Feat: Add generators for char type

Author: jockbert

DOCUMENTATION.md

@@ -214,6 +214,16 @@ let some_longs = gens::i64::ranged(10..=20);
 let mostly_true = gens::bool::with_ratio(1,20);
 ```
 
+Various generators for `char` type:
+
+```rust
+use monkey_test::*;
+let same_as_unicode = gens::char::any();
+let unicode = gens::char::unicode();
+let alpha_lower = gens::char::alpha_lower();
+let alpha_numeric = gens::char::alpha_numeric();
+```
+
 There are also specialized generators:
 
 * In `gens::fixed`, generators that produce fixed values without randomness.

src/gens.rs

@@ -2,6 +2,7 @@
 
 pub mod bool;
 mod chain;
+pub mod char;
 mod filter;
 pub mod fixed;
 mod float;

src/gens/char.rs

@@ -0,0 +1,61 @@
+//! Generators for char type.
+
+use crate::BoxGen;
+use crate::FilterWithGen;
+use crate::MapWithGen;
+
+/// Any possible Rust `char` value, that is any valid unicode scalar value.
+/// For reference, see
+/// [Rust official documentation on `char` type](https://doc.rust-lang.org/std/primitive.char.html).
+pub fn unicode() -> BoxGen<char> {
+    crate::gens::u32::ranged(0..=0x10ffff)
+        .filter(|&num| !(0xD800..=0xDFFF).contains(&num))
+        .map(|num| char::from_u32(num).unwrap(), |ch| ch as u32)
+}
+
+/// Shorthand for [unicode].
+pub fn any() -> BoxGen<char> {
+    unicode()
+}
+
+/// Build char generator from u32 range (inclusive)
+fn chars_from_u32_range(min: u32, max_inclusive: u32) -> BoxGen<char> {
+    crate::gens::u32::ranged(min..=max_inclusive)
+        .map(|num| char::from_u32(num).unwrap(), |ch| ch as u32)
+}
+
+/// Any arabic numeral 0..9, unicode values 48..=57.
+pub fn number() -> BoxGen<char> {
+    chars_from_u32_range(48, 57)
+}
+
+/// Any alpha upper char, unicode values 65..=90.
+pub fn alpha_upper() -> BoxGen<char> {
+    chars_from_u32_range(65, 90)
+}
+
+/// Any alpha lower char, unicode values 97..=122.
+pub fn alpha_lower() -> BoxGen<char> {
+    chars_from_u32_range(97, 122)
+}
+
+/// Any alpha char, both lower and upper case.
+pub fn alpha() -> BoxGen<char> {
+    crate::gens::mix_evenly(&[alpha_upper(), alpha_lower()])
+}
+
+/// Any alpha numeric char, see [alpha] and [number].
+pub fn alpha_numeric() -> BoxGen<char> {
+    crate::gens::mix_with_ratio(&[(9, alpha()), (1, number())])
+}
+
+/// Any ASCII printable character, unicode values 32..=126.
+pub fn ascii_printable() -> BoxGen<char> {
+    chars_from_u32_range(32, 126)
+}
+
+/// Any ASCII character, including both printable and non-printable characters,
+/// unicode values 0..=127.
+pub fn ascii() -> BoxGen<char> {
+    chars_from_u32_range(0, 127)
+}