Add support for exclusion of field via field tag.

examples/__snapshots__/simple_test.snap

@@ -68,3 +68,11 @@ it's okay
 [TestSimple/.* - 1]
 ignore regex patterns on names
 ---
+
+[TestSimpleTable/buffer#01 - 1]
+&bytes.Buffer{
+    buf:      {0x42, 0x75, 0x66, 0x66, 0x65, 0x72, 0x20, 0x73, 0x74, 0x72, 0x69, 0x6e, 0x67},
+    off:      0,
+    lastRead: 0,
+}
+---

go.mod

@@ -5,7 +5,6 @@ go 1.16
 require (
 	github.com/gkampitakis/ciinfo v0.1.1
 	github.com/gkampitakis/go-diff v1.3.0
-	github.com/kr/pretty v0.3.0
 )
 
-require github.com/rogpeppe/go-internal v1.9.0 // indirect
+require github.com/kr/text v0.2.0

go.sum

@@ -3,16 +3,5 @@ github.com/gkampitakis/ciinfo v0.1.1 h1:dz1LCkOd+zmZ3YYlFNpr0hRDqGY7Ox2mcaltHzda
 github.com/gkampitakis/ciinfo v0.1.1/go.mod h1:bVaOGziPqf8PoeYZxatq1HmCsJUmv191hLnFboYxd9Y=
 github.com/gkampitakis/go-diff v1.3.0 h1:Szdbo5w73LSQ9sQ02h+NSSf2ZlW/E8naJCI1ZzQtWgE=
 github.com/gkampitakis/go-diff v1.3.0/go.mod h1:QUJDQRA0JkEX0d7tgDaBHzJv9IH6k6e91TByC+9/RFk=
-github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
-github.com/kr/pretty v0.3.0 h1:WgNl7dwNpEZ6jJ9k1snq4pZsg7DOEN8hP9Xw0Tsjwk0=
-github.com/kr/pretty v0.3.0/go.mod h1:640gp4NfQd8pI5XOwp5fnNeVWj67G7CFk/SaSQn7NBk=
-github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
-github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
-github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
-github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
-github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
-github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=

