Make unit constants const in conversion.rs

src/conversions.rs

@@ -14,65 +14,65 @@ struct Conversion {
 }
 
 fn get_conversion(unit: NonMetric) -> Conversion {
-	let inch_from = 10_000.0;
-	let inch_to = 254.0;
+	const INCH_FROM: f64 = 10_000.0;
+	const INCH_TO: f64 = 254.0;
 
-	let pound_from = 100_000.0;
-	let pound_to = 45359237.0;
+	const POUND_FROM: f64 = 100_000.0;
+	const POUND_TO: f64 = 45359237.0;
 
-	let imperial_gallon_from = 100_000.0;
-	let imperial_gallon_to = 454609.0;
+	const IMPERIAL_GALLON_FROM: f64 = 100_000.0;
+	const IMPERIAL_GALLON_TO: f64 = 454609.0;
 
-	let us_gallon_from = inch_from * inch_from * inch_from;
-	let us_gallon_to = 231.0 * inch_to * inch_to * inch_to * 1000.0;
+	const US_GALLON_FROM: f64 = INCH_FROM * INCH_FROM * INCH_FROM;
+	const US_GALLON_TO: f64 = 231.0 * INCH_TO * INCH_TO * INCH_TO * 1000.0;
 
 	match unit {
 		// Length
 		NonMetric::Inch => Conversion {
 			offset: 0.0,
-			from: inch_from,
-			to: MetricQuantity { amount: inch_to, unit: Metric::Metre },
+			from: INCH_FROM,
+			to: MetricQuantity { amount: INCH_TO, unit: Metric::Metre },
 		},
 		NonMetric::Foot => Conversion {
 			offset: 0.0,
-			from: inch_from,
-			to: MetricQuantity { amount: 12.0 * inch_to, unit: Metric::Metre },
+			from: INCH_FROM,
+			to: MetricQuantity { amount: 12.0 * INCH_TO, unit: Metric::Metre },
 		},
 		NonMetric::Yard => Conversion {
 			offset: 0.0,
-			from: inch_from,
-			to: MetricQuantity { amount: 3.0 * 12.0 * inch_to, unit: Metric::Metre },
+			from: INCH_FROM,
+			to: MetricQuantity { amount: 3.0 * 12.0 * INCH_TO, unit: Metric::Metre },
 		},
 		NonMetric::Mile => Conversion {
 			offset: 0.0,
-			from: inch_from,
-			to: MetricQuantity { amount: 1760.0 * 3.0 * 12.0 * inch_to, unit: Metric::Metre },
+			from: INCH_FROM,
+			to: MetricQuantity { amount: 1760.0 * 3.0 * 12.0 * INCH_TO, unit: Metric::Metre },
 		},
 		// Mass
 		NonMetric::Ounce => Conversion {
 			offset: 0.0,
-			from: 16.0 * pound_from,
-			to: MetricQuantity { amount: pound_to, unit: Metric::Gram },
+			from: 16.0 * POUND_FROM,
+			to: MetricQuantity { amount: POUND_TO, unit: Metric::Gram },
 		},
 		NonMetric::Pound => Conversion {
 			offset: 0.0,
-			from: pound_from,
-			to: MetricQuantity { amount: pound_to, unit: Metric::Gram },
+			from: POUND_FROM,
+			to: MetricQuantity { amount: POUND_TO, unit: Metric::Gram },
 		},
 		NonMetric::Stone => Conversion {
 			offset: 0.0,
-			from: pound_from,
-			to: MetricQuantity { amount: 14.0 * pound_to, unit: Metric::Gram },
+			from: POUND_FROM,
+			to: MetricQuantity { amount: 14.0 * POUND_TO, unit: Metric::Gram },
 		},
 		NonMetric::ShortTon => Conversion {
 			offset: 0.0,
-			from: pound_from,
-			to: MetricQuantity { amount: 2000.0 * pound_to, unit: Metric::Gram },
+			from: POUND_FROM,
+			to: MetricQuantity { amount: 2000.0 * POUND_TO, unit: Metric::Gram },
 		},
 		NonMetric::LongTon => Conversion {
 			offset: 0.0,
-			from: pound_from,
-			to: MetricQuantity { amount: 2240.0 * pound_to, unit: Metric::Gram },
+			from: POUND_FROM,
+			to: MetricQuantity { amount: 2240.0 * POUND_TO, unit: Metric::Gram },
