wirefilter/ast/
mod.rs

1mod combined_expr;
2mod field_expr;
3mod simple_expr;
4
5use self::combined_expr::CombinedExpr;
6use filter::{CompiledExpr, Filter};
7use lex::{LexResult, LexWith};
8use scheme::{Field, Scheme, UnknownFieldError};
9use serde::Serialize;
10use std::fmt::{self, Debug};
11
12trait Expr<'s>: Sized + Eq + Debug + for<'i> LexWith<'i, &'s Scheme> + Serialize {
13    fn uses(&self, field: Field<'s>) -> bool;
14    fn compile(self) -> CompiledExpr<'s>;
15}
16
17/// A parsed filter AST.
18///
19/// It's attached to its corresponding [`Scheme`](struct@Scheme) because all
20/// parsed fields are represented as indices and are valid only when
21/// [`ExecutionContext`](::ExecutionContext) is created from the same scheme.
22#[derive(PartialEq, Eq, Serialize, Clone)]
23#[serde(transparent)]
24pub struct FilterAst<'s> {
25    #[serde(skip)]
26    scheme: &'s Scheme,
27
28    op: CombinedExpr<'s>,
29}
30
31impl<'s> Debug for FilterAst<'s> {
32    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
33        self.op.fmt(f)
34    }
35}
36
37impl<'i, 's> LexWith<'i, &'s Scheme> for FilterAst<'s> {
38    fn lex_with(input: &'i str, scheme: &'s Scheme) -> LexResult<'i, Self> {
39        let (op, input) = CombinedExpr::lex_with(input, scheme)?;
40        Ok((FilterAst { scheme, op }, input))
41    }
42}
43
44impl<'s> FilterAst<'s> {
45    /// Recursively checks whether a [`FilterAst`] uses a given field name.
46    ///
47    /// This is useful to lazily initialise expensive fields only if necessary.
48    pub fn uses(&self, field_name: &str) -> Result<bool, UnknownFieldError> {
49        self.scheme
50            .get_field_index(field_name)
51            .map(|field| self.op.uses(field))
52    }
53
54    /// Compiles a [`FilterAst`] into a [`Filter`].
55    pub fn compile(self) -> Filter<'s> {
56        Filter::new(self.op.compile(), self.scheme)
57    }
58}
wirefilter/ast/mod.rs

wirefilter/ast/
mod.rs
