first commit

8 files changed, 400 insertions, 0 deletions

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diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..d3c194f
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diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..49ad710
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "rand-word-gen"
+version = "1.0.0"
+authors = ["nsfisis"]
+edition = "2018"
+description = "Generates random pseudo-English words."
+license = "MIT"
+
+[dependencies]
+anyhow = "1.0.34"
+clap = "2.33.3"
+rand = "0.7.3"
diff --git a/LICENSE-MIT b/LICENSE-MIT
new file mode 100644
index 0000000..bcfcb41
--- /dev/null
+++ b/LICENSE-MIT
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 nsfisis
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..1cbb290
--- /dev/null
+++ b/README.md
@@ -0,0 +1,56 @@
+# Random word generator
+
+Generates random pseudo-English words. It is mainly for naming your hobby projects in a moment.
+
+It internally uses "Markov chain" to generate words. The chain model is built in a compiling phase of the tool, referring to `words` file (`/usr/share/dict/words`).
+
+## Usage
+
+```
+$ rand-word-gen
+eendo
+ddips
+uphr
+blinta
+unto
+ont
+vedaro
+dera
+ekarrb
+goice
+sfodo
+ainis
+rier
+fatem
+myimd
+grasic
+honge
+ustoge
+ear
+nal
+
+# Sets a number of generated words.
+$ rand-word-gen -n 5
+piva
+ors
+glo
+mapt
+blclyp
+```
+
+See `rand-word-gen --help` for details.
+
+## Build
+
+```
+$ cargo build --release
+```
+
+## TODO
+
+* Pass a custom words file at runtime.
+* Specify length of generated words.
+
+## License
+
+MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
diff --git a/build.rs b/build.rs
new file mode 100644
index 0000000..dcf1cc3
--- /dev/null
+++ b/build.rs
@@ -0,0 +1,46 @@
+use std::fs::File;
+use std::io::{BufRead, BufReader, BufWriter, Result, Write};
+use std::path::Path;
+
+const NUM_LETTERS: usize = 26;
+
+fn main() -> Result<()> {
+    let chars = {
+        let file = File::open("/usr/share/dict/words")?;
+        let reader = BufReader::new(file);
+        parse(reader)?
+    };
+
+    let out_path = Path::new(&std::env::var("OUT_DIR").unwrap()).join("prebuilt_model.rs");
+    let file = File::create(out_path)?;
+    let mut writer = BufWriter::new(file);
+    writeln!(writer, "[")?;
+    for i in 0..(NUM_LETTERS + 1) {
+        write!(writer, "[")?;
+        for j in 0..(NUM_LETTERS + 1) {
+            write!(writer, "{},", chars[i][j])?;
+        }
+        writeln!(writer, "],")?;
+    }
+    writeln!(writer, "]")?;
+
+    Ok(())
+}
+
+fn parse(r: BufReader<File>) -> Result<[[usize; NUM_LETTERS + 1]; NUM_LETTERS + 1]> {
+    let mut chars = [[0; NUM_LETTERS + 1]; NUM_LETTERS + 1];
+    for line in r.lines() {
+        let word = line?;
+        let mut prefix = NUM_LETTERS;
+        for c in word.bytes() {
+            let c = c.to_ascii_lowercase();
+            if !c.is_ascii_lowercase() {
+                continue;
+            }
+            let i = (c - b'a') as usize;
+            chars[prefix][i] += 1;
+            prefix = i;
+        }
+    }
+    Ok(chars)
+}
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)
+}