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| 1 | +package main |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "fmt" |
| 6 | + "go/types" |
| 7 | + "reflect" |
| 8 | + "strings" |
| 9 | + |
| 10 | + "golang.org/x/tools/go/packages" |
| 11 | + "golang.org/x/xerrors" |
| 12 | + |
| 13 | + "cdr.dev/slog" |
| 14 | +) |
| 15 | + |
| 16 | +type Generator struct { |
| 17 | + pkg *packages.Package // Package we are scanning. |
| 18 | + log slog.Logger |
| 19 | +} |
| 20 | + |
| 21 | +// parsePackage takes a list of patterns such as a directory, and parses them. |
| 22 | +// All parsed packages will accumulate "foundTypes". |
| 23 | +func (g *Generator) parsePackage(ctx context.Context, patterns ...string) error { |
| 24 | + cfg := &packages.Config{ |
| 25 | + Mode: packages.NeedTypes | packages.NeedName | packages.NeedTypesInfo | |
| 26 | + packages.NeedTypesSizes | packages.NeedSyntax, |
| 27 | + Tests: false, |
| 28 | + Context: ctx, |
| 29 | + } |
| 30 | + |
| 31 | + pkgs, err := packages.Load(cfg, patterns...) |
| 32 | + if err != nil { |
| 33 | + return xerrors.Errorf("load package: %w", err) |
| 34 | + } |
| 35 | + |
| 36 | + if len(pkgs) != 1 { |
| 37 | + return xerrors.Errorf("expected 1 package, found %d", len(pkgs)) |
| 38 | + } |
| 39 | + |
| 40 | + g.pkg = pkgs[0] |
| 41 | + return nil |
| 42 | +} |
| 43 | + |
| 44 | +// generateAll will generate for all types found in the pkg |
| 45 | +func (g *Generator) generateAll() error { |
| 46 | + for _, n := range g.pkg.Types.Scope().Names() { |
| 47 | + err := g.generate(n) |
| 48 | + if err != nil { |
| 49 | + return xerrors.Errorf("generate %q: %w", n, err) |
| 50 | + } |
| 51 | + } |
| 52 | + return nil |
| 53 | +} |
| 54 | + |
| 55 | +// generate generates the typescript for a singular Go type. |
| 56 | +func (g *Generator) generate(typeName string) error { |
| 57 | + obj := g.pkg.Types.Scope().Lookup(typeName) |
| 58 | + if obj == nil || obj.Type() == nil { |
| 59 | + return xerrors.Errorf("pkg is missing type %q", typeName) |
| 60 | + } |
| 61 | + |
| 62 | + st, ok := obj.Type().Underlying().(*types.Struct) |
| 63 | + if !ok { |
| 64 | + return nil |
| 65 | + //return xerrors.Errorf("only generate for structs, found %q", obj.Type().String()) |
| 66 | + } |
| 67 | + |
| 68 | + return g.buildStruct(obj, st) |
| 69 | +} |
| 70 | + |
| 71 | +// buildStruct just prints the typescript def for a type. |
| 72 | +// TODO: Write to a buffer instead |
| 73 | +func (g *Generator) buildStruct(obj types.Object, st *types.Struct) error { |
| 74 | + var s strings.Builder |
| 75 | + s.WriteString("export interface " + obj.Name() + "{\n") |
| 76 | + for i := 0; i < st.NumFields(); i++ { |
| 77 | + field := st.Field(i) |
| 78 | + tag := reflect.StructTag(st.Tag(i)) |
| 79 | + jsonName := tag.Get("json") |
| 80 | + arr := strings.Split(jsonName, ",") |
| 81 | + jsonName = arr[0] |
| 82 | + if jsonName == "" { |
| 83 | + jsonName = field.Name() |
| 84 | + } |
| 85 | + |
| 86 | + ts, err := g.typescriptType(field.Type()) |
| 87 | + if err != nil { |
| 88 | + return xerrors.Errorf("typescript type: %w", err) |
| 89 | + } |
| 90 | + s.WriteString(fmt.Sprintf("\treadonly %s: %s\n", jsonName, ts)) |
| 91 | + } |
| 92 | + s.WriteString("}") |
| 93 | + fmt.Println(s.String()) |
| 94 | + return nil |
| 95 | +} |
| 96 | + |
| 97 | +// typescriptType this function returns a typescript type for a given |
| 98 | +// golang type. |
| 99 | +// Eg: |
| 100 | +// []byte returns "string" |
| 101 | +func (g *Generator) typescriptType(ty types.Type) (string, error) { |
| 102 | + switch ty.(type) { |
| 103 | + case *types.Basic: |
| 104 | + bs := ty.(*types.Basic) |
| 105 | + // All basic literals (string, bool, int, etc). |
| 106 | + // TODO: Actually ensure the golang names are ok, otherwise, |
| 107 | + // we want to put another switch to capture these types |
| 108 | + // and rename to typescript. |
| 109 | + return bs.Name(), nil |
| 110 | + case *types.Struct: |
| 111 | + // TODO: This kinda sucks right now. It just dumps the struct def |
| 112 | + return ty.String(), nil |
| 113 | + case *types.Map: |
| 114 | + // TODO: Typescript dictionary??? Object? |
| 115 | + return "map", nil |
| 116 | + case *types.Slice, *types.Array: |
| 117 | + type hasElem interface { |
| 118 | + Elem() types.Type |
| 119 | + } |
| 120 | + |
| 121 | + arr := ty.(hasElem) |
| 122 | + // All byte arrays should be strings in typescript? |
| 123 | + if arr.Elem().String() == "byte" { |
| 124 | + return "string", nil |
| 125 | + } |
| 126 | + |
| 127 | + // Array of underlying type. |
| 128 | + underlying, err := g.typescriptType(arr.Elem()) |
| 129 | + if err != nil { |
| 130 | + return "", xerrors.Errorf("array: %w", err) |
| 131 | + } |
| 132 | + return underlying + "[]", nil |
| 133 | + case *types.Named: |
| 134 | + // Named is a named type like |
| 135 | + // type EnumExample string |
| 136 | + // Use the underlying type |
| 137 | + n := ty.(*types.Named) |
| 138 | + name := n.Obj().Name() |
| 139 | + // If we have the type, just put the name because it will be defined |
| 140 | + // elsewhere in the typescript gen. |
| 141 | + if obj := g.pkg.Types.Scope().Lookup(n.String()); obj != nil { |
| 142 | + return name, nil |
| 143 | + } |
| 144 | + |
| 145 | + // If it's a struct, just use the name for now. |
| 146 | + if _, ok := ty.Underlying().(*types.Struct); ok { |
| 147 | + return name, nil |
| 148 | + } |
| 149 | + |
| 150 | + // Defer to the underlying type. |
| 151 | + return g.typescriptType(ty.Underlying()) |
| 152 | + case *types.Pointer: |
| 153 | + // Dereference pointers. |
| 154 | + // TODO: Nullable fields? |
| 155 | + pt := ty.(*types.Pointer) |
| 156 | + return g.typescriptType(pt.Elem()) |
| 157 | + } |
| 158 | + |
| 159 | + // These are all the other types we need to support. |
| 160 | + // time.Time, uuid, etc. |
| 161 | + return "", xerrors.Errorf("unknown type: %s", ty.String()) |
| 162 | +} |
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