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Increase structural sharing by using Rc<> instead of Box<>
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@adaszko
adaszko committed Jun 10, 2023
1 parent d3146d4 commit 310fdcc
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Showing 2 changed files with 34 additions and 31 deletions.
8 changes: 4 additions & 4 deletions src/dfa.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -608,7 +608,7 @@ mod tests {
#[test]
fn accept_hangs() {
use Expr::*;
let expr = Sequence(vec![Alternative(vec![Sequence(vec![Optional(Box::new(Alternative(vec![Many1(Box::new(Optional(Box::new(Many1(Box::new(Sequence(vec![Literal(u("foo")), Literal(u("foo"))]))))))), Literal(u("bar"))]))), Variable(u("DIRECTORY"))]), Many1(Box::new(Literal(u("--quux"))))]), Sequence(vec![Sequence(vec![Many1(Box::new(Many1(Box::new(Many1(Box::new(Literal(u("bar")))))))), Many1(Box::new(Sequence(vec![Many1(Box::new(Many1(Box::new(Literal(u("--baz")))))), Sequence(vec![Alternative(vec![Variable(u("DIRECTORY")), Variable(u("PATH"))]), Alternative(vec![Literal(u("--baz")), Sequence(vec![Sequence(vec![Literal(u("--baz")), Variable(u("FILE"))]), Sequence(vec![Literal(u("foo")), Variable(u("FILE"))])])])])])))]), Literal(u("bar"))])]);
let expr = Sequence(vec![Alternative(vec![Sequence(vec![Optional(Rc::new(Alternative(vec![Many1(Rc::new(Optional(Rc::new(Many1(Rc::new(Sequence(vec![Literal(u("foo")), Literal(u("foo"))]))))))), Literal(u("bar"))]))), Variable(u("DIRECTORY"))]), Many1(Rc::new(Literal(u("--quux"))))]), Sequence(vec![Sequence(vec![Many1(Rc::new(Many1(Rc::new(Many1(Rc::new(Literal(u("bar")))))))), Many1(Rc::new(Sequence(vec![Many1(Rc::new(Many1(Rc::new(Literal(u("--baz")))))), Sequence(vec![Alternative(vec![Variable(u("DIRECTORY")), Variable(u("PATH"))]), Alternative(vec![Literal(u("--baz")), Sequence(vec![Sequence(vec![Literal(u("--baz")), Variable(u("FILE"))]), Sequence(vec![Literal(u("foo")), Variable(u("FILE"))])])])])])))]), Literal(u("bar"))])]);
let input = [
"--quux",
"--quux",
Expand Down Expand Up @@ -684,7 +684,7 @@ mod tests {
#[test]
fn minimization_fails() {
use Expr::*;
let (expr, input) = (Alternative(vec![Many1(Box::new(Alternative(vec![Literal(u("--quux")), Sequence(vec![Optional(Box::new(Sequence(vec![Many1(Box::new(Many1(Box::new(Alternative(vec![Literal(u("--baz")), Variable(u("FILE"))]))))), Variable(u("FILE"))]))), Sequence(vec![Variable(u("FILE")), Literal(u("foo"))])])]))), Variable(u("FILE"))]), [u("--quux"), u("--baz"), u("anything"), u("anything"), u("foo")]);
let (expr, input) = (Alternative(vec![Many1(Rc::new(Alternative(vec![Literal(u("--quux")), Sequence(vec![Optional(Rc::new(Sequence(vec![Many1(Rc::new(Many1(Rc::new(Alternative(vec![Literal(u("--baz")), Variable(u("FILE"))]))))), Variable(u("FILE"))]))), Sequence(vec![Variable(u("FILE")), Literal(u("foo"))])])]))), Variable(u("FILE"))]), [u("--quux"), u("--baz"), u("anything"), u("anything"), u("foo")]);
dbg!(&expr);
dbg!(&input);
let arena = Bump::new();
Expand All @@ -702,7 +702,7 @@ mod tests {
#[test]
fn minimization_counterexample1() {
use Expr::*;
let (expr, input) = (Alternative(vec![Many1(Box::new(Sequence(vec![Variable(u("FILE")), Variable(u("FILE"))]))), Variable(u("FILE"))]), [u("anything"), u("anything"), u("anything"), u("anything"), u("anything"), u("anything")]);
let (expr, input) = (Alternative(vec![Many1(Rc::new(Sequence(vec![Variable(u("FILE")), Variable(u("FILE"))]))), Variable(u("FILE"))]), [u("anything"), u("anything"), u("anything"), u("anything"), u("anything"), u("anything")]);
dbg!(&expr);
let arena = Bump::new();
let regex = AugmentedRegex::from_expr(&expr, &arena);
Expand All @@ -721,7 +721,7 @@ mod tests {
#[test]
fn minimization_counterexample2() {
use Expr::*;
let (expr, input) = (Sequence(vec![Sequence(vec![Alternative(vec![Many1(Box::new(Many1(Box::new(Literal(u("--baz")))))), Variable(u("FILE"))]), Literal(u("--baz"))]), Many1(Box::new(Alternative(vec![Variable(u("FILE")), Variable(u("FILE"))])))]), [u("anything"), u("--baz"), u("anything"), u("anything")]);
let (expr, input) = (Sequence(vec![Sequence(vec![Alternative(vec![Many1(Rc::new(Many1(Rc::new(Literal(u("--baz")))))), Variable(u("FILE"))]), Literal(u("--baz"))]), Many1(Rc::new(Alternative(vec![Variable(u("FILE")), Variable(u("FILE"))])))]), [u("anything"), u("--baz"), u("anything"), u("anything")]);
dbg!(&expr);
let arena = Bump::new();
let regex = AugmentedRegex::from_expr(&expr, &arena);
Expand Down
57 changes: 30 additions & 27 deletions src/grammar.rs
View file
Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
use std::rc::Rc;

