signer/fourbyte: add support for nested types in selectors (#24407)

This replaces the simple selector parser in signer/fourbyte with one that
can actually handle most types. The new parser is added in accounts/abi
to also make it useable elsewhere.

accounts/abi/selector_parser_test.go

@@ -0,0 +1,54 @@
+package abi
+
+import (
+	"fmt"
+	"log"
+	"reflect"
+	"testing"
+)
+
+func TestParseSelector(t *testing.T) {
+	mkType := func(types ...interface{}) []ArgumentMarshaling {
+		var result []ArgumentMarshaling
+		for i, typeOrComponents := range types {
+			name := fmt.Sprintf("name%d", i)
+			if typeName, ok := typeOrComponents.(string); ok {
+				result = append(result, ArgumentMarshaling{name, typeName, typeName, nil, false})
+			} else if components, ok := typeOrComponents.([]ArgumentMarshaling); ok {
+				result = append(result, ArgumentMarshaling{name, "tuple", "tuple", components, false})
+			} else {
+				log.Fatalf("unexpected type %T", typeOrComponents)
+			}
+		}
+		return result
+	}
+	tests := []struct {
+		input string
+		name  string
+		args  []ArgumentMarshaling
+	}{
+		{"noargs()", "noargs", []ArgumentMarshaling{}},
+		{"simple(uint256,uint256,uint256)", "simple", mkType("uint256", "uint256", "uint256")},
+		{"other(uint256,address)", "other", mkType("uint256", "address")},
+		{"withArray(uint256[],address[2],uint8[4][][5])", "withArray", mkType("uint256[]", "address[2]", "uint8[4][][5]")},
+		{"singleNest(bytes32,uint8,(uint256,uint256),address)", "singleNest", mkType("bytes32", "uint8", mkType("uint256", "uint256"), "address")},
+		{"multiNest(address,(uint256[],uint256),((address,bytes32),uint256))", "multiNest",
+			mkType("address", mkType("uint256[]", "uint256"), mkType(mkType("address", "bytes32"), "uint256"))},
+	}
+	for i, tt := range tests {
+		selector, err := ParseSelector(tt.input)
+		if err != nil {
+			t.Errorf("test %d: failed to parse selector '%v': %v", i, tt.input, err)
+		}
+		if selector.Name != tt.name {
+			t.Errorf("test %d: unexpected function name: '%s' != '%s'", i, selector.Name, tt.name)
+		}
+
+		if selector.Type != "function" {
+			t.Errorf("test %d: unexpected type: '%s' != '%s'", i, selector.Type, "function")
+		}
+		if !reflect.DeepEqual(selector.Inputs, tt.args) {
+			t.Errorf("test %d: unexpected args: '%v' != '%v'", i, selector.Inputs, tt.args)
+		}
+	}
+}