accouns/abi: refactored ABI package

Refactored the abi package parsing and type handling. Relying mostly on
package reflect as opposed to most of our own type reflection. Our own
type reflection is still used however for cases such as Bytes and
FixedBytes (abi: bytes•).

This also inclused several fixes for slice handling of arbitrary and
fixed size for all supported types.

This also further removes implicit type casting such as assigning,
for example `[2]T{} = []T{1}` will fail, however `[2]T{} == []T{1, 2}`
(notice assigning *slice* to fixed size *array*). Assigning arrays to
slices will always succeed if they are of the same element type.

Incidentally also fixes #2379

1 files changed, 80 insertions, 0 deletions

diff --git a/accounts/abi/error.go b/accounts/abi/error.go
new file mode 100644
index 000000000..91a0374fd
--- /dev/null
+++ b/accounts/abi/error.go
@@ -0,0 +1,80 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package abi
+
+import (
+	"fmt"
+	"reflect"
+)
+
+// formatSliceString formats the reflection kind with the given slice size
+// and returns a formatted string representation.
+func formatSliceString(kind reflect.Kind, sliceSize int) string {
+	if sliceSize == -1 {
+		return fmt.Sprintf("[]%v", kind)
+	}
+	return fmt.Sprintf("[%d]%v", sliceSize, kind)
+}
+
+// sliceTypeCheck checks that the given slice can by assigned to the reflection
+// type in t.
+func sliceTypeCheck(t Type, val reflect.Value) error {
+	if !(val.Kind() == reflect.Slice || val.Kind() == reflect.Array) {
+		return typeErr(formatSliceString(t.Kind, t.SliceSize), val.Type())
+	}
+	if t.IsArray && val.Len() != t.SliceSize {
+		return typeErr(formatSliceString(t.Elem.Kind, t.SliceSize), formatSliceString(val.Type().Elem().Kind(), val.Len()))
+	}
+
+	if t.Elem.IsSlice {
+		if val.Len() > 0 {
+			return sliceTypeCheck(*t.Elem, val.Index(0))
+		}
+	} else if t.Elem.IsArray {
+		return sliceTypeCheck(*t.Elem, val.Index(0))
+	}
+
+	elemKind := val.Type().Elem().Kind()
+	if elemKind != t.Elem.Kind {
+		return typeErr(formatSliceString(t.Elem.Kind, t.SliceSize), val.Type())
+	}
+	return nil
+}
+
+// typeCheck checks that thet given reflection val can be assigned to the reflection
+// type in t.
+func typeCheck(t Type, value reflect.Value) error {
+	if t.IsSlice || t.IsArray {
+		return sliceTypeCheck(t, value)
+	}
+
+	// Check base type validity. Element types will be checked later on.
+	if t.Kind != value.Kind() {
+		return typeErr(t.Kind, value.Kind())
+	}
+	return nil
+}
+
+// varErr returns a formatted error.
+func varErr(expected, got reflect.Kind) error {
+	return typeErr(expected, got)
+}
+
+// typeErr returns a formatted type casting error.
+func typeErr(expected, got interface{}) error {
+	return fmt.Errorf("abi: cannot use %v as type %v as argument", got, expected)
+}