use nom::{
branch::alt,
bytes::complete::{is_not, tag, take_while1, escaped},
Expand All @@ -9,27 +11,15 @@ use nom::{
use complgen::{Error, Result};
use ustr::{Ustr, ustr, UstrMap};

#[derive(Debug, Clone, PartialEq)]
enum Statement {
CallVariant {
lhs: Ustr,
rhs: Expr,
},
VariableDefinition {
symbol: Ustr,
rhs: Expr,
},
}

// Can't use an arena here until proptest supports non-owned types: https://github.com/proptest-rs/proptest/issues/9
#[derive(Clone, PartialEq)]
pub enum Expr {
Literal(Ustr), // e.g. an option: "--help", or a command: "build"
Variable(Ustr), // e.g. <FILE>, <PATH>, <DIR>, etc.
Sequence(Vec<Expr>),
Alternative(Vec<Expr>),
Optional(Box<Expr>),
Many1(Box<Expr>),
Optional(Rc<Expr>),
Many1(Rc<Expr>),
}

impl std::fmt::Debug for Expr {
Expand Down Expand Up @@ -79,7 +69,7 @@ fn optional_expr(input: &str) -> IResult<&str, Expr> {
let (input, expr) = expr(input)?;
let (input, _) = multispace0(input)?;
let (input, _) = char(']')(input)?;
Ok((input, Expr::Optional(Box::new(expr))))
Ok((input, Expr::Optional(Rc::new(expr))))
}

fn parenthesized_expr(input: &str) -> IResult<&str, Expr> {
Expand All @@ -106,7 +96,7 @@ fn expr_no_alternative_no_sequence(input: &str) -> IResult<&str, Expr> {
))(input)?;

if let Ok((input, ())) = one_or_more_tag(input) {
return Ok((input, Expr::Many1(Box::new(e))));
return Ok((input, Expr::Many1(Rc::new(e))));
}

Ok((input, e))
Expand Down Expand Up @@ -162,6 +152,20 @@ fn expr(input: &str) -> IResult<&str, Expr> {
alternative_expr(input)
}


#[derive(Debug, Clone, PartialEq)]
enum Statement {
CallVariant {
lhs: Ustr,
rhs: Expr,
},
VariableDefinition {
symbol: Ustr,
rhs: Expr,
},
}


fn call_variant(input: &str) -> IResult<&str, Statement> {
let (input, name) = terminal(input)?;
let (input, _) = multispace1(input)?;
Expand Down Expand Up @@ -221,7 +225,6 @@ pub struct Validated {
}


// XXX Due to lots of necesasry .clones(), replace Box<> in Expr with Rc<>s.
fn do_resolve_variables(expr: &Expr, vars: &UstrMap<Expr>, at_least_one_variable_resolved: &mut bool) -> Expr {
match expr {
Expr::Literal(s) => Expr::Literal(*s),
Expand All @@ -238,8 +241,8 @@ fn do_resolve_variables(expr: &Expr, vars: &UstrMap<Expr>, at_least_one_variable
},
Expr::Sequence(children) => Expr::Sequence(children.iter().map(|child| do_resolve_variables(child, vars, at_least_one_variable_resolved)).collect()),
Expr::Alternative(children) => Expr::Alternative(children.iter().map(|child| do_resolve_variables(child, vars, at_least_one_variable_resolved)).collect()),
Expr::Optional(child) => Expr::Optional(Box::new(do_resolve_variables(child, vars, at_least_one_variable_resolved))),
Expr::Many1(child) => Expr::Many1(Box::new(do_resolve_variables(child, vars, at_least_one_variable_resolved))),
Expr::Optional(child) => Expr::Optional(Rc::new(do_resolve_variables(child, vars, at_least_one_variable_resolved))),
Expr::Many1(child) => Expr::Many1(Rc::new(do_resolve_variables(child, vars, at_least_one_variable_resolved))),
}
}

