Crate cssparser

Implementation of CSS Syntax Module Level 3 for Rust.

Input

Everything is based on Parser objects, which borrow a &str input. If you have bytes (from a file, the network, or something) and want to support character encodings other than UTF-8, see the stylesheet_encoding function, which can be used together with rust-encoding or encoding-rs.

Conventions for parsing functions

• Take (at least) a input: &mut cssparser::Parser parameter
• Return Result<_, ()>
• When returning Ok(_), the function must have consumed exactly the amount of input that represents the parsed value.
• When returning Err(()), any amount of input may have been consumed.

As a consequence, when calling another parsing function, either:

• Any Err(()) return value must be propagated. This happens by definition for tail calls, and can otherwise be done with the ? operator.
• Or the call must be wrapped in a Parser::try call. try takes a closure that takes a Parser and returns a Result, calls it once, and returns itself that same result. If the result is Err, it restores the position inside the input to the one saved before calling the closure.

Examples:

// 'none' | <image>
fn parse_background_image(context: &ParserContext, input: &mut Parser)
                                    -> Result<Option<Image>, ()> {
    if input.try_parse(|input| input.expect_ident_matching("none")).is_ok() {
        Ok(None)
    } else {
        Image::parse(context, input).map(Some)  // tail call
    }
}

// [ <length> | <percentage> ] [ <length> | <percentage> ]?
fn parse_border_spacing(_context: &ParserContext, input: &mut Parser)
                          -> Result<(LengthOrPercentage, LengthOrPercentage), ()> {
    let first = LengthOrPercentage::parse?;
    let second = input.try_parse(LengthOrPercentage::parse).unwrap_or(first);
    (first, second)
}

Modules

• Delimiter
  Delimiters constants.
• color
  General color-parsing utilities, independent on the specific color storage and parsing implementation.

Macros

• _cssparser_internal_max_len
• ascii_case_insensitive_phf_map
  Define a function $name(&str) -> Option<&'static $ValueType>
• match_byte
  Expand a TokenStream corresponding to the match_byte macro.
• match_ignore_ascii_case
  Expands to a match expression with string patterns, matching case-insensitively in the ASCII range.

Structs

• BasicParseError
  The fundamental parsing errors that can be triggered by built-in parsing routines.
• CowRcStr
  A string that is either shared (heap-allocated and reference-counted) or borrowed.
• CssStringWriter
  A fmt::Write adapter that escapes text for writing as a double-quoted CSS string. Quotes are not included.
• Delimiters
  A set of characters, to be used with the Parser::parse_until* methods.
• ParseError
  Extensible parse errors that can be encountered by client parsing implementations.
• Parser
  A CSS parser that borrows its &str input, yields Tokens, and keeps track of nested blocks and functions.
• ParserInput
  The owned input for a parser.
• ParserState
  A capture of the internal state of a Parser (including the position within the input), obtained from the Parser::position method.
• RuleBodyParser
  Provides an iterator for rule bodies and declaration lists.
• SourceLocation
  The line and column number for a given position within the input.
• SourcePosition
  A position from the start of the input, counted in UTF-8 bytes.
• StyleSheetParser
  Provides an iterator for rule list parsing at the top-level of a stylesheet.
• UnicodeRange
  One contiguous range of code points.

Enums

• BasicParseErrorKind
  Details about a BasicParseError
• ParseErrorKind
  Details of a ParseError
• Token
  One of the pieces the CSS input is broken into.
• TokenSerializationType
  A category of token. See the needs_separator_when_before method.

Traits

• AtRuleParser
  A trait to provide various parsing of at-rules.
• DeclarationParser
  A trait to provide various parsing of declaration values.
• EncodingSupport
  Abstraction for avoiding a dependency from cssparser to an encoding library
• QualifiedRuleParser
  A trait to provide various parsing of qualified rules.
• RuleBodyItemParser
  A parser for a rule body item.
• ToCss
  Trait for things the can serialize themselves in CSS syntax.

Functions

• parse_important
  Parse !important.
• parse_nth
  Parse the An+B notation, as found in the :nth-child() selector. The input is typically the arguments of a function, in which case the caller needs to check if the arguments’ parser is exhausted. Return Ok((A, B)), or an Err(..) for a syntax error.
• parse_one_declaration
  Parse a single declaration, such as an ( /* ... */ ) parenthesis in an @supports prelude.
• parse_one_rule
  Parse a single rule, such as for CSSOM’s CSSStyleSheet.insertRule.
• serialize_identifier
  Write a CSS identifier, escaping characters as necessary.
• serialize_name
  Write a CSS name, like a custom property name.
• serialize_string
  Write a double-quoted CSS string token, escaping content as necessary.
• stylesheet_encoding
  Determine the character encoding of a CSS stylesheet.