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Diffstat (limited to '')
-rw-r--r-- | dependencies/pkg/mod/github.com/jmoiron/sqlx@v1.3.5/reflectx/reflect.go | 444 |
1 files changed, 444 insertions, 0 deletions
diff --git a/dependencies/pkg/mod/github.com/jmoiron/sqlx@v1.3.5/reflectx/reflect.go b/dependencies/pkg/mod/github.com/jmoiron/sqlx@v1.3.5/reflectx/reflect.go new file mode 100644 index 0000000..0b10994 --- /dev/null +++ b/dependencies/pkg/mod/github.com/jmoiron/sqlx@v1.3.5/reflectx/reflect.go @@ -0,0 +1,444 @@ +// Package reflectx implements extensions to the standard reflect lib suitable +// for implementing marshalling and unmarshalling packages. The main Mapper type +// allows for Go-compatible named attribute access, including accessing embedded +// struct attributes and the ability to use functions and struct tags to +// customize field names. +// +package reflectx + +import ( + "reflect" + "runtime" + "strings" + "sync" +) + +// A FieldInfo is metadata for a struct field. +type FieldInfo struct { + Index []int + Path string + Field reflect.StructField + Zero reflect.Value + Name string + Options map[string]string + Embedded bool + Children []*FieldInfo + Parent *FieldInfo +} + +// A StructMap is an index of field metadata for a struct. +type StructMap struct { + Tree *FieldInfo + Index []*FieldInfo + Paths map[string]*FieldInfo + Names map[string]*FieldInfo +} + +// GetByPath returns a *FieldInfo for a given string path. +func (f StructMap) GetByPath(path string) *FieldInfo { + return f.Paths[path] +} + +// GetByTraversal returns a *FieldInfo for a given integer path. It is +// analogous to reflect.FieldByIndex, but using the cached traversal +// rather than re-executing the reflect machinery each time. +func (f StructMap) GetByTraversal(index []int) *FieldInfo { + if len(index) == 0 { + return nil + } + + tree := f.Tree + for _, i := range index { + if i >= len(tree.Children) || tree.Children[i] == nil { + return nil + } + tree = tree.Children[i] + } + return tree +} + +// Mapper is a general purpose mapper of names to struct fields. A Mapper +// behaves like most marshallers in the standard library, obeying a field tag +// for name mapping but also providing a basic transform function. +type Mapper struct { + cache map[reflect.Type]*StructMap + tagName string + tagMapFunc func(string) string + mapFunc func(string) string + mutex sync.Mutex +} + +// NewMapper returns a new mapper using the tagName as its struct field tag. +// If tagName is the empty string, it is ignored. +func NewMapper(tagName string) *Mapper { + return &Mapper{ + cache: make(map[reflect.Type]*StructMap), + tagName: tagName, + } +} + +// NewMapperTagFunc returns a new mapper which contains a mapper for field names +// AND a mapper for tag values. This is useful for tags like json which can +// have values like "name,omitempty". +func NewMapperTagFunc(tagName string, mapFunc, tagMapFunc func(string) string) *Mapper { + return &Mapper{ + cache: make(map[reflect.Type]*StructMap), + tagName: tagName, + mapFunc: mapFunc, + tagMapFunc: tagMapFunc, + } +} + +// NewMapperFunc returns a new mapper which optionally obeys a field tag and +// a struct field name mapper func given by f. Tags will take precedence, but +// for any other field, the mapped name will be f(field.Name) +func NewMapperFunc(tagName string, f func(string) string) *Mapper { + return &Mapper{ + cache: make(map[reflect.Type]*StructMap), + tagName: tagName, + mapFunc: f, + } +} + +// TypeMap returns a mapping of field strings to int slices representing +// the traversal down the struct to reach the field. +func (m *Mapper) TypeMap(t reflect.Type) *StructMap { + m.mutex.Lock() + mapping, ok := m.cache[t] + if !ok { + mapping = getMapping(t, m.tagName, m.mapFunc, m.tagMapFunc) + m.cache[t] = mapping + } + m.mutex.Unlock() + return mapping +} + +// FieldMap returns the mapper's mapping of field names to reflect values. Panics +// if v's Kind is not Struct, or v is not Indirectable to a struct kind. +func (m *Mapper) FieldMap(v reflect.Value) map[string]reflect.Value { + v = reflect.Indirect(v) + mustBe(v, reflect.Struct) + + r := map[string]reflect.Value{} + tm := m.TypeMap(v.Type()) + for tagName, fi := range tm.Names { + r[tagName] = FieldByIndexes(v, fi.Index) + } + return r +} + +// FieldByName returns a field by its mapped name as a reflect.Value. +// Panics if v's Kind is not Struct