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types.go
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types.go
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package gotype
import (
"go/types"
"strconv"
"strings"
)
// Pkg describes a type's package.
type Pkg struct {
// The package import path.
Path string
// The package's name.
Name string
}
// Type is the representation of a Go type.
type Type struct {
// The type's package.
Pkg Pkg
// The name of a named type or empty string for unnamed types
Name string
// The kind of the go type.
Kind Kind
// Indicates whether or not the field is exported.
IsExported bool
// If the base type's an array type, this field will hold the array's length.
ArrayLen int64
// If kind is func, indicates whether or not the function is variadic.
IsVariadic bool
// Indicates whether or not the type is the "byte" alias type.
IsByte bool
// Indicates whether or not the type is the "rune" alias type.
IsRune bool
// If kind is map, Key will hold the info on the map's key type.
Key *Type
// If kind is map, Elem will hold the info on the map's value type.
// If kind is ptr, Elem will hold the info on pointed-to type.
// If kind is slice/array, Elem will hold the info on slice/array element type.
Elem *Type
// The method set of a named type or an interface type.
Methods []*Method
Embeddeds []*Type
// If kind is func, In & Out will hold the
// function's parameter and result types.
In, Out []*Var
// If kind is struct, Fields will hold the
// list of the struct's fields.
Fields []*StructField
// If the Type is an instantiated named type then
// Origin points to the original generic type.
Origin *Type
// If the Type is an instantiated named type then
// TypeArgs is the list of type arguments.
TypeArgs []*Type
// If the Type is a generic named type or a generic function
// signature then TypeParams is the list of type parameters.
TypeParams []*TypeParam
// If the Type is a union then Terms holds
// the union's of terms.
Terms []*Term
}
type TypeParam struct {
// The type param's package.
Pkg Pkg
// The type name of the type param.
Name string
// The constraint specified for the type param.
Constraint *Type
}
type TypeParamer interface {
TypeParams() *types.TypeParamList
}
type Term struct {
// Indicates whether or not the term
// was declared with a tilde.
Tilde bool
// The term's type.
Type *Type
}
// Reports whether or not the type's kind is is one of the provided kinds.
func (t Type) Is(kinds ...Kind) bool {
for _, k := range kinds {
if t.Kind == k {
return true
}
}
return false
}
// IsStructPointer indicates that t is a pointer-to-struct type.
func (t Type) IsStructPointer() bool {
return t.Kind == K_PTR && t.Elem != nil && t.Elem.Kind == K_STRUCT
}
// IsStructOrStructPointer indicates that t is either a struct type or a pointer-to-struct type.
func (t Type) IsStructOrStructPointer() bool {
return t.Kind == K_STRUCT || t.IsStructPointer()
}
// Indicates whether or not the type is an empty interface type.
func (t *Type) IsEmptyInterface() bool {
return t.Kind == K_INTERFACE && len(t.Methods) == 0
}
// IsIncluded reports whether or not the Type was
// declared in the github.com/frk/valid package.
func (t *Type) IsIncluded() bool {
return t.Pkg.Path == "github.com/frk/valid"
}
// IsGoString reports whether or not t is the Go builtin string type.
func (t *Type) IsGoString() bool {
return t.Pkg == Pkg{} && t.Kind == K_STRING && t.Name == ""
}
// IsGoError reports whether or not t is the Go builtin error type.
func (t *Type) IsGoError() bool {
return t.Pkg == Pkg{} && t.Kind == K_INTERFACE && t.Name == "error"
}
// IsGoAny reports whether or not t is the Go builtin any/interface{} type.
func (t *Type) IsGoAny() bool {
return t.Pkg == Pkg{} && t.Kind == K_INTERFACE &&
(t.Name == "any" || len(t.Methods) == 0)
}
// IsGoAnySlice reports whether or not t is the Go builtin []any/[]interface{} type.
func (t *Type) IsGoAnySlice() bool {
if t.Kind == K_SLICE {
return t.Elem.IsGoAny()
}
return false
}
// IsComparable reports wether or not a value of the Go
// type represented by t is comparable.
