Fix Unmarshaler call when value is missing (#439)

Fixes #431

azure-pipelines.yml

@@ -13,9 +13,9 @@ stages:
       vmImage: ubuntu-latest
     steps:
     - task: GoTool@0
-      displayName: "Install Go 1.14"
+      displayName: "Install Go 1.15"
       inputs:
-        version: "1.14"
+        version: "1.15"
     - script: echo "##vso[task.setvariable variable=PATH]${PATH}:/home/vsts/go/bin/"
     - script: mkdir -p ${HOME}/go/src/github.com/pelletier/go-toml
     - script: cp -R . ${HOME}/go/src/github.com/pelletier/go-toml
@@ -36,9 +36,9 @@ stages:
       vmImage: ubuntu-latest
     steps:
     - task: GoTool@0
-      displayName: "Install Go 1.14"
+      displayName: "Install Go 1.15"
       inputs:
-        version: "1.14"
+        version: "1.15"
     - task: Go@0
       displayName: "go fmt ./..."
       inputs:
@@ -51,9 +51,9 @@ stages:
       vmImage: ubuntu-latest
     steps:
     - task: GoTool@0
-      displayName: "Install Go 1.14"
+      displayName: "Install Go 1.15"
       inputs:
-        version: "1.14"
+        version: "1.15"
     - task: Go@0
       displayName: "Generate coverage"
       inputs:
@@ -71,9 +71,9 @@ stages:
       vmImage: ubuntu-latest
     steps:
     - task: GoTool@0
-      displayName: "Install Go 1.14"
+      displayName: "Install Go 1.15"
       inputs:
-        version: "1.14"
+        version: "1.15"
     - script: echo "##vso[task.setvariable variable=PATH]${PATH}:/home/vsts/go/bin/"
     - task: Bash@3
       inputs:
@@ -86,9 +86,9 @@ stages:
       vmImage: ubuntu-latest
     steps:
     - task: GoTool@0
-      displayName: "Install Go 1.14"
+      displayName: "Install Go 1.15"
       inputs:
-        version: "1.14"
+        version: "1.15"
     - script: echo "##vso[task.setvariable variable=PATH]${PATH}:/home/vsts/go/bin/"
     - script: mkdir -p ${HOME}/go/src/github.com/pelletier/go-toml
     - script: cp -R . ${HOME}/go/src/github.com/pelletier/go-toml
@@ -102,6 +102,15 @@ stages:
     displayName: "unit tests"
     strategy:
       matrix:
+        linux 1.15:
+          goVersion: '1.15'
+          imageName: 'ubuntu-latest'
+        mac 1.15:
+          goVersion: '1.15'
+          imageName: 'macOS-latest'
+        windows 1.15:
+          goVersion: '1.15'
+          imageName: 'windows-latest'
         linux 1.14:
           goVersion: '1.14'
           imageName: 'ubuntu-latest'
@@ -111,15 +120,6 @@ stages:
         windows 1.14:
           goVersion: '1.14'
           imageName: 'windows-latest'
-        linux 1.13:
-          goVersion: '1.13'
-          imageName: 'ubuntu-latest'
-        mac 1.13:
-          goVersion: '1.13'
-          imageName: 'macOS-latest'
-        windows 1.13:
-          goVersion: '1.13'
-          imageName: 'windows-latest'
     pool:
       vmImage: $(imageName)
     steps:
@@ -155,7 +155,7 @@ stages:
     - task: GoTool@0
       displayName: "Install Go"
       inputs:
-        version: 1.14
+        version: 1.15
     - task: Bash@3
       inputs:
         targetType: inline

benchmark.sh

@@ -20,11 +20,15 @@ git clone ${reference_git} ${ref_tempdir} >/dev/null 2>/dev/null
 pushd ${ref_tempdir} >/dev/null
 git checkout ${reference_ref} >/dev/null 2>/dev/null
 go test -bench=. -benchmem | tee ${ref_benchmark}
+cd benchmark
+go test -bench=. -benchmem | tee -a ${ref_benchmark}
 popd >/dev/null
 
 echo ""
 echo "=== local"
 go test -bench=. -benchmem  | tee ${local_benchmark}
+cd benchmark
+go test -bench=. -benchmem | tee -a ${local_benchmark}
 
 echo ""
 echo "=== diff"

benchmark/benchmark_test.go

@@ -1,4 +1,4 @@
-package toml
+package benchmark
 
 import (
 	"bytes"
@@ -8,7 +8,8 @@ import (
 	"time"
 
 	burntsushi "github.com/BurntSushi/toml"
-	yaml "gopkg.in/yaml.v2"
+	"github.com/pelletier/go-toml"
+	"gopkg.in/yaml.v2"
 )
 
