289 lines
7.4 KiB
Rust
289 lines
7.4 KiB
Rust
use crate::units::{NonMetric, NonMetricQuantity};
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enum Expect {
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Number,
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Unit,
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}
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#[derive(Debug, PartialEq)]
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pub enum ParseError {
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NotValidNumber(String),
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UnexpectedUnit(String),
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UnknownUnit(String),
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ExpectedUnit,
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}
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pub fn parse(input: &str) -> Result<Vec<NonMetricQuantity>, ParseError> {
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let mut quantities = Vec::new();
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let mut state = Expect::Number;
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let mut amount = None;
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for token in tokenize(input) {
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match (&state, token) {
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(Expect::Number, Token::Number(number)) => {
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let number = match number.trim().parse() {
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Ok(number) => number,
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Err(_) => {
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return Err(ParseError::NotValidNumber(number));
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}
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};
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amount = Some(number);
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state = Expect::Unit;
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}
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(Expect::Number, Token::Unit(unit)) => {
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return Err(ParseError::UnexpectedUnit(unit));
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}
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(Expect::Unit, Token::Number(_)) => {
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unreachable!("token stream can't contain two numbers in a row");
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}
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(Expect::Unit, Token::Unit(unit)) => {
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let unit = match parse_unit(&unit) {
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Some(unit) => unit,
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None => {
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return Err(ParseError::UnknownUnit(unit));
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}
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};
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let quantity = NonMetricQuantity {
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amount: amount.take().expect("must have read a number to be in this state"),
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unit: unit,
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};
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quantities.push(quantity);
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state = Expect::Number;
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}
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}
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}
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match state {
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Expect::Number => {},
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Expect::Unit => {
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return Err(ParseError::ExpectedUnit);
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}
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}
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Ok(quantities)
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}
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fn parse_unit(input: &str) -> Option<NonMetric> {
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match input {
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// Length
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"inch" => Some(NonMetric::Inch),
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"inches" => Some(NonMetric::Inch),
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"in" => Some(NonMetric::Inch),
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"\"" => Some(NonMetric::Inch),
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"″" => Some(NonMetric::Inch),
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"foot" => Some(NonMetric::Foot),
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"feet" => Some(NonMetric::Foot),
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"ft" => Some(NonMetric::Foot),
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"'" => Some(NonMetric::Foot),
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"′" => Some(NonMetric::Foot),
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"yard" => Some(NonMetric::Yard),
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"yards" => Some(NonMetric::Yard),
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"yd" => Some(NonMetric::Yard),
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"mile" => Some(NonMetric::Mile),
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"miles" => Some(NonMetric::Mile),
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"mi" => Some(NonMetric::Mile),
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"m" => Some(NonMetric::Mile),
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// Weight
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"ounce" => Some(NonMetric::Ounce),
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"ounces" => Some(NonMetric::Ounce),
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"oz" => Some(NonMetric::Ounce),
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"pound" => Some(NonMetric::Pound),
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"pounds" => Some(NonMetric::Pound),
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"lb" => Some(NonMetric::Pound),
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"lbs" => Some(NonMetric::Pound),
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"#" => Some(NonMetric::Pound),
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"stone" => Some(NonMetric::Stone),
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"stones" => Some(NonMetric::Stone),
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"st" => Some(NonMetric::Stone),
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_ => None,
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}
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}
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#[derive(Debug, PartialEq)]
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enum Token {
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Number(String),
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Unit(String),
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}
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enum TokState {
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Neutral,
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Number,
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Unit,
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}
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fn tokenize(input: &str) -> Vec<Token> {
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let mut tokens = Vec::new();
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let mut token = String::new();
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let mut state = TokState::Neutral;
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for c in input.chars() {
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match state {
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TokState::Neutral => {
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if c.is_ascii_digit() || c == '-' {
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token.push(c);
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state = TokState::Number;
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} else if !c.is_whitespace() {
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token.push(c);
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state = TokState::Unit;
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}
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}
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TokState::Number => {
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if c.is_ascii_digit() ||
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c.is_whitespace() ||
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c == '.' {
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token.push(c);
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} else {
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tokens.push(Token::Number(token.trim().to_string()));
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state = TokState::Unit;
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token = String::new();
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token.push(c);
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}
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}
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TokState::Unit => {
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if c.is_ascii_digit() || c == '-' {