func (t *Type) IsComparable() bool {
if t.Kind == K_MAP || t.Kind == K_SLICE || t.Kind == K_FUNC {
return false
}
if t.Kind == K_ARRAY {
return t.Elem.IsComparable()
}
if t.Kind == K_STRUCT {
for _, f := range t.Fields {
if !f.Type.IsComparable() {
return false
}
}
}
return true
}
// IsNilable reports wether or not a value of the Go
// type represented by t can be set to nil.
func (t *Type) IsNilable() bool {
return t.Kind == K_PTR ||
t.Kind == K_SLICE ||
t.Kind == K_MAP ||
t.Kind == K_INTERFACE ||
t.Kind == K_FUNC ||
t.Kind == K_CHAN
}
// HasLength reports whether or not the Go type
// represented by t has a length.
func (t *Type) HasLength() bool {
return t.Kind == K_STRING ||
t.Kind == K_ARRAY ||
t.Kind == K_SLICE ||
t.Kind == K_MAP ||
t.Kind == K_CHAN
}
// IsValid reports whether or not the "IsValid() bool"
// method belongs to the method set of the type t.
func (t *Type) HasIsValid() bool {
for _, m := range t.Methods {
if m.Name == "IsValid" &&
len(m.Type.In) == 0 &&
len(m.Type.Out) == 1 &&
m.Type.Out[0].Type.Kind == K_BOOL {
return true
}
}
return false
}
// Reports whether or not the type t represents a pointer type of u.
func (t *Type) PtrOf(u *Type) bool {
return t.Kind == K_PTR && t.Elem.IsIdentical(u)
}
// Reports whether the types represented by t and u are equal. Note that this
// does not handle unnamed struct, interface (non-empty), func, and channel types.
func (t *Type) IsIdentical(u *Type) bool {
// named with same name and same package, accept
if t.Name != "" {
if t.Name == u.Name && t.Pkg.Path == u.Pkg.Path {
return true
}
}
// different kinds, reject
if t.Kind != u.Kind {
return false
}
// different names, reject
if t.Name != u.Name {
return false
}
// different packages, reject
if t.Pkg.Path != u.Pkg.Path {
return false
}
// channel, reject
if t.Kind == K_CHAN {
return false
}
// unnamed struct, reject
if t.Kind == K_STRUCT && t.Name == "" {
return false
}
// unnamed
switch t.Kind {
case K_ARRAY:
return t.ArrayLen == u.ArrayLen && t.Elem.IsIdentical(u.Elem)
case K_MAP:
return t.Key.IsIdentical(u.Key) && t.Elem.IsIdentical(u.Elem)
case K_SLICE, K_PTR:
return t.Elem.IsIdentical(u.Elem)
case K_INTERFACE:
// TODO range over the methods and compare those
return t.IsEmptyInterface() && u.IsEmptyInterface()
case K_FUNC:
// incompatible number of in/out parameters, reject
if len(t.In) != len(u.In) || len(t.Out) != len(u.Out) {
return false
}
// non-identical input parameter types, reject
for i := range t.In {
if !t.In[i].Type.IsIdentical(u.In[i].Type) {
return false
}
}
// non-identical output parameter types, reject
for i := range t.Out {
if !t.Out[i].Type.IsIdentical(u.Out[i].Type) {
return false
}
}
}
// accept
return true
}
// Reports whether or not a value of type t needs to be converted
// before it can be assigned to a variable of type u.
func (t *Type) NeedsConversion(u *Type) bool {
if u.IsIdentical(t) {
return false
}
if u.Kind == K_INTERFACE {
return false
}
return true
}
// CanError reports that the type, if it *is* a K_FUNC type,
// has error as its last return value type.
func (t *Type) CanError() bool {
if t.Kind != K_FUNC {
return false
}
if n := len(t.Out); n > 0 && t.Out[n-1].Type.IsGoError() {
return true
}
return false
}
// String retruns a string representation of the t Type.