 type benchmarkDoc struct {
@@ -124,7 +125,7 @@ func BenchmarkParseToml(b *testing.B) {
 	}
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		_, err := LoadReader(bytes.NewReader(fileBytes))
+		_, err := toml.LoadReader(bytes.NewReader(fileBytes))
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -139,7 +140,7 @@ func BenchmarkUnmarshalToml(b *testing.B) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		target := benchmarkDoc{}
-		err := Unmarshal(bytes, &target)
+		err := toml.Unmarshal(bytes, &target)
 		if err != nil {
 			b.Fatal(err)
 		}

benchmark/go.mod

@@ -0,0 +1,11 @@
+module github.com/pelletier/go-toml/benchmark
+
+go 1.12
+
+require (
+	github.com/BurntSushi/toml v0.3.1
+	github.com/pelletier/go-toml v0.0.0
+	gopkg.in/yaml.v2 v2.3.0
+)
+
+replace github.com/pelletier/go-toml => ../

benchmark/go.sum

@@ -0,0 +1,8 @@
+github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
+gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

go.mod

@@ -2,8 +2,4 @@ module github.com/pelletier/go-toml
 
 go 1.12
 
-require (
+require github.com/davecgh/go-spew v1.1.1
-	github.com/BurntSushi/toml v0.3.1
-	github.com/davecgh/go-spew v1.1.1
-	gopkg.in/yaml.v2 v2.3.0
-)

lexer.go

@@ -306,7 +306,7 @@ func (l *tomlLexer) lexComma() tomlLexStateFn {
 // Parse the key and emits its value without escape sequences.
 // bare keys, basic string keys and literal string keys are supported.
 func (l *tomlLexer) lexKey() tomlLexStateFn {
-	growingString := ""
+	var sb strings.Builder
 
 	for r := l.peek(); isKeyChar(r) || r == '\n' || r == '\r'; r = l.peek() {
 		if r == '"' {
@@ -315,7 +315,9 @@ func (l *tomlLexer) lexKey() tomlLexStateFn {
 			if err != nil {
 				return l.errorf(err.Error())
 			}
-			growingString += "\"" + str + "\""
+			sb.WriteString("\"")
+			sb.WriteString(str)
+			sb.WriteString("\"")
 			l.next()
 			continue
 		} else if r == '\'' {
@@ -324,41 +326,45 @@ func (l *tomlLexer) lexKey() tomlLexStateFn {
 			if err != nil {
 				return l.errorf(err.Error())
 			}
-			growingString += "'" + str + "'"
+			sb.WriteString("'")
+			sb.WriteString(str)
+			sb.WriteString("'")
 			l.next()
 			continue
 		} else if r == '\n' {
 			return l.errorf("keys cannot contain new lines")
 		} else if isSpace(r) {
-			str := " "
+			var str strings.Builder
+			str.WriteString(" ")
+
 			// skip trailing whitespace
 			l.next()
 			for r = l.peek(); isSpace(r); r = l.peek() {
-				str += string(r)
+				str.WriteRune(r)
 				l.next()
 			}
 			// break loop if not a dot
 			if r != '.' {
 				break
 			}
-			str += "."
+			str.WriteString(".")
 			// skip trailing whitespace after dot
 			l.next()
 			for r = l.peek(); isSpace(r); r = l.peek() {
-				str += string(r)
+				str.WriteRune(r)
 				l.next()
 			}
-			growingString += str
+			sb.WriteString(str.String())
 			continue
 		} else if r == '.' {
 			// skip
 		} else if !isValidBareChar(r) {
 			return l.errorf("keys cannot contain %c character", r)
 		}
-		growingString += string(r)
+		sb.WriteRune(r)
 		l.next()
 	}
-	l.emitWithValue(tokenKey, growingString)
+	l.emitWithValue(tokenKey, sb.String())
 	return l.lexVoid
 }
 
@@ -383,7 +389,7 @@ func (l *tomlLexer) lexLeftBracket() tomlLexStateFn {
 }
 
 func (l *tomlLexer) lexLiteralStringAsString(terminator string, discardLeadingNewLine bool) (string, error) {
-	growingString := ""
+	var sb strings.Builder
 
 	if discardLeadingNewLine {
 		if l.follow("\r\n") {
@@ -397,14 +403,14 @@ func (l *tomlLexer) lexLiteralStringAsString(terminator string, discardLeadingNe
 	// find end of string
 	for {
 		if l.follow(terminator) {
-			return growingString, nil
+			return sb.String(), nil
 		}
 
 		next := l.peek()
 		if next == eof {
 			break
 		}
-		growingString += string(l.next())
+		sb.WriteRune(l.next())
 	}
 
 	return "", errors.New("unclosed string")
@@ -438,7 +444,7 @@ func (l *tomlLexer) lexLiteralString() tomlLexStateFn {
 // Terminator is the substring indicating the end of the token.
 // The resulting string does not include the terminator.
 func (l *tomlLexer) lexStringAsString(terminator string, discardLeadingNewLine, acceptNewLines bool) (string, error) {
-	growingString := ""
+	var sb strings.Builder
 
