acounts/abi: refactor abi, generalize abi pack/unpack to Arguments

accounts/abi/argument.go

@@ -19,6 +19,8 @@ package abi
 import (
 	"encoding/json"
 	"fmt"
+	"reflect"
+	"strings"
 )
 
 // Argument holds the name of the argument and the corresponding type.
@@ -29,6 +31,8 @@ type Argument struct {
 	Indexed bool // indexed is only used by events
 }
 
+type Arguments []Argument
+
 // UnmarshalJSON implements json.Unmarshaler interface
 func (a *Argument) UnmarshalJSON(data []byte) error {
 	var extarg struct {
@@ -60,3 +64,160 @@ func countNonIndexedArguments(args []Argument) int {
 	}
 	return out
 }
+func (a *Arguments) isTuple() bool {
+	return a != nil && len(*a) > 1
+}
+
+func (a *Arguments) Unpack(v interface{}, data []byte) error {
+	if a.isTuple() {
+		return a.unpackTuple(v, data)
+	}
+	return a.unpackAtomic(v, data)
+}
+
+func (a *Arguments) unpackTuple(v interface{}, output []byte) error {
+	// make sure the passed value is a pointer
+	valueOf := reflect.ValueOf(v)
+	if reflect.Ptr != valueOf.Kind() {
+		return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
+	}
+
+	var (
+		value = valueOf.Elem()
+		typ   = value.Type()
+		kind  = value.Kind()
+	)
+/* !TODO add this back
+	if err := requireUnpackKind(value, typ, kind, (*a), false); err != nil {
+		return err
+	}
+*/
+	// `i` counts the nonindexed arguments.
+	// `j` counts the number of complex types.
+	// both `i` and `j` are used to to correctly compute `data` offset.
+
+	i, j := -1, 0
+	for _, arg := range(*a) {
+
+		if arg.Indexed {
+			// can't read, continue
+			continue
+		}
+		i++
+		marshalledValue, err := toGoType((i+j)*32, arg.Type, output)
+		if err != nil {
+			return err
+		}
+
+		if arg.Type.T == ArrayTy {
+			// combined index ('i' + 'j') need to be adjusted only by size of array, thus
+			// we need to decrement 'j' because 'i' was incremented
+			j += arg.Type.Size - 1
+		}
+
+		reflectValue := reflect.ValueOf(marshalledValue)
+
+		switch kind {
+		case reflect.Struct:
+			for j := 0; j < typ.NumField(); j++ {
+				field := typ.Field(j)
+				// TODO read tags: `abi:"fieldName"`
+				if field.Name == strings.ToUpper(arg.Name[:1])+arg.Name[1:] {
+					if err := set(value.Field(j), reflectValue, arg); err != nil {
+						return err
+					}
+				}
+			}
+		case reflect.Slice, reflect.Array:
+			if value.Len() < i {
+				return fmt.Errorf("abi: insufficient number of arguments for unpack, want %d, got %d", len(*a), value.Len())
+			}
+			v := value.Index(i)
+			if err := requireAssignable(v, reflectValue); err != nil {
+				return err
+			}
+			reflectValue := reflect.ValueOf(marshalledValue)
+			return set(v.Elem(), reflectValue, arg)
+		default:
+			return fmt.Errorf("abi:[2] cannot unmarshal tuple in to %v", typ)
+		}
+	}
+	return nil
+}
+
+func (a *Arguments) unpackAtomic(v interface{}, output []byte) error {
+	// make sure the passed value is a pointer
+	valueOf := reflect.ValueOf(v)
+	if reflect.Ptr != valueOf.Kind() {
+		return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
+	}
+	arg := (*a)[0]
+	if arg.Indexed {
+		return fmt.Errorf("abi: attempting to unpack indexed variable into element.")
+	}
+
+	value := valueOf.Elem()
+
+	marshalledValue, err := toGoType(0, arg.Type, output)
+	if err != nil {
+		return err
+	}
+	if err := set(value, reflect.ValueOf(marshalledValue), arg); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (arguments *Arguments) Pack(args ...interface{}) ([]byte, error) {
+	// Make sure arguments match up and pack them
+	if arguments == nil {
+		return nil, fmt.Errorf("arguments are nil, programmer error!")
+	}
+
+	abiArgs := *arguments
+	if len(args) != len(abiArgs) {
+		return nil, fmt.Errorf("argument count mismatch: %d for %d", len(args), len(abiArgs))
+	}
+
+	// variable input is the output appended at the end of packed
+	// output. This is used for strings and bytes types input.
+	var variableInput []byte
+
+	// input offset is the bytes offset for packed output
+	inputOffset := 0
+	for _, abiArg := range abiArgs {
+		if abiArg.Type.T == ArrayTy {
+			inputOffset += (32 * abiArg.Type.Size)
+		} else {
+			inputOffset += 32
+		}
+	}
+
+	var ret []byte
+	for i, a := range args {
+		input := abiArgs[i]
+		// pack the input
+		packed, err := input.Type.pack(reflect.ValueOf(a))
+		if err != nil {
+			return nil, err
+		}
+
+		// check for a slice type (string, bytes, slice)
+		if input.Type.requiresLengthPrefix() {
+			// calculate the offset
+			offset := inputOffset + len(variableInput)
+			// set the offset
+			ret = append(ret, packNum(reflect.ValueOf(offset))...)
+			// Append the packed output to the variable input. The variable input
+			// will be appended at the end of the input.
+			variableInput = append(variableInput, packed...)
+		} else {
+			// append the packed value to the input
+			ret = append(ret, packed...)
+		}
+	}
+	// append the variable input at the end of the packed input
+	ret = append(ret, variableInput...)
+
+	return ret, nil
+}