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Favor SmallVec over Box in pluralrules
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This will help avoid heap allocations as most lists are only a few items
long. The only boxed slice that was retained was the SampleRanges, as
this can be of an indeterminate length.
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@gregtatum
gregtatum committed Oct 1, 2020
1 parent e6579f8 commit 0052021
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Showing 4 changed files with 51 additions and 40 deletions.
1 change: 1 addition & 0 deletions components/pluralrules/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@ include = [
[dependencies]
icu-locale = { path = "../locale" }
icu-data-provider = { path = "../data-provider" }
smallvec = "1.4"

[dev-dependencies]
criterion = "0.3"
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56 changes: 32 additions & 24 deletions components/pluralrules/src/rules/ast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,33 +7,35 @@
//! ```
//! use icu_pluralrules::rules::parse_condition;
//! use icu_pluralrules::rules::ast::*;
//! use smallvec::{SmallVec,smallvec};
//!
//! let input = "i = 1";
//!
//! let ast = parse_condition(input.as_bytes())
//! .expect("Parsing failed.");
//!
//! assert_eq!(ast, Condition(Box::new([
//! AndCondition(Box::new([
//! assert_eq!(ast, Condition(smallvec![
//! AndCondition(smallvec![
//! Relation {
//! expression: Expression {
//! operand: Operand::I,
//! modulus: None,
//! },
//! operator: Operator::Eq,
//! range_list: RangeList(Box::new([
//! range_list: RangeList(smallvec![
//! RangeListItem::Value(
//! Value(1)
//! )
//! ]))
//! ])
//! }
//! ]))
//! ])));
//! ])
//! ]));
//! ```
//!
//! [`PluralCategory`]: ../enum.PluralCategory.html
//! [`parse`]: ../fn.parse.html
//! [`test_condition`]: ../fn.test_condition.html
use smallvec::SmallVec;
use std::ops::RangeInclusive;

/// A complete AST representation of a plural rule.
Expand Down Expand Up @@ -89,25 +91,26 @@ pub struct Rule {
/// ```
/// use icu_pluralrules::rules::ast::*;
/// use icu_pluralrules::rules::parse_condition;
/// use smallvec::{SmallVec,smallvec};
///
/// let condition = Condition(Box::new([
/// AndCondition(Box::new([Relation {
/// let condition = Condition(smallvec![
/// AndCondition(smallvec![Relation {
/// expression: Expression {
/// operand: Operand::I,
/// modulus: None,
/// },
/// operator: Operator::Eq,
/// range_list: RangeList(Box::new([RangeListItem::Value(Value(5))])),
/// }])),
/// AndCondition(Box::new([Relation {
/// range_list: RangeList(smallvec![RangeListItem::Value(Value(5))]),
/// }]),
/// AndCondition(smallvec![Relation {
/// expression: Expression {
/// operand: Operand::V,
/// modulus: None,
/// },
/// operator: Operator::Eq,
/// range_list: RangeList(Box::new([RangeListItem::Value(Value(2))])),
/// }])),
/// ]));
/// range_list: RangeList(smallvec![RangeListItem::Value(Value(2))]),
/// }]),
/// ]);
///
/// assert_eq!(
/// condition,
Expand All @@ -116,7 +119,7 @@ pub struct Rule {
/// )
/// ```
#[derive(Debug, Clone, PartialEq)]
pub struct Condition(pub Box<[AndCondition]>);
pub struct Condition(pub SmallVec<[AndCondition; 2]>);

/// An incomplete AST representation of a plural rule. Comprises a vector of Relations.
///
Expand All @@ -132,29 +135,30 @@ pub struct Condition(pub Box<[AndCondition]>);
///
/// ```
/// use icu_pluralrules::rules::ast::*;
/// use smallvec::{SmallVec,smallvec};
///
/// AndCondition(Box::new([
/// AndCondition(smallvec![
/// Relation {
/// expression: Expression {
/// operand: Operand::I,
/// modulus: None,
/// },
/// operator: Operator::Eq,
/// range_list: RangeList(Box::new([RangeListItem::Value(Value(5))])),
/// range_list: RangeList(smallvec![RangeListItem::Value(Value(5))]),
/// },
/// Relation {
/// expression: Expression {
/// operand: Operand::V,
/// modulus: None,
/// },
/// operator: Operator::NotEq,
/// range_list: RangeList(Box::new([RangeListItem::Value(Value(2))])),
/// range_list: RangeList(smallvec![RangeListItem::Value(Value(2))]),
/// },
/// ]));
/// ]);
///
/// ```
#[derive(Debug, Clone, PartialEq)]
pub struct AndCondition(pub Box<[Relation]>);
pub struct AndCondition(pub SmallVec<[Relation; 2]>);