 	if discardLeadingNewLine {
 		if l.follow("\r\n") {
@@ -451,7 +457,7 @@ func (l *tomlLexer) lexStringAsString(terminator string, discardLeadingNewLine,
 
 	for {
 		if l.follow(terminator) {
-			return growingString, nil
+			return sb.String(), nil
 		}
 
 		if l.follow("\\") {
@@ -469,61 +475,61 @@ func (l *tomlLexer) lexStringAsString(terminator string, discardLeadingNewLine,
 					l.next()
 				}
 			case '"':
-				growingString += "\""
+				sb.WriteString("\"")
 				l.next()
 			case 'n':
-				growingString += "\n"
+				sb.WriteString("\n")
 				l.next()
 			case 'b':
-				growingString += "\b"
+				sb.WriteString("\b")
 				l.next()
 			case 'f':
-				growingString += "\f"
+				sb.WriteString("\f")
 				l.next()
 			case '/':
-				growingString += "/"
+				sb.WriteString("/")
 				l.next()
 			case 't':
-				growingString += "\t"
+				sb.WriteString("\t")
 				l.next()
 			case 'r':
-				growingString += "\r"
+				sb.WriteString("\r")
 				l.next()
 			case '\\':
-				growingString += "\\"
+				sb.WriteString("\\")
 				l.next()
 			case 'u':
 				l.next()
-				code := ""
+				var code strings.Builder
 				for i := 0; i < 4; i++ {
 					c := l.peek()
 					if !isHexDigit(c) {
 						return "", errors.New("unfinished unicode escape")
 					}
 					l.next()
-					code = code + string(c)
+					code.WriteRune(c)
 				}
-				intcode, err := strconv.ParseInt(code, 16, 32)
+				intcode, err := strconv.ParseInt(code.String(), 16, 32)
 				if err != nil {
-					return "", errors.New("invalid unicode escape: \\u" + code)
+					return "", errors.New("invalid unicode escape: \\u" + code.String())
 				}
-				growingString += string(rune(intcode))
+				sb.WriteRune(rune(intcode))
 			case 'U':
 				l.next()
-				code := ""
+				var code strings.Builder
 				for i := 0; i < 8; i++ {
 					c := l.peek()
 					if !isHexDigit(c) {
 						return "", errors.New("unfinished unicode escape")
 					}
 					l.next()
-					code = code + string(c)
+					code.WriteRune(c)
 				}
-				intcode, err := strconv.ParseInt(code, 16, 64)
+				intcode, err := strconv.ParseInt(code.String(), 16, 64)
 				if err != nil {
-					return "", errors.New("invalid unicode escape: \\U" + code)
+					return "", errors.New("invalid unicode escape: \\U" + code.String())
 				}
-				growingString += string(rune(intcode))
+				sb.WriteRune(rune(intcode))
 			default:
 				return "", errors.New("invalid escape sequence: \\" + string(l.peek()))
 			}
@@ -534,7 +540,7 @@ func (l *tomlLexer) lexStringAsString(terminator string, discardLeadingNewLine,
 				return "", fmt.Errorf("unescaped control character %U", r)
 			}
 			l.next()
-			growingString += string(r)
+			sb.WriteRune(r)
 		}
 
 		if l.peek() == eof {

marshal.go

@@ -76,6 +76,7 @@ var textUnmarshalerType = reflect.TypeOf(new(encoding.TextUnmarshaler)).Elem()
 var localDateType = reflect.TypeOf(LocalDate{})
 var localTimeType = reflect.TypeOf(LocalTime{})
 var localDateTimeType = reflect.TypeOf(LocalDateTime{})
+var mapStringInterfaceType = reflect.TypeOf(map[string]interface{}{})
 
 // Check if the given marshal type maps to a Tree primitive
 func isPrimitive(mtype reflect.Type) bool {
@@ -436,6 +437,7 @@ func (e *Encoder) valueToTree(mtype reflect.Type, mval reflect.Value) (*Tree, er
 					if tree, ok := val.(*Tree); ok && mtypef.Anonymous && !opts.nameFromTag && !e.promoteAnon {
 						e.appendTree(tval, tree)
 					} else {
+						val = e.wrapTomlValue(val, tval)
 						tval.SetPathWithOptions([]string{opts.name}, SetOptions{
 							Comment:   opts.comment,
 							Commented: opts.commented,
@@ -474,6 +476,7 @@ func (e *Encoder) valueToTree(mtype reflect.Type, mval reflect.Value) (*Tree, er
 			if err != nil {
 				return nil, err
 			}
+			val = e.wrapTomlValue(val, tval)
 			if e.quoteMapKeys {
 				keyStr, err := tomlValueStringRepresentation(key.String(), "", "", e.order, e.arraysOneElementPerLine)
 				if err != nil {
@@ -516,13 +519,13 @@ func (e *Encoder) valueToOtherSlice(mtype reflect.Type, mval reflect.Value) (int
 
