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1package flatbuffers
2
3// Builder is a state machine for creating FlatBuffer objects.
4// Use a Builder to construct object(s) starting from leaf nodes.
5//
6// A Builder constructs byte buffers in a last-first manner for simplicity and
7// performance.
8type Builder struct {
9	// `Bytes` gives raw access to the buffer. Most users will want to use
10	// FinishedBytes() instead.
11	Bytes []byte
12
13	minalign  int
14	vtable    []UOffsetT
15	objectEnd UOffsetT
16	vtables   []UOffsetT
17	head      UOffsetT
18	nested    bool
19	finished  bool
20
21	sharedStrings map[string]UOffsetT
22}
23
24const fileIdentifierLength = 4
25const sizePrefixLength = 4
26
27// NewBuilder initializes a Builder of size `initial_size`.
28// The internal buffer is grown as needed.
29func NewBuilder(initialSize int) *Builder {
30	if initialSize <= 0 {
31		initialSize = 0
32	}
33
34	b := &Builder{}
35	b.Bytes = make([]byte, initialSize)
36	b.head = UOffsetT(initialSize)
37	b.minalign = 1
38	b.vtables = make([]UOffsetT, 0, 16) // sensible default capacity
39	return b
40}
41
42// Reset truncates the underlying Builder buffer, facilitating alloc-free
43// reuse of a Builder. It also resets bookkeeping data.
44func (b *Builder) Reset() {
45	if b.Bytes != nil {
46		b.Bytes = b.Bytes[:cap(b.Bytes)]
47	}
48
49	if b.vtables != nil {
50		b.vtables = b.vtables[:0]
51	}
52
53	if b.vtable != nil {
54		b.vtable = b.vtable[:0]
55	}
56
57	if b.sharedStrings != nil {
58		for key := range b.sharedStrings {
59			delete(b.sharedStrings, key)
60		}
61	}
62
63	b.head = UOffsetT(len(b.Bytes))
64	b.minalign = 1
65	b.nested = false
66	b.finished = false
67}
68
69// FinishedBytes returns a pointer to the written data in the byte buffer.
70// Panics if the builder is not in a finished state (which is caused by calling
71// `Finish()`).
72func (b *Builder) FinishedBytes() []byte {
73	b.assertFinished()
74	return b.Bytes[b.Head():]
75}
76
77// StartObject initializes bookkeeping for writing a new object.
78func (b *Builder) StartObject(numfields int) {
79	b.assertNotNested()
80	b.nested = true
81
82	// use 32-bit offsets so that arithmetic doesn't overflow.
83	if cap(b.vtable) < numfields || b.vtable == nil {
84		b.vtable = make([]UOffsetT, numfields)
85	} else {
86		b.vtable = b.vtable[:numfields]
87		for i := 0; i < len(b.vtable); i++ {
88			b.vtable[i] = 0
89		}
90	}
91
92	b.objectEnd = b.Offset()
93}
94
95// WriteVtable serializes the vtable for the current object, if applicable.
96//
97// Before writing out the vtable, this checks pre-existing vtables for equality
98// to this one. If an equal vtable is found, point the object to the existing
99// vtable and return.
100//
101// Because vtable values are sensitive to alignment of object data, not all
102// logically-equal vtables will be deduplicated.
103//
104// A vtable has the following format:
105//   <VOffsetT: size of the vtable in bytes, including this value>
106//   <VOffsetT: size of the object in bytes, including the vtable offset>
107//   <VOffsetT: offset for a field> * N, where N is the number of fields in
108//	        the schema for this type. Includes deprecated fields.
109// Thus, a vtable is made of 2 + N elements, each SizeVOffsetT bytes wide.
110//
111// An object has the following format:
112//   <SOffsetT: offset to this object's vtable (may be negative)>
113//   <byte: data>+
114func (b *Builder) WriteVtable() (n UOffsetT) {
115	// Prepend a zero scalar to the object. Later in this function we'll
116	// write an offset here that points to the object's vtable:
117	b.PrependSOffsetT(0)
118
119	objectOffset := b.Offset()
120	existingVtable := UOffsetT(0)
121
122	// Trim vtable of trailing zeroes.
