1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376
use CatCode::*;
/// Enum representing all 16 category codes in TeX.
///
/// Each variant's documentation contains an example character which is mapped to that category code in plainTeX.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Default)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub enum CatCode {
/// Marks the beginning of a control sequence.
/// Example: `\`.
///
/// This category code is never seen outside of the lexer.
Escape = 0,
/// Begins a new group.
/// Example: `{`.
BeginGroup = 1,
/// Ends an existing new group.
/// Example: `}`.
EndGroup = 2,
/// Starts or ends math mode.
/// Example: `$`.
MathShift = 3,
/// Used in typesetting tables to align cells.
/// Example: `&`.
AlignmentTab = 4,
/// Marks a new line in the input.
/// Example: `\n`.
///
/// This code behaves similarly to [Space], but has two additional properties.
/// First, two or more consecutive new lines, modulo intervening [Space] characters, create a `\par` control sequence
/// instead of a regular space.
/// Second, this code terminates a comment that started with a [Comment] character.
///
/// This category code is never seen outside of the lexer.
EndOfLine = 5,
/// Marks the beginning of a parameter number.
/// It must generally be followed by a digit.
/// Example: `#`.
Parameter = 6,
/// Puts following character or group in a superscript.
/// Example: `^`.
Superscript = 7,
/// Puts following character or group in a subscript.
/// Example: `_`.
Subscript = 8,
/// Character that is ignored by the lexer.
/// Example: ASCII null (0).
///
/// This category code is never seen outside of the lexer.
Ignored = 9,
/// Whitespace. Example: ` `.
Space = 10,
/// A character that can be used as a control sequence name.
/// Examples: `[a-zA-z]`.
Letter = 11,
/// A character than cannot be used as a control sequence name.
/// Example: `@`.
#[default]
Other = 12,
/// A single character that behaves like a control sequence.
/// Example: `~`.
Active = 13,
/// Marks the beginning of a comment.
/// All characters until the next [EndOfLine] are ignored.
/// Example: `%`.
///
/// This category code is never seen outside of the lexer.
Comment = 14,
/// An invalid character.
/// If this is encountered in the input, the lexer will return an error.
/// Example: ASCII delete (127).
///
/// This category code is never seen outside of the lexer.
Invalid = 15,
}
impl TryFrom<u8> for CatCode {
type Error = ();
fn try_from(value: u8) -> Result<Self, Self::Error> {
match value {
0 => Ok(Escape),
1 => Ok(BeginGroup),
2 => Ok(EndGroup),
3 => Ok(MathShift),
4 => Ok(AlignmentTab),
5 => Ok(EndOfLine),
6 => Ok(Parameter),
7 => Ok(Superscript),
8 => Ok(Subscript),
9 => Ok(Ignored),
10 => Ok(Space),
11 => Ok(Letter),
12 => Ok(Other),
13 => Ok(Active),
14 => Ok(Comment),
15 => Ok(Invalid),
_ => Err(()),
}
}
}
impl std::fmt::Display for CatCode {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(
f,
"{} ({})",
*self as u8,
match self {
Escape => "escape",
BeginGroup => "begin group",
EndGroup => "end group",
MathShift => "math shift",
AlignmentTab => "alignment tab",
EndOfLine => "end of line",
Parameter => "parameter",
Superscript => "superscript",
Subscript => "subscript",
Ignored => "ignored",
Space => "space",
Letter => "letter",
Other => "other",
Active => "active",
Comment => "comment",
Invalid => "invalid",
}
)?;
Ok(())
}
}
impl CatCode {
/// Default category codes in INITEX for all ASCII characters.
///
/// To find the category code for an ASCII character,
/// convert it to an integer and use it as an index for the array.
///
/// This list was compiled by reading the source code TeX '82,
/// specifically section 232 in the "TeX: the program".
