Add information about error occurrence place

[goredo.git] / err.go

diff --git a/err.go b/err.go
new file mode 100644 (file)
index 0000000..9240a3e
--- /dev/null
+++ b/err.go
@@ -0,0 +1,56 @@
+/*
+goredo -- djb's redo implementation on pure Go
+Copyright (C) 2020-2023 Sergey Matveev <stargrave@stargrave.org>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, version 3 of the License.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package main
+
+import (
+       "errors"
+       "fmt"
+       "runtime"
+)
+
+type ErrLineErr struct {
+       err      error
+       file     string
+       line     int
+       function string
+}
+
+func (err ErrLineErr) Error() string {
+       return fmt.Sprintf("%s:%d: %s: %s", err.file, err.line, err.function, err.err)
+}
+
+func (err ErrLineErr) Unwrap() error {
+       return err.err
+}
+
+func ErrLine(err error) error {
+       if err == nil {
+               return err
+       }
+       pc := make([]uintptr, 10)
+       n := runtime.Callers(2, pc)
+       pc = pc[:n]
+       frames := runtime.CallersFrames(pc)
+       frame, _ := frames.Next()
+       var errLine ErrLineErr
+       if errors.As(err, &errLine) {
+               errLine.function = frame.Function + "," + errLine.function
+               return errLine
+       }
+       return ErrLineErr{err, frame.File, frame.Line, frame.Function}
+}