Add feature 'multithread' to use Rsonpath in multithread context

crates/rsonpath-lib/Cargo.toml

@@ -47,11 +47,12 @@ test-case = { workspace = true }
 default = ["simd"]
 arbitrary = ["dep:arbitrary"]
 simd = []
+multithread = []
 
 [[example]]
 name = "approx_spans_usage"
 path = "examples/approx_spans_usage.rs"
 doc-scrape-examples = true
 
 [lints]
-workspace = true
+workspace = true

crates/rsonpath-lib/src/automaton.rs

@@ -12,10 +12,15 @@ use crate::{automaton::error::CompilerError, debug, string_pattern::StringPatter
 use nfa::NondeterministicAutomaton;
 use rsonpath_syntax::{num::JsonUInt, JsonPathQuery};
 use smallvec::SmallVec;
-use std::{fmt::Display, ops::Index, rc::Rc};
+use std::{fmt::Display, ops::Index};
+
+#[cfg(not(feature = "multithread"))]
+use std::rc::Rc;
+#[cfg(feature = "multithread")]
+use std::sync::Arc as Rc;
 
 /// A minimal, deterministic automaton representing a JSONPath query.
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct Automaton {
     states: Vec<StateTable>,
 }
@@ -25,7 +30,7 @@ pub type MemberTransition = (Rc<StringPattern>, State);
 
 /// Transition on elements of an array with indices specified by either a single index
 /// or a simple slice expression.
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct ArrayTransition {
     label: ArrayTransitionLabel,
     target: State,
@@ -44,7 +49,7 @@ pub(super) enum ArrayTransitionLabel {
 ///
 /// Contains transitions triggered by matching member names or array indices, and a fallback transition
 /// triggered when none of the labelled transitions match.
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct StateTable {
     attributes: StateAttributes,
     member_transitions: SmallVec<[MemberTransition; 2]>,

crates/rsonpath-lib/src/automaton/minimizer.rs

@@ -1,6 +1,9 @@
 //! Determinization and minimization of an NFA into the final DFA used by the engines.
 
+#[cfg(not(feature = "multithread"))]
 use std::rc::Rc;
+#[cfg(feature = "multithread")]
+use std::sync::Arc as Rc;
 
 // NOTE: Some comments in this module are outdated, because the minimizer doesn't
 // actually produce minimal automata as of now - see #91.

crates/rsonpath-lib/src/automaton/nfa.rs

@@ -5,7 +5,12 @@ use crate::{automaton::SimpleSlice, error::UnsupportedFeatureError, string_patte
 
 use super::{error::CompilerError, ArrayTransitionLabel};
 use rsonpath_syntax::{str::JsonString, JsonPathQuery, Step};
-use std::{collections::HashMap, fmt::Display, ops::Index, rc::Rc};
+use std::{collections::HashMap, fmt::Display, ops::Index};
+
+#[cfg(not(feature = "multithread"))]
+use std::rc::Rc;
+#[cfg(feature = "multithread")]
+use std::sync::Arc as Rc;
 
 /// An NFA representing a query. It is always a directed path
 /// from an initial state to the unique accepting state at the end,

crates/rsonpath-lib/src/engine/head_skipping.rs

@@ -1,7 +1,11 @@
 //! Engine decorator that performs **head skipping** – an extremely optimized search for
 //! the first matching member name in a query starting with a self-looping state.
 //! This happens in queries starting with a descendant selector.
+
+#[cfg(not(feature = "multithread"))]
 use std::rc::Rc;
+#[cfg(feature = "multithread")]
+use std::sync::Arc as Rc;
 
 use crate::{
     automaton::{Automaton, State},

crates/rsonpath-lib/src/engine/main.rs

@@ -69,7 +69,8 @@ use smallvec::{smallvec, SmallVec};
 ///
 /// The engine is stateless, meaning that it can be executed
 /// on any number of separate inputs, even on separate threads.
-#[derive(Debug)]
+
+#[derive(Clone, Debug)]
 pub struct MainEngine {
     automaton: Automaton,
     simd: SimdConfiguration,