/// These defaults are also described in the TeXBook p343.
pub const INITEX_DEFAULTS: [CatCode; 128] = [
Ignored, // ASCII null
Other, Other, Other, Other, Other, Other, Other, Other, Other,
EndOfLine, // carriage return
Other, Other, Other, Other, Other, Other, Other, Other, Other, Other, Other, Other, Other,
Other, Other, Other, Other, Other, Other, Other, Other, Space, // space
Other, Other, Other, Other, Comment, // %
Other, Other, Other, Other, Other, Other, Other, Other, Other, Other, Other, Other, Other,
Other, Other, Other, Other, Other, Other, Other, Other, Other, Other, Other, Other, Other,
Other, Letter, // A
Letter, // B
Letter, // C
Letter, // D
Letter, // E
Letter, // F
Letter, // G
Letter, // H
Letter, // I
Letter, // J
Letter, // K
Letter, // L
Letter, // M
Letter, // N
Letter, // O
Letter, // P
Letter, // Q
Letter, // R
Letter, // S
Letter, // T
Letter, // U
Letter, // V
Letter, // W
Letter, // X
Letter, // Y
Letter, // Z
Other, Escape, // \
Other, Other, Other, Other, Letter, // a
Letter, // b
Letter, // c
Letter, // d
Letter, // e
Letter, // f
Letter, // g
Letter, // h
Letter, // i
Letter, // j
Letter, // k
Letter, // l
Letter, // m
Letter, // n
Letter, // o
Letter, // p
Letter, // q
Letter, // r
Letter, // s
Letter, // t
Letter, // u
Letter, // v
Letter, // w
Letter, // x
Letter, // y
Letter, // z
Other, Other, Other, Other, Invalid, // ASCII delete
];
/// Default category codes in plainTeX for all ASCII characters.
///
/// To find the category code for an ASCII character,
/// convert it to an integer and use it as an index for the array.
///
/// This list was compiled by starting with [INITEX_DEFAULTS](CatCode::INITEX_DEFAULTS) and then applying
/// all category code changes in the plainTeX format.
/// These changes are described on p343 of the TeXBook.
pub const PLAIN_TEX_DEFAULTS: [CatCode; 128] = [
Ignored, // ASCII null
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Space, // horizontal tab (\t)
EndOfLine, // line feed (\n)
Other,
Active, // ASCII form-feed
EndOfLine, // carriage return (\r)
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Space, // space
Other,
Other,
Parameter, // #
MathShift, // $
Comment, // %
AlignmentTab, // &
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Other,
Letter, // A
Letter, // B
Letter, // C
Letter, // D
Letter, // E
Letter, // F
Letter, // G
Letter, // H
Letter, // I
Letter, // J
Letter, // K
Letter, // L
Letter, // M
Letter, // N
Letter, // O
Letter, // P
Letter, // Q
Letter, // R
Letter, // S
Letter, // T
Letter, // U
Letter, // V
Letter, // W
Letter, // X
Letter, // Y
Letter, // Z
Other,
Escape, // \
Other,
Superscript, // ^
Subscript, // _
Other,
Letter, // a
Letter, // b
Letter, // c
Letter, // d
Letter, // e
Letter, // f
Letter, // g
Letter, // h
Letter, // i
Letter, // j
Letter, // k
Letter, // l
Letter, // m
Letter, // n
Letter, // o
Letter, // p
Letter, // q
Letter, // r
Letter, // s
Letter, // t
Letter, // u
Letter, // v
Letter, // w
Letter, // x
Letter, // y
Letter, // z
BeginGroup, // {
Other,
EndGroup, // }
Active, // ~
Invalid, // ASCII delete
];
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn serialize_and_deserialize_cat_code() {
let all_raw_cat_codes = vec![
CatCode::BeginGroup,
CatCode::EndGroup,
CatCode::MathShift,
CatCode::AlignmentTab,
CatCode::Parameter,
CatCode::Superscript,
CatCode::Subscript,
CatCode::Space,
CatCode::Letter,
CatCode::Other,
CatCode::Active,
CatCode::Escape,
CatCode::EndOfLine,
CatCode::Ignored,
CatCode::Comment,
CatCode::Invalid,
];
for cat_code in all_raw_cat_codes {
let u: u8 = cat_code as u8;
let recovered: CatCode = u.try_into().unwrap();
assert_eq!(recovered, cat_code);
}
}
}