GoPathCallerEncoder (#304)

Add GoPathCallerEncoder that trims caller file to compile time $GOPATH.
Use it by default.
$GOPATH trim logic based on go-stack/stack which is under Apache license, so can't be put in repo.
So required logic have been moved to another repo, and exported.

glide.yaml

@@ -2,6 +2,7 @@ package: go.uber.org/zap
 license: MIT
 import:
 - package: go.uber.org/atomic
+- package: github.com/skipor/goenv
 testImport:
 - package: github.com/satori/go.uuid
 - package: github.com/sirupsen/logrus

zapcore/encoder.go

@@ -24,7 +24,10 @@ import (
 	"strings"
 	"time"
 
+	"github.com/skipor/goenv"
+
 	"go.uber.org/zap/buffer"
+	"go.uber.org/zap/internal/bufferpool"
 )
 
 // A LevelEncoder serializes a Level to a primitive type.
@@ -146,13 +149,30 @@ func FullPathCallerEncoder(caller EntryCaller, enc PrimitiveArrayEncoder) {
 	enc.AppendString(caller.String())
 }
 
+func GoPathCallerEncoder(caller EntryCaller, enc PrimitiveArrayEncoder) {
+	if !caller.Defined {
+		enc.AppendString("")
+		return
+	}
+	buf := bufferpool.Get()
+	buf.AppendString(goenv.TrimGoPathSrc(caller.File))
+	buf.AppendByte(':')
+	buf.AppendInt(int64(caller.Line))
+	// OPTIMIZE: after adding AppendBytes to PrimitiveArrayEncoder just copy bytes
+	// from buffer to not allocate string.
+	str := buf.String()
+	bufferpool.Put(buf)
+	enc.AppendString(str)
+}
+
 // UnmarshalText unmarshals text to a CallerEncoder.
 // Anything is unmarshaled to FullPathCallerEncoder at that moment.
 func (e *CallerEncoder) UnmarshalText(text []byte) error {
 	switch string(text) {
-	//case "gopath": // TODO
-	default:
+	case "full":
 		*e = FullPathCallerEncoder
+	default:
+		*e = GoPathCallerEncoder
 	}
 	return nil
 }

zapcore/encoder_test.go

@@ -27,6 +27,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	"github.com/skipor/goenv"
 	. "go.uber.org/zap/zapcore"
 )
 
@@ -468,13 +469,14 @@ func TestDurationEncoders(t *testing.T) {
 }
 
 func TestCallerEncoders(t *testing.T) {
-	caller := _testEntry.Caller
+	caller := EntryCaller{Defined: true, File: goenv.GoPathSrc() + "a/b/foo.go", Line: 42}
 	tests := []struct {
 		name     string
 		expected interface{} // output of serializing caller
 	}{
-		{"", "foo.go:42"},
-		{"something-random", "foo.go:42"},
+		{"", "a/b/foo.go:42"},
+		{"something-random", "a/b/foo.go:42"},
+		{"full", caller.File + ":42"},
 	}
 
 	for _, tt := range tests {
@@ -484,7 +486,7 @@ func TestCallerEncoders(t *testing.T) {
 			t,
 			tt.expected,
 			func(arr ArrayEncoder) { ce(caller, arr) },
-			"Unexpected output serializing InfoLevel with %q.", tt.name,
+			"Unexpected output serializing file name as %v with %q.", tt.expected, tt.name,
 		)
 	}
 }