Flatbuffers library added to the list of third party libraries.

2019-08-02 10:46:23 +03:00
parent 59a83bd537
commit 3f34c8d88c
604 changed files with 126053 additions and 0 deletions
@@ -0,0 +1,284 @@
+// Copyright 2018 Google Inc. All rights reserved.
+//
+// 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
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import std
+
+namespace flatbuffers
+
+class handle:
+    buf_:string
+    pos_:int
+
+// More strongly typed than a naked int, at no cost.
+struct offset:
+    o:int
+
+enum sizeof:
+    sz_8 = 1
+    sz_16 = 2
+    sz_32 = 4
+    sz_64 = 8
+    sz_voffset = 2
+    sz_uoffset = 4
+    sz_soffset = 4
+    sz_metadata_fields = 2
+
+class builder:
+    buf = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+    current_vtable:[int] = []
+    head = 0
+    minalign = 1
+    object_end = 0
+    vtables:[int] = []
+    nested = false
+    finished = false
+
+    // Optionally call this right after creating the builder for a larger initial buffer.
+    def Initial(initial_size:int):
+        buf = "\x00".repeat_string(initial_size)
+
+    def Start():
+        // Get the start of useful data in the underlying byte buffer.
+        return buf.length - head
+
+    def Offset():
+        // Offset relative to the end of the buffer.
+        return offset { head }
+
+    // Returns a copy of the part of the buffer containing only the finished FlatBuffer
+    def SizedCopy():
+        assert finished
+        return buf.substring(Start(), -1)
+
+    def StartNesting():
+        assert not nested
+        nested = true
+
+    def EndNesting():
+        assert nested
+        nested = false
+
+    def StartObject(numfields):
+        StartNesting()
+        current_vtable = map(numfields): 0
+        object_end = head
+        minalign = 1
+
+    def EndObject():
+        EndNesting()
+        // Prepend a zero scalar to the object. Later in this function we'll
+        // write an offset here that points to the object's vtable:
+        PrependInt32(0)
+        let object_offset = head
+        // Write out new vtable speculatively.
+        let vtable_size = (current_vtable.length + sz_metadata_fields) * sz_voffset
+        while current_vtable.length:
+            let o = current_vtable.pop()
+            PrependVOffsetT(if o: object_offset - o else: 0)
+        // The two metadata fields are written last.
+        // First, store the object bytesize:
+        PrependVOffsetT(object_offset - object_end)
+        // Second, store the vtable bytesize:
+        PrependVOffsetT(vtable_size)
+        // Search backwards through existing vtables, because similar vtables
+        // are likely to have been recently appended. See
+        // BenchmarkVtableDeduplication for a case in which this heuristic
+        // saves about 30% of the time used in writing objects with duplicate
+        // tables.
+        def find_existing_table():
+            reverse(vtables) vt2_offset:
+                // Find the other vtable:
+                let vt2_start = buf.length - vt2_offset
+                let vt2_len = buf.read_int16_le(vt2_start)
+                // Compare the other vtable to the one under consideration.
+                // If they are equal, return the offset:
+                if vtable_size == vt2_len and
+                    not compare_substring(buf, Start(), buf, vt2_start, vtable_size):
+                        return vt2_offset
+            return 0
+        let existing_vtable = find_existing_table()
+        if existing_vtable:
+            // Found a duplicate vtable, remove the one we wrote.
+            head = object_offset
+            // Write the offset to the found vtable in the
+            // already-allocated offset at the beginning of this object:
+            buf.write_int32_le(Start(), existing_vtable - object_offset)
+        else:
+            // Did not find a vtable, so keep the one we wrote.
+            // Next, write the offset to the new vtable in the
+            // already-allocated offset at the beginning of this object:
+            buf.write_int32_le(buf.length - object_offset, head - object_offset)
+            // Finally, store this vtable in memory for future
+            // deduplication:
+            vtables.push(head)
+        return offset { object_offset }
+
+    def Pad(n):
+        for(n):
+            buf, head = buf.write_int8_le_back(head, 0)
+
+    def Prep(size, additional_bytes):
+        // Track the biggest thing we've ever aligned to.
+        if size > minalign:
+            minalign = size
+        // Find the amount of alignment needed such that `size` is properly
+        // aligned after `additionalBytes`:
+        let align_size = ((~(head + additional_bytes)) + 1) & (size - 1)
+        Pad(align_size)
+
+    def PrependUOffsetTRelative(off:offset):
+        // Prepends an unsigned offset into vector data, relative to where it will be written.
+        Prep(sz_uoffset, 0)
+        assert off.o <= head
+        PlaceUOffsetT(head - off.o + sz_uoffset)
+
+    def StartVector(elem_size, num_elems, alignment):
+        // Initializes bookkeeping for writing a new vector.
+        StartNesting()
+        Prep(sz_32, elem_size * num_elems)
+        Prep(alignment, elem_size * num_elems)  // In case alignment > int.
+        return Offset()
+
+    def EndVector(vector_num_elems):
+        EndNesting()
+        // we already made space for this, so write without PrependUint32
+        PlaceUOffsetT(vector_num_elems)
+        return Offset()
+
+    def CreateString(s:string):
+        // writes a null-terminated byte string.
