| 1 | //! Greetings. |
| 2 | |
| 3 | /// A supported greeting language. |
| 4 | #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)] |
| 5 | pub enum Lang { |
| 6 | #[default] |
| 7 | En, |
| 8 | Es, |
| 9 | Fr, |
| 10 | } |
| 11 | |
| 12 | impl Lang { |
| 13 | /// Parses a language code (`en`, `es` or `fr`). |
| 14 | pub fn parse(code: &str) -> Option<Lang> { |
| 15 | match code { |
| 16 | "en" => Some(Lang::En), |
| 17 | "es" => Some(Lang::Es), |
| 18 | "fr" => Some(Lang::Fr), |
| 19 | _ => None, |
| 20 | } |
| 21 | } |
| 22 | } |
| 23 | |
| 24 | /// Parsed command-line options. |
| 25 | #[derive(Debug, PartialEq, Eq)] |
| 26 | pub struct Options { |
| 27 | /// The name to greet, if one was given. |
| 28 | pub name: Option<String>, |
| 29 | /// Whether to upper-case the greeting (`--shout`). |
| 30 | pub shout: bool, |
| 31 | /// Whether to print the crate version and exit (`--version`). |
| 32 | pub version: bool, |
| 33 | /// How many times to print the greeting (`--times N`). |
| 34 | pub times: usize, |
| 35 | /// The greeting language (`--lang CODE`). |
| 36 | pub lang: Lang, |
| 37 | } |
| 38 | |
| 39 | impl Default for Options { |
| 40 | fn default() -> Self { |
| 41 | Options { |
| 42 | name: None, |
| 43 | shout: false, |
| 44 | version: false, |
| 45 | times: 1, |
| 46 | lang: Lang::En, |
| 47 | } |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | /// Parses command-line arguments (excluding the program name). |
| 52 | /// |
| 53 | /// `--shout` sets [`Options::shout`], `--version` sets |
| 54 | /// [`Options::version`], and `--times N` sets [`Options::times`] (the |
| 55 | /// next argument is consumed as the value), and `--lang CODE` sets |
| 56 | /// [`Options::lang`] (likewise consuming the next argument); other |
| 57 | /// arguments starting with `--` are treated as flags and skipped. The |
| 58 | /// name is the first remaining argument. |
| 59 | /// |
| 60 | /// Returns an error message if `--times` has a missing or non-numeric |
| 61 | /// value, or if `--lang` has a missing or unsupported value. |
| 62 | pub fn parse_args<I: IntoIterator<Item = String>>(args: I) -> Result<Options, String> { |
| 63 | let mut options = Options::default(); |
| 64 | let mut args = args.into_iter(); |
| 65 | while let Some(arg) = args.next() { |
| 66 | if arg == "--shout" { |
| 67 | options.shout = true; |
| 68 | } else if arg == "--version" { |
| 69 | options.version = true; |
| 70 | } else if arg == "--times" { |
| 71 | let value = args |
| 72 | .next() |
| 73 | .ok_or_else(|| "--times requires a value".to_owned())?; |
| 74 | options.times = value |
| 75 | .parse() |
| 76 | .map_err(|_| format!("--times value must be a number, got {value:?}"))?; |
| 77 | } else if arg == "--lang" { |
| 78 | let value = args |
| 79 | .next() |
| 80 | .ok_or_else(|| "--lang requires a value".to_owned())?; |
| 81 | options.lang = Lang::parse(&value).ok_or_else(|| { |
| 82 | format!("--lang value must be one of en, es, fr, got {value:?}") |
| 83 | })?; |
| 84 | } else if !arg.starts_with("--") && options.name.is_none() { |
| 85 | options.name = Some(arg); |
| 86 | } |
| 87 | } |
| 88 | Ok(options) |
| 89 | } |
