Add support for square inches

src/conversions.rs

@@ -64,6 +64,12 @@ fn get_conversion(unit: NonMetric) -> Conversion {
 			from: 9.0,
 			to: MetricQuantity { amount: 5.0, unit: Metric::Celcius },
 		},
+		// Area
+		NonMetric::SquareInch => Conversion {
+			offset: 0.0,
+			from: inch_from * inch_from,
+			to: MetricQuantity { amount: inch_to * inch_to, unit: Metric::SquareMetre },
+		},
 	}
 }
 
@@ -112,6 +118,14 @@ mod test {
 		});
 	}
 
+	#[test]
+	fn area() {
+		let tests = [
+			Test(NonMetric::SquareInch, 0.00064516),
+		];
+		run_tests(&tests, Metric::SquareMetre);
+	}
+
 	fn run_tests(tests: &[Test], unit: Metric) {
 		for test in tests {
 			let from = NonMetricQuantity {

src/format.rs

@@ -84,6 +84,17 @@ fn prefixed_unit(quantity: MetricQuantity) -> PrefixedUnit {
 			}
 		}
 		Metric::Celcius => PrefixedUnit(1.0, "°C"),
+		Metric::SquareMetre => {
+			if absolute >= 1000.0 * 1000.0 {
+				return PrefixedUnit(1000.0 * 1000.0, "km²");
+			} else if absolute >= 1.0 {
+				return PrefixedUnit(1.0, "m²");
+			} else if absolute >= 0.01 * 0.01 {
+				return PrefixedUnit(0.01 * 0.01, "cm²");
+			} else {
+				return PrefixedUnit(0.001 * 0.001, "mm²");
+			}
+		}
 	}
 }
 
@@ -262,4 +273,72 @@ mod test {
 			unit: Metric::Celcius,
 		}));
 	}
+
+	#[test]
+	fn square_metres() {
+		assert_eq!(PrefixedUnit(0.000_001, "mm²"), prefixed_unit(MetricQuantity {
+			amount: 0.000_000_1,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(0.000_001, "mm²"), prefixed_unit(MetricQuantity {
+			amount: 0.000_001,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(0.000_001, "mm²"), prefixed_unit(MetricQuantity {
+			amount: 0.000_01,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(0.000_1, "cm²"), prefixed_unit(MetricQuantity {
+			amount: 0.000_1,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(0.000_1, "cm²"), prefixed_unit(MetricQuantity {
+			amount: 0.001,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(0.000_1, "cm²"), prefixed_unit(MetricQuantity {
+			amount: 0.01,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(0.000_1, "cm²"), prefixed_unit(MetricQuantity {
+			amount: 0.01,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(0.000_1, "cm²"), prefixed_unit(MetricQuantity {
+			amount: 0.1,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(1.0, "m²"), prefixed_unit(MetricQuantity {
+			amount: 1.0,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(1.0, "m²"), prefixed_unit(MetricQuantity {
+			amount: 10.0,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(1.0, "m²"), prefixed_unit(MetricQuantity {
+			amount: 100.0,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(1.0, "m²"), prefixed_unit(MetricQuantity {
+			amount: 1_000.0,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(1.0, "m²"), prefixed_unit(MetricQuantity {
+			amount: 10_000.0,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(1.0, "m²"), prefixed_unit(MetricQuantity {
+			amount: 100_000.0,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(1_000_000.0, "km²"), prefixed_unit(MetricQuantity {
+			amount: 1_000_000.0,
+			unit: Metric::SquareMetre,
+		}));
+		assert_eq!(PrefixedUnit(1_000_000.0, "km²"), prefixed_unit(MetricQuantity {
+			amount: 10_000_000.0,
+			unit: Metric::SquareMetre,
+		}));
+	}
 }

src/lib.rs

@@ -72,6 +72,8 @@ fn unit_to_name(unit: NonMetric) -> &'static str {
 		NonMetric::Stone => "stones",
 		// Temperature
 		NonMetric::Fahrenheit => "degrees Fahrenheit",
+		// Area
+		NonMetric::SquareInch => "square inches",
 	}
 }
 
@@ -104,5 +106,7 @@ mod test {
 		assert_eq!(run("-40 °F"), Ok("-40 °C".to_string()));
 		assert_eq!(run("0 °F"), Ok("-17.78 °C".to_string()));
 		assert_eq!(run("32 °F"), Ok("0 °C".to_string()));
+		// Area
+		assert_eq!(run("1 in²"), Ok("6.452 cm²".to_string()));
 	}
 }

src/parse.rs

@@ -101,6 +101,11 @@ fn parse_unit(input: String) -> Result<NonMetric, ParseError> {
 		"°F" => Ok(NonMetric::Fahrenheit),
 		"F" => Ok(NonMetric::Fahrenheit),
 
+		// Area
+		"inch²" => Ok(NonMetric::SquareInch),
+		"inches²" => Ok(NonMetric::SquareInch),
+		"in²" => Ok(NonMetric::SquareInch),
+
 		_ => Err(ParseError::UnknownUnit(input)),
 	}
 }
@@ -249,6 +254,11 @@ mod test {
 		assert_eq!(parse_unit("°F".to_string()), Ok(NonMetric::Fahrenheit));
 		assert_eq!(parse_unit("F".to_string()), Ok(NonMetric::Fahrenheit));
 
+		// Area
+		assert_eq!(parse_unit("inch²".to_string()), Ok(NonMetric::SquareInch));
+		assert_eq!(parse_unit("inches²".to_string()), Ok(NonMetric::SquareInch));
+		assert_eq!(parse_unit("in²".to_string()), Ok(NonMetric::SquareInch));
+
 		// Unknown unit
 		assert_eq!(parse_unit("hutenosa".to_string()), Err(ParseError::UnknownUnit("hutenosa".to_string())));
 	}

src/units.rs

@@ -3,6 +3,7 @@ pub enum Metric {
 	Metre,
 	Gram,
 	Celcius,
+	SquareMetre,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq)]
@@ -18,6 +19,8 @@ pub enum NonMetric {
 	Stone,
 	// Temperature
 	Fahrenheit,
+	// Area
+	SquareInch,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq)]