 // Convert given marshal value to toml value
 func (e *Encoder) valueToToml(mtype reflect.Type, mval reflect.Value) (interface{}, error) {
-	e.line++
 	if mtype.Kind() == reflect.Ptr {
 		switch {
 		case isCustomMarshaler(mtype):
 			return callCustomMarshaler(mval)
 		case isTextMarshaler(mtype):
-			return callTextMarshaler(mval)
+			b, err := callTextMarshaler(mval)
+			return string(b), err
 		default:
 			return e.valueToToml(mtype.Elem(), mval.Elem())
 		}
@@ -534,7 +537,8 @@ func (e *Encoder) valueToToml(mtype reflect.Type, mval reflect.Value) (interface
 	case isCustomMarshaler(mtype):
 		return callCustomMarshaler(mval)
 	case isTextMarshaler(mtype):
-		return callTextMarshaler(mval)
+		b, err := callTextMarshaler(mval)
+		return string(b), err
 	case isTree(mtype):
 		return e.valueToTree(mtype, mval)
 	case isOtherSequence(mtype), isCustomMarshalerSequence(mtype), isTextMarshalerSequence(mtype):
@@ -577,6 +581,25 @@ func (e *Encoder) appendTree(t, o *Tree) error {
 	return nil
 }
 
+// Create a toml value with the current line number as the position line
+func (e *Encoder) wrapTomlValue(val interface{}, parent *Tree) interface{} {
+	_, isTree := val.(*Tree)
+	_, isTreeS := val.([]*Tree)
+	if isTree || isTreeS {
+		return val
+	}
+
+	ret := &tomlValue{
+		value: val,
+		position: Position{
+			e.line,
+			parent.position.Col,
+		},
+	}
+	e.line++
+	return ret
+}
+
 // Unmarshal attempts to unmarshal the Tree into a Go struct pointed by v.
 // Neither Unmarshaler interfaces nor UnmarshalTOML functions are supported for
 // sub-structs, and only definite types can be unmarshaled.
@@ -681,6 +704,8 @@ func (d *Decoder) unmarshal(v interface{}) error {
 
 	switch elem.Kind() {
 	case reflect.Struct, reflect.Map:
+	case reflect.Interface:
+		elem = mapStringInterfaceType
 	default:
 		return errors.New("only a pointer to struct or map can be unmarshaled from TOML")
 	}
@@ -717,6 +742,10 @@ func (d *Decoder) valueFromTree(mtype reflect.Type, tval *Tree, mval1 *reflect.V
 	if mvalPtr := reflect.New(mtype); isCustomUnmarshaler(mvalPtr.Type()) {
 		d.visitor.visitAll()
 
+		if tval == nil {
+			return mvalPtr.Elem(), nil
+		}
+
 		if err := callCustomUnmarshaler(mvalPtr, tval.ToMap()); err != nil {
 			return reflect.ValueOf(nil), fmt.Errorf("unmarshal toml: %v", err)
 		}

marshal_test.go

@@ -16,6 +16,7 @@ import (
 type basicMarshalTestStruct struct {
 	String     string   `toml:"Zstring"`
 	StringList []string `toml:"Ystrlist"`
+	BasicMarshalTestSubAnonymousStruct
 	Sub     basicMarshalTestSubStruct   `toml:"Xsubdoc"`
 	SubList []basicMarshalTestSubStruct `toml:"Wsublist"`
 }
@@ -24,50 +25,58 @@ type basicMarshalTestSubStruct struct {
 	String2 string
 }
 
+type BasicMarshalTestSubAnonymousStruct struct {
+	String3 string
+}
+
 var basicTestData = basicMarshalTestStruct{
 	String:                             "Hello",
 	StringList:                         []string{"Howdy", "Hey There"},
-	Sub:        basicMarshalTestSubStruct{"One"},
+	BasicMarshalTestSubAnonymousStruct: BasicMarshalTestSubAnonymousStruct{"One"},
-	SubList:    []basicMarshalTestSubStruct{{"Two"}, {"Three"}},
+	Sub:                                basicMarshalTestSubStruct{"Two"},
+	SubList:                            []basicMarshalTestSubStruct{{"Three"}, {"Four"}},
 }
 
-var basicTestToml = []byte(`Ystrlist = ["Howdy", "Hey There"]
+var basicTestToml = []byte(`String3 = "One"
+Ystrlist = ["Howdy", "Hey There"]
 Zstring = "Hello"
 