snaps/internal/formatter/formatter.go

@@ -0,0 +1,338 @@
+package formatter
+
+import (
+	"fmt"
+	"io"
+	"reflect"
+	"strconv"
+	"text/tabwriter"
+
+	"github.com/kr/text"
+)
+
+type formatter struct {
+	v     reflect.Value
+	force bool
+	quote bool
+}
+
+// Formatter makes a wrapper, f, that will format x as go source with line
+// breaks and tabs. Object f responds to the "%v" formatting verb when both the
+// "#" and " " (space) flags are set, for example:
+//
+//	fmt.Sprintf("%# v", Formatter(x))
+//
+// If one of these two flags is not set, or any other verb is used, f will
+// format x according to the usual rules of package fmt.
+// In particular, if x satisfies fmt.Formatter, then x.Format will be called.
+func Formatter(x interface{}) (f fmt.Formatter) {
+	return formatter{v: reflect.ValueOf(x), quote: true}
+}
+
+func (fo formatter) String() string {
+	return fmt.Sprint(fo.v.Interface()) // unwrap it
+}
+
+func (fo formatter) passThrough(f fmt.State, c rune) {
+	s := "%"
+	for i := 0; i < 128; i++ {
+		if f.Flag(i) {
+			s += fmt.Sprint(i)
+		}
+	}
+	if w, ok := f.Width(); ok {
+		s += fmt.Sprintf("%d", w)
+	}
+	if p, ok := f.Precision(); ok {
+		s += fmt.Sprintf(".%d", p)
+	}
+	s += string(c)
+	fmt.Fprintf(f, s, fo.v.Interface())
+}
+
+func (fo formatter) Format(f fmt.State, c rune) {
+	if fo.force || c == 'v' && f.Flag('#') && f.Flag(' ') {
+		w := tabwriter.NewWriter(f, 4, 4, 1, ' ', 0)
+		p := &printer{tw: w, Writer: w, visited: make(map[visit]int)}
+		p.printValue(fo.v, true, fo.quote)
+		w.Flush()
+		return
+	}
+	fo.passThrough(f, c)
+}
+
+type printer struct {
+	io.Writer
+	tw      *tabwriter.Writer
+	visited map[visit]int
+	depth   int
+}
+
+func (p *printer) indent() *printer {
+	q := *p
+	q.tw = tabwriter.NewWriter(p.Writer, 4, 4, 1, ' ', 0)
+	q.Writer = text.NewIndentWriter(q.tw, []byte{'\t'})
+	return &q
+}
+
+func (p *printer) printInline(v reflect.Value, x interface{}, showType bool) {
+	if showType {
+		io.WriteString(p, v.Type().String())
+		fmt.Fprintf(p, "(%#v)", x)
+	} else {
+		fmt.Fprintf(p, "%#v", x)
+	}
+}
+
+// printValue must keep track of already-printed pointer values to avoid
+// infinite recursion.
+type visit struct {
+	v   uintptr
+	typ reflect.Type
+}
+
+func (p *printer) printValue(v reflect.Value, showType, quote bool) {
+	if p.depth > 10 {
+		io.WriteString(p, "!%v(DEPTH EXCEEDED)")
+		return
+	}
+
+	switch v.Kind() {
+	case reflect.Bool:
+		p.printInline(v, v.Bool(), showType)
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		p.printInline(v, v.Int(), showType)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		p.printInline(v, v.Uint(), showType)
+	case reflect.Float32, reflect.Float64:
+		p.printInline(v, v.Float(), showType)
+	case reflect.Complex64, reflect.Complex128:
+		fmt.Fprintf(p, "%#v", v.Complex())
+	case reflect.String:
+		p.fmtString(v.String(), quote)
+	case reflect.Map:
+		t := v.Type()
+		if showType {
+			io.WriteString(p, t.String())
+		}
+		writeByte(p, '{')
+		if nonzero(v) {
+			expand := !canInline(v.Type())
+			pp := p
+			if expand {
+				writeByte(p, '\n')
+				pp = p.indent()
+			}
+			keys := v.MapKeys()
+			for i := 0; i < v.Len(); i++ {
+				showTypeInStruct := true
+				k := keys[i]
+				mv := v.MapIndex(k)
+				pp.printValue(k, false, true)
+				writeByte(pp, ':')
+				if expand {
+					writeByte(pp, '\t')
+				}
+				showTypeInStruct = t.Elem().Kind() == reflect.Interface
+				pp.printValue(mv, showTypeInStruct, true)
+				if expand {
+					io.WriteString(pp, ",\n")
+				} else if i < v.Len()-1 {
+					io.WriteString(pp, ", ")
+				}
+			}
+			if expand {
+				pp.tw.Flush()
+			}
+		}
+		writeByte(p, '}')
+	case reflect.Struct:
+		t := v.Type()
+		if v.CanAddr() {
+			addr := v.UnsafeAddr()
+			vis := visit{addr, t}
+			if vd, ok := p.visited[vis]; ok && vd < p.depth {
+				p.fmtString(t.String()+"{(CYCLIC REFERENCE)}", false)
+				break // don't print v again