or v is not Indirectable to a struct Kind. +// Returns zero Value if the name is not found. +func (m *Mapper) FieldByName(v reflect.Value, name string) reflect.Value { + v = reflect.Indirect(v) + mustBe(v, reflect.Struct) + + tm := m.TypeMap(v.Type()) + fi, ok := tm.Names[name] + if !ok { + return v + } + return FieldByIndexes(v, fi.Index) +} + +// FieldsByName returns a slice of values corresponding to the slice of names +// for the value. Panics if v's Kind is not Struct or v is not Indirectable +// to a struct Kind. Returns zero Value for each name not found. +func (m *Mapper) FieldsByName(v reflect.Value, names []string) []reflect.Value { + v = reflect.Indirect(v) + mustBe(v, reflect.Struct) + + tm := m.TypeMap(v.Type()) + vals := make([]reflect.Value, 0, len(names)) + for _, name := range names { + fi, ok := tm.Names[name] + if !ok { + vals = append(vals, *new(reflect.Value)) + } else { + vals = append(vals, FieldByIndexes(v, fi.Index)) + } + } + return vals +} + +// TraversalsByName returns a slice of int slices which represent the struct +// traversals for each mapped name. Panics if t is not a struct or Indirectable +// to a struct. Returns empty int slice for each name not found. +func (m *Mapper) TraversalsByName(t reflect.Type, names []string) [][]int { + r := make([][]int, 0, len(names)) + m.TraversalsByNameFunc(t, names, func(_ int, i []int) error { + if i == nil { + r = append(r, []int{}) + } else { + r = append(r, i) + } + + return nil + }) + return r +} + +// TraversalsByNameFunc traverses the mapped names and calls fn with the index of +// each name and the struct traversal represented by that name. Panics if t is not +// a struct or Indirectable to a struct. Returns the first error returned by fn or nil. +func (m *Mapper) TraversalsByNameFunc(t reflect.Type, names []string, fn func(int, []int) error) error { + t = Deref(t) + mustBe(t, reflect.Struct) + tm := m.TypeMap(t) + for i, name := range names { + fi, ok := tm.Names[name] + if !ok { + if err := fn(i, nil); err != nil { + return err + } + } else { + if err := fn(i, fi.Index); err != nil { + return err + } + } + } + return nil +} + +// FieldByIndexes returns a value for the field given by the struct traversal +// for the given value. +func FieldByIndexes(v reflect.Value, indexes []int) reflect.Value { + for _, i := range indexes { + v = reflect.Indirect(v).Field(i) + // if this is a pointer and it's nil, allocate a new value and set it + if v.Kind() == reflect.Ptr && v.IsNil() { + alloc := reflect.New(Deref(v.Type())) + v.Set(alloc) + } + if v.Kind() == reflect.Map && v.IsNil() { + v.Set(reflect.MakeMap(v.Type())) + } + } + return v +} + +// FieldByIndexesReadOnly returns a value for a particular struct traversal, +// but is not concerned with allocating nil pointers because the value is +// going to be used for reading and not setting. +func FieldByIndexesReadOnly(v reflect.Value, indexes []int) reflect.Value { + for _, i := range indexes { + v = reflect.Indirect(v).Field(i) + } + return v +} + +// Deref is Indirect for reflect.Types +func Deref(t reflect.Type) reflect.Type { + if t.Kind() == reflect.Ptr { + t = t.Elem() + } + return t +} + +// -- helpers & utilities -- + +type kinder interface { + Kind() reflect.Kind +} + +// mustBe checks a value against a kind, panicing with a reflect.ValueError +// if the kind isn't that which is required. +func mustBe(v kinder, expected reflect.Kind) { + if k := v.Kind(); k != expected { + panic(&reflect.ValueError{Method: methodName(), Kind: k}) + } +} + +// methodName returns the caller of the function calling methodName +func methodName() string { + pc, _, _, _ := runtime.Caller(2) + f := runtime.FuncForPC(pc) + if f == nil { + return "unknown method" + } + return f.Name() +} + +type typeQueue struct { + t reflect.Type + fi *FieldInfo + pp string // Parent path +} + +// A copying append that creates a new slice each time. +func apnd(is []int, i int) []int { + x := make([]int, len(is)+1) + copy(x, is) + x[len(x)-1] = i + return x +} + +type mapf func(string) string + +// parseName parses the tag and the target name for the given field using +// the tagName (eg 'json' for `json:"foo"` tags), mapFunc for mapping the +// field's name to a target name, and tagMapFunc for mapping the tag to +// a target name. +func parseName(field reflect.StructField, tagName string, mapFunc, tagMapFunc mapf) (tag, fieldName string) { + // first, set