123	i := len(b.vtable) - 1
124	for ; i >= 0 && b.vtable[i] == 0; i-- {
125	}
126	b.vtable = b.vtable[:i+1]
127
128	// Search backwards through existing vtables, because similar vtables
129	// are likely to have been recently appended. See
130	// BenchmarkVtableDeduplication for a case in which this heuristic
131	// saves about 30% of the time used in writing objects with duplicate
132	// tables.
133	for i := len(b.vtables) - 1; i >= 0; i-- {
134		// Find the other vtable, which is associated with `i`:
135		vt2Offset := b.vtables[i]
136		vt2Start := len(b.Bytes) - int(vt2Offset)
137		vt2Len := GetVOffsetT(b.Bytes[vt2Start:])
138
139		metadata := VtableMetadataFields * SizeVOffsetT
140		vt2End := vt2Start + int(vt2Len)
141		vt2 := b.Bytes[vt2Start+metadata : vt2End]
142
143		// Compare the other vtable to the one under consideration.
144		// If they are equal, store the offset and break:
145		if vtableEqual(b.vtable, objectOffset, vt2) {
146			existingVtable = vt2Offset
147			break
148		}
149	}
150
151	if existingVtable == 0 {
152		// Did not find a vtable, so write this one to the buffer.
153
154		// Write out the current vtable in reverse , because
155		// serialization occurs in last-first order:
156		for i := len(b.vtable) - 1; i >= 0; i-- {
157			var off UOffsetT
158			if b.vtable[i] != 0 {
159				// Forward reference to field;
160				// use 32bit number to assert no overflow:
161				off = objectOffset - b.vtable[i]
162			}
163
164			b.PrependVOffsetT(VOffsetT(off))
165		}
166
167		// The two metadata fields are written last.
168
169		// First, store the object bytesize:
170		objectSize := objectOffset - b.objectEnd
171		b.PrependVOffsetT(VOffsetT(objectSize))
172
173		// Second, store the vtable bytesize:
174		vBytes := (len(b.vtable) + VtableMetadataFields) * SizeVOffsetT
175		b.PrependVOffsetT(VOffsetT(vBytes))
176
177		// Next, write the offset to the new vtable in the
178		// already-allocated SOffsetT at the beginning of this object:
179		objectStart := SOffsetT(len(b.Bytes)) - SOffsetT(objectOffset)
180		WriteSOffsetT(b.Bytes[objectStart:],
181			SOffsetT(b.Offset())-SOffsetT(objectOffset))
182
183		// Finally, store this vtable in memory for future
184		// deduplication:
185		b.vtables = append(b.vtables, b.Offset())
186	} else {
187		// Found a duplicate vtable.
188
189		objectStart := SOffsetT(len(b.Bytes)) - SOffsetT(objectOffset)
190		b.head = UOffsetT(objectStart)
191
192		// Write the offset to the found vtable in the
193		// already-allocated SOffsetT at the beginning of this object:
194		WriteSOffsetT(b.Bytes[b.head:],
195			SOffsetT(existingVtable)-SOffsetT(objectOffset))
196	}
197
198	b.vtable = b.vtable[:0]
199	return objectOffset
200}
201
202// EndObject writes data necessary to finish object construction.
203func (b *Builder) EndObject() UOffsetT {
204	b.assertNested()
205	n := b.WriteVtable()
206	b.nested = false
207	return n
208}
209
210// Doubles the size of the byteslice, and copies the old data towards the
211// end of the new byteslice (since we build the buffer backwards).
