Support parsing type parameters

v2/parser/parse.go

@@ -587,9 +587,16 @@ func goNameToName(in string) types.Name {
 		return types.Name{Name: in}
 	}
 
+	// There may be '.' characters within a generic. Temporarily remove
+	// the generic.
+	genericIndex := strings.IndexRune(in, '[')
+	if genericIndex == -1 {
+		genericIndex = len(in)
+	}
+
 	// Otherwise, if there are '.' characters present, the name has a
 	// package path in front.
-	nameParts := strings.Split(in, ".")
+	nameParts := strings.Split(in[:genericIndex], ".")
 	name := types.Name{Name: in}
 	if n := len(nameParts); n >= 2 {
 		// The final "." is the name of the type--previous ones must
@@ -738,6 +745,27 @@ func (p *Parser) walkType(u types.Universe, useName *types.Name, in gotypes.Type
 			}
 			out.Kind = types.Alias
 			out.Underlying = p.walkType(u, nil, t.Underlying())
+		case *gotypes.Struct:
+			name := goNameToName(t.String())
+			tpMap := map[string]*types.Type{}
+			if t.TypeParams().Len() != 0 {
+				// Remove generics, then readd them without the encoded
+				// type, e.g. Foo[T any] => Foo[T]
+				var tpNames []string
+				for i := 0; i < t.TypeParams().Len(); i++ {
+					tp := t.TypeParams().At(i)
+					tpName := tp.Obj().Name()
+					tpNames = append(tpNames, tpName)
+					tpMap[tpName] = p.walkType(u, nil, tp.Constraint())
+				}
+				name.Name = fmt.Sprintf("%s[%s]", strings.SplitN(name.Name, "[", 2)[0], strings.Join(tpNames, ","))
+			}
+
+			if out := u.Type(name); out.Kind != types.Unknown {
+				return out // short circuit if we've already made this.
+			}
+			out = p.walkType(u, &name, t.Underlying())
+			out.TypeParams = tpMap
 		default:
 			// gotypes package makes everything "named" with an
 			// underlying anonymous type--we remove that annoying
@@ -764,6 +792,15 @@ func (p *Parser) walkType(u types.Universe, useName *types.Name, in gotypes.Type
 			}
 		}
 		return out
+	case *gotypes.TypeParam:
+		// DO NOT retrieve the type from the universe. The default type-param name is only the
+		// generic variable name. Ideally, it would be namespaced by package and struct but it is
+		// not. Thus, if we try to use the universe, we would start polluting it.
+		// e.g. if Foo[T] and Bar[T] exists, we'd mistakenly use the same type T for both.
+		return &types.Type{
+			Name: name,
+			Kind: types.TypeParam,
+		}
 	default:
 		out := u.Type(name)
 		if out.Kind != types.Unknown {

v2/parser/parse_test.go

@@ -20,6 +20,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"path/filepath"
+	"reflect"
 	"sort"
 	"testing"
 