the fieldName to the field's name + fieldName = field.Name + // if a mapFunc is set, use that to override the fieldName + if mapFunc != nil { + fieldName = mapFunc(fieldName) + } + + // if there's no tag to look for, return the field name + if tagName == "" { + return "", fieldName + } + + // if this tag is not set using the normal convention in the tag, + // then return the fieldname.. this check is done because according + // to the reflect documentation: + // If the tag does not have the conventional format, + // the value returned by Get is unspecified. + // which doesn't sound great. + if !strings.Contains(string(field.Tag), tagName+":") { + return "", fieldName + } + + // at this point we're fairly sure that we have a tag, so lets pull it out + tag = field.Tag.Get(tagName) + + // if we have a mapper function, call it on the whole tag + // XXX: this is a change from the old version, which pulled out the name + // before the tagMapFunc could be run, but I think this is the right way + if tagMapFunc != nil { + tag = tagMapFunc(tag) + } + + // finally, split the options from the name + parts := strings.Split(tag, ",") + fieldName = parts[0] + + return tag, fieldName +} + +// parseOptions parses options out of a tag string, skipping the name +func parseOptions(tag string) map[string]string { + parts := strings.Split(tag, ",") + options := make(map[string]string, len(parts)) + if len(parts) > 1 { + for _, opt := range parts[1:] { + // short circuit potentially expensive split op + if strings.Contains(opt, "=") { + kv := strings.Split(opt, "=") + options[kv[0]] = kv[1] + continue + } + options[opt] = "" + } + } + return options +} + +// getMapping returns a mapping for the t type, using the tagName, mapFunc and +// tagMapFunc to determine the canonical names of fields. +func getMapping(t reflect.Type, tagName string, mapFunc, tagMapFunc mapf) *StructMap { + m := []*FieldInfo{} + + root := &FieldInfo{} + queue := []typeQueue{} + queue = append(queue, typeQueue{Deref(t), root, ""}) + +QueueLoop: + for len(queue) != 0 { + // pop the first item off of the queue + tq := queue[0] + queue = queue[1:] + + // ignore recursive field + for p := tq.fi.Parent; p != nil; p = p.Parent { + if tq.fi.Field.Type == p.Field.Type { + continue QueueLoop + } + } + + nChildren := 0 + if tq.t.Kind() == reflect.Struct { + nChildren = tq.t.NumField() + } + tq.fi.Children = make([]*FieldInfo, nChildren) + + // iterate through all of its fields + for fieldPos := 0; fieldPos < nChildren; fieldPos++ { + + f := tq.t.Field(fieldPos) + + // parse the tag and the target name using the mapping options for this field + tag, name := parseName(f, tagName, mapFunc, tagMapFunc) + + // if the name is "-", disabled via a tag, skip it + if name == "-" { + continue + } + + fi := FieldInfo{ + Field: f, + Name: name, + Zero: reflect.New(f.Type).Elem(), + Options: parseOptions(tag), + } + + // if the path is empty this path is just the name + if tq.pp == "" { + fi.Path = fi.Name + } else { + fi.Path = tq.pp + "." + fi.Name + } + + // skip unexported fields + if len(f.PkgPath) != 0 && !f.Anonymous { + continue + } + + // bfs search of anonymous embedded structs + if f.Anonymous { + pp := tq.pp + if tag != "" { + pp = fi.Path + } + + fi.Embedded = true + fi.Index = apnd(tq.fi.Index, fieldPos) + nChildren := 0 + ft := Deref(f.Type) + if ft.Kind() == reflect.Struct { + nChildren = ft.NumField() + } + fi.Children = make([]*FieldInfo, nChildren) + queue = append(queue, typeQueue{Deref(f.Type), &fi, pp}) + } else if fi.Zero.Kind() == reflect.Struct || (fi.Zero.Kind() == reflect.Ptr && fi.Zero.Type().Elem().Kind() == reflect.Struct) { + fi.Index = apnd(tq.fi.Index, fieldPos) + fi.Children = make([]*FieldInfo, Deref(f.Type).NumField()) + queue = append(queue, typeQueue{Deref(f.Type), &fi, fi.Path}) + } + + fi.Index = apnd(tq.fi.Index, fieldPos) + fi.Parent = tq.fi + tq.fi.Children[fieldPos] = &fi + m = append(m, &fi) + } + } + + flds := &StructMap{Index: m, Tree: root, Paths: map[string]*FieldInfo{}, Names: map[string]*FieldInfo{}} + for _, fi := range flds.Index { + // check if nothing has already been pushed with the same path + // sometimes you can choose to override a type using embedded struct + fld, ok := flds.Paths[fi.Path] + if !ok || fld.Embedded { + flds.Paths[fi.Path] = fi + if fi.Name != "" && !fi.Embedded { + flds.Names[fi.Path] = fi + } + } + } + + return flds +} |