first commit

2 files changed, 73 insertions, 0 deletions

diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..db8020e
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,32 @@
+use rand::distributions::{Distribution, WeightedIndex};
+use rand::RngCore;
+
+const NUM_OF_LETTERS: usize = 26;
+
+pub struct Model {
+    chars: [[usize; NUM_OF_LETTERS + 1]; NUM_OF_LETTERS + 1],
+}
+
+impl Model {
+    pub fn new() -> Model {
+        let chars = include!(concat!(env!("OUT_DIR"), "/prebuilt_model.rs"));
+        Model { chars }
+    }
+
+    pub fn generate<Rng: RngCore>(&self, rng: &mut Rng, len: usize) -> String {
+        let mut result = String::with_capacity(len);
+        let mut prefix = NUM_OF_LETTERS;
+        for _ in 0..len {
+            let chars = &self.chars[prefix];
+            let c = select_one_char(rng, &chars);
+            result.push(c as char);
+            prefix = (c - b'a') as usize;
+        }
+        result
+    }
+}
+
+fn select_one_char<Rng: RngCore>(rng: &mut Rng, freq: &[usize; NUM_OF_LETTERS + 1]) -> u8 {
+    let dist = WeightedIndex::new(freq).expect("invalid frequency");
+    b'a' + (dist.sample(rng) as u8)
+}
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..4ebe0fa
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,41 @@
+use anyhow::{Context, Result};
+use rand::distributions::{Distribution, Uniform};
+use rand_word_gen::Model;
+use std::io::{BufWriter, Write};
+
+fn main() -> Result<()> {
+    let words = parse_args()?;
+
+    let model = Model::new();
+    let out = std::io::stdout();
+    let mut out = BufWriter::new(out.lock());
+    let mut rng = rand::thread_rng();
+    let dist = Uniform::from(3..=6);
+    for _ in 0..words {
+        let len = dist.sample(&mut rng);
+        writeln!(out, "{}", model.generate(&mut rng, len))?;
+    }
+
+    Ok(())
+}
+
+fn parse_args() -> Result<usize> {
+    use clap::{crate_description, crate_version, value_t, App, Arg};
+
+    let matches = App::new("rand-word-gen")
+        .version(crate_version!())
+        .version_short("v")
+        .about(crate_description!())
+        .arg(
+            Arg::with_name("words")
+                .short("n")
+                .long("words")
+                .value_name("NUMBER_OF_WORDS")
+                .default_value("20")
+                .help("Sets number of generated words"),
+        )
+        .get_matches();
+
+    let words = value_t!(matches, "words", usize).context("'--words' must be a number")?;
+    Ok(words)
+}