@@ -816,3 +817,245 @@ func TestAddOnePkgToUniverse(t *testing.T) {
 		}
 	}
 }
+
+func TestStructParse(t *testing.T) {
+	testCases := []struct {
+		description string
+		testFile    string
+		expected    func() *types.Type
+	}{
+		{
+			description: "basic comments",
+			testFile:    "k8s.io/gengo/v2/parser/testdata/basic",
+			expected: func() *types.Type {
+				return &types.Type{
+					Name: types.Name{
+						Package: "k8s.io/gengo/v2/parser/testdata/basic",
+						Name:    "Blah",
+					},
+					Kind:                      types.Struct,
+					CommentLines:              []string{"Blah is a test.", "A test, I tell you."},
+					SecondClosestCommentLines: []string{""},
+					Members: []types.Member{
+						{
+							Name:         "A",
+							Embedded:     false,
+							CommentLines: []string{"A is the first field."},
+							Tags:         `json:"a"`,
+							Type:         types.Int64,
+						},
+						{
+							Name:         "B",
+							Embedded:     false,
+							CommentLines: []string{"B is the second field.", "Multiline comments work."},
+							Tags:         `json:"b"`,
+							Type:         types.String,
+						},
+					},
+					TypeParams: map[string]*types.Type{},
+				}
+			},
+		},
+		{
+			description: "generic",
+			testFile:    "./testdata/generic",
+			expected: func() *types.Type {
+				return &types.Type{
+					Name: types.Name{
+						Package: "k8s.io/gengo/v2/parser/testdata/generic",
+						Name:    "Blah[T]",
+					},
+					Kind:                      types.Struct,
+					CommentLines:              []string{""},
+					SecondClosestCommentLines: []string{""},
+					Members: []types.Member{
+						{
+							Name:         "V",
+							Embedded:     false,
+							CommentLines: []string{"V is the first field."},
+							Tags:         `json:"v"`,
+							Type: &types.Type{
+								Kind: types.TypeParam,
+								Name: types.Name{
+									Name: "T",
+								},
+							},
+						},
+					},
+					TypeParams: map[string]*types.Type{
+						"T": {
+							Name: types.Name{
+								Name: "any",
+							},
+							Kind: types.Interface,
+						},
+					},
+				}
+			},
+		},
+		{
+			description: "generic multiple",
+			testFile:    "./testdata/generic-multi",
+			expected: func() *types.Type {
+				return &types.Type{
+					Name: types.Name{
+						Package: "k8s.io/gengo/v2/parser/testdata/generic-multi",
+						Name:    "Blah[T,U,V]",
+					},
+					Kind:                      types.Struct,
+					CommentLines:              []string{""},
+					SecondClosestCommentLines: []string{""},
+					Members: []types.Member{
+						{
+							Name:         "V1",
+							Embedded:     false,
+							CommentLines: []string{"V1 is the first field."},
+							Tags:         `json:"v1"`,
+							Type: &types.Type{
+								Kind: types.TypeParam,
+								Name: types.Name{
+									Name: "T",
+								},
+							},
+						},
+						{
+							Name:         "V2",
+							Embedded:     false,
+							CommentLines: []string{"V2 is the second field."},
+							Tags:         `json:"v2"`,
+							Type: &types.Type{
+								Kind: types.TypeParam,
+								Name: types.Name{
+									Name: "U",
+								},
+							},
+						},
+						{
+							Name:         "V3",
+							Embedded:     false,
+							CommentLines: []string{"V3 is the third field."},
+							Tags:         `json:"v3"`,
+							Type: &types.Type{
+								Kind: types.TypeParam,
+								Name: types.Name{
+									Name: "V",
+								},
+							},
+						},
+					},
+					TypeParams: map[string]*types.Type{
+						"T": {
+							Name: types.Name{
+								Name: "any",
+							},
+							Kind: types.Interface,
+						},
+						"U": {
+							Name: types.Name{
+								Name: "any",
+							},
+							Kind: types.Interface,
+						},
+						"V": {
+							Name: types.Name{
+								Name: "any",
+							},
+							Kind: types.Interface,
+						},
+					},
+				}
+			},
+		},
+		{
+			description: "generic recursive",
+			testFile:    "./testdata/generic-recursive",
+			expected: func() *types.Type {
+				recursiveT := &types.Type{
+					Name: types.Name{
+						Package: "k8s.io/gengo/v2/parser/testdata/generic-recursive",
+						Name:    "DeepCopyable",
+					},
+					Kind:                      types.Interface,
+					CommentLines:              []string{""},
+					SecondClosestCommentLines: []string{""},
+					Methods:                   map[string]*types.Type{},
+				}
+				recursiveT.Methods["DeepCopy"] = &types.Type{
+					Name: types.Name{
+						Name: "func (k8s.io/gengo/v2/parser/testdata/generic-recursive.DeepCopyable[T]).DeepCopy() T",
+					},
+					Kind:         types.Func,
+					CommentLines: []string{""},
+					Signature: &types.Signature{
+						Receiver: recursiveT,
+						Results: []*types.ParamResult{
+							{
+								Name: "",
+								Type: &types.Type{
+									Name: types.Name{
+										Name: "T",
+									},
+									Kind: types.TypeParam,
+								},
+							},
+						},
+					},
+				}
+				return &types.Type{
+					Name: types.Name{
+						Package: "k8s.io/gengo/v2/parser/testdata/generic-recursive",
+						Name:    "Blah[T]",
+					},
+					Kind:                      types.Struct,
+					CommentLines:              []string{""},
+					SecondClosestCommentLines: []string{""},
+					Members: []types.Member{
+						{
+							Name:         "V",
+							Embedded:     false,
+							CommentLines: []string{"V is the first field."},
+							Tags:         `json:"v"`,
+							Type: &types.Type{
+								Name: types.Name{
+									Name: "T",
+								},
+								Kind: types.TypeParam,
+							},
+						},
+					},
+					TypeParams: map[string]*types.Type{
+						"T": recursiveT,
+					},
+				}
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			parser := New()
+
+			pkgs, err := parser.loadPackages(tc.testFile)
+			if err != nil {
+				t.Errorf("unexpected error: %v", err)
+			}
+			u := types.Universe{}
+			if err := parser.addPkgToUniverse(pkgs[0], &u); err != nil {
+				t.Errorf("unexpected error: %v", err)
+			}
+
+			expected := tc.expected()
+			pkg, ok := u[expected.Name.Package]
+			if !ok {
+				t.Fatalf("package %s not found", expected.Name.Package)
+			}
+			st := pkg.Type(expected.Name.Name)
+			if st == nil || st.Kind == types.Unknown {
+				t.Fatalf("type %s not found", expected.Name.Name)
+			}
+			if e, a := expected, st; !reflect.DeepEqual(e, a) {
+				t.Errorf("wanted, got:\n%#v\n%#v", e, a)
+			}
+		})
+	}
+}

