rewrite visitor architecture to support arbitrary visitor lifetime

Author: rrevenantt

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "antlr-rust"
-version = "0.2.0-dev.1"
+version = "0.2.0-dev.2"
 authors = ["Konstantin Anisimov <rrevenantt@gmail.com>"]
 homepage = "https://github.com/rrevenantt/antlr4rust"
 repository = "https://github.com/rrevenantt/antlr4rust"

README.md

@@ -1,6 +1,6 @@
 # antlr4rust
-[![docs](https://docs.rs/antlr-rust/badge.svg)](https://docs.rs/antlr-rust)
-[![Crate](https://img.shields.io/crates/v/antlr_rust.svg)](https://crates.io/crates/antlr_rust)
+[![Crate](https://flat.badgen.net/crates/v/antlr-rust)](https://crates.io/crates/antlr_rust)
+[![docs](https://flat.badgen.net/badge/docs.rs/v0.2.0-dev.2)](https://docs.rs/antlr-rust/0.2.0-dev.2)
 
 [ANTLR4](https://github.com/antlr/antlr4) runtime for Rust programming language.
 

src/char_stream.rs

@@ -15,6 +15,8 @@ use crate::utils::Sealed;
 pub trait CharStream<Data>: IntStream {
     /// Returns underlying data piece, either slice or owned copy.
     /// Panics if provided indexes are invalid
+    /// Called by parser only on token intervals.
+    /// This fact can be used by custom implementations  
     fn get_text(&self, a: isize, b: isize) -> Data;
     fn get_text_from_interval(&self, i: &Interval) -> Data { self.get_text(i.a, i.b) }
 }

src/diagnostic_error_listener.rs

@@ -14,6 +14,7 @@
 #![warn(missing_docs)] // warn if there is missing docs
 #![warn(missing_debug_implementations)]
 #![warn(trivial_numeric_casts)]
+
 //! # Antlr4 runtime
 //!
 //! **This is pre-release version.**
@@ -58,18 +59,16 @@
 //! If you need to generate owned versions of parse tree or you want simpler usage,
 //! you can opt out zero-copy by requiring `'input` to be static. In this case it is easier to also use
 //! types that contains "owned" in their name or constructor function like `OwningTokenFactory`
-//! or `InputStream::new_owned()`
+//! or `InputStream::new_owned()`.
 //!
 //! ### Visitors and Listeners
 //!
-//! Currently visitors and listeners must outlive `'input`.
-//! In practice this means that visitor has either `'static` or `'input` lifetime.
-//! Thus you can retrieve references to parsed data from syntax tree to save in listener/visitor
-//! (as example you can see visitor test). This should cover 99% of usecases.
+//! Parse listeners must outlive 'input because they have to be stored inside of the parser.
+//! It still allows to retrieve borrowed data from parse tree which should be enough to cover 99% use cases.
+//!
+//! `ParseTreeWalker` can accept listeners with arbitrary lifetime.
 //!
-//! You can try to give visitor outside references but in this case
-//! if those references do not outlive `'input` you will get very confusing error messages,
-//! so this is not recommended.
+//! Visitors also can have arbitrary lifetime
 //!
 //! ### Downcasting
 //!

src/lib.rs

@@ -21,6 +21,7 @@ use crate::token::Token;
 use crate::token_factory::{CommonTokenFactory, TokenFactory};
 use crate::tree::{
     ErrorNode, ParseTree, ParseTreeListener, ParseTreeVisitor, TerminalNode, Tree, Visitable,
+    VisitableDyn,
 };
 use better_any::{Tid, TidAble, TidExt};
 
@@ -131,7 +132,7 @@ pub trait RuleContextExt<'input>: ParserRuleContext<'input> {
     fn accept_children<V>(&self, visitor: &mut V)
     where
         V: ParseTreeVisitor<'input, Self::Ctx> + ?Sized,
-        <Self::Ctx as ParserNodeType<'input>>::Type: Visitable<V>;
+        <Self::Ctx as ParserNodeType<'input>>::Type: VisitableDyn<V>;
 }
 
 impl<'input, T: ParserRuleContext<'input> + ?Sized + 'input> RuleContextExt<'input> for T {
@@ -177,9 +178,10 @@ impl<'input, T: ParserRuleContext<'input> + ?Sized + 'input> RuleContextExt<'inp
     fn accept_children<V>(&self, visitor: &mut V)
     where
         V: ParseTreeVisitor<'input, Self::Ctx> + ?Sized,
-        <Self::Ctx as ParserNodeType<'input>>::Type: Visitable<V>,
+        <Self::Ctx as ParserNodeType<'input>>::Type: VisitableDyn<V>,
     {
-        self.get_children().for_each(|child| child.accept(visitor))
+        self.get_children()
+            .for_each(|child| child.accept_dyn(visitor))
     }
 }
 

src/parser_rule_context.rs

@@ -221,24 +221,23 @@ pub trait ParseTreeVisitor<'input, Node: ParserNodeType<'input>>:
     fn visit_children(&mut self, node: &Node::Type) { self.visit_children_inner(node) }
 }
 
