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vendor/google.golang.org/appengine/search/struct.go

@@ -0,0 +1,251 @@
+// Copyright 2015 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 search
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+	"sync"
+)
+
+// ErrFieldMismatch is returned when a field is to be loaded into a different
+// than the one it was stored from, or when a field is missing or unexported in
+// the destination struct.
+type ErrFieldMismatch struct {
+	FieldName string
+	Reason    string
+}
+
+func (e *ErrFieldMismatch) Error() string {
+	return fmt.Sprintf("search: cannot load field %q: %s", e.FieldName, e.Reason)
+}
+
+// ErrFacetMismatch is returned when a facet is to be loaded into a different
+// type than the one it was stored from, or when a field is missing or
+// unexported in the destination struct. StructType is the type of the struct
+// pointed to by the destination argument passed to Iterator.Next.
+type ErrFacetMismatch struct {
+	StructType reflect.Type
+	FacetName  string
+	Reason     string
+}
+
+func (e *ErrFacetMismatch) Error() string {
+	return fmt.Sprintf("search: cannot load facet %q into a %q: %s", e.FacetName, e.StructType, e.Reason)
+}
+
+// structCodec defines how to convert a given struct to/from a search document.
+type structCodec struct {
+	// byIndex returns the struct tag for the i'th struct field.
+	byIndex []structTag
+
+	// fieldByName returns the index of the struct field for the given field name.
+	fieldByName map[string]int
+
+	// facetByName returns the index of the struct field for the given facet name,
+	facetByName map[string]int
+}
+
+// structTag holds a structured version of each struct field's parsed tag.
+type structTag struct {
+	name   string
+	facet  bool
+	ignore bool
+}
+
+var (
+	codecsMu sync.RWMutex
+	codecs   = map[reflect.Type]*structCodec{}
+)
+
+func loadCodec(t reflect.Type) (*structCodec, error) {
+	codecsMu.RLock()
+	codec, ok := codecs[t]
+	codecsMu.RUnlock()
+	if ok {
+		return codec, nil
+	}
+
+	codecsMu.Lock()
+	defer codecsMu.Unlock()
+	if codec, ok := codecs[t]; ok {
+		return codec, nil
+	}
+
+	codec = &structCodec{
+		fieldByName: make(map[string]int),
+		facetByName: make(map[string]int),
+	}
+
+	for i, I := 0, t.NumField(); i < I; i++ {
+		f := t.Field(i)
+		name, opts := f.Tag.Get("search"), ""
+		if i := strings.Index(name, ","); i != -1 {
+			name, opts = name[:i], name[i+1:]
+		}
+		ignore := false
+		if name == "-" {
+			ignore = true
+		} else if name == "" {
+			name = f.Name
+		} else if !validFieldName(name) {
+			return nil, fmt.Errorf("search: struct tag has invalid field name: %q", name)
+		}
+		facet := opts == "facet"
+		codec.byIndex = append(codec.byIndex, structTag{name: name, facet: facet, ignore: ignore})
+		if facet {
+			codec.facetByName[name] = i
+		} else {
+			codec.fieldByName[name] = i
+		}
+	}
+
+	codecs[t] = codec
+	return codec, nil
+}
+
+// structFLS adapts a struct to be a FieldLoadSaver.
+type structFLS struct {
+	v     reflect.Value
+	codec *structCodec
+}
+
+func (s structFLS) Load(fields []Field, meta *DocumentMetadata) error {
+	var err error
+	for _, field := range fields {
+		i, ok := s.codec.fieldByName[field.Name]
+		if !ok {
+			// Note the error, but keep going.
+			err = &ErrFieldMismatch{
+				FieldName: field.Name,
+				Reason:    "no such struct field",
+			}
+			continue
+
+		}
+		f := s.v.Field(i)
+		if !f.CanSet() {
+			// Note the error, but keep going.
+			err = &ErrFieldMismatch{
+				FieldName: field.Name,
+				Reason:    "cannot set struct field",
+			}
+			continue
+		}
+		v := reflect.ValueOf(field.Value)
+		if ft, vt := f.Type(), v.Type(); ft != vt {
+			err = &ErrFieldMismatch{
+				FieldName: field.Name,
+				Reason:    fmt.Sprintf("type mismatch: %v for %v data", ft, vt),
+			}
+			continue
+		}
+		f.Set(v)
+	}
+	if meta == nil {
+		return err
+	}
+	for _, facet := range meta.Facets {
+		i, ok := s.codec.facetByName[facet.Name]
+		if !ok {
+			// Note the error, but keep going.
+			if err == nil {
+				err = &ErrFacetMismatch{
+					StructType: s.v.Type(),
+					FacetName:  facet.Name,
+					Reason:     "no matching field found",
+				}
+			}
+			continue
+		}
+		f := s.v.Field(i)
+		if !f.CanSet() {
+			// Note the error, but keep going.
+			if err == nil {
+				err = &ErrFacetMismatch{
+					StructType: s.v.Type(),
+					FacetName:  facet.Name,
+					Reason:     "unable to set unexported field of struct",
+				}
+			}
+			continue
+		}
+		v := reflect.ValueOf(facet.Value)
+		if ft, vt := f.Type(), v.Type(); ft != vt {
+			if err == nil {
+				err = &ErrFacetMismatch{
+					StructType: s.v.Type(),
+					FacetName:  facet.Name,
+					Reason:     fmt.Sprintf("type mismatch: %v for %d data", ft, vt),
+				}
+				continue
+			}
+		}
+		f.Set(v)
+	}
+	return err
+}
+
+func (s structFLS) Save() ([]Field, *DocumentMetadata, error) {
+	fields := make([]Field, 0, len(s.codec.fieldByName))
+	var facets []Facet
+	for i, tag := range s.codec.byIndex {
+		if tag.ignore {
+			continue
+		}
+		f := s.v.Field(i)
+		if !f.CanSet() {
+			continue
+		}
+		if tag.facet {
+			facets = append(facets, Facet{Name: tag.name, Value: f.Interface()})
+		} else {
+			fields = append(fields, Field{Name: tag.name, Value: f.Interface()})
+		}
+	}
+	return fields, &DocumentMetadata{Facets: facets}, nil
+}
+
+// newStructFLS returns a FieldLoadSaver for the struct pointer p.
+func newStructFLS(p interface{}) (FieldLoadSaver, error) {
+	v := reflect.ValueOf(p)
+	if v.Kind() != reflect.Ptr || v.IsNil() || v.Elem().Kind() != reflect.Struct {
+		return nil, ErrInvalidDocumentType
+	}
+	codec, err := loadCodec(v.Elem().Type())
+	if err != nil {
+		return nil, err
+	}
+	return structFLS{v.Elem(), codec}, nil
+}
+
+func loadStructWithMeta(dst interface{}, f []Field, meta *DocumentMetadata) error {
+	x, err := newStructFLS(dst)
+	if err != nil {
+		return err
+	}
+	return x.Load(f, meta)
+}
+
+func saveStructWithMeta(src interface{}) ([]Field, *DocumentMetadata, error) {
+	x, err := newStructFLS(src)
+	if err != nil {
+		return nil, nil, err
+	}
+	return x.Save()
+}
+
+// LoadStruct loads the fields from f to dst. dst must be a struct pointer.
+func LoadStruct(dst interface{}, f []Field) error {
+	return loadStructWithMeta(dst, f, nil)
+}
+
+// SaveStruct returns the fields from src as a slice of Field.
+// src must be a struct pointer.
+func SaveStruct(src interface{}) ([]Field, error) {
+	f, _, err := saveStructWithMeta(src)
+	return f, err
+}