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Diffstat (limited to 'vendor/google.golang.org/appengine/datastore/prop.go')
| -rw-r--r-- | vendor/google.golang.org/appengine/datastore/prop.go | 330 |
1 files changed, 330 insertions, 0 deletions
diff --git a/vendor/google.golang.org/appengine/datastore/prop.go b/vendor/google.golang.org/appengine/datastore/prop.go new file mode 100644 index 000000000..5cb2079d8 --- /dev/null +++ b/vendor/google.golang.org/appengine/datastore/prop.go @@ -0,0 +1,330 @@ +// Copyright 2011 Google Inc. All rights reserved. +// Use of this source code is governed by the Apache 2.0 +// license that can be found in the LICENSE file. + +package datastore + +import ( + "fmt" + "reflect" + "strings" + "sync" + "unicode" +) + +// Entities with more than this many indexed properties will not be saved. +const maxIndexedProperties = 20000 + +// []byte fields more than 1 megabyte long will not be loaded or saved. +const maxBlobLen = 1 << 20 + +// Property is a name/value pair plus some metadata. A datastore entity's +// contents are loaded and saved as a sequence of Properties. An entity can +// have multiple Properties with the same name, provided that p.Multiple is +// true on all of that entity's Properties with that name. +type Property struct { + // Name is the property name. + Name string + // Value is the property value. The valid types are: + // - int64 + // - bool + // - string + // - float64 + // - ByteString + // - *Key + // - time.Time + // - appengine.BlobKey + // - appengine.GeoPoint + // - []byte (up to 1 megabyte in length) + // - *Entity (representing a nested struct) + // This set is smaller than the set of valid struct field types that the + // datastore can load and save. A Property Value cannot be a slice (apart + // from []byte); use multiple Properties instead. Also, a Value's type + // must be explicitly on the list above; it is not sufficient for the + // underlying type to be on that list. For example, a Value of "type + // myInt64 int64" is invalid. Smaller-width integers and floats are also + // invalid. Again, this is more restrictive than the set of valid struct + // field types. + // + // A Value will have an opaque type when loading entities from an index, + // such as via a projection query. Load entities into a struct instead + // of a PropertyLoadSaver when using a projection query. + // + // A Value may also be the nil interface value; this is equivalent to + // Python's None but not directly representable by a Go struct. Loading + // a nil-valued property into a struct will set that field to the zero + // value. + Value interface{} + // NoIndex is whether the datastore cannot index this property. + NoIndex bool + // Multiple is whether the entity can have multiple properties with + // the same name. Even if a particular instance only has one property with + // a certain name, Multiple should be true if a struct would best represent + // it as a field of type []T instead of type T. + Multiple bool +} + +// An Entity is the value type for a nested struct. +// This type is only used for a Property's Value. +type Entity struct { + Key *Key + Properties []Property +} + +// ByteString is a short byte slice (up to 1500 bytes) that can be indexed. +type ByteString []byte + +// PropertyLoadSaver can be converted from and to a slice of Properties. +type PropertyLoadSaver interface { + Load([]Property) error + Save() ([]Property, error) +} + +// PropertyList converts a []Property to implement PropertyLoadSaver. +type PropertyList []Property + +var ( + typeOfPropertyLoadSaver = reflect.TypeOf((*PropertyLoadSaver)(nil)).Elem() + typeOfPropertyList = reflect.TypeOf(PropertyList(nil)) +) + +// Load loads all of the provided properties into l. +// It does not first reset *l to an empty slice. +func (l *PropertyList) Load(p []Property) error { + *l = append(*l, p...) + return nil +} + +// Save saves all of l's properties as a slice or Properties. +func (l *PropertyList) Save() ([]Property, error) { + return *l, nil +} + +// validPropertyName returns whether name consists of one or more valid Go +// identifiers joined by ".". +func validPropertyName(name string) bool { + if name == "" { + return false + } + for _, s := range strings.Split(name, ".") { + if s == "" { + return false + } + first := true + for _, c := range s { + if first { + first = false + if c != '_' && !unicode.IsLetter(c) { + return false + } + } else { + if c != '_' && !unicode.IsLetter(c) && !unicode.IsDigit(c) { + return false + } + } + } + } + return true +} + +// structCodec describes how to convert a struct to and from a sequence of +// properties. +type structCodec struct { + // fields gives the field codec for the structTag with the given name. + fields map[string]fieldCodec + // hasSlice is whether a struct or any of its nested or embedded structs + // has a slice-typed field (other than []byte). + hasSlice bool + // keyField is the index of a *Key field with structTag __key__. + // This field is not relevant for the top level struct, only for + // nested structs. + keyField int + // complete is whether the structCodec is complete. An incomplete + // structCodec may be encountered