btree/
node_type.rs

1use crate::error::Error;
2use crate::page_layout::PTR_SIZE;
3use std::cmp::{Eq, Ord, Ordering, PartialOrd};
4use std::convert::From;
5use std::convert::TryFrom;
6
7#[derive(Clone, Eq, PartialEq, Debug)]
8pub struct Offset(pub usize);
9
10/// Converts an array of length len(usize) to a usize as a BigEndian integer.
11impl TryFrom<[u8; PTR_SIZE]> for Offset {
12    type Error = Error;
13
14    fn try_from(arr: [u8; PTR_SIZE]) -> Result<Self, Self::Error> {
15        Ok(Offset(usize::from_be_bytes(arr)))
16    }
17}
18
19#[derive(Clone, Eq, PartialEq, PartialOrd, Ord, Debug)]
20pub struct Key(pub String);
21
22#[derive(Clone, Eq, Debug)]
23pub struct KeyValuePair {
24    pub key: String,
25    pub value: String,
26}
27
28impl Ord for KeyValuePair {
29    fn cmp(&self, other: &Self) -> Ordering {
30        self.key.cmp(&other.key)
31    }
32}
33
34impl PartialOrd for KeyValuePair {
35    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
36        Some(self.cmp(other))
37    }
38}
39
40impl PartialEq for KeyValuePair {
41    fn eq(&self, other: &Self) -> bool {
42        self.key == other.key && self.value == other.value
43    }
44}
45
46impl KeyValuePair {
47    pub fn new(key: String, value: String) -> KeyValuePair {
48        KeyValuePair { key, value }
49    }
50}
51
52// NodeType Represents different node types in the BTree.
53#[derive(PartialEq, Eq, Clone, Debug)]
54pub enum NodeType {
55    /// Internal nodes contain a vector of pointers to their children and a vector of keys.
56    Internal(Vec<Offset>, Vec<Key>),
57
58    /// Leaf nodes contain a vector of Keys and values.
59    Leaf(Vec<KeyValuePair>),
60
61    Unexpected,
62}
63
64// Converts a byte to a NodeType.
65impl From<u8> for NodeType {
66    fn from(orig: u8) -> NodeType {
67        match orig {
68            0x01 => NodeType::Internal(Vec::<Offset>::new(), Vec::<Key>::new()),
69            0x02 => NodeType::Leaf(Vec::<KeyValuePair>::new()),
70            _ => NodeType::Unexpected,
71        }
72    }
73}
74
75// Converts a NodeType to a byte.
76impl From<&NodeType> for u8 {
77    fn from(orig: &NodeType) -> u8 {
78        match orig {
79            NodeType::Internal(_, _) => 0x01,
80            NodeType::Leaf(_) => 0x02,
81            NodeType::Unexpected => 0x03,
82        }
83    }
84}
btree/node_type.rs

btree/
node_type.rs