 		},
 		// Temperature
 		NonMetric::Fahrenheit => Conversion {
@@ -83,100 +83,100 @@ fn get_conversion(unit: NonMetric) -> Conversion {
 		// Area
 		NonMetric::SquareInch => Conversion {
 			offset: 0.0,
-			from: inch_from * inch_from,
-			to: MetricQuantity { amount: inch_to * inch_to, unit: Metric::SquareMetre },
+			from: INCH_FROM * INCH_FROM,
+			to: MetricQuantity { amount: INCH_TO * INCH_TO, unit: Metric::SquareMetre },
 		},
 		NonMetric::SquareFoot => Conversion {
 			offset: 0.0,
-			from: inch_from * inch_from,
-			to: MetricQuantity { amount: 12.0 * inch_to * 12.0 * inch_to, unit: Metric::SquareMetre },
+			from: INCH_FROM * INCH_FROM,
+			to: MetricQuantity { amount: 12.0 * INCH_TO * 12.0 * INCH_TO, unit: Metric::SquareMetre },
 		},
 		NonMetric::SquareYard => Conversion {
 			offset: 0.0,
-			from: inch_from * inch_from,
-			to: MetricQuantity { amount: 3.0 * 12.0 * inch_to * 3.0 * 12.0 * inch_to, unit: Metric::SquareMetre },
+			from: INCH_FROM * INCH_FROM,
+			to: MetricQuantity { amount: 3.0 * 12.0 * INCH_TO * 3.0 * 12.0 * INCH_TO, unit: Metric::SquareMetre },
 		},
 		NonMetric::Acre => Conversion {
 			offset: 0.0,
-			from: inch_from * inch_from,
-			to: MetricQuantity { amount: 43_560.0 * 12.0 * inch_to * 12.0 * inch_to, unit: Metric::SquareMetre },
+			from: INCH_FROM * INCH_FROM,
+			to: MetricQuantity { amount: 43_560.0 * 12.0 * INCH_TO * 12.0 * INCH_TO, unit: Metric::SquareMetre },
 		},
 		NonMetric::SquareMile => Conversion {
 			offset: 0.0,
-			from: inch_from * inch_from,
-			to: MetricQuantity { amount: 1760.0 * 3.0 * 12.0 * inch_to * 1760.0 * 3.0 * 12.0 * inch_to, unit: Metric::SquareMetre },
+			from: INCH_FROM * INCH_FROM,
+			to: MetricQuantity { amount: 1760.0 * 3.0 * 12.0 * INCH_TO * 1760.0 * 3.0 * 12.0 * INCH_TO, unit: Metric::SquareMetre },
 		},
 		// Volume
 		NonMetric::CubicInch => Conversion {
 			offset: 0.0,
-			from: inch_from * inch_from * inch_from,
-			to: MetricQuantity { amount: inch_to * inch_to * inch_to, unit: Metric::CubicMetre },
+			from: INCH_FROM * INCH_FROM * INCH_FROM,
+			to: MetricQuantity { amount: INCH_TO * INCH_TO * INCH_TO, unit: Metric::CubicMetre },
 		},
 		NonMetric::CubicFoot => Conversion {
 			offset: 0.0,
-			from: inch_from * inch_from * inch_from,
-			to: MetricQuantity { amount: 12.0 * inch_to * 12.0 * inch_to * 12.0 * inch_to, unit: Metric::CubicMetre },
+			from: INCH_FROM * INCH_FROM * INCH_FROM,
+			to: MetricQuantity { amount: 12.0 * INCH_TO * 12.0 * INCH_TO * 12.0 * INCH_TO, unit: Metric::CubicMetre },
 		},
 		NonMetric::CubicYard => Conversion {
 			offset: 0.0,
-			from: inch_from * inch_from * inch_from,
-			to: MetricQuantity { amount: 3.0 * 12.0 * inch_to * 3.0 * 12.0 * inch_to * 3.0 * 12.0 * inch_to, unit: Metric::CubicMetre },
+			from: INCH_FROM * INCH_FROM * INCH_FROM,
+			to: MetricQuantity { amount: 3.0 * 12.0 * INCH_TO * 3.0 * 12.0 * INCH_TO * 3.0 * 12.0 * INCH_TO, unit: Metric::CubicMetre },
 		},
 		// Fluid volume
 		NonMetric::ImperialFluidOunce => Conversion {
 			offset: 0.0,
-			from: 20.0 * 2.0 * 4.0 * imperial_gallon_from,