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tokens.push(Token::Unit(token));
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state = TokState::Number;
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token = String::new();
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token.push(c);
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}
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else if !c.is_whitespace() {
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token.push(c);
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} else {
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tokens.push(Token::Unit(token));
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state = TokState::Neutral;
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token = String::new();
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}
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}
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}
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}
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match state {
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TokState::Neutral => { assert!(token.len() == 0); }
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TokState::Number => { tokens.push(Token::Number(token.trim().to_string())); }
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TokState::Unit => { tokens.push(Token::Unit(token)); }
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}
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tokens
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn parsing() {
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assert_eq!(parse(""), Ok(vec![]));
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assert_eq!(parse("5 ft"), Ok(vec![
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NonMetricQuantity { amount: 5.0, unit: NonMetric::Foot },
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]));
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assert_eq!(parse("5 ft 8 in"), Ok(vec![
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NonMetricQuantity { amount: 5.0, unit: NonMetric::Foot },
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NonMetricQuantity { amount: 8.0, unit: NonMetric::Inch },
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]));
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assert_eq!(parse("12.0."), Err(ParseError::NotValidNumber("12.0.".to_string())));
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assert_eq!(parse("ft"), Err(ParseError::UnexpectedUnit("ft".to_string())));
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assert_eq!(parse("5 tf"), Err(ParseError::UnknownUnit("tf".to_string())));
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assert_eq!(parse("12"), Err(ParseError::ExpectedUnit));
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}
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#[test]
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fn units() {
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// Length
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assert_eq!(parse_unit("inch"), Some(NonMetric::Inch));
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assert_eq!(parse_unit("inches"), Some(NonMetric::Inch));
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assert_eq!(parse_unit("in"), Some(NonMetric::Inch));
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assert_eq!(parse_unit("\""), Some(NonMetric::Inch));
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assert_eq!(parse_unit("″"), Some(NonMetric::Inch));
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assert_eq!(parse_unit("foot"), Some(NonMetric::Foot));
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assert_eq!(parse_unit("feet"), Some(NonMetric::Foot));
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assert_eq!(parse_unit("ft"), Some(NonMetric::Foot));
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assert_eq!(parse_unit("'"), Some(NonMetric::Foot));
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assert_eq!(parse_unit("′"), Some(NonMetric::Foot));
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assert_eq!(parse_unit("yard"), Some(NonMetric::Yard));
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assert_eq!(parse_unit("yards"), Some(NonMetric::Yard));
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assert_eq!(parse_unit("yd"), Some(NonMetric::Yard));
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assert_eq!(parse_unit("mile"), Some(NonMetric::Mile));
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assert_eq!(parse_unit("miles"), Some(NonMetric::Mile));
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assert_eq!(parse_unit("mi"), Some(NonMetric::Mile));
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assert_eq!(parse_unit("m"), Some(NonMetric::Mile));
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// Weight
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assert_eq!(parse_unit("ounce"), Some(NonMetric::Ounce));
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assert_eq!(parse_unit("ounces"), Some(NonMetric::Ounce));
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assert_eq!(parse_unit("oz"), Some(NonMetric::Ounce));
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assert_eq!(parse_unit("pound"), Some(NonMetric::Pound));
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assert_eq!(parse_unit("pounds"), Some(NonMetric::Pound));
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assert_eq!(parse_unit("lb"), Some(NonMetric::Pound));
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assert_eq!(parse_unit("lbs"), Some(NonMetric::Pound));
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assert_eq!(parse_unit("#"), Some(NonMetric::Pound));
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assert_eq!(parse_unit("stone"), Some(NonMetric::Stone));
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assert_eq!(parse_unit("stones"), Some(NonMetric::Stone));
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assert_eq!(parse_unit("st"), Some(NonMetric::Stone));
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// Unknown unit
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assert_eq!(parse_unit("hutenosa"), None);
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}
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#[test]
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fn tokens() {
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assert_eq!(tokenize(""), vec![]);
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assert_eq!(tokenize("10"), vec![Token::Number("10".to_string())]);
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assert_eq!(tokenize(" 10 "), vec![Token::Number("10".to_string())]);
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assert_eq!(tokenize("10 000"), vec![Token::Number("10 000".to_string())]);
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assert_eq!(tokenize("10.0.1"), vec![Token::Number("10.0.1".to_string())]);
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assert_eq!(tokenize("ft"), vec![Token::Unit("ft".to_string())]);
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assert_eq!(
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tokenize("10 ft"),
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vec![
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Token::Number("10".to_string()),
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Token::Unit("ft".to_string()),
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]
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);
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assert_eq!(
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tokenize("ft in"),
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vec![
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Token::Unit("ft".to_string()),
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Token::Unit("in".to_string()),
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]
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);
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assert_eq!(
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tokenize("5 ft 7 in"),
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vec![
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Token::Number("5".to_string()),
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Token::Unit("ft".to_string()),
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Token::Number("7".to_string()),
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Token::Unit("in".to_string()),
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]
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);
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assert_eq!(
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tokenize("5\"7'"),
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vec![
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Token::Number("5".to_string()),
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Token::Unit("\"".to_string()),
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Token::Number("7".to_string()),
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Token::Unit("'".to_string()),
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]
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);
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assert_eq!(
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tokenize(" 2.2lbs "),
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vec![
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Token::Number("2.2".to_string()),
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Token::Unit("lbs".to_string()),
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]
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);
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}
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}
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