func (t Type) TypeString(pkg *Pkg) string {
if len(t.Name) > 0 {
if pkg == nil || *pkg != t.Pkg {
return t.Pkg.Name + "." + t.Name
}
return t.Name
}
if t.IsByte {
return "byte"
} else if t.IsRune {
return "rune"
} else if t.Kind.IsBasic() {
return _kindstring[t.Kind]
}
switch t.Kind {
case K_ARRAY:
return "[" + strconv.FormatInt(t.ArrayLen, 10) + "]" + t.Elem.TypeString(pkg)
case K_INTERFACE:
if !t.IsEmptyInterface() {
return "interface{ ... }"
}
return "interface{}"
case K_MAP:
return "map[" + t.Key.TypeString(pkg) + "]" + t.Elem.TypeString(pkg)
case K_PTR:
return "*" + t.Elem.TypeString(pkg)
case K_SLICE:
return "[]" + t.Elem.TypeString(pkg)
case K_STRUCT:
if len(t.Fields) > 0 {
return "struct{ ... }"
}
return "struct{}"
case K_CHAN:
return "<chan>"
case K_FUNC:
in := make([]string, len(t.In))
for i := range t.In {
in[i] = t.In[i].Type.TypeString(pkg)
}
out := make([]string, len(t.Out))
for i := range t.Out {
out[i] = t.Out[i].Type.TypeString(pkg)
}
s := "func(" + strings.Join(in, ", ") + ")"
if len(out) > 1 {
s += " (" + strings.Join(out, ", ") + ")"
} else if len(out) == 1 {
s += " " + out[0]
}
return s
}
return "<unknown>"
}
////////////////////////////////////////////////////////////////////////////////
// Func
////////////////////////////////////////////////////////////////////////////////
// Func is used to represent a function.
type Func struct {
Name string
Type *Type
}
////////////////////////////////////////////////////////////////////////////////
// Var
////////////////////////////////////////////////////////////////////////////////
// Var is used to represent a function's parameters and results.
type Var struct {
Name string
Type *Type
}
func (v *Var) ShallowCopy() *Var {
u := *v
return &u
}
////////////////////////////////////////////////////////////////////////////////
// Fields
////////////////////////////////////////////////////////////////////////////////
// StructField describes a single struct field in a struct.
type StructField struct {
// The package to which the field belongs.
Pkg Pkg
// Name of the field.
Name string
// The field's type.
Type *Type
// The field's raw, uparsed struct tag.
Tag string
// Indicates that the tag `is:"-"` was used.
CanIgnore bool
// Indicates whether or not the field is embedded.
IsEmbedded bool
// Indicates whether or not the field is exported.
IsExported bool
// Var holds a reference to the *types.Var
// representation of the field.
Var *types.Var `cmp:"+"`
}
func (f *StructField) CanAccess(from Pkg) bool {
if f.Name == "_" {
return false
}
if f.CanIgnore {
return false
}
if !f.IsExported && !f.IsEmbedded && f.Pkg != from {
return false
}
return true
}
// FieldSelector is a list of fields that represents a chain of selectors where
// the 0th field is the "root" field and the len-1 field is the "leaf" field.
type FieldSelector []*StructField
// Last returns the last field in the selector.
func (s FieldSelector) Last() *StructField {
return s[len(s)-1]
}
// CopyWith returns a copy of the receiver with f appended to the end.
func (s FieldSelector) CopyWith(f *StructField) FieldSelector {
s2 := make(FieldSelector, len(s)+1)
copy(s2, s)
s2[len(s2)-1] = f
return s2
}
////////////////////////////////////////////////////////////////////////////////
// Methods
////////////////////////////////////////////////////////////////////////////////
// Method describes a single method in the method set of a named type or interface.
type Method struct {
// The package to which the method belongs.
Pkg Pkg
// The name of the method.
Name string
// The method's type.
Type *Type
// Indicates whether or not the method is exported.
IsExported bool
}
// Methoder represents a type with methods. It is implicitly
// implemented by *types.Interface and *types.Named.
type Methoder interface {
NumMethods() int
Method(i int) *types.Func
}
////////////////////////////////////////////////////////////////////////////////
// Kind
////////////////////////////////////////////////////////////////////////////////
// Kind indicates the specific kind of a Go type.
type Kind uint
const (
// basic
K_INVALID Kind = iota
_basic_kind_start
K_BOOL
_numeric_kind_start // int/uint/float
_integer_kind_start // int
K_INT
K_INT8
K_INT16
K_INT32
K_INT64
_integer_kind_end
_unsigned_kind_start // uint
K_UINT
K_UINT8
K_UINT16
K_UINT32
K_UINT64
K_UINTPTR
_unsigned_kind_end
K_FLOAT32
K_FLOAT64
_numeric_kind_end
K_COMPLEX64
K_COMPLEX128
K_STRING
K_UNSAFEPOINTER
_basic_kind_end
// non-basic
K_ARRAY // try to validate individual elements
K_INTERFACE // try to validate ... ???
