stri_opts_regex: Generate a List with Regex Matcher Options

In stringi: THE string processing package for R

Description

A convenience function to tune regular expressions matcher 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
comments	logical; allow white space and comments within patterns
dotall	logical; if set, '.' matches line terminators, otherwise matching of '.' stops at a line end
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 (with opts_collator=NA).
multiline	logical; controls the behavior of '$' and '^'. If set, recognize line terminators within a string, otherwise, match only at start and end of input string
unix_lines	logical; Unix-only line endings. When this mode is enabled, only U+000a is recognized as a line ending by '.', '$', 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. 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. Note that some regex options may be changed using ICU regex flag settings 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.

Value

Returns a named list object; missing options 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

See Also

Other search_regex: stri_count_regex; stri_detect_regex; stri_extract_all_regex, stri_extract_all_regex, stri_extract_first_regex, stri_extract_first_regex, stri_extract_last_regex, stri_extract_last_regex; stri_locate_all_regex, stri_locate_all_regex, stri_locate_first_regex, stri_locate_first_regex, stri_locate_last_regex, stri_locate_last_regex; stri_match_all_regex, stri_match_all_regex, stri_match_first_regex, stri_match_first_regex, stri_match_last_regex, stri_match_last_regex; stri_replace_all_regex, stri_replace_all_regex, stri_replace_first_regex, stri_replace_first_regex, stri_replace_last_regex, stri_replace_last_regex; stri_split_regex, stri_split_regex; stringi-search-regex; stringi-search

Examples

## Not run: 
stri_detect_regex("ala", "ALA") # case-sensitive by default
stri_detect_regex("ala", "ALA", stri_opts_regex(case_insensitive=TRUE))
stri_detect_regex("ala", "(?i:)ALA") # equivalent

## End(Not run)

Example output

[1] FALSE
[1] TRUE
[1] FALSE

stringi documentation built on May 2, 2019, 4:54 p.m.