| 90 | |
| 91 | /// `text` upper-cased. |
| 92 | pub fn shout(text: &str) -> String { |
| 93 | text.to_uppercase() |
| 94 | } |
| 95 | |
| 96 | /// The greeting for `name`. |
| 97 | pub fn greeting(name: &str) -> String { |
| 98 | greeting_in(name, Lang::En) |
| 99 | } |
| 100 | |
| 101 | /// The greeting for `name` in `lang`. |
| 102 | pub fn greeting_in(name: &str, lang: Lang) -> String { |
| 103 | let trimmed = name.trim(); |
| 104 | let display_name = if trimmed.is_empty() { "world" } else { trimmed }; |
| 105 | match lang { |
| 106 | Lang::En => format!("Hi, {display_name}!"), |
| 107 | Lang::Es => format!("¡Hola, {display_name}!"), |
| 108 | Lang::Fr => format!("Bonjour, {display_name} !"), |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | /// The farewell for `name`. |
| 113 | pub fn farewell(name: &str) -> String { |
| 114 | let trimmed = name.trim(); |
| 115 | let display_name = if trimmed.is_empty() { "world" } else { trimmed }; |
| 116 | format!("Goodbye, {display_name}!") |
| 117 | } |
| 118 | |
| 119 | #[cfg(test)] |
| 120 | mod tests { |
| 121 | use super::*; |
| 122 | |
| 123 | fn args(list: &[&str]) -> Vec<String> { |
| 124 | list.iter().map(|s| s.to_string()).collect() |
| 125 | } |
| 126 | |
| 127 | #[test] |
| 128 | fn parse_args_no_args() { |
| 129 | assert_eq!(parse_args(args(&[])).unwrap().name, None); |
| 130 | } |
| 131 | |
| 132 | #[test] |
| 133 | fn parse_args_name() { |
| 134 | assert_eq!(parse_args(args(&["Ada"])).unwrap().name.as_deref(), Some("Ada")); |
| 135 | } |
| 136 | |
| 137 | #[test] |
| 138 | fn parse_args_skips_leading_flag() { |
| 139 | assert_eq!( |
| 140 | parse_args(args(&["--unknown", "Ada"])).unwrap().name.as_deref(), |
| 141 | Some("Ada") |
| 142 | ); |
| 143 | } |
| 144 | |
| 145 | #[test] |
| 146 | fn parse_args_shout_defaults_off() { |
| 147 | assert!(!parse_args(args(&["Ada"])).unwrap().shout); |
| 148 | } |
| 149 | |
| 150 | #[test] |
| 151 | fn parse_args_shout_before_name() { |
| 152 | let options = parse_args(args(&["--shout", "Ada"])).unwrap(); |
| 153 | assert!(options.shout); |
| 154 | assert_eq!(options.name.as_deref(), Some("Ada")); |
| 155 | } |
| 156 | |
| 157 | #[test] |
| 158 | fn parse_args_shout_after_name() { |
| 159 | let options = parse_args(args(&["Ada", "--shout"])).unwrap(); |
| 160 | assert!(options.shout); |
| 161 | assert_eq!(options.name.as_deref(), Some("Ada")); |
| 162 | } |
| 163 | |
| 164 | #[test] |
| 165 | fn parse_args_shout_alone() { |
| 166 | let options = parse_args(args(&["--shout"])).unwrap(); |
| 167 | assert!(options.shout); |
| 168 | assert_eq!(options.name, None); |
| 169 | } |
| 170 | |
| 171 | #[test] |
| 172 | fn parse_args_version_defaults_off() { |
| 173 | assert!(!parse_args(args(&["Ada"])).unwrap().version); |
| 174 | } |
| 175 | |
| 176 | #[test] |
| 177 | fn parse_args_version() { |
| 178 | let options = parse_args(args(&["--version"])).unwrap(); |
| 179 | assert!(options.version); |
| 180 | assert_eq!(options.name, None); |
| 181 | } |
| 182 | |
| 183 | #[test] |
| 184 | fn parse_args_times_defaults_to_one() { |
| 185 | assert_eq!(parse_args(args(&["Ada"])).unwrap().times, 1); |
| 186 | } |
