Bidi Data Adapter

components/properties/Cargo.toml

@@ -38,6 +38,7 @@ icu_provider = { version = "0.5", path = "../../provider/core", features = ["mac
 icu_uniset = { version = "0.4.1", path = "../../utils/uniset"}
 serde = { version = "1.0", default-features = false, features = ["derive", "alloc"], optional = true }
 zerovec = { version = "0.6", path = "../../utils/zerovec", features = ["derive"] }
+unicode-bidi = { version = "0.3.8", optional = true , default-features = false }
 
 [dev-dependencies]
 icu = { path = "../icu", default-features = false }
@@ -52,3 +53,4 @@ std = ["icu_provider/std"]
 default = []
 serde = ["dep:serde", "zerovec/serde", "icu_uniset/serde", "icu_codepointtrie/serde"]
 datagen = ["serde", "zerovec/serde_serialize", "icu_uniset/serde_serialize", "icu_codepointtrie/serde_serialize"]
+bidi = [ "dep:unicode-bidi" ]

components/properties/src/bidi.rs

@@ -0,0 +1,163 @@
+// This file is part of ICU4X. For terms of use, please see the file
+// called LICENSE at the top level of the ICU4X source tree
+// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
+
+//! This module exposes tooling for running the [unicode bidi algorithm](https://unicode.org/reports/tr9/) using ICU4X data.
+//!
+//! `BidiClassAdapter` enables ICU4X to provide data to [`unicode-bidi`].
+//!
+//! # Examples
+//!
+//!```
+//! use icu_properties::bidi::BidiClassAdapter;
+//! use icu_properties::{maps, BidiClass};
+//! use icu_codepointtrie::CodePointTrie;
+//! use unicode_bidi::BidiClass as DataSourceBidiClass;
+//! use unicode_bidi::BidiDataSource;
+//! use unicode_bidi::BidiInfo;
+//! // This example text is defined using `concat!` because some browsers
+//! // and text editors have trouble displaying bidi strings.
+//! let text = concat![
+//!   "א",
+//!   "ב",
+//!   "ג",
+//!   "a",
+//!   "b",
+//!   "c",
+//! ];
+//!
+//! // Create an adapter to provide the data to `BidiInfo`.
+//! let provider = icu_testdata::get_provider();
+//!
+//! let payload =
+//!     maps::get_bidi_class(&provider)
+//!         .expect("The data should be valid");
+//! let data_struct = payload.get();
+//! let bc = &data_struct.code_point_trie;
+//!
+//! let adapter = BidiClassAdapter::new(&bc);
+//! // Resolve embedding levels within the text.  Pass `None` to detect the
+//! // paragraph level automatically.
+//!
+//! let bidi_info = BidiInfo::new_with_data_source(&adapter, &text, None);
+//!
+//! // This paragraph has embedding level 1 because its first strong character is RTL.
+//! assert_eq!(bidi_info.paragraphs.len(), 1);
+//! let para = &bidi_info.paragraphs[0];
+//! assert_eq!(para.level.number(), 1);
+//! assert_eq!(para.level.is_rtl(), true);
+//!
+//! // Re-ordering is done after wrapping each paragraph into a sequence of
+//! // lines. For this example, I'll just use a single line that spans the
+//! // entire paragraph.
+//! let line = para.range.clone();
+//!
+//! let display = bidi_info.reorder_line(para, line);
+//! assert_eq!(display, concat![
+//!   "a",
+//!   "b",
+//!   "c",
+//!   "ג",
+//!   "ב",
+//!   "א",
+//! ]);
+//! ```
+
+use crate::props::BidiClass;
+use icu_codepointtrie::CodePointTrie;
+use unicode_bidi::data_source::BidiDataSource;
+use unicode_bidi::BidiClass as DataSourceBidiClass;
+
+/// An adapter to convert from icu4x `BidiClass` to `unicode_bidi::BidiClass`.
+///
+/// # Example
+///
+/// ```
+/// use icu_properties::bidi::BidiClassAdapter;
+/// use icu_properties::{maps, BidiClass};
+/// use icu_codepointtrie::CodePointTrie;
+/// use unicode_bidi::BidiClass as DataSourceBidiClass;
+/// use unicode_bidi::BidiDataSource;
+///
+/// let provider = icu_testdata::get_provider();