+			}
+			p.visited[vis] = p.depth
+		}
+
+		if showType {
+			io.WriteString(p, t.String())
+		}
+		writeByte(p, '{')
+		if nonzero(v) {
+			expand := !canInline(v.Type())
+			pp := p
+			if expand {
+				writeByte(p, '\n')
+				pp = p.indent()
+			}
+
+			numfields := v.NumField()
+			writecomma := false
+			for i := 0; i < numfields; i++ {
+				fieldTag := t.Field(i)
+				val := fieldTag.Tag.Get("go-snaps")
+				if val == "-" {
+					continue
+				}
+				if writecomma && !expand && i > 0 {
+					io.WriteString(pp, ", ")
+				}
+				showTypeInStruct := true
+				if f := t.Field(i); f.Name != "" {
+					io.WriteString(pp, f.Name)
+					writeByte(pp, ':')
+					if expand {
+						writeByte(pp, '\t')
+					}
+					showTypeInStruct = labelType(f.Type)
+					writecomma = true
+				}
+				pp.printValue(getField(v, i), showTypeInStruct, true)
+				if expand {
+					io.WriteString(pp, ",\n")
+				}
+			}
+			if expand {
+				pp.tw.Flush()
+			}
+		}
+		writeByte(p, '}')
+	case reflect.Interface:
+		switch e := v.Elem(); {
+		case e.Kind() == reflect.Invalid:
+			io.WriteString(p, "nil")
+		case e.IsValid():
+			pp := *p
+			pp.depth++
+			pp.printValue(e, showType, true)
+		default:
+			io.WriteString(p, v.Type().String())
+			io.WriteString(p, "(nil)")
+		}
+	case reflect.Array, reflect.Slice:
+		t := v.Type()
+		if showType {
+			io.WriteString(p, t.String())
+		}
+		if v.Kind() == reflect.Slice && v.IsNil() && showType {
+			io.WriteString(p, "(nil)")
+			break
+		}
+		if v.Kind() == reflect.Slice && v.IsNil() {
+			io.WriteString(p, "nil")
+			break
+		}
+		writeByte(p, '{')
+		expand := !canInline(v.Type())
+		pp := p
+		if expand {
+			writeByte(p, '\n')
+			pp = p.indent()
+		}
+		for i := 0; i < v.Len(); i++ {
+			showTypeInSlice := t.Elem().Kind() == reflect.Interface
+			pp.printValue(v.Index(i), showTypeInSlice, true)
+			if expand {
+				io.WriteString(pp, ",\n")
+			} else if i < v.Len()-1 {
+				io.WriteString(pp, ", ")
+			}
+		}
+		if expand {
+			pp.tw.Flush()
+		}
+		writeByte(p, '}')
+	case reflect.Ptr:
+		e := v.Elem()
+		if !e.IsValid() {
+			writeByte(p, '(')
+			io.WriteString(p, v.Type().String())
+			io.WriteString(p, ")(nil)")
+		} else {
+			pp := *p
+			pp.depth++
+			writeByte(pp, '&')
+			pp.printValue(e, true, true)
+		}
+	case reflect.Chan:
+		x := v.Pointer()
+		if showType {
+			writeByte(p, '(')
+			io.WriteString(p, v.Type().String())
+			fmt.Fprintf(p, ")(%#v)", x)
+		} else {
+			fmt.Fprintf(p, "%#v", x)
+		}
+	case reflect.Func:
+		io.WriteString(p, v.Type().String())
+		io.WriteString(p, " {...}")
+	case reflect.UnsafePointer:
+		p.printInline(v, v.Pointer(), showType)
+	case reflect.Invalid:
+		io.WriteString(p, "nil")
+	}
+}
+
+func canInline(t reflect.Type) bool {
+	switch t.Kind() {
+	case reflect.Map:
+		return !canExpand(t.Elem())
+	case reflect.Struct:
+		for i := 0; i < t.NumField(); i++ {
+			if canExpand(t.Field(i).Type) {
+				return false
+			}
+		}
+		return true
+	case reflect.Interface:
+		return false
+	case reflect.Array, reflect.Slice:
+		return !canExpand(t.Elem())
+	case reflect.Ptr:
+		return false
+	case reflect.Chan, reflect.Func, reflect.UnsafePointer:
+		return false
+	}
+	return true
+}
+
+func canExpand(t reflect.Type) bool {
+	switch t.Kind() {
+	case reflect.Map, reflect.Struct,
+		reflect.Interface, reflect.Array, reflect.Slice,
+		reflect.Ptr:
+		return true
+	}
+	return false
+}
+
+func labelType(t reflect.Type) bool {
+	switch t.Kind() {
+	case reflect.Interface, reflect.Struct:
+		return true
+	}
+	return false
+}
+
+func (p *printer) fmtString(s string, quote bool) {
+	if quote {
+		s = strconv.Quote(s)
+	}
+	io.WriteString(p, s)
+}
+
+func writeByte(w io.Writer, b byte) {
+	w.Write([]byte{b})
+}
+
+func getField(v reflect.Value, i int) reflect.Value {
+	val := v.Field(i)
+	if val.Kind() == reflect.Interface && !val.IsNil() {
+		val = val.Elem()
+	}
+	return val
+}