commit 55b870b7b136c61c4a5ec2d2c1888fe94c1ff9d1
Author: FliegendeWurst <2012gdwu@web.de>
Date:   Mon May 18 09:55:43 2020 +0200

    Initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..eb5a316
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+target
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..7ce308f
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,23 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "decimal-code"
+version = "0.1.0"
+dependencies = [
+ "itertools",
+]
+
+[[package]]
+name = "either"
+version = "1.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bb1f6b1ce1c140482ea30ddd3335fc0024ac7ee112895426e0a629a6c20adfe3"
+
+[[package]]
+name = "itertools"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "284f18f85651fe11e8a991b2adb42cb078325c996ed026d994719efcfca1d54b"
+dependencies = [
+ "either",
+]
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..ed49c44
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "decimal-code"
+version = "0.1.0"
+authors = ["FliegendeWurst <2012gdwu@web.de>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+itertools = "0.9.0"
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..f7c370c
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,166 @@
+use itertools::join;
+
+use std::env;
+use std::error::Error;
+use std::{convert::{TryInto, TryFrom}, io::{self, BufRead, stdin}, iter::once};
+
+fn main() -> Result<(), Box<dyn Error>> {
+	let args = env::args().skip(1).collect::<Vec<_>>();
+	if args.is_empty() {
+		// batch mode
+		for line in stdin().lock().lines() {
+			let line = line?;
+			let mut parts = line.split_ascii_whitespace();
+			let format = parts.next().ok_or(io::Error::new(io::ErrorKind::Other, "no encoding"))?;
+			let value = parts.next().ok_or(io::Error::new(io::ErrorKind::Other, "no value"))?;
+			let number = match format {
+				"decimal" => parse_decimal(value)?,
+				"bcd" => parse_bcd(value)?,
+				"aiken" => parse_aiken(value)?,
+				"stibitz" => parse_stibitz(value)?,
+				_ => Err("unknown encoding")?
+			};
+			let x = convert(&number);
+			println!("{}\t{}\t{}\t{}", x.0, x.1, x.2, x.3);
+		}
+		Ok(())
+	} else {
+		Err("too many arguments".into())
+	}
+}
+
+fn convert(number: &Decimal) -> (String, String, String, String) {
+	(
+		number.format_decimal(),
+		number.format_bcd(),
+		number.format_aiken(),
+		number.format_stibitz()
+	)
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+struct Decimal {
+	digits: Vec<Digit>,
+	digits_fractional: Vec<Digit>
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
+enum Digit {
+	Zero, One, Two, Three, Four, Five, Six, Seven, Eight, Nine
+}
+
+use Digit::*;
+
+impl TryFrom<char> for Digit {
+	type Error = Box<dyn Error>;
+
+	fn try_from(x: char) -> Result<Self, Self::Error> {
+		match x {
+			'0' => Ok(Zero),
+			'1' => Ok(One),
+			'2' => Ok(Two),
+			'3' => Ok(Three),
+			'4' => Ok(Four),
+			'5' => Ok(Five),
+			'6' => Ok(Six),
+			'7' => Ok(Seven),
+			'8' => Ok(Eight),
+			'9' => Ok(Nine),
+			x => Err(format!("unknown digit {:?}", x).into())
+		}
+	}
+}
+
+impl Digit {
+	fn value(&self) -> usize {
+		match self {
+			Zero => 0,
+			One => 1,
+			Two => 2,
+			Three => 3,
+			Four => 4,
+			Five => 5,
+			Six => 6,
+			Seven => 7,
+			Eight => 8,
+			Nine => 9
+		}
+	}
+}
+
+fn parse_decimal(value: &str) -> Result<Decimal, Box<dyn Error>> {
+	let mut digits = Vec::new();
+	let mut digits_fractional = Vec::new();
+
+	let mut fractional = false;
+	for c in value.chars() {
+		if !fractional && (c == '.' || c == ',') {
+			fractional = true;
+			continue;
+		}
+		let digit: Digit = c.try_into()?;
+		if !fractional {
+			digits.push(digit);
+		} else {
+			digits_fractional.push(digit);
+		}
+	}
+
+	Ok(Decimal {
+		digits, digits_fractional
+	})
+}
+
+#[test]
+fn parse_decimal_test() {
+	assert_eq!(parse_decimal("42.35").unwrap(), Decimal { digits: vec![Four, Two], digits_fractional: vec![Three, Five] });
+}
+
+fn parse_bcd(value: &str) -> Result<Decimal, Box<dyn Error>> {
+	todo!("BCD parsing");
+}
+
+fn parse_aiken(value: &str) -> Result<Decimal, Box<dyn Error>> {
+	todo!("AIKEN parsing");
+}
+
+fn parse_stibitz(value: &str) -> Result<Decimal, Box<dyn Error>> {
+	todo!("STIBITZ parsing");
+}
+
+impl Decimal {
+	fn format_decimal(&self) -> String {
+		self.format_specified(&["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"])
+	}
+
+	fn format_bcd(&self) -> String {
+		self.format_specified(&["0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001"])
+	}
+
+	fn format_aiken(&self) -> String {
+		self.format_specified(&["0000", "0001", "0010", "0011", "0100", "1011", "1100", "1101", "1110", "1111"])
+	}
+
+	fn format_stibitz(&self) -> String {
+		self.format_specified(&["0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100"])
+	}
+
+	fn format_specified(&self, table: &[&str]) -> String {
+		if self.digits_fractional.is_empty() {
+			join(self.digits.iter().map(|x| table[x.value()]), " ")
+		} else {
+			join(
+				self.digits.iter().map(|x| table[x.value()])
+					.chain(once("."))
+					.chain(self.digits_fractional.iter().map(|x| table[x.value()])),
+				" "
+			)
+		}
+	}
+}
+
+#[test]
+fn format_decimal_test() {
+	let number = Decimal { digits: vec![Four, Four], digits_fractional: vec![Five, One] };
+	assert_eq!(convert(&number), ("4 4 . 5 1".into(), "0100 0100 . 0101 0001".into(), "0100 0100 . 1011 0001".into(), "0111 0111 . 1000 0100".into()));
+}