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-rw-r--r--accounts/abi/abi.go155
1 files changed, 155 insertions, 0 deletions
diff --git a/accounts/abi/abi.go b/accounts/abi/abi.go
new file mode 100644
index 000000000..067381a48
--- /dev/null
+++ b/accounts/abi/abi.go
@@ -0,0 +1,155 @@
+package abi
+
+import (
+ "encoding/json"
+ "fmt"
+ "io"
+ "strings"
+
+ "github.com/ethereum/go-ethereum/crypto"
+)
+
+// Callable method given a `Name` and whether the method is a constant.
+// If the method is `Const` no transaction needs to be created for this
+// particular Method call. It can easily be simulated using a local VM.
+// For example a `Balance()` method only needs to retrieve something
+// from the storage and therefor requires no Tx to be send to the
+// network. A method such as `Transact` does require a Tx and thus will
+// be flagged `true`.
+// Input specifies the required input parameters for this gives method.
+type Method struct {
+ Name string
+ Const bool
+ Input []Argument
+ Return Type // not yet implemented
+}
+
+// Returns the methods string signature according to the ABI spec.
+//
+// Example
+//
+// function foo(uint32 a, int b) = "foo(uint32,int256)"
+//
+// Please note that "int" is substitute for its canonical representation "int256"
+func (m Method) String() (out string) {
+ out += m.Name
+ types := make([]string, len(m.Input))
+ i := 0
+ for _, input := range m.Input {
+ types[i] = input.Type.String()
+ i++
+ }
+ out += "(" + strings.Join(types, ",") + ")"
+
+ return
+}
+
+func (m Method) Id() []byte {
+ return crypto.Sha3([]byte(m.String()))[:4]
+}
+
+// Argument holds the name of the argument and the corresponding type.
+// Types are used when packing and testing arguments.
+type Argument struct {
+ Name string
+ Type Type
+}
+
+func (a *Argument) UnmarshalJSON(data []byte) error {
+ var extarg struct {
+ Name string
+ Type string
+ }
+ err := json.Unmarshal(data, &extarg)
+ if err != nil {
+ return fmt.Errorf("argument json err: %v", err)
+ }
+
+ a.Type, err = NewType(extarg.Type)
+ if err != nil {
+ return err
+ }
+ a.Name = extarg.Name
+
+ return nil
+}
+
+// The ABI holds information about a contract's context and available
+// invokable methods. It will allow you to type check function calls and
+// packs data accordingly.
+type ABI struct {
+ Methods map[string]Method
+}
+
+// tests, tests whether the given input would result in a successful
+// call. Checks argument list count and matches input to `input`.
+func (abi ABI) pack(name string, args ...interface{}) ([]byte, error) {
+ method := abi.Methods[name]
+
+ var ret []byte
+ for i, a := range args {
+ input := method.Input[i]
+
+ packed, err := input.Type.pack(a)
+ if err != nil {
+ return nil, fmt.Errorf("`%s` %v", name, err)
+ }
+ ret = append(ret, packed...)
+
+ }
+
+ return ret, nil
+}
+
+// Pack the given method name to conform the ABI. Method call's data
+// will consist of method_id, args0, arg1, ... argN. Method id consists
+// of 4 bytes and arguments are all 32 bytes.
+// Method ids are created from the first 4 bytes of the hash of the
+// methods string signature. (signature = baz(uint32,string32))
+func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error) {
+ method, exist := abi.Methods[name]
+ if !exist {
+ return nil, fmt.Errorf("method '%s' not found", name)
+ }
+
+ // start with argument count match
+ if len(args) != len(method.Input) {
+ return nil, fmt.Errorf("argument count mismatch: %d for %d", len(args), len(method.Input))
+ }
+
+ arguments, err := abi.pack(name, args...)
+ if err != nil {
+ return nil, err
+ }
+
+ // Set function id
+ packed := abi.Methods[name].Id()
+ packed = append(packed, arguments...)
+
+ return packed, nil
+}
+
+func (abi *ABI) UnmarshalJSON(data []byte) error {
+ var methods []Method
+ if err := json.Unmarshal(data, &methods); err != nil {
+ return err
+ }
+
+ abi.Methods = make(map[string]Method)
+ for _, method := range methods {
+ abi.Methods[method.Name] = method
+ }
+
+ return nil
+}
+
+func JSON(reader io.Reader) (ABI, error) {
+ dec := json.NewDecoder(reader)
+
+ var abi ABI
+ if err := dec.Decode(&abi); err != nil {
+ return ABI{}, err
+ }
+
+ return abi, nil
+}