when walking a recursive struct. + complete bool +} + +// fieldCodec is a struct field's index and, if that struct field's type is +// itself a struct, that substruct's structCodec. +type fieldCodec struct { + // path is the index path to the field + path []int + noIndex bool + // omitEmpty indicates that the field should be omitted on save + // if empty. + omitEmpty bool + // structCodec is the codec fot the struct field at index 'path', + // or nil if the field is not a struct. + structCodec *structCodec +} + +// structCodecs collects the structCodecs that have already been calculated. +var ( + structCodecsMutex sync.Mutex + structCodecs = make(map[reflect.Type]*structCodec) +) + +// getStructCodec returns the structCodec for the given struct type. +func getStructCodec(t reflect.Type) (*structCodec, error) { + structCodecsMutex.Lock() + defer structCodecsMutex.Unlock() + return getStructCodecLocked(t) +} + +// getStructCodecLocked implements getStructCodec. The structCodecsMutex must +// be held when calling this function. +func getStructCodecLocked(t reflect.Type) (ret *structCodec, retErr error) { + c, ok := structCodecs[t] + if ok { + return c, nil + } + c = &structCodec{ + fields: make(map[string]fieldCodec), + // We initialize keyField to -1 so that the zero-value is not + // misinterpreted as index 0. + keyField: -1, + } + + // Add c to the structCodecs map before we are sure it is good. If t is + // a recursive type, it needs to find the incomplete entry for itself in + // the map. + structCodecs[t] = c + defer func() { + if retErr != nil { + delete(structCodecs, t) + } + }() + + for i := 0; i < t.NumField(); i++ { + f := t.Field(i) + // Skip unexported fields. + // Note that if f is an anonymous, unexported struct field, + // we will promote its fields. + if f.PkgPath != "" && !f.Anonymous { + continue + } + + tags := strings.Split(f.Tag.Get("datastore"), ",") + name := tags[0] + opts := make(map[string]bool) + for _, t := range tags[1:] { + opts[t] = true + } + switch { + case name == "": + if !f.Anonymous { + name = f.Name + } + case name == "-": + continue + case name == "__key__": + if f.Type != typeOfKeyPtr { + return nil, fmt.Errorf("datastore: __key__ field on struct %v is not a *datastore.Key", t) + } + c.keyField = i + case !validPropertyName(name): + return nil, fmt.Errorf("datastore: struct tag has invalid property name: %q", name) + } + + substructType, fIsSlice := reflect.Type(nil), false + switch f.Type.Kind() { + case reflect.Struct: + substructType = f.Type + case reflect.Slice: + if f.Type.Elem().Kind() == reflect.Struct { + substructType = f.Type.Elem() + } + fIsSlice = f.Type != typeOfByteSlice + c.hasSlice = c.hasSlice || fIsSlice + } + + var sub *structCodec + if substructType != nil && substructType != typeOfTime && substructType != typeOfGeoPoint { + var err error + sub, err = getStructCodecLocked(substructType) + if err != nil { + return nil, err + } + if !sub.complete { + return nil, fmt.Errorf("datastore: recursive struct: field %q", f.Name) + } + if fIsSlice && sub.hasSlice { + return nil, fmt.Errorf( + "datastore: flattening nested structs leads to a slice of slices: field %q", f.Name) + } + c.hasSlice = c.hasSlice || sub.hasSlice + // If f is an anonymous struct field, we promote the substruct's fields up to this level + // in the linked list of struct codecs. + if f.Anonymous { + for subname, subfield := range sub.fields { + if name != "" { + subname = name + "." + subname + } + if _, ok := c.fields[subname]; ok { + return nil, fmt.Errorf("datastore: struct tag has repeated property name: %q", subname) + } + c.fields[subname] = fieldCodec{ + path: append([]int{i}, subfield.path...), + noIndex: subfield.noIndex || opts["noindex"], + omitEmpty: subfield.omitEmpty, + structCodec: subfield.structCodec, + } + } + continue + } + } + + if _, ok := c.fields[name]; ok { + return nil, fmt.Errorf("datastore: struct tag has repeated property name: %q", name) + } + c.fields[name] = fieldCodec{ + path: []int{i}, + noIndex: opts["noindex"], + omitEmpty: opts["omitempty"], + structCodec: sub, + } + } + c.complete = true + return c, nil +} + +// structPLS adapts a struct to be a PropertyLoadSaver. +type structPLS struct { + v reflect.Value + codec *structCodec +} + +// newStructPLS returns a structPLS, which implements the +// PropertyLoadSaver interface, for the struct pointer p. +func newStructPLS(p interface{}) (*structPLS, error) { + v := reflect.ValueOf(p) + if v.Kind() != reflect.Ptr || v.Elem().Kind() != reflect.Struct { + return nil, ErrInvalidEntityType + } + v = v.Elem() + codec, err := getStructCodec(v.Type()) + if err != nil { + return nil, err + } + return &structPLS{v, codec}, nil +} + +// LoadStruct loads the properties from p to dst. +// dst must be a struct pointer. +func LoadStruct(dst interface{}, p []Property) error { + x, err := newStructPLS(dst) + if err != nil { + return err + } + return x.Load(p) +} + +// SaveStruct returns the properties from src as a slice of Properties. +// src must be a struct pointer. +func SaveStruct(src interface{}) ([]Property, error) { + x, err := newStructPLS(src) + if err != nil { + return nil, err + } + return x.Save() +} |