Rollup merge of #101401 - mx00s:expand-const, r=fee1-dead

Make `char::is_lowercase` and `char::is_uppercase` const

Implements #101400.

Author: matthiaskrgr

core/src/char/methods.rs

@@ -746,10 +746,19 @@ impl char {
     /// assert!(!'中'.is_lowercase());
     /// assert!(!' '.is_lowercase());
     /// ```
+    ///
+    /// In a const context:
+    ///
+    /// ```
+    /// #![feature(const_unicode_case_lookup)]
+    /// const CAPITAL_DELTA_IS_LOWERCASE: bool = 'Δ'.is_lowercase();
+    /// assert!(!CAPITAL_DELTA_IS_LOWERCASE);
+    /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_unicode_case_lookup", issue = "101400")]
     #[inline]
-    pub fn is_lowercase(self) -> bool {
+    pub const fn is_lowercase(self) -> bool {
         match self {
             'a'..='z' => true,
             c => c > '\x7f' && unicode::Lowercase(c),
@@ -779,10 +788,19 @@ impl char {
     /// assert!(!'中'.is_uppercase());
     /// assert!(!' '.is_uppercase());
     /// ```
+    ///
+    /// In a const context:
+    ///
+    /// ```
+    /// #![feature(const_unicode_case_lookup)]
+    /// const CAPITAL_DELTA_IS_UPPERCASE: bool = 'Δ'.is_uppercase();
+    /// assert!(CAPITAL_DELTA_IS_UPPERCASE);
+    /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_unicode_case_lookup", issue = "101400")]
     #[inline]
-    pub fn is_uppercase(self) -> bool {
+    pub const fn is_uppercase(self) -> bool {
         match self {
             'A'..='Z' => true,
             c => c > '\x7f' && unicode::Uppercase(c),

core/src/lib.rs

@@ -143,6 +143,7 @@
 #![feature(const_type_id)]
 #![feature(const_type_name)]
 #![feature(const_default_impls)]
+#![feature(const_unicode_case_lookup)]
 #![feature(const_unsafecell_get_mut)]
 #![feature(core_panic)]
 #![feature(duration_consts_float)]

core/src/unicode/unicode_data.rs

@@ -1,7 +1,8 @@
 ///! This file is generated by src/tools/unicode-table-generator; do not edit manually!
 
+#[rustc_const_unstable(feature = "const_unicode_case_lookup", issue = "101400")]
 #[inline(always)]
-fn bitset_search<
+const fn bitset_search<
     const N: usize,
     const CHUNK_SIZE: usize,
     const N1: usize,
@@ -17,14 +18,18 @@ fn bitset_search<
     let bucket_idx = (needle / 64) as usize;
     let chunk_map_idx = bucket_idx / CHUNK_SIZE;
     let chunk_piece = bucket_idx % CHUNK_SIZE;
-    let chunk_idx = if let Some(&v) = chunk_idx_map.get(chunk_map_idx) {
-        v
+    // FIXME: const-hack: Revert to `slice::get` after `const_slice_index`
+    // feature stabilizes.
+    let chunk_idx = if chunk_map_idx < chunk_idx_map.len() {
+        chunk_idx_map[chunk_map_idx]
     } else {
         return false;
     };
     let idx = bitset_chunk_idx[chunk_idx as usize][chunk_piece] as usize;
-    let word = if let Some(word) = bitset_canonical.get(idx) {
-        *word
+    // FIXME: const-hack: Revert to `slice::get` after `const_slice_index`
+    // feature stabilizes.
+    let word = if idx < bitset_canonical.len() {
+        bitset_canonical[idx]
     } else {
         let (real_idx, mapping) = bitset_canonicalized[idx - bitset_canonical.len()];
         let mut word = bitset_canonical[real_idx as usize];
@@ -318,14 +323,14 @@ pub mod grapheme_extend {
 