K_MAP // try to validate individual elements
K_PTR // try to validate the element
K_SLICE // try to validate the individual elements
K_STRUCT // try to validate the individual fields
K_CHAN // don't validate
K_FUNC // don't validate
K_UNION
// alisases (basic)
K_BYTE = K_UINT8
K_RUNE = K_INT32
)
// Reports whether or not k is of a basic kind.
func (k Kind) IsBasic() bool { return _basic_kind_start < k && k < _basic_kind_end }
// Reports whether or not k is of the numeric kind, note that this
// does not include the complex64 and complex128 kinds.
func (k Kind) IsNumeric() bool { return _numeric_kind_start < k && k < _numeric_kind_end }
// Reports whether or not k is one of the int types. (does not include unsigned integers)
func (k Kind) IsInteger() bool { return _integer_kind_start < k && k < _integer_kind_end }
// Reports whether or not k is one of the uint types.
func (k Kind) IsUnsigned() bool { return _unsigned_kind_start < k && k < _unsigned_kind_end }
// Reports whether or not k is one of the float types.
func (k Kind) IsFloat() bool { return k == K_FLOAT32 || k == K_FLOAT64 }
// BasicString returns a string representation of the basic kind k.
func (k Kind) BasicString() string {
if k.IsBasic() {
return _kindstring[k]
}
return "<unknown>"
}
func (k Kind) String() string {
if int(k) < len(_kindstring) {
return _kindstring[k]
}
return "<unknown>"
}
var _kindstring = [...]string{
K_INVALID: "<invalid>",
K_BOOL: "bool",
K_INT: "int",
K_INT8: "int8",
K_INT16: "int16",
K_INT32: "int32",
K_INT64: "int64",
K_UINT: "uint",
K_UINT8: "uint8",
K_UINT16: "uint16",
K_UINT32: "uint32",
K_UINT64: "uint64",
K_UINTPTR: "uintptr",
K_FLOAT32: "float32",
K_FLOAT64: "float64",
K_COMPLEX64: "complex64",
K_COMPLEX128: "complex128",
K_STRING: "string",
// ...
K_ARRAY: "array",
K_INTERFACE: "interface",
K_MAP: "map",
K_PTR: "ptr",
K_SLICE: "slice",
K_STRUCT: "struct",
K_CHAN: "chan",
K_FUNC: "func",
}
////////////////////////////////////////////////////////////////////////////////
// Assignment
////////////////////////////////////////////////////////////////////////////////
type AssignmentStatus uint
const (
ASSIGNMENT_INVALID AssignmentStatus = iota // cannot assign
ASSIGNMENT_CONVERT // can assign but needs explicit converstion
ASSIGNMENT_OK // can assign as is
)
// CanConvert reports whether or not a value of type u
// can be converted to a value of type t.
func (t *Type) CanConvert(u *Type) bool {
return t.CanAssign(u) > ASSIGNMENT_INVALID
}
// CanAssign reports whether or not a value of type u can be
// assigned to a variable of type t. Note that this does not
// handle unnamed struct, interface, func, and channel types.