-[[Wsublist]]
-  String2 = "Two"
-
 [[Wsublist]]
   String2 = "Three"
 
+[[Wsublist]]
+  String2 = "Four"
+
 [Xsubdoc]
-  String2 = "One"
+  String2 = "Two"
 `)
 
-var basicTestTomlCustomIndentation = []byte(`Ystrlist = ["Howdy", "Hey There"]
+var basicTestTomlCustomIndentation = []byte(`String3 = "One"
+Ystrlist = ["Howdy", "Hey There"]
 Zstring = "Hello"
 
-[[Wsublist]]
-	String2 = "Two"
-
 [[Wsublist]]
 	String2 = "Three"
 
+[[Wsublist]]
+	String2 = "Four"
+
 [Xsubdoc]
-	String2 = "One"
+	String2 = "Two"
 `)
 
 var basicTestTomlOrdered = []byte(`Zstring = "Hello"
 Ystrlist = ["Howdy", "Hey There"]
+String3 = "One"
 
 [Xsubdoc]
-  String2 = "One"
-
-[[Wsublist]]
   String2 = "Two"
 
 [[Wsublist]]
   String2 = "Three"
+
+[[Wsublist]]
+  String2 = "Four"
 `)
 
 var marshalTestToml = []byte(`title = "TOML Marshal Testing"
@@ -979,6 +988,40 @@ func TestCustomMarshaler(t *testing.T) {
 	}
 }
 
+type IntOrString string
+
+func (x *IntOrString) MarshalTOML() ([]byte, error) {
+	s := *(*string)(x)
+	_, err := strconv.Atoi(s)
+	if err != nil {
+		return []byte(fmt.Sprintf(`"%s"`, s)), nil
+	}
+	return []byte(s), nil
+}
+
+func TestNestedCustomMarshaler(t *testing.T) {
+	num := IntOrString("100")
+	str := IntOrString("hello")
+	var parent = struct {
+		IntField    *IntOrString `toml:"int"`
+		StringField *IntOrString `toml:"string"`
+	}{
+		&num,
+		&str,
+	}
+
+	result, err := Marshal(parent)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := `int = 100
+string = "hello"
+`
+	if !bytes.Equal(result, []byte(expected)) {
+		t.Errorf("Bad nested text marshaler: expected\n-----\n%s\n-----\ngot\n-----\n%s\n-----\n", expected, result)
+	}
+}
+
 type textMarshaler struct {
 	FirstName string
 	LastName  string
@@ -1079,7 +1122,7 @@ type customPointerMarshaler struct {
 }
 
 func (m *customPointerMarshaler) MarshalTOML() ([]byte, error) {
-	return []byte("hidden"), nil
+	return []byte(`"hidden"`), nil
 }
 
 type textPointerMarshaler struct {
@@ -2151,10 +2194,7 @@ func TestUnmarshalBadDuration(t *testing.T) {
 	result := testBadDuration{}
 	err := NewDecoder(buf).Decode(&result)
 	if err == nil {
-		t.Fatal()
+		t.Fatal("expected bad duration error")
-	}
-	if err.Error() != "(1, 1): Can't convert 1z(string) to time.Duration. time: unknown unit z in duration 1z" {
-		t.Fatalf("unexpected error: %s", err)
 	}
 }
 
@@ -3848,3 +3888,91 @@ func TestPreserveNotEmptyField(t *testing.T) {
 		t.Errorf("Bad unmarshal: expected %+v, got %+v", expected, actual)
 	}
 }
+
+// github issue 432
+func TestUnmarshalEmptyInterface(t *testing.T) {
+	doc := []byte(`User = "pelletier"`)
+
+	var v interface{}
+
+	err := Unmarshal(doc, &v)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	x, ok := v.(map[string]interface{})
+	if !ok {
+		t.Fatal(err)
+	}
+
+	if x["User"] != "pelletier" {
+		t.Fatalf("expected User=pelletier, but got %v", x)
+	}
+}
+
+func TestUnmarshalEmptyInterfaceDeep(t *testing.T) {
+	doc := []byte(`
+User = "pelletier"
+Age = 99
+
+[foo]
+bar = 42
+`)
+
+	var v interface{}
+
+	err := Unmarshal(doc, &v)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	x, ok := v.(map[string]interface{})
+	if !ok {
+		t.Fatal(err)
+	}
+
+	expected := map[string]interface{}{
+		"User": "pelletier",
+		"Age":  99,
+		"foo": map[string]interface{}{
+			"bar": 42,
+		},
+	}
+
+	reflect.DeepEqual(x, expected)
+}
+
+type Config struct {
+	Key string `toml:"key"`
+	Obj Custom `toml:"obj"`
+}
+
+type Custom struct {
+	v string
+}
+
+func (c *Custom) UnmarshalTOML(v interface{}) error {
+	c.v = "called"
+	return nil
+}
+
+func TestGithubIssue431(t *testing.T) {
+	doc := `key = "value"`
+	tree, err := LoadBytes([]byte(doc))
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+
+	var c Config
+	if err := tree.Unmarshal(&c); err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+
+	if c.Key != "value" {
+		t.Errorf("expected c.Key='value', not '%s'", c.Key)
+	}
+
+	if c.Obj.v == "called" {
+		t.Errorf("UnmarshalTOML should not have been called")
+	}
+}