212func (b *Builder) growByteBuffer() {
213	if (int64(len(b.Bytes)) & int64(0xC0000000)) != 0 {
214		panic("cannot grow buffer beyond 2 gigabytes")
215	}
216	newLen := len(b.Bytes) * 2
217	if newLen == 0 {
218		newLen = 1
219	}
220
221	if cap(b.Bytes) >= newLen {
222		b.Bytes = b.Bytes[:newLen]
223	} else {
224		extension := make([]byte, newLen-len(b.Bytes))
225		b.Bytes = append(b.Bytes, extension...)
226	}
227
228	middle := newLen / 2
229	copy(b.Bytes[middle:], b.Bytes[:middle])
230}
231
232// Head gives the start of useful data in the underlying byte buffer.
233// Note: unlike other functions, this value is interpreted as from the left.
234func (b *Builder) Head() UOffsetT {
235	return b.head
236}
237
238// Offset relative to the end of the buffer.
239func (b *Builder) Offset() UOffsetT {
240	return UOffsetT(len(b.Bytes)) - b.head
241}
242
243// Pad places zeros at the current offset.
244func (b *Builder) Pad(n int) {
245	for i := 0; i < n; i++ {
246		b.PlaceByte(0)
247	}
248}
249
250// Prep prepares to write an element of `size` after `additional_bytes`
251// have been written, e.g. if you write a string, you need to align such
252// the int length field is aligned to SizeInt32, and the string data follows it
253// directly.
254// If all you need to do is align, `additionalBytes` will be 0.
255func (b *Builder) Prep(size, additionalBytes int) {
256	// Track the biggest thing we've ever aligned to.
257	if size > b.minalign {
258		b.minalign = size
259	}
260	// Find the amount of alignment needed such that `size` is properly
261	// aligned after `additionalBytes`:
262	alignSize := (^(len(b.Bytes) - int(b.Head()) + additionalBytes)) + 1
263	alignSize &= (size - 1)
264
265	// Reallocate the buffer if needed:
266	for int(b.head) <= alignSize+size+additionalBytes {
267		oldBufSize := len(b.Bytes)
268		b.growByteBuffer()
269		b.head += UOffsetT(len(b.Bytes) - oldBufSize)
270	}
271	b.Pad(alignSize)
272}
273
274// PrependSOffsetT prepends an SOffsetT, relative to where it will be written.
275func (b *Builder) PrependSOffsetT(off SOffsetT) {
276	b.Prep(SizeSOffsetT, 0) // Ensure alignment is already done.
277	if !(UOffsetT(off) <= b.Offset()) {
278		panic("unreachable: off <= b.Offset()")
279	}
280	off2 := SOffsetT(b.Offset()) - off + SOffsetT(SizeSOffsetT)
281	b.PlaceSOffsetT(off2)
282}
283
284// PrependUOffsetT prepends an UOffsetT, relative to where it will be written.
285func (b *Builder) PrependUOffsetT(off UOffsetT) {
286	b.Prep(SizeUOffsetT, 0) // Ensure alignment is already done.
287	if !(off <= b.Offset()) {
288		panic("unreachable: off <= b.Offset()")
289	}
290	off2 := b.Offset() - off + UOffsetT(SizeUOffsetT)
291	b.PlaceUOffsetT(off2)
292}
293
294// StartVector initializes bookkeeping for writing a new vector.
295//
296// A vector has the following format:
297//   <UOffsetT: number of elements in this vector>
298//   <T: data>+, where T is the type of elements of this vector.
299func (b *Builder) StartVector(elemSize, numElems, alignment int) UOffsetT {
300	b.assertNotNested()
301	b.nested = true
302	b.Prep(SizeUint32, elemSize*numElems)
303	b.Prep(alignment, elemSize*numElems) // Just in case alignment > int.
304	return b.Offset()
305}
306
307// EndVector writes data necessary to finish vector construction.
