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document.go
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document.go
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// Copyright (C) MongoDB, Inc. 2017-present.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
package birch
import (
"bytes"
"fmt"
"io"
"github.com/tychoish/birch/bsonerr"
"github.com/tychoish/birch/elements"
"github.com/tychoish/fun"
"github.com/tychoish/fun/adt"
"github.com/tychoish/fun/dt"
)
var bufpool = adt.DefaultBufferPool()
// Document is a mutable ordered map that compactly represents a BSON document.
type Document struct {
elems []*Element
cache DocumentMap
cacheValid bool
}
// ReadDocument will create a Document using the provided slice of bytes. If the
// slice of bytes is not a valid BSON document, this method will return an error.
func ReadDocument(b []byte) (*Document, error) {
var doc = new(Document)
if err := doc.UnmarshalBSON(b); err != nil {
return nil, err
}
return doc, nil
}
// Copy makes a shallow copy of this document.
func (d *Document) Copy() *Document {
doc := &Document{elems: make([]*Element, len(d.elems), cap(d.elems))}
copy(doc.elems, d.elems)
return doc
}
// Len returns the number of elements in the document.
func (d *Document) Len() int { return len(d.elems) }
// Append adds each element to the end of the document, in order. If a nil element is passed
// as a parameter this method will panic. To change this behavior to silently
// ignore a nil element, set IgnoreNilInsert to true on the Document.
//
// If a nil element is inserted and this method panics, it does not remove the
// previously added elements.
func (d *Document) Append(elems ...*Element) *Document {
for _, elem := range elems {
if elem == nil {
panic(bsonerr.NilElement)
}
d.elems = append(d.elems, elem)
}
d.cacheValid = false
return d
}
// AppendOmitEmpty adds all non-empty values to the document, and has
// no impact otherwise.
func (d *Document) AppendOmitEmpty(elems ...*Element) *Document {
for _, elem := range elems {
if elem == nil || elem.Value().IsEmpty() {
continue
}
d.Append(elem)
}
d.cacheValid = false
return d
}
// Set replaces an element of a document. If an element with a matching key is
// found, the element will be replaced with the one provided. If the document
// does not have an element with that key, the element is appended to the
// document instead. If a nil element is passed as a parameter this method will
// panic.
//
// If a nil element is inserted and this method panics.
func (d *Document) Set(elem *Element) *Document {
if elem == nil {
panic(bsonerr.NilElement)
}
for idx, e := range d.elems {
if elem.Key() == e.Key() {
d.elems[idx] = elem
return d
}
}
d.elems = append(d.elems, elem)
d.cacheValid = false
return d
}
// Delete removes the keys from the Document. The deleted element is
// returned. If the key does not exist, then nil is returned and the delete is
// a no-op.
func (d *Document) Delete(key string) *Element {
for idx := range d.elems {
if d.elems[idx].Key() == key {
elem := d.elems[idx]
d.elems = append(d.elems[:idx], d.elems[idx+1:]...)
return elem
}
}
d.cacheValid = false
return nil
}
// ElementAt retrieves the element at the given index in a
// Document. It panics if the index is out-of-bounds.
func (d *Document) ElementAt(index uint) *Element {
return d.elems[index]
}
// ElementAtOK is the same as ElementAt, but returns a boolean instead of panicking.
func (d *Document) ElementAtOK(index uint) (*Element, bool) {
if index >= uint(len(d.elems)) {
return nil, false
}
return d.ElementAt(index), true
}
// Iterator creates an Iterator for this document and returns it.
func (d *Document) Iterator() *fun.Iterator[*Element] {
return legacyIteratorConverter[*Element, *elementIterator](&elementIterator{d: d}).Iterator()
}
// Extend merges a second document into the document. It may produce a
// document with duplicate keys.
func (d *Document) Extend(d2 *Document) *Document { d.Append(d2.elems...); return d }
// Reset clears a document so it can be reused. This method clears references
// to the underlying pointers to elements so they can be garbage collected.
func (d *Document) Reset() {
for idx := range d.elems {
d.elems[idx] = nil
}
d.cacheValid = false
d.elems = d.elems[:0]
}
// Search iterates through the keys in the document, returning the
// element with the matching key, and nil othe
func (d *Document) Search(keys ...string) (*Element, error) {
if d == nil || len(keys) == 0 {
return nil, bsonerr.ElementNotFound
}
elem := d.findElemForKey(keys[0])
if elem == nil {
return nil, bsonerr.ElementNotFound
}
if len(keys) == 1 {
return elem, nil
}
if sd, ok := elem.Value().MutableDocumentOK(); ok {
return sd.Search(keys[1:]...)