toml.go

@@ -122,6 +122,89 @@ func (t *Tree) GetPath(keys []string) interface{} {
 	}
 }
 
+// GetArray returns the value at key in the Tree.
+// It returns []string, []int64, etc type if key has homogeneous lists
+// Key is a dot-separated path (e.g. a.b.c) without single/double quoted strings.
+// Returns nil if the path does not exist in the tree.
+// If keys is of length zero, the current tree is returned.
+func (t *Tree) GetArray(key string) interface{} {
+	if key == "" {
+		return t
+	}
+	return t.GetArrayPath(strings.Split(key, "."))
+}
+
+// GetArrayPath returns the element in the tree indicated by 'keys'.
+// If keys is of length zero, the current tree is returned.
+func (t *Tree) GetArrayPath(keys []string) interface{} {
+	if len(keys) == 0 {
+		return t
+	}
+	subtree := t
+	for _, intermediateKey := range keys[:len(keys)-1] {
+		value, exists := subtree.values[intermediateKey]
+		if !exists {
+			return nil
+		}
+		switch node := value.(type) {
+		case *Tree:
+			subtree = node
+		case []*Tree:
+			// go to most recent element
+			if len(node) == 0 {
+				return nil
+			}
+			subtree = node[len(node)-1]
+		default:
+			return nil // cannot navigate through other node types
+		}
+	}
+	// branch based on final node type
+	switch node := subtree.values[keys[len(keys)-1]].(type) {
+	case *tomlValue:
+		switch n := node.value.(type) {
+		case []interface{}:
+			return getArray(n)
+		default:
+			return node.value
+		}
+	default:
+		return node
+	}
+}
+
+// if homogeneous array, then return slice type object over []interface{}
+func getArray(n []interface{}) interface{} {
+	var s []string
+	var i64 []int64
+	var f64 []float64
+	var bl []bool
+	for _, value := range n {
+		switch v := value.(type) {
+		case string:
+			s = append(s, v)
+		case int64:
+			i64 = append(i64, v)
+		case float64:
+			f64 = append(f64, v)
+		case bool:
+			bl = append(bl, v)
+		default:
+			return n
+		}
+	}
+	if len(s) == len(n) {
+		return s
+	} else if len(i64) == len(n) {
+		return i64
+	} else if len(f64) == len(n) {
+		return f64
+	} else if len(bl) == len(n) {
+		return bl
+	}
+	return n
+}
+
 // GetPosition returns the position of the given key.
 func (t *Tree) GetPosition(key string) Position {
 	if key == "" {
@@ -130,6 +213,50 @@ func (t *Tree) GetPosition(key string) Position {
 	return t.GetPositionPath(strings.Split(key, "."))
 }
 
+// SetPositionPath sets the position of element in the tree indicated by 'keys'.
+// If keys is of length zero, the current tree position is set.
+func (t *Tree) SetPositionPath(keys []string, pos Position) {
+	if len(keys) == 0 {
+		t.position = pos
+		return
+	}
+	subtree := t
+	for _, intermediateKey := range keys[:len(keys)-1] {
+		value, exists := subtree.values[intermediateKey]
+		if !exists {
+			return
+		}
+		switch node := value.(type) {
+		case *Tree:
+			subtree = node
+		case []*Tree:
+			// go to most recent element
+			if len(node) == 0 {
+				return
+			}
+			subtree = node[len(node)-1]
+		default:
+			return
+		}
+	}
+	// branch based on final node type
+	switch node := subtree.values[keys[len(keys)-1]].(type) {
+	case *tomlValue:
+		node.position = pos
+		return
+	case *Tree:
+		node.position = pos
+		return
+	case []*Tree:
+		// go to most recent element
+		if len(node) == 0 {
+			return
+		}
+		node[len(node)-1].position = pos
+		return
+	}
+}
+
 // GetPositionPath returns the element in the tree indicated by 'keys'.
 // If keys is of length zero, the current tree is returned.
 func (t *Tree) GetPositionPath(keys []string) Position {
@@ -212,7 +339,8 @@ func (t *Tree) SetPathWithOptions(keys []string, opts SetOptions, value interfac
 			// go to most recent element
 			if len(node) == 0 {
 				// create element if it does not exist
-				subtree.values[intermediateKey] = append(node, newTreeWithPosition(Position{Line: t.position.Line + i, Col: t.position.Col}))
+				node = append(node, newTreeWithPosition(Position{Line: t.position.Line + i, Col: t.position.Col}))
+				subtree.values[intermediateKey] = node
 			}
 			subtree = node[len(node)-1]
 		}
@@ -232,6 +360,8 @@ func (t *Tree) SetPathWithOptions(keys []string, opts SetOptions, value interfac
 		toInsert = value
 	case *tomlValue:
 		v.comment = opts.Comment
+		v.commented = opts.Commented
+		v.multiline = opts.Multiline
 		toInsert = v
 	default:
 		toInsert = &tomlValue{value: value,