v2/parser/testdata/basic/file.go

@@ -0,0 +1,12 @@
+package foo
+
+// Blah is a test.
+// A test, I tell you.
+type Blah struct {
+	// A is the first field.
+	A int64 `json:"a"`
+
+	// B is the second field.
+	// Multiline comments work.
+	B string `json:"b"`
+}

v2/parser/testdata/generic-multi/file.go

@@ -0,0 +1,10 @@
+package foo
+
+type Blah[T any, U any, V any] struct {
+	// V1 is the first field.
+	V1 T `json:"v1"`
+	// V2 is the second field.
+	V2 U `json:"v2"`
+	// V3 is the third field.
+	V3 V `json:"v3"`
+}

v2/parser/testdata/generic-recursive/file.go

@@ -0,0 +1,10 @@
+package foo
+
+type DeepCopyable[T any] interface {
+	DeepCopy() T
+}
+
+type Blah[T DeepCopyable[T]] struct {
+	// V is the first field.
+	V T `json:"v"`
+}

v2/parser/testdata/generic/file.go

@@ -0,0 +1,6 @@
+package foo
+
+type Blah[T any] struct {
+	// V is the first field.
+	V T `json:"v"`
+}

v2/types/types.go

@@ -98,6 +98,7 @@ const (
 	DeclarationOf Kind = "DeclarationOf"
 	Unknown       Kind = ""
 	Unsupported   Kind = "Unsupported"
+	TypeParam     Kind = "TypeParam"
 
 	// Protobuf is protobuf type.
 	Protobuf Kind = "Protobuf"
@@ -324,6 +325,9 @@ type Type struct {
 	// If Kind == Struct
 	Members []Member
 
+	// If Kind == Struct
+	TypeParams map[string]*Type
+
 	// If Kind == Map, Slice, Pointer, or Chan
 	Elem *Type