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
163
164
165

//! A stream generator such as a `Collection` or a mapping or aggregation of its items

use std::convert::TryInto;

use async_trait::async_trait;
use destream::en;
use futures::future;
use futures::stream::TryStreamExt;
use log::debug;
use sha2::digest::{Digest, Output};
use sha2::Sha256;

use tc_error::*;
use tc_transact::IntoView;
use tc_value::Number;
use tcgeneric::{Id, TCBoxTryStream};

use crate::closure::Closure;
use crate::fs;
use crate::state::{State, StateView};
use crate::txn::Txn;

use group::Aggregate;
use range::Range;
use source::*;

pub use source::Source;

mod group;
mod range;
mod source;

/// A stream generator such as a `Collection` or a mapping or aggregation of its items
#[derive(Clone)]
pub enum TCStream {
    Aggregate(Box<Aggregate>),
    Collection(Collection),
    Filter(Box<Filter>),
    Flatten(Box<Flatten>),
    Map(Box<Map>),
    Range(Range),
}

impl TCStream {
    /// Group equal sequential items in this stream.
    ///
    /// For example, aggregating the stream `['b', 'b', 'a', 'a', 'b']`
    /// will produce `['b', 'a', 'b']`.
    pub fn aggregate(self) -> Self {
        Aggregate::new(self).into()
    }

    /// Return a new stream with only the elements in this stream which match the given `filter`.
    pub fn filter(self, filter: Closure) -> Self {
        Filter::new(self, filter).into()
    }

    /// Flatten a stream of streams into a stream of `State`s.
    pub fn flatten(self) -> Self {
        Flatten::new(self).into()
    }

    /// Fold this stream with the given initial `State` and `Closure`.
    ///
    /// For example, folding `[1, 2, 3]` with `0` and `Number::add` will produce `6`.
    pub async fn fold(
        self,
        txn: Txn,
        item_name: Id,
        mut state: tcgeneric::Map<State>,
        op: Closure,
    ) -> TCResult<State> {
        let mut source = self.into_stream(txn.clone()).await?;

        while let Some(item) = source.try_next().await? {
            let mut args = state.clone();
            args.insert(item_name.clone(), item);

            let result = op.clone().call(&txn, args.into()).await?;
            state = result.try_into()?;
        }

        Ok(State::Map(state))
    }

    /// Execute the given [`Closure`] with each item in the stream as its `args`.
    pub async fn for_each(self, txn: &Txn, op: Closure) -> TCResult<()> {
        debug!("Stream::for_each {}", op);

        let stream = self.into_stream(txn.clone()).await?;

        stream
            .map_ok(move |args| {
                debug!("Stream::for_each calling op with args {}", args);
                op.clone().call(&txn, args)
            })
            .try_buffer_unordered(num_cpus::get())
            .try_fold((), |(), _none| future::ready(Ok(())))
            .await
    }

    /// Compute the SHA256 hash of this `TCStream`.
    pub async fn hash(self, txn: Txn) -> TCResult<Output<Sha256>> {
        let stream = self.into_stream(txn.clone()).await?;
        let mut hashes = stream
            .map_ok(|state| state.hash(txn.clone()))
            .try_buffered(num_cpus::get());

        let mut hasher = Sha256::default();
        while let Some(hash) = hashes.try_next().await? {
            hasher.update(&hash);
        }
        Ok(hasher.finalize())
    }

    /// Return a `TCStream` produced by calling the given [`Closure`] on each item in this stream.
    pub fn map(self, op: Closure) -> Self {
        Map::new(self, op).into()
    }

    /// Return a `TCStream` of numbers at the given `step` within the given range.
    pub fn range(start: Number, stop: Number, step: Number) -> Self {
        Range::new(start, stop, step).into()
    }
}

#[async_trait]
impl Source for TCStream {
    async fn into_stream(self, txn: Txn) -> TCResult<TCBoxTryStream<'static, State>> {
        match self {
            Self::Aggregate(aggregate) => aggregate.into_stream(txn).await,
            Self::Collection(collection) => collection.into_stream(txn).await,
            Self::Filter(filter) => filter.into_stream(txn).await,
            Self::Flatten(source) => source.into_stream(txn).await,
            Self::Map(map) => map.into_stream(txn).await,
            Self::Range(range) => range.into_stream(txn).await,
        }
    }
}

#[async_trait]
impl<'en> IntoView<'en, fs::Dir> for TCStream {
    type Txn = Txn;
    type View = en::SeqStream<TCResult<StateView<'en>>, TCBoxTryStream<'en, StateView<'en>>>;

    async fn into_view(self, txn: Self::Txn) -> TCResult<Self::View> {
        let stream = self.into_stream(txn.clone()).await?;
        let view_stream: TCBoxTryStream<'en, StateView<'en>> = Box::pin(
            stream
                .map_ok(move |state| state.into_view(txn.clone()))
                .try_buffered(num_cpus::get()),
        );

        Ok(en::SeqStream::from(view_stream))
    }
}

impl<T> From<T> for TCStream
where
    crate::collection::Collection: From<T>,
{
    fn from(collection: T) -> Self {
        Self::Collection(crate::collection::Collection::from(collection).into())
    }
}