/// An incomplete AST representation of a plural rule. Comprises an Expression, an Operator, and a RangeList.
///
Expand All @@ -170,14 +174,15 @@ pub struct AndCondition(pub Box<[Relation]>);
///
/// ```
/// use icu_pluralrules::rules::ast::*;
/// use smallvec::{SmallVec,smallvec};
///
/// Relation {
/// expression: Expression {
/// operand: Operand::I,
/// modulus: None,
/// },
/// operator: Operator::Eq,
/// range_list: RangeList(Box::new([RangeListItem::Value(Value(3))])),
/// range_list: RangeList(smallvec![RangeListItem::Value(Value(3))]),
/// };
///
/// ```
Expand Down Expand Up @@ -277,15 +282,16 @@ pub enum Operand {
///
/// ```
/// use icu_pluralrules::rules::ast::*;
/// use smallvec::{SmallVec,smallvec};
///
/// RangeList(Box::new([
/// RangeList(smallvec![
/// RangeListItem::Value(Value(5)),
/// RangeListItem::Value(Value(7)),
/// RangeListItem::Value(Value(9)),
/// ]));
/// ]);
/// ```
#[derive(Debug, Clone, PartialEq)]
pub struct RangeList(pub Box<[RangeListItem]>);
pub struct RangeList(pub SmallVec<[RangeListItem; 2]>);

/// An enum of items that appear in a RangeList: Range or a Value.
///
Expand Down Expand Up @@ -376,6 +382,8 @@ pub struct Samples {
///
/// ```
/// use icu_pluralrules::rules::ast::*;
/// use smallvec::{SmallVec,smallvec};
///
/// SampleList {
/// sample_ranges: Box::new([
/// SampleRange {
Expand Down
19 changes: 10 additions & 9 deletions components/pluralrules/src/rules/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -48,41 +48,42 @@
//! When parsed, the resulting [`AST`] will look like this:
//!
//! ```
//! use smallvec::{SmallVec,smallvec};
//! use icu_pluralrules::rules::parse_condition;
//! use icu_pluralrules::rules::ast::*;
//!
//! let input = "i = 1 and v = 0 @integer 1";
//!
//! let ast = parse_condition(input.as_bytes())
//! .expect("Parsing failed.");
//! assert_eq!(ast, Condition(Box::new([
//! AndCondition(Box::new([
//! assert_eq!(ast, Condition(smallvec![
//! AndCondition(smallvec![
//! Relation {
//! expression: Expression {
//! operand: Operand::I,
//! modulus: None,
//! },
//! operator: Operator::Eq,
//! range_list: RangeList(Box::new([
//! range_list: RangeList(smallvec![
//! RangeListItem::Value(
//! Value(1)
//! )
//! ]))
//! ])
//! },
//! Relation {
//! expression: Expression {
//! operand: Operand::V,
//! modulus: None,
//! },
//! operator: Operator::Eq,
//! range_list: RangeList(Box::new([
//! range_list: RangeList(smallvec![
//! RangeListItem::Value(
//! Value(0)
//! )
//! ]))
//! },
//! ])),
//! ])));
//! ])
//! }
//! ]),
//! ]));
//! ```
//!
//! Finally, we can pass this [`AST`] (in fact, just the [`Condition`] node),
Expand Down
15 changes: 8 additions & 7 deletions components/pluralrules/src/rules/parser.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
use super::ast;
use super::lexer::{Lexer, Token};
use smallvec::smallvec;
use std::iter::Peekable;

#[derive(Debug, PartialEq, Eq)]
Expand Down Expand Up @@ -99,12 +100,12 @@ impl<'p> Parser<'p> {
}

fn get_condition(&mut self) -> Result<ast::Condition, ParserError> {
let mut result = vec![];
let mut result = smallvec![];

if let Some(cond) = self.get_and_condition()? {
result.push(cond);
} else {
return Ok(ast::Condition(result.into_boxed_slice()));
return Ok(ast::Condition(result));
}

while self.take_if(Token::Or) {
Expand All @@ -115,12 +116,12 @@ impl<'p> Parser<'p> {
}
}
// If lexer is not done, error?
Ok(ast::Condition(result.into_boxed_slice()))
Ok(ast::Condition(result))
}

fn get_and_condition(&mut self) -> Result<Option<ast::AndCondition>, ParserError> {
if let Some(relation) = self.get_relation()? {
let mut rel = vec![relation];
let mut rel = smallvec![relation];

while self.take_if(Token::And) {
if let Some(relation) = self.get_relation()? {
Expand All @@ -129,7 +130,7 @@ impl<'p> Parser<'p> {
return Err(ParserError::ExpectedRelation);
}
}
Ok(Some(ast::AndCondition(rel.into_boxed_slice())))
Ok(Some(ast::AndCondition(rel)))
} else {
Ok(None)
}
Expand Down Expand Up @@ -168,14 +169,14 @@ impl<'p> Parser<'p> {
}

fn get_range_list(&mut self) -> Result<ast::RangeList, ParserError> {
let mut range_list = Vec::with_capacity(1);
let mut range_list = smallvec![];
loop {
range_list.push(self.get_range_list_item()?);
if !self.take_if(Token::Comma) {
break;
}
}
Ok(ast::RangeList(range_list.into_boxed_slice()))
Ok(ast::RangeList(range_list))
}

fn take_if(&mut self, token: Token) -> bool {
Expand Down

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