-/// How visitor is supposed to visit children
+/// Workaround for default recursive children visiting
 ///
-/// Default implementation visits children recursively
-/// To override it you would need to enable specialization feature
-///
-/// It is already implemented for visitors that are bound by `'input`.
+/// Already blanket implemented for all visitors.
+/// To override it you would need to implement `ParseTreeVisitor::visit_children`
 pub trait VisitChildren<'input, Node: ParserNodeType<'input>> {
     fn visit_children_inner(&mut self, node: &Node::Type);
 }
 
 impl<'input, Node, T> VisitChildren<'input, Node> for T
 where
     Node: ParserNodeType<'input>,
-    T: ParseTreeVisitor<'input, Node>,
-    for<'a> &'a mut Self: CoerceUnsized<&'a mut Node::Visitor>,
-    Node::Type: Visitable<Node::Visitor>,
+    T: ParseTreeVisitor<'input, Node> + ?Sized,
+    // for<'a> &'a mut Self: CoerceUnsized<&'a mut Node::Visitor>,
+    Node::Type: VisitableDyn<T>,
 {
-    default fn visit_children_inner(&mut self, node: &Node::Type) { node.accept_children(self) }
+    #[inline(always)]
+    fn visit_children_inner(&mut self, node: &Node::Type) { node.accept_children(self) }
 }
 
 pub trait Visitable<Vis: ?Sized> {
@@ -247,6 +246,12 @@ pub trait Visitable<Vis: ?Sized> {
     }
 }
 
+pub trait VisitableDyn<Vis: ?Sized> {
+    fn accept_dyn(&self, visitor: &mut Vis) {
+        unreachable!("should have been properly implemented by generated context when reachable")
+    }
+}
+
 pub trait ParseTreeListener<'input, Node: ParserNodeType<'input>> {
     fn visit_terminal(&mut self, _node: &TerminalNode<'input, Node>) {}
     fn visit_error_node(&mut self, _node: &ErrorNode<'input, Node>) {}
@@ -279,9 +284,6 @@ where
     T: ParseTreeListener<'input, Node> + 'a + ?Sized,
     Node::Type: Listenable<T>,
 {
-    // #[doc(hidden)]
-    // pub fn new() -> Self{ Self(PhantomData) }
-
     pub fn walk<Listener, Ctx>(mut listener: Box<Listener>, t: &Ctx) -> Box<Listener>
     where
         for<'x> &'x mut Listener: CoerceUnsized<&'x mut T>,

src/tree.rs

@@ -22,10 +22,7 @@ use antlr_rust::token::{OwningToken, Token, TOKEN_EOF};
 use antlr_rust::token_factory::{CommonTokenFactory, TokenAware, TokenFactory};
 use antlr_rust::token_source::TokenSource;
 use antlr_rust::token_stream::TokenStream;
-use antlr_rust::tree::{
-    ErrorNode, LeafNode, Listenable, ParseTree, ParseTreeListener, ParseTreeVisitor,
-    ParseTreeWalker, TerminalNode, Visitable,
-};
+use antlr_rust::tree::*;
 use antlr_rust::vocabulary::{Vocabulary, VocabularyImpl};
 use antlr_rust::PredictionContextCache;
 
@@ -147,6 +144,15 @@ pub trait CSVParserContext<'input>:
 {
 }
 
+impl<'input, 'x, T> VisitableDyn<T> for dyn CSVParserContext<'input> + 'input
+where
+    T: CSVVisitor<'input> + 'x,
+{
+    fn accept_dyn(&self, visitor: &mut T) {
+        self.accept(visitor as &mut (dyn CSVVisitor<'input> + 'x))
+    }
+}
+
 impl<'input> CSVParserContext<'input> for TerminalNode<'input, CSVParserContextType> {}
 impl<'input> CSVParserContext<'input> for ErrorNode<'input, CSVParserContextType> {}
 

tests/gen/csvparser.rs

@@ -22,10 +22,7 @@ use antlr_rust::token::{OwningToken, Token, TOKEN_EOF};
 use antlr_rust::token_factory::{CommonTokenFactory, TokenAware, TokenFactory};
 use antlr_rust::token_source::TokenSource;
 use antlr_rust::token_stream::TokenStream;
-use antlr_rust::tree::{
-    ErrorNode, LeafNode, Listenable, ParseTree, ParseTreeListener, ParseTreeVisitor,
-    ParseTreeWalker, TerminalNode, Visitable,
-};
+use antlr_rust::tree::*;
 use antlr_rust::vocabulary::{Vocabulary, VocabularyImpl};
 use antlr_rust::PredictionContextCache;
 use antlr_rust::{TidAble, TidExt};

tests/gen/labelsparser.rs

@@ -22,10 +22,7 @@ use antlr_rust::token::{OwningToken, Token, TOKEN_EOF};
 use antlr_rust::token_factory::{CommonTokenFactory, TokenAware, TokenFactory};
 use antlr_rust::token_source::TokenSource;
 use antlr_rust::token_stream::TokenStream;
-use antlr_rust::tree::{
-    ErrorNode, LeafNode, Listenable, ParseTree, ParseTreeListener, ParseTreeVisitor,
-    ParseTreeWalker, TerminalNode, Visitable,
-};
+use antlr_rust::tree::*;
 use antlr_rust::vocabulary::{Vocabulary, VocabularyImpl};
 use antlr_rust::PredictionContextCache;
 use antlr_rust::{TidAble, TidExt};