From b321a1a5c0ab924bd6ff3786b4b5f50e3738cbea Mon Sep 17 00:00:00 2001
From: "T. Jameson Little" <t.jameson.little@gmail.com>
Date: Thu, 29 May 2014 18:39:33 -0600
Subject: [PATCH] add factor

---
 Makefile         |   1 +
 README.md        |   1 -
 factor/factor.rs | 105 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 106 insertions(+), 1 deletion(-)
 create mode 100644 factor/factor.rs

diff --git a/Makefile b/Makefile
index 26e6ccf32..72364b595 100644
--- a/Makefile
+++ b/Makefile
@@ -14,6 +14,7 @@ PROGS       := \
   echo \
   env \
   du \
+  factor \
   false \
   fold \
   md5sum \
diff --git a/README.md b/README.md
index 95872fe98..f57754021 100644
--- a/README.md
+++ b/README.md
@@ -86,7 +86,6 @@ To do
 - expand (in progress)
 - expr
 - extent-scan
-- factor
 - find-mount-point
 - fmt
 - getlimits
diff --git a/factor/factor.rs b/factor/factor.rs
new file mode 100644
index 000000000..5d78cab0e
--- /dev/null
+++ b/factor/factor.rs
@@ -0,0 +1,105 @@
+#![crate_id(name="factor", vers="1.0.0", author="T. Jameson Little")]
+#![feature(macro_rules)]
+
+/*
+* This file is part of the uutils coreutils package.
+*
+* (c) T. Jameson Little <t.jameson.little@gmail.com>
+*
+* For the full copyright and license information, please view the LICENSE file
+* that was distributed with this source code.
+*/
+
+extern crate getopts;
+extern crate libc;
+
+use std::u64;
+use std::os;
+use std::vec::{Vec};
+use std::io::{stdin};
+
+#[path="../common/util.rs"]
+mod util;
+
+static VERSION: &'static str = "1.0.0";
+static NAME: &'static str = "factor";
+
+fn factor(mut num: u64) -> Vec<u64> {
+    let mut ret = Vec::new();
+
+    while num % 2 == 0 {
+        num /= 2;
+        ret.push(2);
+    }
+    let mut i = 3;
+    while i * i <= num {
+        while num % i == 0 {
+            num /= i;
+            ret.push(i);
+        }
+        i += 2;
+    }
+    if num > 1 {
+        ret.push(num);
+    }
+    ret
+}
+
+fn print_factors(num: u64) {
+    print!("{}:", num);
+    for fac in factor(num).iter() {
+        print!(" {}", fac);
+    }
+    println!("");
+}
+
+fn print_factors_str(num_str: &str) {
+    let num = match u64::parse_bytes(num_str.as_bytes(), 10) {
+        Some(x) => x,
+        None => { crash!(1, "{} not a number", num_str); }
+    };
+    print_factors(num);
+}
+
+
+#[allow(dead_code)]
+fn main() { uumain(os::args()); }
+
+pub fn uumain(args: Vec<String>) {
+    let program = args.get(0).as_slice();
+    let opts = [
+        getopts::optflag("h", "help", "show this help message"),
+        getopts::optflag("v", "version", "print the version and exit"),
+    ];
+
+    let matches = match getopts::getopts(args.tail(), opts) {
+        Ok(m) => m,
+        Err(f) => crash!(1, "Invalid options\n{}", f.to_err_msg())
+    };
+
+    if matches.opt_present("help") {
+        print!("{program} {version}\n\
+                \n\
+                Usage:\n\
+                \t{program} [NUMBER]...\n\
+                \t{program} [OPTION]\n\
+                \n\
+                {usage}", program = program, version = VERSION, usage = getopts::usage("Print the prime factors of the given number(s). \
+                                        If none are specified, read from standard input.", opts));
+        return;
+    }
+    if matches.opt_present("version") {
+        println!("{} {}", program, VERSION);
+        return;
+    }
+
+    if matches.free.is_empty() {
+        for line in stdin().lines() {
+            print_factors_str(line.unwrap().as_slice().trim());
+        }
+    } else {
+        for num_str in matches.free.iter() {
+            print_factors_str(num_str.as_slice());
+        }
+    }
+}