+///
+/// let payload =
+///     maps::get_bidi_class(&provider)
+///         .expect("The data should be valid");
+/// let data_struct = payload.get();
+/// let bc = &data_struct.code_point_trie;
+///
+/// let adapter = BidiClassAdapter::new(&bc);
+/// assert_eq!(adapter.bidi_class('a'), DataSourceBidiClass::L);
+/// assert_eq!(adapter.bidi_class('ع'), DataSourceBidiClass::AL);
+/// ```
+pub struct BidiClassAdapter<'a> {
+    bidi_trie: &'a CodePointTrie<'a, BidiClass>,
+}
+
+impl<'a> BidiClassAdapter<'a> {
+    /// Creates new instance of `BidiClassAdapter`.
+    pub fn new(bidi_trie: &'a CodePointTrie<'a, BidiClass>) -> BidiClassAdapter<'a> {
+        BidiClassAdapter { bidi_trie }
+    }
+}
+
+impl<'a> BidiDataSource for BidiClassAdapter<'a> {
+    /// Returns a [`DataSourceBidiClass`] given a unicode character.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use icu_properties::bidi::BidiClassAdapter;
+    /// use icu_properties::{maps, BidiClass};
+    /// use icu_codepointtrie::CodePointTrie;
+    /// use unicode_bidi::BidiClass as DataSourceBidiClass;
+    /// use unicode_bidi::BidiDataSource;
+    ///
+    /// let provider = icu_testdata::get_provider();
+    ///
+    /// let payload =
+    ///     maps::get_bidi_class(&provider)
+    ///         .expect("The data should be valid");
+    /// let data_struct = payload.get();
+    /// let bc = &data_struct.code_point_trie;
+    ///
+    /// let adapter = BidiClassAdapter::new(&bc);
+    /// assert_eq!(adapter.bidi_class('a'), DataSourceBidiClass::L);
+    /// ```
+    ///
+    /// [`CodePointTrie`]: icu_codepointtrie::CodePointTrie
+    fn bidi_class(&self, c: char) -> DataSourceBidiClass {
+        let bidi_class = self.bidi_trie.get(c as u32);
+        match bidi_class {
+            BidiClass::LeftToRight => DataSourceBidiClass::L,
+            BidiClass::RightToLeft => DataSourceBidiClass::R,
+            BidiClass::EuropeanNumber => DataSourceBidiClass::EN,
+            BidiClass::EuropeanSeparator => DataSourceBidiClass::ES,
+            BidiClass::EuropeanTerminator => DataSourceBidiClass::ET,
+            BidiClass::ArabicNumber => DataSourceBidiClass::AN,
+            BidiClass::CommonSeparator => DataSourceBidiClass::CS,
+            BidiClass::ParagraphSeparator => DataSourceBidiClass::B,
+            BidiClass::SegmentSeparator => DataSourceBidiClass::S,
+            BidiClass::WhiteSpace => DataSourceBidiClass::WS,
+            BidiClass::OtherNeutral => DataSourceBidiClass::ON,
+            BidiClass::LeftToRightEmbedding => DataSourceBidiClass::LRE,
+            BidiClass::LeftToRightOverride => DataSourceBidiClass::LRO,
+            BidiClass::ArabicLetter => DataSourceBidiClass::AL,
+            BidiClass::RightToLeftEmbedding => DataSourceBidiClass::RLE,
+            BidiClass::RightToLeftOverride => DataSourceBidiClass::RLO,
+            BidiClass::PopDirectionalFormat => DataSourceBidiClass::PDF,
+            BidiClass::NonspacingMark => DataSourceBidiClass::NSM,
+            BidiClass::BoundaryNeutral => DataSourceBidiClass::BN,
+            BidiClass::FirstStrongIsolate => DataSourceBidiClass::FSI,
+            BidiClass::LeftToRightIsolate => DataSourceBidiClass::LRI,
+            BidiClass::RightToLeftIsolate => DataSourceBidiClass::RLI,
+            BidiClass::PopDirectionalIsolate => DataSourceBidiClass::PDI,
+            _ =>
+            // This must not happen.
+            {
+                DataSourceBidiClass::ON
+            }
+        }
+    }
+}

components/properties/src/lib.rs

@@ -82,6 +82,9 @@
     )
 )]
 
+#[cfg(feature = "bidi")]
+pub mod bidi;
+
 mod error;
 pub mod maps;
 mod props;