}
if ar, ok := elem.Value().MutableArrayOK(); ok {
if em := ar.findElementForStrKey(keys[1:]...); em != nil {
return em, nil
}
}
return nil, bsonerr.ElementNotFound
}
func (d *Document) findElemForKey(key string) *Element {
for idx := range d.elems {
if d.elems[idx].Key() == key {
return d.elems[idx]
}
}
return nil
}
// Validate validates the document and returns its total size.
func (d *Document) Validate() (uint32, error) {
if d == nil {
return 0, bsonerr.NilDocument
}
// Header and Footer
var size uint32 = 4 + 1
for _, elem := range d.elems {
n, err := elem.Validate()
if err != nil {
return 0, err
}
size += n
}
return size, nil
}
// WriteTo implements the io.WriterTo interface.
//
// TODO(skriptble): We can optimize this by having creating implementations of
// writeByteSlice that write directly to an io.Writer instead.
func (d *Document) WriteTo(w io.Writer) (int64, error) {
b, err := d.MarshalBSON()
if err != nil {
return 0, err
}
n, err := w.Write(b)
return int64(n), err
}
// writeByteSlice handles serializing this document to a slice of bytes starting
// at the given start position.
func (d *Document) writeByteSlice(start uint, size uint32, b []byte) (int64, error) {
var total int64
var pos uint
pos = start
if len(b) < int(start)+int(size) {
return 0, errTooSmall
}
n, err := elements.Int32.Encode(start, b, int32(size))
total += int64(n)
pos += uint(n)
if err != nil {
return total, err
}
for _, elem := range d.elems {
n, err := elem.writeElement(true, pos, b)
total += n
pos += uint(n)
if err != nil {
return total, err
}
}
n, err = elements.Byte.Encode(pos, b, '\x00')
total += int64(n)
if err != nil {
return total, err
}
return total, nil
}
// MarshalBSON implements the Marshaler interface.
func (d *Document) MarshalBSON() ([]byte, error) {
size, err := d.Validate()
if err != nil {
return nil, err
}
b := make([]byte, size)
_, err = d.writeByteSlice(0, size, b)
if err != nil {
return nil, err
}
return b, nil
}
// UnmarshalBSON implements the Unmarshaler interface.
func (d *Document) UnmarshalBSON(b []byte) error {
iter, err := Reader(b).Iterator()
if err != nil {
return err
}
d.elems = make([]*Element, 0, 128)
for iter.Next(iterCtx) {
d.elems = append(d.elems, iter.Value())
}
return iter.Close()
}
// ReadFrom will read one BSON document from the given io.Reader.
func (d *Document) ReadFrom(r io.Reader) (int64, error) {
var total int64
sizeBuf := dt.Sliceify(bufpool.Get())
sizeBuf.Grow(4)
defer bufpool.Put(sizeBuf)
n, err := io.ReadFull(r, sizeBuf)
total += int64(n)
if err != nil {
return total, err
}
givenLength := readi32(sizeBuf)
b := dt.Sliceify(bufpool.Make())
b.Grow(int(givenLength))
copy(b[0:4], sizeBuf)
n, err = io.ReadFull(r, b[4:])
total += int64(n)
if err != nil {
return total, err
}
return total, d.UnmarshalBSON(b)
}
// String implements the fmt.Stringer interface.
func (d *Document) String() string {
buf := &bytes.Buffer{}
buf.WriteString("bson.Document{")
for idx, elem := range d.elems {
if idx > 0 {
buf.WriteString(", ")
}
buf.WriteString(elem.String())
}
buf.WriteByte('}')
return buf.String()
}
// Unmarshal attempts to read the bson document into the interface
// value provided, with the semantics dependent on the input type. The
// semantics are loose (particularly for sized integers), work
// reasonably well for simple map types and will not always round
// trip. While unmarshal will overwrite values in an existing input
// structure, it will not delete other values, and will avoid writing
// fields in the document which cannot be easily converted. While this
// method does not work with arbitrary types that do not implement
// DocumentUnmarshaler, it does not use reflection.
func (d *Document) Unmarshal(into any) error {
switch out := into.(type) {
case DocumentUnmarshaler:
return out.UnmarshalDocument(d)
case Unmarshaler:
raw, err := d.MarshalBSON()
if err != nil {
return err
}
return out.UnmarshalBSON(raw)
case map[string]string:
for _, elem := range d.elems {
if val, ok := elem.value.StringValueOK(); ok {
out[elem.Key()] = val
}
}
case map[string]any:
for _, elem := range d.elems {
out[elem.Key()] = elem.value.Interface()
}
case map[any]any:
for _, elem := range d.elems {
out[elem.Key()] = elem.value.Interface()
}
default:
// TODO consider falling back to reflection
return fmt.Errorf("cannot unmarshal into %T", into)
}
return nil
}