308func (b *Builder) EndVector(vectorNumElems int) UOffsetT {
309	b.assertNested()
310
311	// we already made space for this, so write without PrependUint32
312	b.PlaceUOffsetT(UOffsetT(vectorNumElems))
313
314	b.nested = false
315	return b.Offset()
316}
317
318// CreateSharedString Checks if the string is already written
319// to the buffer before calling CreateString
320func (b *Builder) CreateSharedString(s string) UOffsetT {
321	if b.sharedStrings == nil {
322		b.sharedStrings = make(map[string]UOffsetT)
323	}
324	if v, ok := b.sharedStrings[s]; ok {
325		return v
326	}
327	off := b.CreateString(s)
328	b.sharedStrings[s] = off
329	return off
330}
331
332// CreateString writes a null-terminated string as a vector.
333func (b *Builder) CreateString(s string) UOffsetT {
334	b.assertNotNested()
335	b.nested = true
336
337	b.Prep(int(SizeUOffsetT), (len(s)+1)*SizeByte)
338	b.PlaceByte(0)
339
340	l := UOffsetT(len(s))
341
342	b.head -= l
343	copy(b.Bytes[b.head:b.head+l], s)
344
345	return b.EndVector(len(s))
346}
347
348// CreateByteString writes a byte slice as a string (null-terminated).
349func (b *Builder) CreateByteString(s []byte) UOffsetT {
350	b.assertNotNested()
351	b.nested = true
352
353	b.Prep(int(SizeUOffsetT), (len(s)+1)*SizeByte)
354	b.PlaceByte(0)
355
356	l := UOffsetT(len(s))
357
358	b.head -= l
359	copy(b.Bytes[b.head:b.head+l], s)
360
361	return b.EndVector(len(s))
362}
363
364// CreateByteVector writes a ubyte vector
365func (b *Builder) CreateByteVector(v []byte) UOffsetT {
366	b.assertNotNested()
367	b.nested = true
368
369	b.Prep(int(SizeUOffsetT), len(v)*SizeByte)
370
371	l := UOffsetT(len(v))
372
373	b.head -= l
374	copy(b.Bytes[b.head:b.head+l], v)
375
376	return b.EndVector(len(v))
377}
378
379func (b *Builder) assertNested() {
380	// If you get this assert, you're in an object while trying to write
381	// data that belongs outside of an object.
382	// To fix this, write non-inline data (like vectors) before creating
383	// objects.
384	if !b.nested {
385		panic("Incorrect creation order: must be inside object.")
386	}
387}
388
389func (b *Builder) assertNotNested() {
390	// If you hit this, you're trying to construct a Table/Vector/String
391	// during the construction of its parent table (between the MyTableBuilder
392	// and builder.Finish()).
393	// Move the creation of these sub-objects to above the MyTableBuilder to
394	// not get this assert.
395	// Ignoring this assert may appear to work in simple cases, but the reason
396	// it is here is that storing objects in-line may cause vtable offsets
397	// to not fit anymore. It also leads to vtable duplication.
398	if b.nested {
399		panic("Incorrect creation order: object must not be nested.")
400	}
401}
402
403func (b *Builder) assertFinished() {
404	// If you get this assert, you're attempting to get access a buffer
405	// which hasn't been finished yet. Be sure to call builder.Finish()
406	// with your root table.
407	// If you really need to access an unfinished buffer, use the Bytes
408	// buffer directly.
409	if !b.finished {
410		panic("Incorrect use of FinishedBytes(): must call 'Finish' first.")
411	}
412}
413
414// PrependBoolSlot prepends a bool onto the object at vtable slot `o`.
415// If value `x` equals default `d`, then the slot will be set to zero and no
416// other data will be written.
417func (b *Builder) PrependBoolSlot(o int, x, d bool) {
418	val := byte(0)
419	if x {
420		val = 1
421	}
422	def := byte(0)
423	if d {
424		def = 1
425	}
426	b.PrependByteSlot(o, val, def)
427}
428
429// PrependByteSlot prepends a byte onto the object at vtable slot `o`.
430// If value `x` equals default `d`, then the slot will be set to zero and no
431// other data will be written.
