Reading/Parsing CSS

library(cssparser)

Introduction

cssparser::read_css() is used to parse CSS stored in a string or in a file.

The returned object is a named list where:

• the names correspond to the CSS selectors
• the values are declaration blocks which are named lists where:
  • the name is the CSS property e.g. background-color, font-size etc
  • the value represents the setting for that property e.g. #ff88bb, 12px

Example

library(cssparser)

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# a Stylesheet to read
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
stylesheet <- '
#main {
  background-color: red !important;
  color: blue;
}

.footer {
  border-color: rgb(50 100 255);
  font-weight: lighter;
  margin-left: 1cm;
}

.footer > p {
  background-color: green;
}
'

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Read the above stylesheet into a CSS object in R
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
css <- cssparser::read_css(stylesheet)

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Access the declaration block for `#main` id selector
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
css[['#main']]

#> $`background-color`
#> [1] "red"
#> attr(,"important")
#> [1] TRUE
#> 
#> $color
#> [1] "blue"

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Access the 'font-weight' for the '.footer' class selector
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
css[['.footer']][['font-weight']]

#> [1] "lighter"