+        StartNesting()
+        Prep(sz_32, s.length + 1)
+        buf, head = buf.write_substring_back(head, s, true)
+        return EndVector(s.length)
+
+    def CreateByteVector(s:string):
+        // writes a non-null-terminated byte string.
+        StartNesting()
+        Prep(sz_32, s.length)
+        buf, head = buf.write_substring_back(head, s, false)
+        return EndVector(s.length)
+
+    def Slot(slotnum):
+        assert nested
+        while current_vtable.length <= slotnum: current_vtable.push(0)
+        current_vtable[slotnum] = head
+
+    def __Finish(root_table:offset, size_prefix:int):
+        // Finish finalizes a buffer, pointing to the given root_table
+        assert not finished
+        assert not nested
+        var prep_size = sz_32
+        if size_prefix:
+            prep_size += sz_32
+        Prep(minalign, prep_size)
+        PrependUOffsetTRelative(root_table)
+        if size_prefix:
+            PrependInt32(head)
+        finished = true
+        return Start()
+
+    def Finish(root_table:offset):
+        return __Finish(root_table, false)
+
+    def FinishSizePrefixed(root_table:offset):
+        return __Finish(root_table, true)
+
+    def PrependBool(x):
+        buf, head = buf.write_int8_le_back(head, x)
+
+    def PrependByte(x):
+        buf, head = buf.write_int8_le_back(head, x)
+
+    def PrependUint8(x):
+        buf, head = buf.write_int8_le_back(head, x)
+
+    def PrependUint16(x):
+        Prep(sz_16, 0)
+        buf, head = buf.write_int16_le_back(head, x)
+
+    def PrependUint32(x):
+        Prep(sz_32, 0)
+        buf, head = buf.write_int32_le_back(head, x)
+
+    def PrependUint64(x):
+        Prep(sz_64, 0)
+        buf, head = buf.write_int64_le_back(head, x)
+
+    def PrependInt8(x):
+        buf, head = buf.write_int8_le_back(head, x)
+
+    def PrependInt16(x):
+        Prep(sz_16, 0)
+        buf, head = buf.write_int16_le_back(head, x)
+
+    def PrependInt32(x):
+        Prep(sz_32, 0)
+        buf, head = buf.write_int32_le_back(head, x)
+
+    def PrependInt64(x):
+        Prep(sz_64, 0)
+        buf, head = buf.write_int64_le_back(head, x)
+
+    def PrependFloat32(x):
+        Prep(sz_32, 0)
+        buf, head = buf.write_float32_le_back(head, x)
+
+    def PrependFloat64(x):
+        Prep(sz_64, 0)
+        buf, head = buf.write_float64_le_back(head, x)
+
+    def PrependVOffsetT(x):
+        Prep(sz_voffset, 0)
+        buf, head = buf.write_int16_le_back(head, x)
+
+    def PlaceVOffsetT(x):
+        buf, head = buf.write_int16_le_back(head, x)
+
+    def PlaceSOffsetT(x):
+        buf, head = buf.write_int32_le_back(head, x)
+
+    def PlaceUOffsetT(x):
+        buf, head = buf.write_int32_le_back(head, x)
+
+    def PrependSlot(o:int, x, d, f):
+        if x != d:
+            f(x)
+            Slot(o)
+
+    def PrependBoolSlot(o, x, d): PrependSlot(o, x, d): PrependBool(_)
+    def PrependByteSlot(o, x, d): PrependSlot(o, x, d): PrependByte(_)
+    def PrependUint8Slot(o, x, d): PrependSlot(o, x, d): PrependUint8(_)
+    def PrependUint16Slot(o, x, d): PrependSlot(o, x, d): PrependUint16(_)
+    def PrependUint32Slot(o, x, d): PrependSlot(o, x, d): PrependUint32(_)
+    def PrependUint64Slot(o, x, d): PrependSlot(o, x, d): PrependUint64(_)
+    def PrependInt8Slot(o, x, d): PrependSlot(o, x, d): PrependInt8(_)
+    def PrependInt16Slot(o, x, d): PrependSlot(o, x, d): PrependInt16(_)
+    def PrependInt32Slot(o, x, d): PrependSlot(o, x, d): PrependInt32(_)
+    def PrependInt64Slot(o, x, d): PrependSlot(o, x, d): PrependInt64(_)
+    def PrependFloat32Slot(o, x, d): PrependSlot(o, x, d): PrependFloat32(_)
+    def PrependFloat64Slot(o, x, d): PrependSlot(o, x, d): PrependFloat64(_)
+
+    def PrependUOffsetTRelativeSlot(o:int, x:offset):
+        if x.o:
+            PrependUOffsetTRelative(x)
+            Slot(o)
+
+    def PrependStructSlot(v:int, x:offset):
+        if x.o:
+            // Structs are always stored inline, so need to be created right
+            // where they are used. You'll get this error if you created it
+            // elsewhere.
+            assert x.o == head
+            Slot(v)