432func (b *Builder) PrependByteSlot(o int, x, d byte) {
433	if x != d {
434		b.PrependByte(x)
435		b.Slot(o)
436	}
437}
438
439// PrependUint8Slot prepends a uint8 onto the object at vtable slot `o`.
440// If value `x` equals default `d`, then the slot will be set to zero and no
441// other data will be written.
442func (b *Builder) PrependUint8Slot(o int, x, d uint8) {
443	if x != d {
444		b.PrependUint8(x)
445		b.Slot(o)
446	}
447}
448
449// PrependUint16Slot prepends a uint16 onto the object at vtable slot `o`.
450// If value `x` equals default `d`, then the slot will be set to zero and no
451// other data will be written.
452func (b *Builder) PrependUint16Slot(o int, x, d uint16) {
453	if x != d {
454		b.PrependUint16(x)
455		b.Slot(o)
456	}
457}
458
459// PrependUint32Slot prepends a uint32 onto the object at vtable slot `o`.
460// If value `x` equals default `d`, then the slot will be set to zero and no
461// other data will be written.
462func (b *Builder) PrependUint32Slot(o int, x, d uint32) {
463	if x != d {
464		b.PrependUint32(x)
465		b.Slot(o)
466	}
467}
468
469// PrependUint64Slot prepends a uint64 onto the object at vtable slot `o`.
470// If value `x` equals default `d`, then the slot will be set to zero and no
471// other data will be written.
472func (b *Builder) PrependUint64Slot(o int, x, d uint64) {
473	if x != d {
474		b.PrependUint64(x)
475		b.Slot(o)
476	}
477}
478
479// PrependInt8Slot prepends a int8 onto the object at vtable slot `o`.
480// If value `x` equals default `d`, then the slot will be set to zero and no
481// other data will be written.
482func (b *Builder) PrependInt8Slot(o int, x, d int8) {
483	if x != d {
484		b.PrependInt8(x)
485		b.Slot(o)
486	}
487}
488
489// PrependInt16Slot prepends a int16 onto the object at vtable slot `o`.
490// If value `x` equals default `d`, then the slot will be set to zero and no
491// other data will be written.
492func (b *Builder) PrependInt16Slot(o int, x, d int16) {
493	if x != d {
494		b.PrependInt16(x)
495		b.Slot(o)
496	}
497}
498
499// PrependInt32Slot prepends a int32 onto the object at vtable slot `o`.
500// If value `x` equals default `d`, then the slot will be set to zero and no
501// other data will be written.
502func (b *Builder) PrependInt32Slot(o int, x, d int32) {
503	if x != d {
504		b.PrependInt32(x)
505		b.Slot(o)
506	}
507}
508
509// PrependInt64Slot prepends a int64 onto the object at vtable slot `o`.
510// If value `x` equals default `d`, then the slot will be set to zero and no
511// other data will be written.
512func (b *Builder) PrependInt64Slot(o int, x, d int64) {
513	if x != d {
514		b.PrependInt64(x)
515		b.Slot(o)
516	}
517}
518
519// PrependFloat32Slot prepends a float32 onto the object at vtable slot `o`.
520// If value `x` equals default `d`, then the slot will be set to zero and no
521// other data will be written.
522func (b *Builder) PrependFloat32Slot(o int, x, d float32) {
523	if x != d {
524		b.PrependFloat32(x)
525		b.Slot(o)
526	}
527}
528
529// PrependFloat64Slot prepends a float64 onto the object at vtable slot `o`.
530// If value `x` equals default `d`, then the slot will be set to zero and no
531// other data will be written.
532func (b *Builder) PrependFloat64Slot(o int, x, d float64) {
533	if x != d {
534		b.PrependFloat64(x)
535		b.Slot(o)
536	}
537}
538
539// PrependUOffsetTSlot prepends an UOffsetT onto the object at vtable slot `o`.
540// If value `x` equals default `d`, then the slot will be set to zero and no
541// other data will be written.
