flatbuffers/
table.rs

1/*
2 * Copyright 2018 Google Inc. All rights reserved.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17use crate::follow::Follow;
18use crate::primitives::*;
19use crate::vtable::VTable;
20
21#[derive(Clone, Copy, Debug, PartialEq, Eq)]
22pub struct Table<'a> {
23    buf: &'a [u8],
24    loc: usize,
25}
26
27impl<'a> Table<'a> {
28    #[inline]
29    pub fn buf(&self) -> &'a [u8] {
30        self.buf
31    }
32
33    #[inline]
34    pub fn loc(&self) -> usize {
35        self.loc
36    }
37
38    /// # Safety
39    ///
40    /// `buf` must contain a `soffset_t` at `loc`, which points to a valid vtable
41    #[inline]
42    pub unsafe fn new(buf: &'a [u8], loc: usize) -> Self {
43        Table { buf, loc }
44    }
45
46    #[inline]
47    pub fn vtable(&self) -> VTable<'a> {
48        // Safety:
49        // Table::new is created with a valid buf and location
50        unsafe { <BackwardsSOffset<VTable<'a>>>::follow(self.buf, self.loc) }
51    }
52
53    /// Retrieves the value at the provided `slot_byte_loc` returning `default`
54    /// if no value present
55    ///
56    /// # Safety
57    ///
58    /// The value of the corresponding slot must have type T
59    #[inline]
60    pub unsafe fn get<T: Follow<'a> + 'a>(
61        &self,
62        slot_byte_loc: VOffsetT,
63        default: Option<T::Inner>,
64    ) -> Option<T::Inner> {
65        let o = self.vtable().get(slot_byte_loc) as usize;
66        if o == 0 {
67            return default;
68        }
69        Some(<T>::follow(self.buf, self.loc + o))
70    }
71}
72
73impl<'a> Follow<'a> for Table<'a> {
74    type Inner = Table<'a>;
75    #[inline]
76    unsafe fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
77        Table { buf, loc }
78    }
79}
80
81/// Returns true if data contains a prefix of `ident`
82#[inline]
83pub fn buffer_has_identifier(data: &[u8], ident: &str, size_prefixed: bool) -> bool {
84    assert_eq!(ident.len(), FILE_IDENTIFIER_LENGTH);
85
86    let got = if size_prefixed {
87        assert!(data.len() >= SIZE_SIZEPREFIX + SIZE_UOFFSET + FILE_IDENTIFIER_LENGTH);
88        // Safety:
89        // Verified data has sufficient bytes
90        unsafe { <SkipSizePrefix<SkipRootOffset<FileIdentifier>>>::follow(data, 0) }
91    } else {
92        assert!(data.len() >= SIZE_UOFFSET + FILE_IDENTIFIER_LENGTH);
93        // Safety:
94        // Verified data has sufficient bytes
95        unsafe { <SkipRootOffset<FileIdentifier>>::follow(data, 0) }
96    };
97
98    ident.as_bytes() == got
99}
flatbuffers/table.rs

flatbuffers/
table.rs
