ... args)
+        : Error(args...)  // TODO addErrNo for hintfmt
+        // : Error(addErrno(hintfmt(args...)))
+    { }
+
+private:
+
+    std::string addErrno(const std::string & s);
+};
+
+}