 #[rustfmt::skip]
 pub mod lowercase {
-    static BITSET_CHUNKS_MAP: [u8; 123] = [
+    const BITSET_CHUNKS_MAP: &'static [u8; 123] = &[
         14, 17, 0, 0, 9, 0, 0, 12, 13, 10, 0, 16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         0, 0, 0, 4, 1, 0, 15, 0, 8, 0, 0, 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 18, 0,
         3, 0, 0, 7,
     ];
-    static BITSET_INDEX_CHUNKS: [[u8; 16]; 19] = [
+    const BITSET_INDEX_CHUNKS: &'static [[u8; 16]; 19] = &[
         [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
         [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 59, 0, 0],
         [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 16, 14, 55, 0],
@@ -346,7 +351,7 @@ pub mod lowercase {
         [16, 49, 2, 20, 66, 9, 57, 0, 0, 0, 0, 0, 0, 0, 0, 0],
         [63, 39, 54, 12, 73, 61, 18, 1, 6, 62, 71, 19, 68, 69, 3, 44],
     ];
-    static BITSET_CANONICAL: [u64; 55] = [
+    const BITSET_CANONICAL: &'static [u64; 55] = &[
         0b0000000000000000000000000000000000000000000000000000000000000000,
         0b1111111111111111110000000000000000000000000011111111111111111111,
         0b1010101010101010101010101010101010101010101010101010100000000010,
@@ -403,13 +408,14 @@ pub mod lowercase {
         0b1110011111111111111111111111111111111111111111110000000000000000,
         0b1110101111000000000000000000000000001111111111111111111111111100,
     ];
-    static BITSET_MAPPING: [(u8, u8); 20] = [
+    const BITSET_MAPPING: &'static [(u8, u8); 20] = &[
         (0, 64), (1, 188), (1, 183), (1, 176), (1, 109), (1, 124), (1, 126), (1, 66), (1, 70),
         (1, 77), (2, 146), (2, 144), (2, 83), (3, 12), (3, 6), (4, 156), (4, 78), (5, 187),
         (6, 132), (7, 93),
     ];
 
-    pub fn lookup(c: char) -> bool {
+    #[rustc_const_unstable(feature = "const_unicode_case_lookup", issue = "101400")]
+    pub const fn lookup(c: char) -> bool {
         super::bitset_search(
             c as u32,
             &BITSET_CHUNKS_MAP,
@@ -454,14 +460,14 @@ pub mod n {
 
 #[rustfmt::skip]
 pub mod uppercase {
-    static BITSET_CHUNKS_MAP: [u8; 125] = [
+    const BITSET_CHUNKS_MAP: &'static [u8; 125] = &[
         12, 15, 6, 6, 0, 6, 6, 2, 4, 11, 6, 16, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
         6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 8, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
         6, 6, 6, 5, 6, 14, 6, 10, 6, 6, 1, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
         6, 7, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 13, 6, 6,
         6, 6, 9, 6, 3,
     ];
-    static BITSET_INDEX_CHUNKS: [[u8; 16]; 17] = [
+    const BITSET_INDEX_CHUNKS: &'static [[u8; 16]; 17] = &[
         [43, 43, 5, 34, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 5, 1],
         [43, 43, 5, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43],
         [43, 43, 39, 43, 43, 43, 43, 43, 17, 17, 62, 17, 42, 29, 24, 23],
@@ -480,7 +486,7 @@ pub mod uppercase {
         [57, 19, 2, 18, 10, 47, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43],
         [57, 37, 17, 27, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43],
     ];
-    static BITSET_CANONICAL: [u64; 43] = [
+    const BITSET_CANONICAL: &'static [u64; 43] = &[
         0b0000011111111111111111111111111000000000000000000000000000000000,
         0b0000000000111111111111111111111111111111111111111111111111111111,
         0b0101010101010101010101010101010101010101010101010101010000000001,
@@ -525,13 +531,14 @@ pub mod uppercase {
         0b1111011111111111000000000000000000000000000000000000000000000000,
         0b1111111100000000111111110000000000111111000000001111111100000000,
     ];
-    static BITSET_MAPPING: [(u8, u8); 25] = [
+    const BITSET_MAPPING: &'static [(u8, u8); 25] = &[
         (0, 187), (0, 177), (0, 171), (0, 167), (0, 164), (0, 32), (0, 47), (0, 51), (0, 121),
         (0, 117), (0, 109), (1, 150), (1, 148), (1, 142), (1, 134), (1, 131), (1, 64), (2, 164),
         (2, 146), (2, 20), (3, 146), (3, 140), (3, 134), (4, 178), (4, 171),
     ];
 
-    pub fn lookup(c: char) -> bool {
+    #[rustc_const_unstable(feature = "const_unicode_case_lookup", issue = "101400")]
+    pub const fn lookup(c: char) -> bool {
         super::bitset_search(
             c as u32,
             &BITSET_CHUNKS_MAP,