Performance improvements and cleanup

.editorconfig

@@ -0,0 +1,2 @@
+[*]
+end_of_line = lf

.gitattributes

@@ -0,0 +1 @@
+* text=auto eol=lf

README.md

@@ -158,15 +158,18 @@ err = err.Unwrap()
 
 ## Performance
 
-Stack trace causes a performance overhead, depending on a stack trace depth. This can be insignificant in a number of situations (such as HTTP request handling), however, avoid of adding a stack trace for really hot spots where a high number of errors created frequently, this can be inefficient.
-
-> Benchmarks done on a MacBook Pro 2015 with go 1.11.
-
 Benchmarks for creating a new error with a stack trace of different depth:
 
 ```
-BenchmarkNew/5    200000    5646 ns/op    976 B/op   4 allocs/op
-BenchmarkNew/10   200000   11565 ns/op    976 B/op   4 allocs/op
-BenchmarkNew/20    50000   25629 ns/op    976 B/op   4 allocs/op
-BenchmarkNew/40    20000   65833 ns/op   2768 B/op   5 allocs/op
+GOMAXPROCS=1 go test -bench=. -benchmem
+goos: linux
+goarch: amd64
+pkg: github.com/ztrue/tracerr
+cpu: Intel(R) Core(TM) i7-14700KF
+BenchmarkNew/5           4500129               267.1 ns/op           256 B/op          4 allocs/op
+BenchmarkNew/10          3325456               359.5 ns/op           256 B/op          4 allocs/op
+BenchmarkNew/20          1000000              1001 ns/op             576 B/op          5 allocs/op
+BenchmarkNew/40           538689              2171 ns/op            1216 B/op          6 allocs/op
+PASS
+ok      github.com/ztrue/tracerr        5.246s
 ```

colors.go

@@ -15,7 +15,7 @@ func bold(in string) string {
 }
 
 func black(in string) string {
-	return color(30, in)
+	return color(90, in)
 }
 
 func red(in string) string {

error.go

@@ -24,7 +24,9 @@ type Error interface {
 type errorData struct {
 	// err contains original error.
 	err error
-	// frames contains stack trace of an error.
+	// pcs contains raw program counters, resolved lazily to frames.
+	pcs []uintptr
+	// frames contains pre-resolved stack trace.
 	frames []Frame
 }
 
@@ -76,8 +78,26 @@ func (e *errorData) Error() string {
 	return e.err.Error()
 }
 
-// StackTrace returns stack trace of an error.
+// StackTrace resolves and returns the stack trace, caching the result.
 func (e *errorData) StackTrace() []Frame {
+	if e.pcs == nil {
+		return e.frames
+	}
+	cf := runtime.CallersFrames(e.pcs)
+	frames := make([]Frame, 0, len(e.pcs))
+	for {
+		f, more := cf.Next()
+		frames = append(frames, Frame{
+			Func: f.Function,
+			Line: f.Line,
+			Path: f.File,
+		})
+		if !more {
+			break
+		}
+	}
+	e.frames = frames
+	e.pcs = nil
 	return e.frames
 }
 
@@ -112,23 +132,17 @@ func (f Frame) String() string {
 }
 
 func trace(err error, skip int) Error {
-	frames := make([]Frame, 0, DefaultCap)
+	pcs := make([]uintptr, DefaultCap)
 	for {
-		pc, path, line, ok := runtime.Caller(skip)
-		if !ok {
+		n := runtime.Callers(skip+1, pcs)
+		if n < len(pcs) {
+			pcs = pcs[:n]
 			break
 		}
-		fn := runtime.FuncForPC(pc)
-		frame := Frame{
-			Func: fn.Name(),
-			Line: line,
-			Path: path,
-		}
-		frames = append(frames, frame)
-		skip++
+		pcs = make([]uintptr, len(pcs)*2)
 	}
 	return &errorData{
-		err:    err,
-		frames: frames,
+		err: err,
+		pcs: pcs,
 	}
 }

error_test.go

@@ -235,6 +235,20 @@ func TestCustomError(t *testing.T) {
 	}
 }
 
+func TestDeepStack(t *testing.T) {
+	var recurse func(n int) error
+	recurse = func(n int) error {
+		if n == 0 {
+			return tracerr.New("deep error")
+		}
+		return recurse(n - 1)
+	}
+	err := recurse(25).(tracerr.Error)
+	if len(err.StackTrace()) < 25 {
+		t.Errorf("expected at least 25 frames, got %d", len(err.StackTrace()))
+	}
+}
+
 func TestErrorNil(t *testing.T) {
 	wrapped := wrapError(nil)
 	if wrapped != nil {

