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
166
167
168
169
170
171

//! `parent()` predicate factory.

use predicates::{
    reflection::{Case, PredicateReflection, Product},
    Predicate,
};

use std::{fmt, iter};

use crate::{Captured, CapturedSpan};

/// Creates a predicate for the direct parent [`CapturedSpan`] of a span or a [`CapturedEvent`].
///
/// [`CapturedEvent`]: crate::CapturedEvent
///
/// # Examples
///
/// ```
/// # use predicates::ord::eq;
/// # use tracing_core::Level;
/// # use tracing_subscriber::{layer::SubscriberExt, Registry};
/// # use tracing_capture::{predicates::*, CaptureLayer, SharedStorage};
/// let storage = SharedStorage::default();
/// let subscriber = Registry::default().with(CaptureLayer::new(&storage));
/// tracing::subscriber::with_default(subscriber, || {
///     tracing::info_span!("compute").in_scope(|| {
///         tracing::info!(answer = 42, "done");
///     });
/// });
///
/// let storage = storage.lock();
/// let parent_pred = level(Level::INFO) & name(eq("compute"));
/// let _ = storage.scan_events().single(&parent(parent_pred));
/// ```
pub fn parent<P>(matches: P) -> ParentPredicate<P>
where
    P: for<'a> Predicate<CapturedSpan<'a>>,
{
    ParentPredicate { matches }
}

/// Predicate for the parent of a [`CapturedSpan`] or [`CapturedEvent`] returned
/// by the [`parent()`] function.
///
/// [`CapturedEvent`]: crate::CapturedEvent
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct ParentPredicate<P> {
    matches: P,
}

impl_bool_ops!(ParentPredicate<P>);

impl<P> fmt::Display for ParentPredicate<P>
where
    P: for<'a> Predicate<CapturedSpan<'a>>,
{
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(formatter, "parent({})", self.matches)
    }
}

impl<P> PredicateReflection for ParentPredicate<P> where P: for<'a> Predicate<CapturedSpan<'a>> {}

impl<'a, P, T> Predicate<T> for ParentPredicate<P>
where
    T: Captured<'a>,
    P: for<'p> Predicate<CapturedSpan<'p>>,
{
    fn eval(&self, variable: &T) -> bool {
        let parent = variable.parent();
        parent.map_or(false, |parent| self.matches.eval(&parent))
    }

    fn find_case(&self, expected: bool, variable: &T) -> Option<Case<'_>> {
        let parent = variable.parent();
        let parent = if let Some(parent) = parent {
            parent
        } else {
            return if expected {
                None // was expecting a parent, but there is none
            } else {
                let product = Product::new("parent", "None");
                Some(Case::new(Some(self), expected).add_product(product))
            };
        };

        let child = self.matches.find_case(expected, &parent)?;
        Some(Case::new(Some(self), expected).add_child(child))
    }
}

/// Creates a predicate for ancestor [`CapturedSpan`]s of a span or a [`CapturedEvent`].
/// The predicate is true iff the wrapped span predicate holds true for *any* of the ancestors.
///
/// [`CapturedEvent`]: crate::CapturedEvent
///
/// # Examples
///
/// ```
/// # use predicates::ord::eq;
/// # use tracing_core::Level;
/// # use tracing_subscriber::{layer::SubscriberExt, Registry};
/// # use tracing_capture::{predicates::*, CaptureLayer, SharedStorage};
/// let storage = SharedStorage::default();
/// let subscriber = Registry::default().with(CaptureLayer::new(&storage));
/// tracing::subscriber::with_default(subscriber, || {
///     let _entered = tracing::info_span!("wrapper").entered();
///     tracing::info_span!("compute").in_scope(|| {
///         tracing::info!(answer = 42, "done");
///     });
/// });
///
/// let storage = storage.lock();
/// let parent_pred = level(Level::INFO) & name(eq("wrapper"));
/// let _ = storage.scan_events().single(&ancestor(parent_pred));
/// ```
pub fn ancestor<P>(matches: P) -> AncestorPredicate<P>
where
    P: for<'a> Predicate<CapturedSpan<'a>>,
{
    AncestorPredicate { matches }
}

/// Predicate for the ancestors of a [`CapturedSpan`] or [`CapturedEvent`] returned
/// by the [`ancestor()`] function.
///
/// [`CapturedEvent`]: crate::CapturedEvent
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct AncestorPredicate<P> {
    matches: P,
}

impl_bool_ops!(AncestorPredicate<P>);

impl<P> fmt::Display for AncestorPredicate<P>
where
    P: for<'a> Predicate<CapturedSpan<'a>>,
{
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(formatter, "ancestor({})", self.matches)
    }
}

impl<P> PredicateReflection for AncestorPredicate<P> where P: for<'a> Predicate<CapturedSpan<'a>> {}

impl<'a, P, T> Predicate<T> for AncestorPredicate<P>
where
    T: Captured<'a>,
    P: for<'p> Predicate<CapturedSpan<'p>>,
{
    fn eval(&self, variable: &T) -> bool {
        let mut ancestors = iter::successors(variable.parent(), CapturedSpan::parent);
        ancestors.any(|span| self.matches.eval(&span))
    }

    fn find_case(&self, expected: bool, variable: &T) -> Option<Case<'_>> {
        let mut ancestors = iter::successors(variable.parent(), CapturedSpan::parent);
        if expected {
            // Return the first of ancestor cases.
            let child = ancestors.find_map(|span| self.matches.find_case(expected, &span))?;
            Some(Case::new(Some(self), expected).add_child(child))
        } else {
            // Need all ancestor cases.
            let case = Case::new(Some(self), expected);
            ancestors.try_fold(case, |case, span| {
                let child = self.matches.find_case(expected, &span)?;
                Some(case.add_child(child))
            })
        }
    }
}