542func (b *Builder) PrependUOffsetTSlot(o int, x, d UOffsetT) {
543	if x != d {
544		b.PrependUOffsetT(x)
545		b.Slot(o)
546	}
547}
548
549// PrependStructSlot prepends a struct onto the object at vtable slot `o`.
550// Structs are stored inline, so nothing additional is being added.
551// In generated code, `d` is always 0.
552func (b *Builder) PrependStructSlot(voffset int, x, d UOffsetT) {
553	if x != d {
554		b.assertNested()
555		if x != b.Offset() {
556			panic("inline data write outside of object")
557		}
558		b.Slot(voffset)
559	}
560}
561
562// Slot sets the vtable key `voffset` to the current location in the buffer.
563func (b *Builder) Slot(slotnum int) {
564	b.vtable[slotnum] = UOffsetT(b.Offset())
565}
566
567// FinishWithFileIdentifier finalizes a buffer, pointing to the given `rootTable`.
568// as well as applys a file identifier
569func (b *Builder) FinishWithFileIdentifier(rootTable UOffsetT, fid []byte) {
570	if fid == nil || len(fid) != fileIdentifierLength {
571		panic("incorrect file identifier length")
572	}
573	// In order to add a file identifier to the flatbuffer message, we need
574	// to prepare an alignment and file identifier length
575	b.Prep(b.minalign, SizeInt32+fileIdentifierLength)
576	for i := fileIdentifierLength - 1; i >= 0; i-- {
577		// place the file identifier
578		b.PlaceByte(fid[i])
579	}
580	// finish
581	b.Finish(rootTable)
582}
583
584// FinishSizePrefixed finalizes a buffer, pointing to the given `rootTable`.
585// The buffer is prefixed with the size of the buffer, excluding the size
586// of the prefix itself.
587func (b *Builder) FinishSizePrefixed(rootTable UOffsetT) {
588	b.finish(rootTable, true)
589}
590
591// FinishSizePrefixedWithFileIdentifier finalizes a buffer, pointing to the given `rootTable`
592// and applies a file identifier. The buffer is prefixed with the size of the buffer,
593// excluding the size of the prefix itself.
594func (b *Builder) FinishSizePrefixedWithFileIdentifier(rootTable UOffsetT, fid []byte) {
595	if fid == nil || len(fid) != fileIdentifierLength {
596		panic("incorrect file identifier length")
597	}
598	// In order to add a file identifier and size prefix to the flatbuffer message,
599	// we need to prepare an alignment, a size prefix length, and file identifier length
600	b.Prep(b.minalign, SizeInt32+fileIdentifierLength+sizePrefixLength)
601	for i := fileIdentifierLength - 1; i >= 0; i-- {
602		// place the file identifier
603		b.PlaceByte(fid[i])
604	}
605	// finish
606	b.finish(rootTable, true)
607}
608
609// Finish finalizes a buffer, pointing to the given `rootTable`.
610func (b *Builder) Finish(rootTable UOffsetT) {
611	b.finish(rootTable, false)
612}
613
614// finish finalizes a buffer, pointing to the given `rootTable`
615// with an optional size prefix.
616func (b *Builder) finish(rootTable UOffsetT, sizePrefix bool) {
617	b.assertNotNested()
618
619	if sizePrefix {
620		b.Prep(b.minalign, SizeUOffsetT+sizePrefixLength)
621	} else {
622		b.Prep(b.minalign, SizeUOffsetT)
623	}
624
625	b.PrependUOffsetT(rootTable)
626
627	if sizePrefix {
628		b.PlaceUint32(uint32(b.Offset()))
629	}
630
631	b.finished = true
632}
633
634// vtableEqual compares an unwritten vtable to a written vtable.