-			to: MetricQuantity { amount: imperial_gallon_to, unit: Metric::Litre },
+			from: 20.0 * 2.0 * 4.0 * IMPERIAL_GALLON_FROM,
+			to: MetricQuantity { amount: IMPERIAL_GALLON_TO, unit: Metric::Litre },
 		},
 		NonMetric::ImperialPint => Conversion {
 			offset: 0.0,
-			from: 2.0 * 4.0 * imperial_gallon_from,
-			to: MetricQuantity { amount: imperial_gallon_to, unit: Metric::Litre },
+			from: 2.0 * 4.0 * IMPERIAL_GALLON_FROM,
+			to: MetricQuantity { amount: IMPERIAL_GALLON_TO, unit: Metric::Litre },
 		},
 		NonMetric::ImperialQuart => Conversion {
 			offset: 0.0,
-			from: 4.0 * imperial_gallon_from,
-			to: MetricQuantity { amount: imperial_gallon_to, unit: Metric::Litre },
+			from: 4.0 * IMPERIAL_GALLON_FROM,
+			to: MetricQuantity { amount: IMPERIAL_GALLON_TO, unit: Metric::Litre },
 		},
 		NonMetric::ImperialGallon => Conversion {
 			offset: 0.0,
-			from: imperial_gallon_from,
-			to: MetricQuantity { amount: imperial_gallon_to, unit: Metric::Litre },
+			from: IMPERIAL_GALLON_FROM,
+			to: MetricQuantity { amount: IMPERIAL_GALLON_TO, unit: Metric::Litre },
 		},
 		NonMetric::USTeaspoon => Conversion {
 			offset: 0.0,
-			from: 6.0 * 16.0 * 2.0 * 4.0 * us_gallon_from,
-			to: MetricQuantity { amount: us_gallon_to, unit: Metric::Litre },
+			from: 6.0 * 16.0 * 2.0 * 4.0 * US_GALLON_FROM,
+			to: MetricQuantity { amount: US_GALLON_TO, unit: Metric::Litre },
 		},
 		NonMetric::USTablespoon => Conversion {
 			offset: 0.0,
-			from: 2.0 * 16.0 * 2.0 * 4.0 * us_gallon_from,
-			to: MetricQuantity { amount: us_gallon_to, unit: Metric::Litre },
+			from: 2.0 * 16.0 * 2.0 * 4.0 * US_GALLON_FROM,
+			to: MetricQuantity { amount: US_GALLON_TO, unit: Metric::Litre },
 		},
 		NonMetric::USFluidOunce => Conversion {
 			offset: 0.0,
-			from: 16.0 * 2.0 * 4.0 * us_gallon_from,
-			to: MetricQuantity { amount: us_gallon_to, unit: Metric::Litre },
+			from: 16.0 * 2.0 * 4.0 * US_GALLON_FROM,
+			to: MetricQuantity { amount: US_GALLON_TO, unit: Metric::Litre },
 		},
 		NonMetric::USCup => Conversion {
 			offset: 0.0,
-			from: 2.0 * 2.0 * 4.0 * us_gallon_from,
-			to: MetricQuantity { amount: us_gallon_to, unit: Metric::Litre },
+			from: 2.0 * 2.0 * 4.0 * US_GALLON_FROM,
+			to: MetricQuantity { amount: US_GALLON_TO, unit: Metric::Litre },
 		},
 		NonMetric::USLiquidPint => Conversion {
 			offset: 0.0,
-			from: 2.0 * 4.0 * us_gallon_from,
-			to: MetricQuantity { amount: us_gallon_to, unit: Metric::Litre },
+			from: 2.0 * 4.0 * US_GALLON_FROM,
+			to: MetricQuantity { amount: US_GALLON_TO, unit: Metric::Litre },
 		},
 		NonMetric::USLiquidQuart => Conversion {
 			offset: 0.0,
-			from: 4.0 * us_gallon_from,
-			to: MetricQuantity { amount: us_gallon_to, unit: Metric::Litre },
+			from: 4.0 * US_GALLON_FROM,
+			to: MetricQuantity { amount: US_GALLON_TO, unit: Metric::Litre },
 		},
 		NonMetric::USGallon => Conversion {
 			offset: 0.0,
-			from: us_gallon_from,
-			to: MetricQuantity { amount: us_gallon_to, unit: Metric::Litre },
+			from: US_GALLON_FROM,
+			to: MetricQuantity { amount: US_GALLON_TO, unit: Metric::Litre },
 		},
 	}
 }