toml_test.go

@@ -3,6 +3,7 @@
 package toml
 
 import (
+	"reflect"
 	"testing"
 )
 
@@ -39,6 +40,41 @@ func TestTomlGet(t *testing.T) {
 	}
 }
 
+func TestTomlGetArray(t *testing.T) {
+	tree, _ := Load(`
+		[test]
+		key = ["one", "two"]
+		key2 = [true, false, false]
+		key3 = [1.5,2.5]
+	`)
+
+	if tree.GetArray("") != tree {
+		t.Errorf("GetArray should return the tree itself when given an empty path")
+	}
+
+	expect := []string{"one", "two"}
+	actual := tree.GetArray("test.key").([]string)
+	if !reflect.DeepEqual(actual, expect) {
+		t.Errorf("GetArray should return the []string value")
+	}
+
+	expect2 := []bool{true, false, false}
+	actual2 := tree.GetArray("test.key2").([]bool)
+	if !reflect.DeepEqual(actual2, expect2) {
+		t.Errorf("GetArray should return the []bool value")
+	}
+
+	expect3 := []float64{1.5, 2.5}
+	actual3 := tree.GetArray("test.key3").([]float64)
+	if !reflect.DeepEqual(actual3, expect3) {
+		t.Errorf("GetArray should return the []float64 value")
+	}
+
+	if tree.GetArray(`\`) != nil {
+		t.Errorf("should return nil when the key is malformed")
+	}
+}
+
 func TestTomlGetDefault(t *testing.T) {
 	tree, _ := Load(`
 		[test]
@@ -148,6 +184,51 @@ func TestTomlGetPath(t *testing.T) {
 	}
 }
 
+func TestTomlGetArrayPath(t *testing.T) {
+	for idx, item := range []struct {
+		Name string
+		Path []string
+		Make func() (tree *Tree, expected interface{})
+	}{
+		{
+			Name: "empty",
+			Path: []string{},
+			Make: func() (tree *Tree, expected interface{}) {
+				tree = newTree()
+				expected = tree
+				return
+			},
+		},
+		{
+			Name: "int64",
+			Path: []string{"a"},
+			Make: func() (tree *Tree, expected interface{}) {
+				var err error
+				tree, err = Load(`a = [1,2,3]`)
+				if err != nil {
+					panic(err)
+				}
+				expected = []int64{1, 2, 3}
+				return
+			},
+		},
+	} {
+		t.Run(item.Name, func(t *testing.T) {
+			tree, expected := item.Make()
+			result := tree.GetArrayPath(item.Path)
+			if !reflect.DeepEqual(result, expected) {
+				t.Errorf("GetArrayPath[%d] %v - expected %#v, got %#v instead.", idx, item.Path, expected, result)
+			}
+		})
+	}
+
+	tree, _ := Load("[foo.bar]\na=1\nb=2\n[baz.foo]\na=3\nb=4\n[gorf.foo]\na=5\nb=6")
+	if tree.GetArrayPath([]string{"whatever"}) != nil {
+		t.Error("GetArrayPath should return nil when the key does not exist")
+	}
+
+}
+
 func TestTomlFromMap(t *testing.T) {
 	simpleMap := map[string]interface{}{"hello": 42}
 	tree, err := TreeFromMap(simpleMap)

tomltree_create.go

@@ -57,6 +57,19 @@ func simpleValueCoercion(object interface{}) (interface{}, error) {
 		return float64(original), nil
 	case fmt.Stringer:
 		return original.String(), nil
+	case []interface{}:
+		value := reflect.ValueOf(original)
+		length := value.Len()
+		arrayValue := reflect.MakeSlice(value.Type(), 0, length)
+		for i := 0; i < length; i++ {
+			val := value.Index(i).Interface()
+			simpleValue, err := simpleValueCoercion(val)
+			if err != nil {
+				return nil, err
+			}
+			arrayValue = reflect.Append(arrayValue, reflect.ValueOf(simpleValue))
+		}
+		return arrayValue.Interface(), nil
 	default:
 		return nil, fmt.Errorf("cannot convert type %T to Tree", object)
 	}

