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

use crate::types::connection::{EmptyEdgeFields, QueryOperation};
use crate::{Connection, Context, DataSource, FieldResult};
use byteorder::{ReadBytesExt, BE};

#[async_trait::async_trait]
impl<'a, T: Sync> DataSource for &'a [T] {
    type Element = &'a T;
    type EdgeFieldsObj = EmptyEdgeFields;

    async fn query_operation(
        &self,
        _ctx: &Context<'_>,
        operation: &QueryOperation,
    ) -> FieldResult<Connection<Self::Element, Self::EdgeFieldsObj>> {
        let (start, end) = match operation {
            QueryOperation::None => {
                let start = 0;
                let end = self.len();
                (start, end)
            }
            QueryOperation::After { after } => {
                let start = base64::decode(after.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| (idx + 1) as usize)
                    .unwrap_or(0);
                let end = self.len();
                (start, end)
            }
            QueryOperation::Before { before } => {
                let end = base64::decode(before.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| idx as usize)
                    .unwrap_or_else(|| self.len());
                let start = 0;
                (start, end)
            }
            QueryOperation::Between { after, before } => {
                let start = base64::decode(after.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| (idx + 1) as usize)
                    .unwrap_or(0);
                let end = base64::decode(before.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| idx as usize)
                    .unwrap_or_else(|| self.len());
                (start, end)
            }
            QueryOperation::First { limit } => {
                let start = 0;
                let end = (start + *limit).min(self.len());
                (start, end)
            }
            QueryOperation::FirstAfter { after, limit } => {
                let start = base64::decode(after.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| (idx + 1) as usize)
                    .unwrap_or(0);
                let end = (start + *limit).min(self.len());
                (start, end)
            }
            QueryOperation::FirstBefore { before, limit } => {
                let end_cursor = base64::decode(before.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| idx as usize)
                    .unwrap_or_else(|| self.len());
                let start = (end_cursor - *limit).max(0);
                let end = (start + *limit).min(end_cursor);
                (start, end)
            }
            QueryOperation::FirstBetween {
                after,
                before,
                limit,
            } => {
                let start = base64::decode(after.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| (idx + 1) as usize)
                    .unwrap_or(0);
                let end_cursor = base64::decode(before.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| idx as usize)
                    .unwrap_or_else(|| self.len());
                let end = (start + *limit).min(end_cursor);
                (start, end)
            }
            QueryOperation::Last { limit } => {
                let end = self.len();
                let start = (end - *limit).max(0);
                (start, end)
            }
            QueryOperation::LastAfter { after, limit } => {
                let end = self.len();
                let start_cursor = base64::decode(after.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| (idx + 1) as usize)
                    .unwrap_or(0);
                let start = (end - *limit).max(start_cursor);
                (start, end)
            }
            QueryOperation::LastBefore { before, limit } => {
                let end = base64::decode(before.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| idx as usize)
                    .unwrap_or_else(|| self.len());
                let start = (end - *limit).max(0);
                (start, end)
            }
            QueryOperation::LastBetween {
                after,
                before,
                limit,
            } => {
                let start_cursor = base64::decode(after.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| (idx + 1) as usize)
                    .unwrap_or(0);
                let end = base64::decode(before.to_string())
                    .ok()
                    .and_then(|data| data.as_slice().read_u32::<BE>().ok())
                    .map(|idx| idx as usize)
                    .unwrap_or_else(|| self.len());
                let start = (end - *limit).max(start_cursor);
                (start, end)
            }
            QueryOperation::Invalid => {
                let start = 0;
                let end = 0;
                (start, end)
            }
        };

        let mut nodes = Vec::with_capacity(end - start);
        if nodes.capacity() != 0 {
            for (idx, item) in self[start..end].iter().enumerate() {
                nodes.push((
                    base64::encode((idx as u32).to_be_bytes()).into(),
                    EmptyEdgeFields,
                    item,
                ));
            }
        }

        Ok(Connection::new(None, start > 0, end < self.len(), nodes))
    }
}