635func vtableEqual(a []UOffsetT, objectStart UOffsetT, b []byte) bool {
636	if len(a)*SizeVOffsetT != len(b) {
637		return false
638	}
639
640	for i := 0; i < len(a); i++ {
641		x := GetVOffsetT(b[i*SizeVOffsetT : (i+1)*SizeVOffsetT])
642
643		// Skip vtable entries that indicate a default value.
644		if x == 0 && a[i] == 0 {
645			continue
646		}
647
648		y := SOffsetT(objectStart) - SOffsetT(a[i])
649		if SOffsetT(x) != y {
650			return false
651		}
652	}
653	return true
654}
655
656// PrependBool prepends a bool to the Builder buffer.
657// Aligns and checks for space.
658func (b *Builder) PrependBool(x bool) {
659	b.Prep(SizeBool, 0)
660	b.PlaceBool(x)
661}
662
663// PrependUint8 prepends a uint8 to the Builder buffer.
664// Aligns and checks for space.
665func (b *Builder) PrependUint8(x uint8) {
666	b.Prep(SizeUint8, 0)
667	b.PlaceUint8(x)
668}
669
670// PrependUint16 prepends a uint16 to the Builder buffer.
671// Aligns and checks for space.
672func (b *Builder) PrependUint16(x uint16) {
673	b.Prep(SizeUint16, 0)
674	b.PlaceUint16(x)
675}
676
677// PrependUint32 prepends a uint32 to the Builder buffer.
678// Aligns and checks for space.
679func (b *Builder) PrependUint32(x uint32) {
680	b.Prep(SizeUint32, 0)
681	b.PlaceUint32(x)
682}
683
684// PrependUint64 prepends a uint64 to the Builder buffer.
685// Aligns and checks for space.
686func (b *Builder) PrependUint64(x uint64) {
687	b.Prep(SizeUint64, 0)
688	b.PlaceUint64(x)
689}
690
691// PrependInt8 prepends a int8 to the Builder buffer.
692// Aligns and checks for space.
693func (b *Builder) PrependInt8(x int8) {
694	b.Prep(SizeInt8, 0)
695	b.PlaceInt8(x)
696}
697
698// PrependInt16 prepends a int16 to the Builder buffer.
699// Aligns and checks for space.
700func (b *Builder) PrependInt16(x int16) {
701	b.Prep(SizeInt16, 0)
702	b.PlaceInt16(x)
703}
704
705// PrependInt32 prepends a int32 to the Builder buffer.
706// Aligns and checks for space.
707func (b *Builder) PrependInt32(x int32) {
708	b.Prep(SizeInt32, 0)
709	b.PlaceInt32(x)
710}
711
712// PrependInt64 prepends a int64 to the Builder buffer.
713// Aligns and checks for space.
714func (b *Builder) PrependInt64(x int64) {
715	b.Prep(SizeInt64, 0)
716	b.PlaceInt64(x)
717}
718
719// PrependFloat32 prepends a float32 to the Builder buffer.
720// Aligns and checks for space.
721func (b *Builder) PrependFloat32(x float32) {
722	b.Prep(SizeFloat32, 0)
723	b.PlaceFloat32(x)
724}
725
726// PrependFloat64 prepends a float64 to the Builder buffer.
727// Aligns and checks for space.
728func (b *Builder) PrependFloat64(x float64) {
729	b.Prep(SizeFloat64, 0)
730	b.PlaceFloat64(x)
731}
732
733// PrependByte prepends a byte to the Builder buffer.
734// Aligns and checks for space.
735func (b *Builder) PrependByte(x byte) {
736	b.Prep(SizeByte, 0)
737	b.PlaceByte(x)
738}
739
740// PrependVOffsetT prepends a VOffsetT to the Builder buffer.
741// Aligns and checks for space.
742func (b *Builder) PrependVOffsetT(x VOffsetT) {
743	b.Prep(SizeVOffsetT, 0)
744	b.PlaceVOffsetT(x)
745}
746
747// PlaceBool prepends a bool to the Builder, without checking for space.