tomltree_create_test.go

@@ -1,6 +1,7 @@
 package toml
 
 import (
+	"reflect"
 	"strconv"
 	"testing"
 	"time"
@@ -124,3 +125,119 @@ func TestRoundTripArrayOfTables(t *testing.T) {
 		t.Errorf("want:\n%s\ngot:\n%s", want, got)
 	}
 }
+
+func TestTomlSliceOfSlice(t *testing.T) {
+	tree, err := Load(` hosts=[["10.1.0.107:9092","10.1.0.107:9093", "192.168.0.40:9094"] ] `)
+	m := tree.ToMap()
+	tree, err = TreeFromMap(m)
+	if err != nil {
+		t.Error("should not error", err)
+	}
+	type Struct struct {
+		Hosts [][]string
+	}
+	var actual Struct
+	tree.Unmarshal(&actual)
+
+	expected := Struct{Hosts: [][]string{[]string{"10.1.0.107:9092", "10.1.0.107:9093", "192.168.0.40:9094"}}}
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("Bad unmarshal: expected %+v, got %+v", expected, actual)
+	}
+}
+
+func TestTomlSliceOfSliceOfSlice(t *testing.T) {
+	tree, err := Load(` hosts=[[["10.1.0.107:9092","10.1.0.107:9093", "192.168.0.40:9094"] ]] `)
+	m := tree.ToMap()
+	tree, err = TreeFromMap(m)
+	if err != nil {
+		t.Error("should not error", err)
+	}
+	type Struct struct {
+		Hosts [][][]string
+	}
+	var actual Struct
+	tree.Unmarshal(&actual)
+
+	expected := Struct{Hosts: [][][]string{[][]string{[]string{"10.1.0.107:9092", "10.1.0.107:9093", "192.168.0.40:9094"}}}}
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("Bad unmarshal: expected %+v, got %+v", expected, actual)
+	}
+}
+
+func TestTomlSliceOfSliceInt(t *testing.T) {
+	tree, err := Load(` hosts=[[1,2,3],[4,5,6] ] `)
+	m := tree.ToMap()
+	tree, err = TreeFromMap(m)
+	if err != nil {
+		t.Error("should not error", err)
+	}
+	type Struct struct {
+		Hosts [][]int
+	}
+	var actual Struct
+	err = tree.Unmarshal(&actual)
+	if err != nil {
+		t.Error("should not error", err)
+	}
+
+	expected := Struct{Hosts: [][]int{[]int{1, 2, 3}, []int{4, 5, 6}}}
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("Bad unmarshal: expected %+v, got %+v", expected, actual)
+	}
+
+}
+func TestTomlSliceOfSliceInt64(t *testing.T) {
+	tree, err := Load(` hosts=[[1,2,3],[4,5,6] ] `)
+	m := tree.ToMap()
+	tree, err = TreeFromMap(m)
+	if err != nil {
+		t.Error("should not error", err)
+	}
+	type Struct struct {
+		Hosts [][]int64
+	}
+	var actual Struct
+	err = tree.Unmarshal(&actual)
+	if err != nil {
+		t.Error("should not error", err)
+	}
+
+	expected := Struct{Hosts: [][]int64{[]int64{1, 2, 3}, []int64{4, 5, 6}}}
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("Bad unmarshal: expected %+v, got %+v", expected, actual)
+	}
+
+}
+
+func TestTomlSliceOfSliceInt64FromMap(t *testing.T) {
+	tree, err := TreeFromMap(map[string]interface{}{"hosts": [][]interface{}{[]interface{}{int32(1), int8(2), 3}}})
+	if err != nil {
+		t.Error("should not error", err)
+	}
+	type Struct struct {
+		Hosts [][]int64
+	}
+	var actual Struct
+	err = tree.Unmarshal(&actual)
+	if err != nil {
+		t.Error("should not error", err)
+	}
+
+	expected := Struct{Hosts: [][]int64{[]int64{1, 2, 3}}}
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("Bad unmarshal: expected %+v, got %+v", expected, actual)
+	}
+
+}
+func TestTomlSliceOfSliceError(t *testing.T) { // make Codecov happy
+	_, err := TreeFromMap(map[string]interface{}{"hosts": [][]interface{}{[]interface{}{1, 2, []struct{}{}}}})
+	expected := "cannot convert type []struct {} to Tree"
+	if err.Error() != expected {
+		t.Fatalf("unexpected error: %s", err)
+	}
+}

tomltree_write.go

@@ -163,7 +163,7 @@ func tomlValueStringRepresentation(v interface{}, commented string, indent strin
 		return "\"" + encodeTomlString(value) + "\"", nil
 	case []byte:
 		b, _ := v.([]byte)
-		return tomlValueStringRepresentation(string(b), commented, indent, ord, arraysOneElementPerLine)
+		return string(b), nil
 	case bool:
 		if value {
 			return "true", nil