Add new type parse from string (#114)

* Add new type parse from string

* Add link

accounts/abi/type2.go

@@ -0,0 +1,123 @@
+package abi
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+func NewTypeFromString(s string) (Type, error) {
+	if strings.HasPrefix(s, "tuple") {
+		sig, args, err := newTypeForTuple(s)
+		if err != nil {
+			return Type{}, err
+		}
+		return NewType(sig, "", args)
+	}
+	return NewType(s, "", nil)
+}
+
+func (t Type) Pack(v interface{}) ([]byte, error) {
+	return t.pack(reflect.ValueOf(v))
+}
+
+func (t Type) Unpack(data []byte, obj interface{}) error {
+	fmt.Println(toGoType(0, t, data))
+
+	return nil
+}
+
+// newTypeForTuple implements the format described in https://blog.ricmoo.com/human-readable-contract-abis-in-ethers-js-141902f4d917
+func newTypeForTuple(s string) (string, []ArgumentMarshaling, error) {
+	if !strings.HasPrefix(s, "tuple") {
+		return "", nil, fmt.Errorf("'tuple' prefix not found")
+	}
+
+	pos := strings.Index(s, "(")
+	if pos == -1 {
+		return "", nil, fmt.Errorf("not a tuple, '(' not found")
+	}
+
+	// this is the type of the tuple. It can either be
+	// tuple, tuple[] or tuple[x]
+	sig := s[:pos]
+	s = s[pos:]
+
+	// Now, decode the arguments of the tuple
+	// tuple(arg1, arg2, tuple(arg3, arg4)).
+	// We need to find the commas that are not inside a nested tuple.
+	// We do this by keeping a counter of the number of open parens.
+
+	var (
+		parenthesisCount int
+		fields           []string
+	)
+
+	lastComma := 1
+	for indx, c := range s {
+		switch c {
+		case '(':
+			parenthesisCount++
+		case ')':
+			parenthesisCount--
+			if parenthesisCount == 0 {
+				fields = append(fields, s[lastComma:indx])
+
+				// this should be the end of the tuple
+				if indx != len(s)-1 {
+					return "", nil, fmt.Errorf("invalid tuple, it does not end with ')'")
+				}
+			}
+		case ',':
+			if parenthesisCount == 1 {
+				fields = append(fields, s[lastComma:indx])
+				lastComma = indx + 1
+			}
+		}
+	}
+
+	// trim the args of spaces
+	for i := range fields {
+		fields[i] = strings.TrimSpace(fields[i])
+	}
+
+	// decode the type of each field
+	var args []ArgumentMarshaling
+	for _, field := range fields {
+		// anonymous fields are not supported so the first
+		// string should be the identifier of the field.
+
+		spacePos := strings.Index(field, " ")
+		if spacePos == -1 {
+			return "", nil, fmt.Errorf("invalid tuple field name not found '%s'", field)
+		}
+
+		name := field[:spacePos]
+		field = field[spacePos+1:]
+
+		if strings.HasPrefix(field, "tuple") {
+			// decode a recursive tuple
+			sig, elems, err := newTypeForTuple(field)
+			if err != nil {
+				return "", nil, err
+			}
+			args = append(args, ArgumentMarshaling{
+				Name:       name,
+				Type:       sig,
+				Components: elems,
+			})
+		} else {
+			// basic type. Try to decode it to see
+			// if it is a correct abi type.
+			if _, err := NewType(field, "", nil); err != nil {
+				return "", nil, fmt.Errorf("invalid tuple basic field '%s': %v", field, err)
+			}
+			args = append(args, ArgumentMarshaling{
+				Name: name,
+				Type: field,
+			})
+		}
+	}
+
+	return sig, args, nil
+}

accounts/abi/type2_test.go

@@ -0,0 +1,94 @@
+package abi
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewType2FromString(t *testing.T) {
+	type struct1 struct {
+		A uint64
+		B []struct {
+			X struct {
+				C uint64
+			}
+			D uint64
+		}
+		E struct {
+			F uint64
+			G uint64
+		}
+	}
+
+	cases := []struct {
+		input string
+		want  string
+		obj   interface{}
+	}{
+		{
+			"uint64[]",
+			"uint64[]",
+			[]uint64{1, 2, 3},
+		},
+		{
+			"tuple(a uint64, b uint64)",
+			"(uint64,uint64)",
+			&struct {
+				A uint64
+				B uint64
+			}{A: 1, B: 2},
+		},
+		{
+			"tuple(a uint64, b tuple(c uint64), d uint64)",
+			"(uint64,(uint64),uint64)",
+			&struct {
+				A uint64
+				B struct {
+					C uint64
+				}
+				D uint64
+			}{A: 1, B: struct{ C uint64 }{C: 2}, D: 3},
+		},
+		{
+			"tuple(a uint64, b tuple[](x tuple(c uint64), d uint64), e tuple(f uint64, g uint64))",
+			"(uint64,((uint64),uint64)[],(uint64,uint64))",
+			&struct1{
+				A: 1,
+				B: []struct {
+					X struct {
+						C uint64
+					}
+					D uint64
+				}{
+					{
+						X: struct {
+							C uint64
+						}{C: 2},
+						D: 3,
+					},
+					{
+						X: struct {
+							C uint64
+						}{C: 4},
+						D: 5,
+					},
+				},
+				E: struct {
+					F uint64
+					G uint64
+				}{F: 6, G: 7},
+			},
+		},
+	}
+
+	for _, c := range cases {
+		typ, err := NewTypeFromString(c.input)
+
+		require.NoError(t, err)
+		require.Equal(t, c.want, typ.String())
+
+		_, err = typ.Pack(c.obj)
+		require.NoError(t, err)
+	}
+}