eth/abi: support dynamic array encoding (#122)

* eth/abi: support dynamic array encoding

* eth/abi: support dynamic array encoding

* Update spec/eth/abi_spec.rb

Co-authored-by: Afri <58883403+q9f@users.noreply.github.com>

* fix rspec

* format abi_spec

Co-authored-by: Afri <58883403+q9f@users.noreply.github.com>

lib/eth/abi.rb

@@ -74,7 +74,7 @@ def encode(types, args)
     # @return [String] the encoded type.
     # @raise [EncodingError] if value does not match type.
     def encode_type(type, arg)
-      if %w(string bytes).include? type.base_type and type.sub_type.empty?
+      if %w(string bytes).include? type.base_type and type.sub_type.empty? and type.dimensions.empty?
         raise EncodingError, "Argument must be a String" unless arg.instance_of? String
 
         # encodes strings and bytes
@@ -89,10 +89,24 @@ def encode_type(type, arg)
         head += encode_type Type.size_type, arg.size
         nested_sub = type.nested_sub
         nested_sub_size = type.nested_sub.size
-        arg.size.times do |i|
 
-          # ref https://github.com/ethereum/tests/issues/691
-          raise NotImplementedError, "Encoding dynamic arrays with nested dynamic sub-types is not implemented for ABI." if nested_sub.is_dynamic?
+        # calculate offsets
+        if %w(string bytes).include?(type.base_type) && type.sub_type.empty?
+          offset = 0
+          arg.size.times do |i|
+            if i == 0
+              offset = arg.size * 32
+            else
+              number_of_words = ((arg[i - 1].size + 32 - 1) / 32).floor
+              total_bytes_length = number_of_words * 32
+              offset += total_bytes_length + 32
+            end
+
+            head += encode_type Type.size_type, offset
+          end
+        end
+
+        arg.size.times do |i|
           head += encode_type nested_sub, arg[i]
         end
         return "#{head}#{tail}"

lib/eth/contract/function.rb

@@ -43,7 +43,7 @@ def initialize(data)
     # @param inputs [Array<Eth::Contract::FunctionInput>] function input class list.
     # @return [String] function string.
     def self.calc_signature(name, inputs)
-      "#{name}(#{inputs.collect { |x| x.type }.join(",")})"
+      "#{name}(#{inputs.collect { |x| x.raw_type }.join(",")})"
     end
 
     # Encodes a function signature.

lib/eth/contract/function_input.rb

@@ -19,12 +19,13 @@ module Eth
 
   # Provide classes for contract function input.
   class Contract::FunctionInput
-    attr_accessor :type, :name
+    attr_accessor :type, :raw_type, :name
 
     # Constructor of the {Eth::Contract::FunctionInput} class.
     #
     # @param data [Hash] contract abi data.
     def initialize(data)
+      @raw_type = data["type"]
       @type = Eth::Abi::Type.parse(data["type"])
       @name = data["name"]
     end

spec/eth/abi_spec.rb

@@ -9,6 +9,30 @@
     let(:basic_abi_tests_file) { File.read "spec/fixtures/ethereum/tests/ABITests/basic_abi_tests.json" }
     subject(:basic_abi_tests) { JSON.parse basic_abi_tests_file }
 
+    describe "dynamic encode" do
+      it "can encode array of string" do
+        encoded = Eth::Util.bin_to_hex(described_class.encode(["string[]"], [["hello", "world"]]))
+        expected = "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000400000000000000000000000000000000000000000000000000000000000000080000000000000000000000000000000000000000000000000000000000000000568656c6c6f0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000005776f726c64000000000000000000000000000000000000000000000000000000"
+        expect(encoded).to eq(expected)
+      end
+
+      it "can encode array of uint256" do
+        encoded = Eth::Util.bin_to_hex(described_class.encode(["uint256[]"], [[123, 456]]))
+        expected = "00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000007b00000000000000000000000000000000000000000000000000000000000001c8"
+        expect(encoded).to eq(expected)
+      end
+
+      it "can encode mix of array of uint256 and string" do
+        encoded = Eth::Util.bin_to_hex(described_class.encode(["uint256[]", "string[]"], [[123, 456], ["hello", "world"]]))
+        expected = "000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000a00000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000007b00000000000000000000000000000000000000000000000000000000000001c8000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000400000000000000000000000000000000000000000000000000000000000000080000000000000000000000000000000000000000000000000000000000000000568656c6c6f0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000005776f726c64000000000000000000000000000000000000000000000000000000"
+        expect(encoded).to eq(expected)
+
+        encoded = Eth::Util.bin_to_hex(described_class.encode(["uint256[]", "string[]", "string[]", "uint8[]"], [[123, 456], ["hello", "world"], ["ruby", "ethereum"], [8]]))
+        expected = "000000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000000000000e000000000000000000000000000000000000000000000000000000000000001c000000000000000000000000000000000000000000000000000000000000002a00000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000007b00000000000000000000000000000000000000000000000000000000000001c8000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000400000000000000000000000000000000000000000000000000000000000000080000000000000000000000000000000000000000000000000000000000000000568656c6c6f0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000005776f726c64000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000400000000000000000000000000000000000000000000000000000000000000080000000000000000000000000000000000000000000000000000000000000000472756279000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000008657468657265756d00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000008"
+        expect(encoded).to eq(expected)
+      end
+    end
+
     it "can encode abi" do
       basic_abi_tests.each do |test|
         types = test.last["types"]