src/format.rs

@@ -51,7 +51,7 @@ fn format_number(number: f64) -> String {
 	// Remove trailing zeroes
 	let decimal = decimal.trim_end_matches('0');
 
-	if decimal.len() == 0 {
+	if decimal.is_empty() {
 		format!("{sign}{grouped}")
 	} else {
 		format!("{sign}{grouped}.{decimal}")
@@ -67,54 +67,54 @@ fn prefixed_unit(quantity: MetricQuantity) -> PrefixedUnit {
 	match quantity.unit {
 		Metric::Metre => {
 			if absolute >= 1000.0 {
-				return PrefixedUnit(1000.0, "km");
+				PrefixedUnit(1000.0, "km")
 			} else if absolute >= 1.0 {
-				return PrefixedUnit(1.0, "m");
+				PrefixedUnit(1.0, "m")
 			} else if absolute >= 0.01 {
-				return PrefixedUnit(0.01, "cm");
+				PrefixedUnit(0.01, "cm")
 			} else {
-				return PrefixedUnit(0.001, "mm");
+				PrefixedUnit(0.001, "mm")
 			}
 		}
 		Metric::Gram => {
 			if absolute >= 1000.0 {
-				return PrefixedUnit(1000.0, "kg");
+				PrefixedUnit(1000.0, "kg")
 			} else {
-				return PrefixedUnit(1.0, "g");
+				PrefixedUnit(1.0, "g")
 			}
 		}
 		Metric::Celsius => PrefixedUnit(1.0, "°C"),
 		Metric::SquareMetre => {
 			if absolute >= 1000.0 * 1000.0 {
-				return PrefixedUnit(1000.0 * 1000.0, "km²");
+				PrefixedUnit(1000.0 * 1000.0, "km²")
 			} else if absolute >= 1.0 {
-				return PrefixedUnit(1.0, "m²");
+				PrefixedUnit(1.0, "m²")
 			} else if absolute >= 0.01 * 0.01 {
-				return PrefixedUnit(0.01 * 0.01, "cm²");
+				PrefixedUnit(0.01 * 0.01, "cm²")
 			} else {
-				return PrefixedUnit(0.001 * 0.001, "mm²");
+				PrefixedUnit(0.001 * 0.001, "mm²")
 			}
 		}
 		Metric::CubicMetre => {
 			if absolute >= 1000.0 * 1000.0 * 1000.0 {
-				return PrefixedUnit(1000.0 * 1000.0 * 1000.0, "km³");
+				PrefixedUnit(1000.0 * 1000.0 * 1000.0, "km³")
 			} else if absolute >= 1.0 {
-				return PrefixedUnit(1.0, "m³");
+				PrefixedUnit(1.0, "m³")
 			} else if absolute >= 0.000_001 { // 0.01 * 0.01 * 0.01 rounds wrong
-				return PrefixedUnit(0.000_001, "cm³");
+				PrefixedUnit(0.000_001, "cm³")
 			} else {
-				return PrefixedUnit(0.001 * 0.001 * 0.001, "mm³");
+				PrefixedUnit(0.001 * 0.001 * 0.001, "mm³")
 			}
 		}
 		Metric::Litre => {
 			if absolute >= 1.0 {
-				return PrefixedUnit(1.0, "l");
+				PrefixedUnit(1.0, "l")
 			} else if absolute >= 0.1 {
-				return PrefixedUnit(0.1, "dl");
+				PrefixedUnit(0.1, "dl")
 			} else if absolute >= 0.01 {
-				return PrefixedUnit(0.01, "cl");
+				PrefixedUnit(0.01, "cl")
 			} else {
-				return PrefixedUnit(0.001, "ml");
+				PrefixedUnit(0.001, "ml")
 			}
 		}
 	}