| 187 | |
| 188 | #[test] |
| 189 | fn parse_args_times_valid() { |
| 190 | let options = parse_args(args(&["--times", "3", "Ada"])).unwrap(); |
| 191 | assert_eq!(options.times, 3); |
| 192 | assert_eq!(options.name.as_deref(), Some("Ada")); |
| 193 | } |
| 194 | |
| 195 | #[test] |
| 196 | fn parse_args_times_missing_value() { |
| 197 | assert!(parse_args(args(&["--times"])).is_err()); |
| 198 | } |
| 199 | |
| 200 | #[test] |
| 201 | fn parse_args_times_non_number() { |
| 202 | assert!(parse_args(args(&["--times", "abc", "Ada"])).is_err()); |
| 203 | } |
| 204 | |
| 205 | #[test] |
| 206 | fn parse_args_lang_defaults_to_en() { |
| 207 | assert_eq!(parse_args(args(&["Ada"])).unwrap().lang, Lang::En); |
| 208 | } |
| 209 | |
| 210 | #[test] |
| 211 | fn parse_args_lang_valid() { |
| 212 | let options = parse_args(args(&["--lang", "es", "Ana"])).unwrap(); |
| 213 | assert_eq!(options.lang, Lang::Es); |
| 214 | assert_eq!(options.name.as_deref(), Some("Ana")); |
| 215 | assert_eq!(parse_args(args(&["--lang", "fr"])).unwrap().lang, Lang::Fr); |
| 216 | } |
| 217 | |
| 218 | #[test] |
| 219 | fn parse_args_lang_missing_value() { |
| 220 | assert_eq!( |
| 221 | parse_args(args(&["--lang"])).unwrap_err(), |
| 222 | "--lang requires a value" |
| 223 | ); |
| 224 | } |
| 225 | |
| 226 | #[test] |
| 227 | fn parse_args_lang_unknown() { |
| 228 | assert_eq!( |
| 229 | parse_args(args(&["--lang", "de"])).unwrap_err(), |
| 230 | "--lang value must be one of en, es, fr, got \"de\"" |
| 231 | ); |
| 232 | } |
| 233 | |
| 234 | #[test] |
| 235 | fn greeting_in_each_language() { |
| 236 | assert_eq!(greeting_in("Ada", Lang::En), "Hi, Ada!"); |
| 237 | assert_eq!(greeting_in("Ana", Lang::Es), "¡Hola, Ana!"); |
| 238 | assert_eq!(greeting_in("Luc", Lang::Fr), "Bonjour, Luc !"); |
| 239 | } |
| 240 | |
| 241 | #[test] |
| 242 | fn greeting_in_trims_and_falls_back_to_world() { |
| 243 | assert_eq!(greeting_in(" Ana ", Lang::Es), "¡Hola, Ana!"); |
| 244 | assert_eq!(greeting_in(" ", Lang::Fr), "Bonjour, world !"); |
| 245 | } |
| 246 | |
| 247 | #[test] |
| 248 | fn shout_upper_cases_greeting() { |
| 249 | assert_eq!(shout(&greeting("Ada")), "HI, ADA!"); |
| 250 | } |
| 251 | |
| 252 | #[test] |
| 253 | fn greets_by_name() { |
| 254 | assert_eq!(greeting("Ada"), "Hi, Ada!"); |
| 255 | } |
| 256 | |
| 257 | #[test] |
| 258 | fn greets_world_with_empty_string() { |
| 259 | assert_eq!(greeting(""), "Hi, world!"); |
| 260 | } |
| 261 | |
| 262 | #[test] |
| 263 | fn greets_world_with_whitespace_only() { |
| 264 | assert_eq!(greeting(" "), "Hi, world!"); |
| 265 | } |
| 266 | |
| 267 | #[test] |
| 268 | fn trims_whitespace_from_name() { |
| 269 | assert_eq!(greeting(" Ada "), "Hi, Ada!"); |
| 270 | } |
| 271 | |
| 272 | #[test] |
| 273 | fn says_goodbye_by_name() { |
| 274 | assert_eq!(farewell("Ada"), "Goodbye, Ada!"); |
| 275 | } |
| 276 | |
| 277 | #[test] |
| 278 | fn says_goodbye_to_world_when_blank() { |
| 279 | assert_eq!(farewell(" "), "Goodbye, world!"); |
| 280 | } |
| 281 | |
| 282 | #[test] |
| 283 | fn farewell_trims_whitespace() { |
| 284 | assert_eq!(farewell(" Ada "), "Goodbye, Ada!"); |
| 285 | } |
| 286 | } |