Expand Down Expand Up @@ -348,11 +351,11 @@ pub mod tests {
}

fn arb_optional(inputs: Rc<Vec<Ustr>>, variables: Rc<Vec<Ustr>>, remaining_depth: usize, max_width: usize) -> BoxedStrategy<Expr> {
arb_expr(inputs, variables, remaining_depth-1, max_width).prop_map(|e| Expr::Optional(Box::new(e))).boxed()
arb_expr(inputs, variables, remaining_depth-1, max_width).prop_map(|e| Expr::Optional(Rc::new(e))).boxed()
}

fn arb_many1(inputs: Rc<Vec<Ustr>>, variables: Rc<Vec<Ustr>>, remaining_depth: usize, max_width: usize) -> BoxedStrategy<Expr> {
arb_expr(inputs, variables, remaining_depth-1, max_width).prop_map(|e| Expr::Many1(Box::new(e))).boxed()
arb_expr(inputs, variables, remaining_depth-1, max_width).prop_map(|e| Expr::Many1(Rc::new(e))).boxed()
}

fn arb_sequence(inputs: Rc<Vec<Ustr>>, variables: Rc<Vec<Ustr>>, remaining_depth: usize, max_width: usize) -> BoxedStrategy<Expr> {
Expand Down Expand Up @@ -460,14 +463,14 @@ pub mod tests {
fn parses_optional_expr() {
const INPUT: &str = "[<foo>]";
let ("", e) = expr(INPUT).unwrap() else { panic!("parsing error"); };
assert_eq!(e, Expr::Optional(Box::new(Expr::Variable(u("foo")))));
assert_eq!(e, Expr::Optional(Rc::new(Expr::Variable(u("foo")))));
}

#[test]
fn parses_one_or_more_expr() {
const INPUT: &str = "<foo>...";
let ("", e) = expr(INPUT).unwrap() else { panic!("parsing error"); };
assert_eq!(e, Expr::Many1(Box::new(Expr::Variable(u("foo")))));
assert_eq!(e, Expr::Many1(Rc::new(Expr::Variable(u("foo")))));
}

#[test]
Expand Down Expand Up @@ -553,13 +556,13 @@ foo baz;
Statement::CallVariant { lhs: u("darcs"), rhs: Sequence(vec![
Literal(u("help")),
Sequence(vec![
Many1(Box::new(Alternative(vec![
Many1(Rc::new(Alternative(vec![
Alternative(vec![Literal(u("-v")), Literal(u("--verbose"))]),
Alternative(vec![Literal(u("-q")), Literal(u("--quiet"))]),
],)),),
Optional(Box::new(Sequence(vec![
Optional(Rc::new(Sequence(vec![
Variable(u("DARCS_COMMAND")),
Optional(Box::new(Literal(u("DARCS_SUBCOMMAND")))),
Optional(Rc::new(Literal(u("DARCS_SUBCOMMAND")))),
]))),
]),
]) },
Expand Down Expand Up @@ -622,7 +625,7 @@ grep [<OPTION>]... <PATTERNS> [<FILE>]...;
g,
Grammar {
statements: vec![
Statement::CallVariant { lhs: u("grep"), rhs: Sequence(vec![Many1(Box::new(Optional(Box::new(Variable(ustr("OPTION")))))), Sequence(vec![Variable(ustr("PATTERNS")), Many1(Box::new(Optional(Box::new(Variable(ustr("FILE"))))))])]) },
Statement::CallVariant { lhs: u("grep"), rhs: Sequence(vec![Many1(Rc::new(Optional(Rc::new(Variable(ustr("OPTION")))))), Sequence(vec![Variable(ustr("PATTERNS")), Many1(Rc::new(Optional(Rc::new(Variable(ustr("FILE"))))))])]) },
Statement::VariableDefinition { symbol: u("OPTION"), rhs: Sequence(vec![Literal(ustr("--color")), Variable(ustr("WHEN"))]) },
Statement::VariableDefinition { symbol: u("WHEN"), rhs: Alternative(vec![Literal(ustr("always")), Literal(ustr("never")), Literal(ustr("auto"))]) },
],
Expand Down

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