src/lib.rs

@@ -28,7 +28,7 @@ pub fn run(input: &str) -> Result<String, String> {
 		}
 	};
 
-	if non_metric.len() == 0 {
+	if non_metric.is_empty() {
 		return Err("Expected quantity or quantities to convert".to_string());
 	}
 
@@ -59,7 +59,7 @@ pub fn run(input: &str) -> Result<String, String> {
 	let amount = metric.into_iter().map(|quantity| { quantity.amount }).sum();
 
 	let quantity = MetricQuantity {
-		amount: amount,
+		amount,
 		unit: metric_unit.expect("we must have at least one quantity by this point"),
 	};
 

src/main.rs

@@ -10,7 +10,7 @@ fn main() {
 	let args = args[1..].join(" ");
 
 
-	if args.len() == 0 {
+	if args.is_empty() {
 		loop {
 			print!("> ");
 			match io::stdout().flush() {
@@ -28,7 +28,7 @@ fn main() {
 					process::exit(1);
 				}
 			}
-			if input.len() == 0 {
+			if input.is_empty() {
 				println!(); // Add a newline if user pressed ^D
 				break;
 			}

src/parse.rs

@@ -36,7 +36,7 @@ pub fn parse(input: &str) -> Result<Vec<NonMetricQuantity>, ParseError> {
 				let unit = parse_unit(unit)?;
 				let quantity = NonMetricQuantity {
 					amount: amount.take().expect("must have read a number to be in this state"),
-					unit: unit,
+					unit,
 				};
 				quantities.push(quantity);
 				state = Expect::Number;
@@ -56,7 +56,7 @@ pub fn parse(input: &str) -> Result<Vec<NonMetricQuantity>, ParseError> {
 
 fn parse_number(input: String) -> Result<f64, ParseError> {
 	let no_whitespace: String = input.chars().filter(|c| !c.is_whitespace()).collect();
-	no_whitespace.parse().or_else(|_| Err(ParseError::NotValidNumber(input)))
+	no_whitespace.parse().map_err(|_| ParseError::NotValidNumber(input))
 }
 
 fn parse_unit(input: String) -> Result<NonMetric, ParseError> {
@@ -411,7 +411,7 @@ fn tokenize(input: &str) -> Vec<Token> {
 	}
 
 	match state {
-		TokState::Neutral => { assert!(token.len() == 0); }
+		TokState::Neutral => { assert!(token.is_empty()); }
 		TokState::Number => { tokens.push(Token::Number(token.trim().to_string())); }
 		TokState::Unit(_) => { tokens.push(Token::Unit(token.trim().to_string())); }
 	}