rxgraph 0.3.0

High-performance graph traversal engine
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
163

use anyhow::{Context, Result};

use crate::{
    dsl::{
        DslKernel, StateRow, StateValues, Value,
        arrow_value::ColumnReader,
        eval::EvalCtx,
        expr::{ColumnRef, Expr},
    },
    graph::{Graph, GraphId, GraphRepo},
};

#[derive(Debug)]
pub(crate) struct BoundKernel {
    visit: Expr<BoundColumn>,
    next_state: Vec<(usize, Expr<BoundColumn>)>,
    stop: Expr<BoundColumn>,
    names: Vec<String>,
    initial_state: StateValues,
}

impl BoundKernel {
    pub(crate) fn bind(graph: &Graph, kernel: DslKernel) -> Result<Self> {
        let names = state_names(&kernel.initial_state, &kernel.next_state);
        let mut bind = |column| BoundColumn::bind(graph, column, &names);

        Ok(Self {
            visit: kernel.visit.try_map_column(&mut bind)?,
            next_state: kernel
                .next_state
                .into_iter()
                .map(|(name, expr)| {
                    Ok((
                        state_index(&names, &name).unwrap(),
                        expr.try_map_column(&mut bind)?,
                    ))
                })
                .collect::<Result<_>>()?,
            stop: kernel.stop.try_map_column(&mut bind)?,
            names: names.clone(),
            initial_state: normalize_state(kernel.initial_state, &names),
        })
    }

    pub(crate) fn initial_state(&self) -> &StateValues {
        &self.initial_state
    }

    pub(crate) fn visit(&self, ctx: &EvalCtx<'_>) -> Result<bool> {
        self.visit.eval(ctx)?.truthy()
    }

    pub(crate) fn next_state(&self, current: &[Value], ctx: &EvalCtx<'_>) -> Result<StateValues> {
        let mut next = current.iter().cloned().collect::<StateValues>();
        for (index, expr) in &self.next_state {
            next[*index] = expr.eval(ctx)?;
        }
        Ok(next)
    }

    pub(crate) fn stop(&self, ctx: &EvalCtx<'_>) -> Result<bool> {
        self.stop.eval(ctx)?.truthy()
    }

    pub(crate) fn state_row(&self, state: &[Value]) -> StateRow {
        self.names
            .iter()
            .cloned()
            .zip(state.iter().cloned())
            .collect()
    }
}

#[derive(Debug, Clone)]
pub(crate) enum BoundColumn {
    SrcId,
    DestId,
    EdgeId,
    Src(ColumnReader),
    Dest(ColumnReader),
    Edge(ColumnReader),
    State(usize),
    MissingState,
}

impl BoundColumn {
    fn bind(graph: &Graph, column: ColumnRef, names: &[String]) -> Result<Self> {
        Ok(match column {
            ColumnRef::SrcId => Self::SrcId,
            ColumnRef::DestId => Self::DestId,
            ColumnRef::EdgeId => Self::EdgeId,
            ColumnRef::SrcField(name) => Self::Src(ColumnReader::bind(&graph.repo.nodes, &name)?),
            ColumnRef::DestField(name) => Self::Dest(ColumnReader::bind(&graph.repo.nodes, &name)?),
            ColumnRef::EdgeField(name) => Self::Edge(ColumnReader::bind(&graph.repo.edges, &name)?),
            ColumnRef::State(name) => state_index(names, &name)
                .map(Self::State)
                .unwrap_or(Self::MissingState),
        })
    }

    pub(crate) fn value(&self, ctx: &EvalCtx<'_>) -> Result<Value> {
        match self {
            Self::SrcId => graph_id_value(
                ctx.graph
                    .repo
                    .external_node(ctx.src)
                    .context("missing src id")?,
            ),
            Self::DestId => graph_id_value(
                ctx.graph
                    .repo
                    .external_node(ctx.dest)
                    .context("missing dest id")?,
            ),
            Self::EdgeId => graph_id_value(
                ctx.graph
                    .repo
                    .external_edge(ctx.edge)
                    .context("missing edge id")?,
            ),
            Self::Src(reader) => reader.value(ctx.src as usize),
            Self::Dest(reader) => reader.value(ctx.dest as usize),
            Self::Edge(reader) => reader.value(ctx.edge as usize),
            Self::State(index) => Ok(ctx.state[*index].clone()),
            Self::MissingState => Ok(Value::Null),
        }
    }
}

fn graph_id_value(id: GraphId<'_>) -> Result<Value> {
    Ok(match id {
        GraphId::U64(value) => Value::U64(value),
        GraphId::Str(value) => Value::Str(std::sync::Arc::from(value)),
    })
}

fn state_names(initial: &StateRow, next: &[(String, Expr<ColumnRef>)]) -> Vec<String> {
    let mut names = initial
        .iter()
        .map(|(name, _)| name.clone())
        .collect::<Vec<_>>();
    names.extend(next.iter().map(|(name, _)| name.clone()));
    names.sort();
    names.dedup();
    names
}

fn normalize_state(state: StateRow, names: &[String]) -> StateValues {
    names
        .iter()
        .map(|name| {
            state
                .binary_search_by(|(key, _)| key.as_str().cmp(name))
                .ok()
                .map(|i| state[i].1.clone())
                .unwrap_or(Value::Null)
        })
        .collect::<StateValues>()
}

fn state_index(names: &[String], name: &str) -> Option<usize> {
    names.binary_search_by(|key| key.as_str().cmp(name)).ok()
}