print.go

@@ -127,22 +127,27 @@ func sourceRows(rows []string, frame Frame, before, after int, colorized bool) [
 	current := frame.Line - 1
 	start := current - before
 	end := current + after
+	maxLine := end + 1
+	if maxLine > len(lines) {
+		maxLine = len(lines)
+	}
+	width := len(strconv.Itoa(maxLine))
 	for i := start; i <= end; i++ {
 		if i < 0 || i >= len(lines) {
 			continue
 		}
 		line := lines[i]
 		var message string
-		// TODO Pad to the same length.
+		lineNum := fmt.Sprintf("%*d", width, i+1)
 		if i == frame.Line-1 {
-			message = fmt.Sprintf("%d\t%s", i+1, line)
+			message = fmt.Sprintf("%s\t%s", lineNum, line)
 			if colorized {
 				message = red(message)
 			}
 		} else if colorized {
-			message = fmt.Sprintf("%s\t%s", black(strconv.Itoa(i+1)), line)
+			message = fmt.Sprintf("%s\t%s", black(lineNum), line)
 		} else {
-			message = fmt.Sprintf("%d\t%s", i+1, line)
+			message = fmt.Sprintf("%s\t%s", lineNum, line)
 		}
 		rows = append(rows, message)
 	}

print_test.go

@@ -85,10 +85,10 @@ func TestPrint(t *testing.T) {
 				"15\t",
 				"",
 				"/tracerr/error_helper_test.go:9 github.com/ztrue/tracerr_test.addFrameA()",
-				"6\t)",
-				"7\t",
-				"8\tfunc addFrameA(message string) error {",
-				"9\t\treturn addFrameB(message)",
+				" 6\t)",
+				" 7\t",
+				" 8\tfunc addFrameA(message string) error {",
+				" 9\t\treturn addFrameB(message)",
 				"10\t}",
 				"11\t",
 				"",
@@ -124,9 +124,9 @@ func TestPrint(t *testing.T) {
 				"14\t}",
 				"",
 				"/tracerr/error_helper_test.go:9 github.com/ztrue/tracerr_test.addFrameA()",
-				"7\t",
-				"8\tfunc addFrameA(message string) error {",
-				"9\t\treturn addFrameB(message)",
+				" 7\t",
+				" 8\tfunc addFrameA(message string) error {",
+				" 9\t\treturn addFrameB(message)",
 				"10\t}",
 				"",
 				"/tracerr/print_test.go:26 github.com/ztrue/tracerr_test.TestPrint()",
@@ -159,9 +159,9 @@ func TestPrint(t *testing.T) {
 				"14\t}",
 				"",
 				"/tracerr/error_helper_test.go:9 github.com/ztrue/tracerr_test.addFrameA()",
-				"7\t",
-				"8\tfunc addFrameA(message string) error {",
-				"9\t\treturn addFrameB(message)",
+				" 7\t",
+				" 8\tfunc addFrameA(message string) error {",
+				" 9\t\treturn addFrameB(message)",
 				"10\t}",
 				"",
 				"/tracerr/print_test.go:26 github.com/ztrue/tracerr_test.TestPrint()",
@@ -217,7 +217,7 @@ func TestPrint(t *testing.T) {
 				"17\t\treturn tracerr.New(message)",
 				"",
 				"/tracerr/error_helper_test.go:9 github.com/ztrue/tracerr_test.addFrameA()",
-				"9\t\treturn addFrameB(message)",
+				" 9\t\treturn addFrameB(message)",
 				"10\t}",
 				"11\t",
 				"12\tfunc addFrameB(message string) error {",
@@ -251,8 +251,8 @@ func TestPrint(t *testing.T) {
 				black("14") + "\t}",
 				"",
 				bold("/tracerr/error_helper_test.go:9 github.com/ztrue/tracerr_test.addFrameA()"),
-				black("8") + "\tfunc addFrameA(message string) error {",
-				red("9\t\treturn addFrameB(message)"),
+				black(" 8") + "\tfunc addFrameA(message string) error {",
+				red(" 9\t\treturn addFrameB(message)"),
 				black("10") + "\t}",
 				"",
 				bold("/tracerr/print_test.go:26 github.com/ztrue/tracerr_test.TestPrint()"),
@@ -459,7 +459,7 @@ func bold(in string) string {
 }
 
 func black(in string) string {
-	return fmt.Sprintf("\x1b[30m%s\x1b[0m", in)
+	return fmt.Sprintf("\x1b[90m%s\x1b[0m", in)
 }
 
 func red(in string) string {