Add example parsing ISO 8601 duration

examples/duration.rs

@@ -0,0 +1,100 @@
+extern crate pom;
+use pom::parser::*;
+use pom::Parser;
+
+use std::str::{self, FromStr};
+
+#[derive(Debug, PartialEq)]
+struct Duration {
+	years: Option<f32>,
+	months: Option<f32>,
+	weeks: Option<f32>,
+	days: Option<f32>,
+	hours: Option<f32>,
+	minutes: Option<f32>,
+	seconds: Option<f32>,
+}
+
+fn number_separator() -> Parser<u8, ()> {
+	// either '.' or ',' can be used as a separator between the whole and decimal part of a number
+	one_of(b".,").discard()
+}
+
+fn number() -> Parser<u8, f32> {
+	let integer = one_of(b"0123456789").repeat(0..);
+	let frac = number_separator() + one_of(b"0123456789").repeat(1..);
+	let number = integer + frac.opt();
+	number.collect().convert(str::from_utf8).convert(f32::from_str)
+}
+
+fn date_part() -> Parser<u8, (Option<f32>, Option<f32>, Option<f32>, Option<f32>)> {
+	(
+		(number() - sym(b'Y')).opt() +
+		(number() - sym(b'M')).opt() +
+		(number() - sym(b'W')).opt() +
+		(number() - sym(b'D')).opt()
+	)
+		.map(|(((years,months), weeks), days)| {
+			(years, months, weeks, days)
+		})
+}
+
+fn time_part() -> Parser<u8, Option<(Option<f32>, Option<f32>, Option<f32>)>> {
+	(
+		sym(b'T') *
+			(
+				(number() - sym(b'H')).opt() +
+					(number() - sym(b'M')).opt() +
+					(number() - sym(b'S')).opt()
+			)
+				.map(|((hours,minutes), seconds)| {
+					(hours, minutes, seconds)
+				})
+	).opt()
+}
+
+fn parser() -> Parser<u8, Duration> {
+	(
+		sym(b'P') *
+		date_part() +
+		time_part()
+	)
+		.map(|(date_elements, time_elements)|{
+			let (years, months, weeks, days) = date_elements;
+			let (hours, minutes, seconds) = match time_elements {
+				None => (None, None, None),
+				Some(elements) => elements,
+			};
+
+			Duration {
+				years,
+				months,
+				weeks,
+				days,
+				hours,
+				minutes,
+				seconds,
+			}
+		})
+}
+
+/// Parses the ISO 8601 Duration standard
+/// https://en.wikipedia.org/wiki/ISO_8601#Durations
+fn main() {
+	let input = "P3Y6M4DT12H30M5S";
+	let result = parser().parse(input.as_bytes());
+
+	assert_eq!(
+		Duration {
+			years: Some(3f32),
+			months: Some(6f32),
+			weeks: None,
+			days: Some(4f32),
+			hours: Some(12f32),
+			minutes: Some(30f32),
+			seconds: Some(5f32)
+		},
+		result.unwrap()
+	);
+
+}