character_class {rex}

Create character classes

Description

There are multiple ways you can define a character class.

Usage

character_class(x)

one_of(...)

any_of(..., type = c("greedy", "lazy", "possessive"))

some_of(..., type = c("greedy", "lazy", "possessive"))

none_of(...)

except_any_of(..., type = c("greedy", "lazy", "possessive"))

except_some_of(..., type = c("greedy", "lazy", "possessive"))

range(start, end)

`:`(start, end)

exclude_range(start, end)

Arguments

x

text to include in the character class (must be escaped manually)

...

shortcuts, R variables, text, or other rex functions.

type

the type of match to perform.

There are three match types

1. greedy: match the longest string. This is the default matching type.

2. lazy: match the shortest string. This matches the shortest string from the same anchor point, not necessarily the shortest global string.

3. possessive: match and don't allow backtracking

start

beginning of character class

end

end of character class

Functions

• character_class: explicitly define a character class

• one_of: matches one of the specified characters.

• any_of: matches zero or more of the specified characters.

• some_of: matches one or more of the specified characters.

• none_of: matches anything but one of the specified characters.

• except_any_of: matches zero or more of anything but the specified characters.

• except_some_of: matches one or more of anything but the specified characters.

• range: matches one of any of the characters in the range.

• :: matches one of any of the characters in the range.

• exclude_range: matches one of any of the characters except those in the range.

See Also

Other rex: %or%(), capture(), counts, group(), lookarounds, not(), rex(), shortcuts, wildcards

Examples

# grey = gray
re <- rex("gr", one_of("a", "e"), "y")
grepl(re, c("grey", "gray")) # TRUE TRUE

# Match non-vowels
re <- rex(none_of("a", "e", "i", "o", "u"))
# They can also be in the same string
re <- rex(none_of("aeiou"))
grepl(re, c("k", "l", "e")) # TRUE TRUE FALSE

# Match range
re <- rex(range("a", "e"))
grepl(re, c("b", "d", "f")) # TRUE TRUE FALSE

# Explicit creation
re <- rex(character_class("abcd\\["))
grepl(re, c("a", "d", "[", "]")) # TRUE TRUE TRUE FALSE