748func (b *Builder) PlaceBool(x bool) {
749	b.head -= UOffsetT(SizeBool)
750	WriteBool(b.Bytes[b.head:], x)
751}
752
753// PlaceUint8 prepends a uint8 to the Builder, without checking for space.
754func (b *Builder) PlaceUint8(x uint8) {
755	b.head -= UOffsetT(SizeUint8)
756	WriteUint8(b.Bytes[b.head:], x)
757}
758
759// PlaceUint16 prepends a uint16 to the Builder, without checking for space.
760func (b *Builder) PlaceUint16(x uint16) {
761	b.head -= UOffsetT(SizeUint16)
762	WriteUint16(b.Bytes[b.head:], x)
763}
764
765// PlaceUint32 prepends a uint32 to the Builder, without checking for space.
766func (b *Builder) PlaceUint32(x uint32) {
767	b.head -= UOffsetT(SizeUint32)
768	WriteUint32(b.Bytes[b.head:], x)
769}
770
771// PlaceUint64 prepends a uint64 to the Builder, without checking for space.
772func (b *Builder) PlaceUint64(x uint64) {
773	b.head -= UOffsetT(SizeUint64)
774	WriteUint64(b.Bytes[b.head:], x)
775}
776
777// PlaceInt8 prepends a int8 to the Builder, without checking for space.
778func (b *Builder) PlaceInt8(x int8) {
779	b.head -= UOffsetT(SizeInt8)
780	WriteInt8(b.Bytes[b.head:], x)
781}
782
783// PlaceInt16 prepends a int16 to the Builder, without checking for space.
784func (b *Builder) PlaceInt16(x int16) {
785	b.head -= UOffsetT(SizeInt16)
786	WriteInt16(b.Bytes[b.head:], x)
787}
788
789// PlaceInt32 prepends a int32 to the Builder, without checking for space.
790func (b *Builder) PlaceInt32(x int32) {
791	b.head -= UOffsetT(SizeInt32)
792	WriteInt32(b.Bytes[b.head:], x)
793}
794
795// PlaceInt64 prepends a int64 to the Builder, without checking for space.
796func (b *Builder) PlaceInt64(x int64) {
797	b.head -= UOffsetT(SizeInt64)
798	WriteInt64(b.Bytes[b.head:], x)
799}
800
801// PlaceFloat32 prepends a float32 to the Builder, without checking for space.
802func (b *Builder) PlaceFloat32(x float32) {
803	b.head -= UOffsetT(SizeFloat32)
804	WriteFloat32(b.Bytes[b.head:], x)
805}
806
807// PlaceFloat64 prepends a float64 to the Builder, without checking for space.
808func (b *Builder) PlaceFloat64(x float64) {
809	b.head -= UOffsetT(SizeFloat64)
810	WriteFloat64(b.Bytes[b.head:], x)
811}
812
813// PlaceByte prepends a byte to the Builder, without checking for space.
814func (b *Builder) PlaceByte(x byte) {
815	b.head -= UOffsetT(SizeByte)
816	WriteByte(b.Bytes[b.head:], x)
817}
818
819// PlaceVOffsetT prepends a VOffsetT to the Builder, without checking for space.
820func (b *Builder) PlaceVOffsetT(x VOffsetT) {
821	b.head -= UOffsetT(SizeVOffsetT)
822	WriteVOffsetT(b.Bytes[b.head:], x)
823}
824
825// PlaceSOffsetT prepends a SOffsetT to the Builder, without checking for space.
826func (b *Builder) PlaceSOffsetT(x SOffsetT) {
827	b.head -= UOffsetT(SizeSOffsetT)
828	WriteSOffsetT(b.Bytes[b.head:], x)
829}
830
831// PlaceUOffsetT prepends a UOffsetT to the Builder, without checking for space.
832func (b *Builder) PlaceUOffsetT(x UOffsetT) {
833	b.head -= UOffsetT(SizeUOffsetT)
834	WriteUOffsetT(b.Bytes[b.head:], x)
835}
836