func (t *Type) CanAssign(u *Type) AssignmentStatus {
// if same, accept
if u.IsIdentical(t) {
return ASSIGNMENT_OK
}
// if t is interface{}, accept
if t.IsEmptyInterface() {
return ASSIGNMENT_OK
}
// if t is interface{ ... } and u implements t, accept
if t.Kind == K_INTERFACE && u.Implements(t) {
return ASSIGNMENT_OK
}
// same basic kind, accept
if t.Kind == u.Kind && t.Kind.IsBasic() {
// TODO if u is unnamed, e.g. a rule arg constant
// then this should return
return ASSIGNMENT_CONVERT
}
// both numeric, accept
if t.Kind.IsNumeric() && u.Kind.IsNumeric() {
return ASSIGNMENT_CONVERT
}
// string from []byte, []rune, []uint8, and []int32, accept
if t.Kind == K_STRING && u.Kind == K_SLICE && u.Elem.Name == "" &&
(u.Elem.Kind == K_UINT8 || u.Elem.Kind == K_INT32) {
return ASSIGNMENT_CONVERT
}
// string to []byte, []rune, []uint8, and []int32, accept
if u.Kind == K_STRING && t.Kind == K_SLICE && t.Elem.Name == "" &&
(t.Elem.Kind == K_UINT8 || t.Elem.Kind == K_INT32) {
return ASSIGNMENT_CONVERT
}
// element types (and key & len) of non-basic are equal, accept
if t.Kind == u.Kind && !t.Kind.IsBasic() {
switch t.Kind {
case K_ARRAY:
if t.ArrayLen == u.ArrayLen && t.Elem.IsIdentical(u.Elem) {
return ASSIGNMENT_CONVERT
}
case K_MAP:
if t.Key.IsIdentical(u.Key) && t.Elem.IsIdentical(u.Elem) {
return ASSIGNMENT_CONVERT
}
case K_SLICE, K_PTR:
if t.Elem.IsIdentical(u.Elem) {
return ASSIGNMENT_CONVERT
}
}
}
return ASSIGNMENT_INVALID
}
func (t *Type) Implements(u *Type) bool {
if u.Kind != K_INTERFACE {
return false
}
if t.Kind == K_PTR {
t = t.Elem
}
methodLoop:
for _, um := range u.Methods {
for _, tm := range t.Methods {
if um.Name != tm.Name {
continue // try next
}
if !um.IsExported && um.Pkg != tm.Pkg {
continue // try next
}
if !tm.Type.IsIdentical(um.Type) {
continue // try next
}
// tm matches um
continue methodLoop
}
// no method in t matched um
return false
}
return true
}
// NOTE: this implementation, and the corresponding tests, is a slightly
// modified and adapted version of https://pkg.go.dev/reflect#VisibleFields.
//
// VisibleFields returns all the visible fields in t, which must be
// a struct type or a pointer to a struct type. A field is defined as
// visible if it's accessible directly from the type's instance.
//
// The returned fields include fields inside anonymous struct members and
// unexported fields. They follow the same order found in the struct, with
// anonymous fields followed immediately by their promoted fields.
func (t *Type) VisibleFields() []*StructField {
x := t
if x.Kind == K_PTR {
x = x.Elem
}
if x.Kind != K_STRUCT {
return nil
}
w := &visibleFieldsWalker{
fields: make([]*StructField, 0, len(x.Fields)),
depth: make(map[*StructField]int, len(x.Fields)),
hidden: make(map[*StructField]bool),
byName: make(map[string]*StructField, len(x.Fields)),
visiting: make(map[*Type]bool),
}
w.walk(t, 0)
// Remove all the fields that have been hidden.
j := 0
for i := range w.fields {
f := w.fields[i]
if w.hidden[f] {
continue
}
if i != j {
// A field has been removed. We need to shuffle
// all the subsequent elements up.
w.fields[j] = f
}
j++
}
return w.fields[:j]
}
type visibleFieldsWalker struct {
fields []*StructField
depth map[*StructField]int
hidden map[*StructField]bool
byName map[string]*StructField
visiting map[*Type]bool
}
func (w *visibleFieldsWalker) walk(t *Type, depth int) {
if w.visiting[t] {
return
}
w.visiting[t] = true
for i := 0; i < len(t.Fields); i++ {
// Use a shallow copy, otherwise a struct that's embedded
// multiple times at different depths will result in the
// same field pointer to appear multiple times in w.fields.
// And the subsequent hidden-field-removal process will,
// because of the matching pointer, remove all instances
// from w.fields, rather than keeping the shallowest one.
v := *t.Fields[i]
f := &v
add := true
if old, ok := w.byName[f.Name]; ok {
switch oldepth := w.depth[old]; {
case depth == oldepth:
// hide old field because access
// is ambiguous with the new field.
w.hidden[old] = true
add = false
case depth < oldepth:
// hide old field because its
// deeper than the new field.
w.hidden[old] = true
case depth > oldepth:
add = false
}
}
if add {
w.fields = append(w.fields, f)
w.depth[f] = depth
w.byName[f.Name] = f
}
if f.IsEmbedded {
t := f.Type
if t.Kind == K_PTR {
t = t.Elem
}
if t.Kind == K_STRUCT {
w.walk(t, depth+1)
}
}
}
delete(w.visiting, t)
}