R: Generate a List with Regex Matcher Settings

stri_opts_regex {stringi}

R Documentation

Generate a List with Regex Matcher Settings

Description

A convenience function to tune the ICU regular expressions matcher's behavior, e.g. in stri_count_regex and other stringi-search-regex functions.

Usage

stri_opts_regex(case_insensitive, comments, dotall, literal, multiline,
  unix_lines, uword, error_on_unknown_escapes, ...)

Arguments

`case_insensitive`	logical; enable case insensitive matching [regex flag `(?i)`]
`comments`	logical; allow white space and comments within patterns [regex flag `(?x)`]
`dotall`	logical; if set, '`.`' matches line terminators, otherwise matching of '`.`' stops at a line end [regex flag `(?s)`]
`literal`	logical; if set, treat the entire pattern as a literal string: metacharacters or escape sequences in the input sequence will be given no special meaning; note that in most cases you would rather use the stringi-search-fixed facilities in this case
`multiline`	logical; controls the behavior of '`$`' and '`^`'. If set, recognize line terminators within a string, otherwise, match only at start and end of input string [regex flag `(?m)`]
`unix_lines`	logical; Unix-only line endings. When this mode is enabled, only `U+000a` is recognized as a line ending by '`.`', '`$`', and '`^`'.
`uword`	logical; Unicode word boundaries. If set, uses the Unicode TR 29 definition of word boundaries; warning: Unicode word boundaries are quite different from traditional regex word boundaries. [regex flag `(?w)`] See http://unicode.org/reports/tr29/#Word_Boundaries
`error_on_unknown_escapes`	logical; whether to generate an error on unrecognized backslash escapes; if set, fail with an error on patterns that contain backslash-escaped ASCII letters without a known special meaning; otherwise, these escaped letters represent themselves
`...`	any other arguments to this function are purposely ignored

Details

Note that some regex settings may be changed using ICU regex flags inside regexes. For example, "(?i)pattern" does a case-insensitive match of a given pattern, see the ICU User Guide entry on Regular Expressions in the References section or stringi-search-regex.

Value

Returns a named list object; missing settings are left with default values.

References

enum URegexpFlag: Constants for Regular Expression Match Modes – ICU4C API Documentation, http://www.icu-project.org/apiref/icu4c/uregex_8h.html

Regular Expressions – ICU User Guide, http://userguide.icu-project.org/strings/regexp

Examples

stri_detect_regex("ala", "ALA") # case-sensitive by default
stri_detect_regex("ala", "ALA", opts_regex=stri_opts_regex(case_insensitive=TRUE))
stri_detect_regex("ala", "ALA", case_insensitive=TRUE) # equivalent
stri_detect_regex("ala", "(?i)ALA") # equivalent

[Package stringi version 1.1.6 Index]