Objects of the root_criterion class decide if a given directory is a project root.

root_criterion(testfun, desc, subdir = NULL)

is_root_criterion(x)

as_root_criterion(x)

# S3 method for character
as_root_criterion(x)

# S3 method for root_criterion
as_root_criterion(x)

# S3 method for root_criterion
|(x, y)

has_file(filepath, contents = NULL, n = -1L, fixed = FALSE)

has_dir(filepath)

has_file_pattern(pattern, contents = NULL, n = -1L, fixed = FALSE)

has_basename(basename, subdir = NULL)

Arguments

testfun

[function|list(function)]
A function with one parameter that returns TRUE if the directory specified by this parameter is the project root, and FALSE otherwise. Can also be a list of such functions.

desc

[character]
A textual description of the test criterion, of the same length as testfun.

subdir

[character]
Subdirectories to start the search in, if found

x

[object]
An object.

y

[object]
An object.

filepath

[character(1)]
File path (can contain directories).

contents, fixed

[character(1)]
If contents is NULL (the default), file contents are not checked. Otherwise, contents is a regular expression (if fixed is FALSE) or a search string (if fixed is TRUE), and file contents are checked matching lines.

n

[integerish(1)]
Maximum number of lines to read to check file contents.

pattern

[character(1)]
Regular expression to match the file name against.

basename

[character(1)]
The required name of the root directory.

Value

An S3 object of class root_criterion wit the following members:

testfun

The testfun argument

desc

The desc argument

subdir

The subdir argument

find_file

A function with ... and path arguments that returns a path relative to the root, as specified by this criterion. The optional path argument specifies the starting directory, which defaults to ".". The function forwards to find_root_file(), which passes ... directly to file.path() if the first argument is an absolute path.

make_fix_file

A function with a path argument that returns a function that finds paths relative to the root. For a criterion cr, the result of cr$make_fix_file(".")(...) is identical to cr$find_file(...). The function created by make_fix_file() can be saved to a variable to be more independent of the current working directory.

Details

Construct criteria using root_criterion in a very general fashion by specifying a function with a path argument, and a description.

The as_root_criterion() function accepts objects of class root_criterion, and character values; the latter will be converted to criteria using has_file.

Root criteria can be combined with the | operator. The result is a composite root criterion that requires either of the original criteria to match.

The has_file() function constructs a criterion that checks for the existence of a specific file (which itself can be in a subdirectory of the root) with specific contents.

The has_dir() function constructs a criterion that checks for the existence of a specific directory.

The has_file_pattern() function constructs a criterion that checks for the existence of a file that matches a pattern, with specific contents.

The has_basename() function constructs a criterion that checks if the base::basename() of the root directory has a specific name, with support for case-insensitive file systems.

Examples

root_criterion(function(path) file.exists(file.path(path, "somefile")), "has somefile")
#> Root criterion: has somefile
has_file("DESCRIPTION")
#> Root criterion: contains a file "DESCRIPTION"
is_r_package
#> Root criterion: contains a file "DESCRIPTION" with contents matching "^Package: "
is_r_package$find_file
#> function (..., path = ".") #> { #> find_root_file(..., criterion = criterion, path = path) #> } #> <bytecode: 0x561e69c04fc0> #> <environment: 0x561e69c02c08>
if (FALSE) { is_r_package$make_fix_file(".") }