This was written to fulfill a need I had to run quickly through a string of CSS and identify what "type" each character was. With an optional ability to parse it into hierarchical data describing nested selectors and/or media queries (most applicable to LESS rather than vanilla CSS since LESS supports nesting of selectors whereas CSS only supports single nesting of a selector within a media query).
IEnumerable<CategorisedCharacterString> ParseCSS(string content)
and
IEnumerable<CategorisedCharacterString> ParseLESS(string content)
(within the static class CSSParser.Parser) do the basic parsing work where CategorisedCharacterString has the properties
public class CategorisedCharacterString
{
/// <summary>
/// This will never be null or an empty string
/// </summary>
public string Value { get; }
/// <summary>
/// This is the location of the start of the string in the source data
/// </summary>
public int IndexInSource { get; }
public CharacterCategorisationOptions CharacterCategorisation { get; }
}
public enum CharacterCategorisationOptions
{
Comment,
CloseBrace,
OpenBrace,
SemiColon,
SelectorOrStyleProperty,
StylePropertyColon,
Value,
Whitespace
}
so calling ParseCSS on
/* Test */ .Content { color: black; }
will return CategorisedCharacterString instances with the data
"/* Test */" Comment (IndexInSource 0)
" " Whitespace (IndexInSource 10)
".Content" SelectorOrStyleProperty (IndexInSource 11)
" " Whitespace (IndexInSource 19)
"{" OpenBrace (IndexInSource 20)
" " Whitespace (IndexInSource 19)
"color" SelectorOrStyleProperty (IndexInSource 22)
":" StylePropertyColon (IndexInSource 27)
" " Whitespace (IndexInSource 28)
"black" Value (IndexInSource 29)
";" SemiColon (IndexInSource 34)
" " Whitespace (IndexInSource 35)
"}" CloseBrace (IndexInSource 36)
This analysis can be done very cheaply as it is only a very simple representation. It does not, for example, differentiate between the type of the ".Content" value or "color", they are both considered to be of type SelectorOrStyleProperty.
To arrange in a hierchical manner and to categorise more strictly, the data return from ParseCSS or ParseLess can be passed into
IEnumerable<ICSSFragment> ParseIntoStructuredData(
IEnumerable<CategorisedCharacterString> segments
)
(within the static class CSSParser.ExtendedLESSParser.LessCssHierarchicalParser) which transforms the data again. The interface ICSSFragment is implemented by the classes Import (describing an import statement for another stylesheet), a MediaQuery or a Selector (both of which have a "ChildFragments" set as they may contain other media queries, selectors and/or properties), a StylePropertyName or StylePropertyValue. Note that comments and whitespace are not included in this data.
So content such as
// Example
html
{
h1
{
color: black;
background: white url("background.jpg") no-repeat top left;
}
p.Intro { padding: 8px; }
}
becomes something like
html
h1
color
black
background
white
url("background.jpg")
no-repat
top
left
p.Intro
padding
8px
(Above: "html" represent a Selector instance with a ChildFragments property containing Selector instances for the "h1" and "p", each with ChildFragments data made up of StylePropertyValue and StylePropertyValue instances).