Add license

Author: Dean Karn

LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2018 Dean Karn
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

errors.go

@@ -4,11 +4,11 @@ package errors
 // a stack trace.
 func Wrap(err error, prefix string) *Wrapped {
 	if w, ok := err.(*Wrapped); ok {
-		w.errors = append(w.errors, newWrapped(err, prefix))
+		w.Errors = append(w.Errors, newWrapped(err, prefix))
 		return w
 	}
 	return &Wrapped{
-		errors: []*Wrapped{newWrapped(err, prefix)},
+		Errors: []*Wrapped{newWrapped(err, prefix)},
 	}
 }
 
@@ -19,9 +19,9 @@ func HasType(err error, typ string) bool {
 	if !ok {
 		return false
 	}
-	for i := len(w.errors) - 1; i >= 0; i-- {
-		for j := 0; j < len(w.errors[i].Types); j++ {
-			if w.errors[i].Types[j] == typ {
+	for i := len(w.Errors) - 1; i >= 0; i-- {
+		for j := 0; j < len(w.Errors[i].Types); j++ {
+			if w.Errors[i].Types[j] == typ {
 				return true
 			}
 		}
@@ -32,7 +32,12 @@ func HasType(err error, typ string) bool {
 // Cause extracts and returns the root error
 func Cause(err error) error {
 	if w, ok := err.(*Wrapped); ok {
-		return w.errors[0]
+		// if root level error
+		if len(w.Errors) > 0 {
+			return w.Errors[0]
+		}
+		// already extracted error
+		return w
 	}
 	return err
 }
@@ -42,8 +47,8 @@ func Cause(err error) error {
 func IsErr(err, errType error) bool {
 	if w, ok := err.(*Wrapped); ok {
 		// if root level error
-		if len(w.errors) > 0 {
-			return w.errors[0].Err == errType
+		if len(w.Errors) > 0 {
+			return w.Errors[0].Err == errType
 		}
 		// already extracted error
 		return w.Err == errType

stack.go

@@ -148,3 +148,11 @@ func Stack() Frame {
 	s := callers()
 	return fr(s, 0)
 }
+
+// StackLevel returns a stack from for parsing into a trace line
+// this is primarily used by other libraries who use this pacakge
+// internally as the level needs to be adjusted.
+func StackLevel(level int) Frame {
+	s := callers()
+	return fr(s, level)
+}

wrapped.go

@@ -29,7 +29,7 @@ func newWrapped(err error, prefix string) *Wrapped {
 // which case it only contains an array of errors
 type Wrapped struct {
 	// hidden field with wrapped errors, will expose a helper method to get this
-	errors []*Wrapped
+	Errors []*Wrapped
 
 	// Err is the wrapped error, either the original or already wrapped
 	Err error
@@ -49,11 +49,11 @@ type Wrapped struct {
 
 // Error returns the formatted error string
 func (w *Wrapped) Error() string {
-	if len(w.errors) > 0 {
-		lines := make([]string, 0, len(w.errors))
+	if len(w.Errors) > 0 {
+		lines := make([]string, 0, len(w.Errors))
 		// source=<source> <prefix>: <error> tag=value tag2=value2 types=type1,type2
-		for i := len(w.errors) - 1; i >= 0; i-- {
-			line := w.errors[i].parseLine()
+		for i := len(w.Errors) - 1; i >= 0; i-- {
+			line := w.Errors[i].parseLine()
 			lines = append(lines, line)
 		}
 		return strings.Join(lines, "\n")
@@ -80,7 +80,7 @@ func (w *Wrapped) parseLine() string {
 
 // helper method to get the current *Wrapped from the top level
 func (w *Wrapped) current() *Wrapped {
-	return w.errors[len(w.errors)-1]
+	return w.Errors[len(w.Errors)-1]
 }
 
 // WithTags allows the addition of multiple tags