stri_opts_regex
Generate a List with Regex Matcher Settings
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; enables case insensitive matching [regex flag
(?i)]- comments
logical; allows 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 `
$` and `^`. If set, recognize line terminators within a string, otherwise, match only at start and end of input string [regex flag(?m)]- unix_lines
logical; Unix-only line endings; when enabled, only
U+000ais recognized as a line ending by `.`, `$`, 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" performs
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
See Also
Other search_regex:
stringi-search-regex,
stringi-search
Examples
# NOT RUN {
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
# }