Merge pull request #75 from pitdicker/char_distrs

Rename `AsciiWordChar` and optimize `Codepoint`

benches/distributions.rs

@@ -51,7 +51,8 @@ distr!(distr_uniform_i64, i64, Uniform);
 distr!(distr_uniform_i128, i128, Uniform);
 
 distr!(distr_uniform_bool, bool, Uniform);
-distr!(distr_uniform_ascii_char, char, AsciiWordChar);
+distr!(distr_uniform_alphanumeric, char, Alphanumeric);
+distr!(distr_uniform_codepoint, char, Codepoint);
 
 distr!(distr_uniform01_float32, f32, Uniform01);
 distr!(distr_closed01_float32, f32, Closed01);

src/distributions/mod.rs

@@ -18,7 +18,7 @@
 use Rng;
 
 pub use self::default::Default;
-pub use self::uniform::{Uniform, Uniform01, Open01, Closed01, Codepoint, AsciiWordChar};
+pub use self::uniform::{Uniform, Uniform01, Open01, Closed01, Codepoint, Alphanumeric};
 pub use self::range::Range;
 
 #[cfg(feature="std")]

src/distributions/range.rs

@@ -179,10 +179,14 @@ macro_rules! range_int_impl {
 
             type X = $ty;
 
+            #[inline] // if the range is constant, this helps LLVM to do the
+                      // calculations at compile-time.
             fn new(low: Self::X, high: Self::X) -> Self {
                 RangeImpl::new_inclusive(low, high - 1)
             }
 
+            #[inline] // if the range is constant, this helps LLVM to do the
+                      // calculations at compile-time.
             fn new_inclusive(low: Self::X, high: Self::X) -> Self {
                 // For a closed range the number of possible numbers we should
                 // generate is `range = (high - low + 1)`. It is not possible to

src/distributions/uniform.rs

@@ -14,7 +14,7 @@ use core::char;
 use core::mem;
 
 use Rng;
-use distributions::Distribution;
+use distributions::{Distribution, Range};
 use utils::FloatConversions;
 
 // ----- Sampling distributions -----
@@ -45,7 +45,7 @@ pub struct Codepoint;
 /// Sample a `char`, uniformly distributed over ASCII letters and numbers:
 /// a-z, A-Z and 0-9.
 #[derive(Debug)]
-pub struct AsciiWordChar;
+pub struct Alphanumeric;
 
 
 // ----- actual implementations -----
@@ -206,29 +206,27 @@ float_impls! { f64, Rng::next_u64 }
 
 impl Distribution<char> for Codepoint {
     fn sample<R: Rng+?Sized>(&self, rng: &mut R) -> char {
-        // a char is 21 bits
-        const CHAR_MASK: u32 = 0x001f_ffff;
+        let range = Range::new(0u32, 0x11_0000);
         loop {
-            // Rejection sampling. About 0.2% of numbers with at most
-            // 21-bits are invalid codepoints (surrogates), so this
-            // will succeed first go almost every time.
-            match char::from_u32(rng.next_u32() & CHAR_MASK) {
+            match char::from_u32(range.sample(rng)) {
                 Some(c) => return c,
+                // About 0.2% of numbers in the range 0..0x110000 are invalid
+                // codepoints (surrogates).
                 None => {}
             }
         }
     }
 }
 
-impl Distribution<char> for AsciiWordChar {
+impl Distribution<char> for Alphanumeric {
     fn sample<R: Rng+?Sized>(&self, rng: &mut R) -> char {
         const RANGE: u32 = 26 + 26 + 10;
         const GEN_ASCII_STR_CHARSET: &'static [u8] =
             b"ABCDEFGHIJKLMNOPQRSTUVWXYZ\
                 abcdefghijklmnopqrstuvwxyz\
                 0123456789";
         loop {
-            let var = rng.next_u32() & 0x3F;
+            let var = rng.next_u32() >> 26;
             if var < RANGE {
                 return GEN_ASCII_STR_CHARSET[var as usize] as char
             }
@@ -241,7 +239,7 @@ impl Distribution<char> for AsciiWordChar {
 mod tests {
     use {Sample, thread_rng, iter};
     use distributions::{Uniform, Uniform01, Open01, Closed01,
-            Codepoint, AsciiWordChar};
+            Codepoint, Alphanumeric};
 
     #[test]
     fn test_integers() {
@@ -269,10 +267,10 @@ mod tests {
         let mut rng = ::test::rng();
 
         let _ = rng.sample(Codepoint);
-        let c = rng.sample(AsciiWordChar);
+        let c = rng.sample(Alphanumeric);
         assert!((c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'));
 
-        let word: String = iter(&mut rng).take(5).map(|rng| rng.sample(AsciiWordChar)).collect();
+        let word: String = iter(&mut rng).take(5).map(|rng| rng.sample(Alphanumeric)).collect();
         assert_eq!(word.len(), 5);
     }
 

src/iter.rs

@@ -37,13 +37,13 @@ pub struct Iter<'a, R: Rng+?Sized+'a> {
 ///
 /// ```
 /// use rand::{thread_rng, Rng, Sample, iter};
-/// use rand::distributions::{Uniform, AsciiWordChar};
+/// use rand::distributions::{Uniform, Alphanumeric};
 ///
 /// let mut rng = thread_rng();
 /// let x: Vec<u32> = iter(&mut rng).take(10).map(|rng| rng.sample(Uniform)).collect();
 /// println!("{:?}", x);
 /// 
-/// let w: String = iter(&mut rng).take(6).map(|rng| rng.sample(AsciiWordChar)).collect();
+/// let w: String = iter(&mut rng).take(6).map(|rng| rng.sample(Alphanumeric)).collect();
 /// println!("{}", w);
 /// ```
 pub fn iter<'a, R: Rng+?Sized+'a>(rng: &'a mut R) -> Iter<'a, R> {
@@ -160,7 +160,7 @@ impl<'a, R:?Sized+'a, U, F> Iterator for FlatMap<'a, R, U, F>
 #[cfg(test)]
 mod tests {
     use {Rng, Sample, thread_rng, iter};
-    use distributions::{Uniform, AsciiWordChar};
+    use distributions::{Uniform, Alphanumeric};
 
     #[test]
     fn test_iter() {
@@ -181,7 +181,7 @@ mod tests {
     fn test_dyn_dispatch() {
         let r: &mut Rng = &mut thread_rng();
 
-        let x: String = iter(r).take(10).map(|rng| rng.sample(AsciiWordChar)).collect();
+        let x: String = iter(r).take(10).map(|rng| rng.sample(Alphanumeric)).collect();
         assert_eq!(x.len(), 10);
     }
 }

src/lib.rs

@@ -435,10 +435,10 @@ pub trait Sample: Rng {
     /// 
     /// ```rust
     /// use rand::{thread_rng, Sample};
-    /// use rand::distributions::AsciiWordChar;
+    /// use rand::distributions::Alphanumeric;
     /// 
     /// let mut rng = thread_rng();
-    /// let x: String = rng.iter().map(|rng| rng.sample(AsciiWordChar)).take(6).collect();
+    /// let x: String = rng.iter().map(|rng| rng.sample(Alphanumeric)).take(6).collect();
     /// ```
     fn iter<'a>(&'a mut self) -> iter::Iter<'a, Self> {
         iter(self)