Parse regular expression with custom flags and obtain the final pattern to be parsed as well as the vector of flags
parse_regex_pattern(
pattern,
authorized_flags,
parse_flags = TRUE,
parse_logical = TRUE,
envir = parent.frame()
)Character scalar, the regular expression pattern to parse.
Character vector representing the flags to be parsed. Use the empty string if no flags are allowed.
Logical scalar, default is TRUE. Whether to parse the
optional regex flags.
Logical scalar, default is TRUE. Whether to parse logical
regex operations, similarly to string_get().
An environment, default is parent.frame(). Only used if the flag
magic is present, it is used to find the variables to be interpolated.
This function always returns a list of 4 elements:
flags: the character vector of flags. If no flags were found, this is the empty string.
patterns: the vector of regex patterns.
is_or: logical vector of the same length as patterns. Indicates for each
pattern if it should be attached to the previous patterns with a logical OR (FALSE
means a logical AND).
is_not: logical vector of the same length as patterns. Indicates for each pattern
if it should be negated.
This is an internal tool that is exposed in order to facilitate checking what's going on.
There is no error handling.
String operations: string_is(), string_get(), string_clean(), string_split2df().
Chain basic operations with string_ops(). Clean character vectors efficiently
with string_clean().
Use string_vec() to create simple string vectors.
String interpolation combined with operation chaining: string_magic(). You can change string_magic
default values with string_magic_alias() and add custom operations with string_magic_register_fun().
Display messages while benefiting from string_magic interpolation with cat_magic() and message_magic().
Other tools with aliases:
cat_magic_alias(),
string_magic(),
string_magic_alias(),
string_ops_alias(),
string_vec_alias()
parse_regex_pattern("f/hello", c("fixed", "ignore"))
#> $flags
#> [1] "fixed"
#>
#> $patterns
#> [1] "hello"
#>
#> $is_or
#> [1] FALSE
#>
#> $is_not
#> [1] FALSE
#>
x = "john"
parse_regex_pattern("fm/{x} | Doe", c("fixed", "ignore", "magic"))
#> $flags
#> [1] "fixed" "magic"
#>
#> $patterns
#> [1] "john" "Doe"
#>
#> $is_or
#> [1] FALSE TRUE
#>
#> $is_not
#> [1] FALSE FALSE
#>