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Locate pattern matches in files

Source: R/locate.R
ac_locate_file.Rd

ac_locate_file() searches files with a compiled automaton and returns one list element per file. Character offsets are 1-based and inclusive, so they can be used directly with substr().

Usage

ac_locate_file(ac, path, ..., overlapping = FALSE)

Arguments

ac

An <ac_automaton> object created by ac_build().

path

A vector of file paths to search.

...

Must be empty. This is used to require optional arguments to be supplied by name.

overlapping

Default is FALSE. If TRUE, report overlapping matches. This is only supported when ac was built with match_kind = "standard".

Value

A list with the same length as path. Each element is a data frame with one row per match and three columns:

  • pattern_id: Index of the matched pattern in ac_patterns(ac).

  • start: 1-based index of the first character in each match.

  • end: 1-based index of the last character in each match.

Details

File location search is always non-streaming. Converting byte offsets from a streaming search into R-facing character offsets would require a second pass over the same file to reconstruct UTF-8 character boundaries. Keeping ac_locate_file() as a simple in-memory search is the clearest implementation.

See also

ac_locate(), ac_detect_file(), ac_count_file(), ac_extract_file().

Examples

ac <- ac_build(c("hello", "world"))
path <- tempfile()
writeLines("hello world", path)
ac_locate_file(ac, path)
#> [[1]]
#>   pattern_id start end
#> 1          1     1   5
#> 2          2     7  11
#>