simple-db-rust 0.1.5

A simple database writing in rust, inspired from mit 6.830
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162

use crate::field::*;
use std::{
    fmt::{self},
    usize,
};

#[derive(Debug)]
pub struct Tuple {
    scheme: TupleScheme,
    fields: Vec<IntField>,
}

impl Tuple {
    pub fn new(scheme: TupleScheme, bytes: &[u8]) -> Tuple {
        let mut cells: Vec<IntField> = Vec::new();
        let mut start: usize = 0;
        let mut end: usize = 0;
        for field in &scheme.fields {
            match field.field_type {
                Type::INT => {
                    end += get_type_length(field.field_type);
                    let cell_bytes = &bytes[start..end];
                    // debug!("cell bytes: {:x?}", cell_bytes);

                    let mut bytes_array = [0; 4];
                    for i in 0..4 {
                        bytes_array[i] = cell_bytes[i];
                    }
                    let value = i32::from_be_bytes(bytes_array);
                    // debug!("cell value : {}", value);

                    cells.push(IntField::new(value));

                    start = end;
                }
            }
        }
        Tuple {
            scheme,
            fields: cells,
        }
    }

    pub fn new_default_tuple(scheme: TupleScheme, _width: i32) -> Tuple {
        let mut cells: Vec<IntField> = Vec::new();
        for field in &scheme.fields {
            match field.field_type {
                Type::INT => {
                    cells.push(IntField::new(0));
                }
            }
        }
        Tuple {
            scheme,
            fields: cells,
        }
    }

    pub fn new_btree_tuple(value: i32, width: i32) -> Tuple {
        let scheme = simple_int_tuple_scheme(width, "");
        let _bytes = [0];
        let mut tuple = Tuple::new_default_tuple(scheme, width);
        for i in 0..tuple.fields.len() {
            tuple.set_field(i, IntField::new(value));
        }
        tuple
    }

    pub fn set_field(&mut self, i: usize, c: IntField) {
        self.fields[i] = c;
    }

    pub fn get_field(&self, i: usize) -> IntField {
        self.fields[i]
    }

    pub fn clone(&self) -> Tuple {
        Tuple {
            scheme: self.scheme.clone(),
            fields: self.fields.to_vec(),
        }
    }
}

impl fmt::Display for Tuple {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let mut content: String = "{".to_owned();
        for cell in &self.fields {
            let cell_str = format!("{}, ", cell.value);
            content.push_str(&cell_str);
        }
        content = content[..content.len() - 2].to_string();
        content.push_str(&"}");
        write!(f, "{}", content,)
    }
}

#[derive(Debug)]
pub struct TupleScheme {
    pub fields: Vec<FieldItem>,
}

impl PartialEq for TupleScheme {
    fn eq(&self, other: &Self) -> bool {
        let matching = self
            .fields
            .iter()
            .zip(&other.fields)
            .filter(|&(a, b)| a == b)
            .count();
        self.fields.len() == matching
    }
}

impl TupleScheme {
    pub fn merge(scheme1: TupleScheme, scheme2: TupleScheme) -> TupleScheme {
        let mut new_scheme = TupleScheme {
            ..Default::default()
        };

        for f in scheme1.fields {
            new_scheme.fields.push(f);
        }
        for f in scheme2.fields {
            new_scheme.fields.push(f);
        }

        new_scheme
    }

    /// get tuple size in bytes
    pub fn get_size(&self) -> usize {
        self.fields.len() * 4
    }
}

impl Clone for TupleScheme {
    fn clone(&self) -> Self {
        Self {
            fields: self.fields.to_vec(),
        }
    }
}

impl Default for TupleScheme {
    fn default() -> TupleScheme {
        TupleScheme { fields: Vec::new() }
    }
}

pub fn simple_int_tuple_scheme(width: i32, name_prefix: &str) -> TupleScheme {
    let mut fields: Vec<FieldItem> = Vec::new();
    for i in 0..width {
        let field = FieldItem {
            field_name: format!("{}-{}", name_prefix, i),
            field_type: Type::INT,
        };
        fields.push(field);
    }

    TupleScheme { fields: fields }
}