R/utils-predicates.R

In sketch: Interactive Sketches

# Predicate functions

# Check if a character string is a weblink
is_web_link <- function(x) {
    has_prefix(x, "http://") || has_prefix(x, "https://")
}

is_local <- function(x) !is_web_link(x)

# Check if input 'x' has the prefix 'y'
has_prefix <- function(x, y) substr(x, 1, nchar(y)) == y

# A predicate function that always returns TRUE.
# This corresponds to the default case.
always_true <- function(x) TRUE

# Extension-related predicates
is_javascript <- function(x) extname(x) == "js"
is_r_script   <- function(x) extname(x) == "r"
is_css        <- function(x) extname(x) == "css"
is_json       <- function(x) extname(x) == "json"
is_gz         <- function(x) extname(x) == "gz"
is_csv        <- function(x) extname(x) == "csv"
is_font       <- function(x) extname(x) %in% c("woff", "ttf", "eot", "otf")

# Get file extension
extname <- purrr::compose(tolower, tools::file_ext)  # handle cases without extension