58 lines
1.4 KiB
Rust
58 lines
1.4 KiB
Rust
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use bytes::BufMut;
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use super::{Block, SIZEOF_U16};
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/// Builds a block
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pub struct BlockBuilder {
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offsets: Vec<u16>,
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data: Vec<u8>,
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target_size: usize,
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}
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impl BlockBuilder {
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/// Creates a new block builder
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pub fn new(target_size: usize) -> Self {
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Self {
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offsets: Vec::new(),
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data: Vec::new(),
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target_size,
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}
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}
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fn estimated_size(&self) -> usize {
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self.offsets.len() * SIZEOF_U16 + self.data.len() + SIZEOF_U16
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}
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/// Adds a key-value pair to the block
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#[must_use]
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pub fn add(&mut self, key: &[u8], value: &[u8]) -> bool {
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assert!(!key.is_empty(), "key must not be empty");
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if self.estimated_size() + key.len() + value.len() + SIZEOF_U16 * 3 > self.target_size
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&& !self.is_empty()
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{
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return false;
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}
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self.offsets.push(self.data.len() as u16);
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self.data.put_u16(key.len() as u16);
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self.data.put(key);
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self.data.put_u16(value.len() as u16);
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self.data.put(value);
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true
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}
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pub fn is_empty(&self) -> bool {
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self.offsets.is_empty()
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}
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/// Builds a block
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pub fn build(self) -> Block {
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if self.is_empty() {
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panic!("block should not be empty");
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}
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Block {
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data: self.data,
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offsets: self.offsets,
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}
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}
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}
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