Class: SyntaxTree::CSS::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/syntax_tree/css/parser.rb

Overview

Parses CSS3 stylesheets according to www.w3.org/TR/css-syntax-3 from the version dated 24 December 2021.

Defined Under Namespace

Classes: ParseError, State

Constant Summary collapse

DIGIT =

www.w3.org/TR/css-syntax-3/#digit

"[0-9]"
UPPERCASE_LETTER =

www.w3.org/TR/css-syntax-3/#uppercase-letter

"[A-Z]"
LOWERCASE_LETTER =

www.w3.org/TR/css-syntax-3/#lowercase-letter

"[a-z]"
LETTER =

www.w3.org/TR/css-syntax-3/#letter

"[#{UPPERCASE_LETTER}#{LOWERCASE_LETTER}]"
NONASCII =

www.w3.org/TR/css-syntax-3/#non-ascii-code-point

"[\u{80}-\u{10FFFF}]"
IDENT_START =

www.w3.org/TR/css-syntax-3/#ident-start-code-point

"[#{LETTER}#{NONASCII}_]"
IDENT =

www.w3.org/TR/css-syntax-3/#ident-code-point

"[#{IDENT_START}#{DIGIT}-]"
NON_PRINTABLE =

www.w3.org/TR/css-syntax-3/#non-printable-code-point

"[\x00-\x08\x0B\x0E-\x1F\x7F]"
WHITESPACE =

www.w3.org/TR/css-syntax-3/#whitespace

"[\n\t ]"

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(source) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/syntax_tree/css/parser.rb', line 52

def initialize(source)
  @source = preprocess(source)
  @errors = []
end

Instance Attribute Details

#errors ⇒ Object (readonly)

Returns the value of attribute errors.



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# File 'lib/syntax_tree/css/parser.rb', line 50

def errors
  @errors
end

#source ⇒ Object (readonly)

Returns the value of attribute source.



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# File 'lib/syntax_tree/css/parser.rb', line 50

def source
  @source
end

Instance Method Details

#error? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/syntax_tree/css/parser.rb', line 57

def error?
  errors.any?
end

#parse(grammar: :stylesheet) ⇒ Object

5.3.1. Parse something according to a CSS grammar www.w3.org/TR/css-syntax-3/#parse-grammar



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# File 'lib/syntax_tree/css/parser.rb', line 68

def parse(grammar: :stylesheet)
  case grammar
  in :stylesheet
    parse_css_stylesheet
  else
    raise ArgumentError, "Unsupported grammar: #{grammar}"
  end
end

#parse_component_value ⇒ Object

5.3.9. Parse a component value www.w3.org/TR/css-syntax-3/#parse-component-value



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# File 'lib/syntax_tree/css/parser.rb', line 189

def parse_component_value
  # 1.
  tokens = tokenize

  # 2.
  loop do
    case tokens.peek
    in CommentToken | WhitespaceToken
      tokens.next
    else
      break
    end
  end

  # 3.
  if tokens.peek.is_a?(EOFToken)
    return ParseError.new("Unexpected end of input parsing component value")
  end

  # 4.
  value = consume_component_value(tokens)

  # 5.
  loop do
    case tokens.peek
    in CommentToken | WhitespaceToken
      tokens.next
    else
      break
    end
  end

  # 6.
  if tokens.peek.is_a?(EOFToken)
    value
  else
    ParseError.new("Expected end of input parsing component value")
  end
end

#parse_component_values ⇒ Object

5.3.10. Parse a list of component values www.w3.org/TR/css-syntax-3/#parse-list-of-component-values



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# File 'lib/syntax_tree/css/parser.rb', line 231

def parse_component_values
  tokens = tokenize
  values = []

  values << consume_component_value(tokens) until tokens.peek.is_a?(EOFToken)
  values
end

#parse_declaration ⇒ Object

5.3.6. Parse a declaration www.w3.org/TR/css-syntax-3/#parse-declaration



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# File 'lib/syntax_tree/css/parser.rb', line 149

def parse_declaration
  # 1.
  tokens = tokenize

  # 2.
  loop do
    case tokens.peek
    in CommentToken | WhitespaceToken
      tokens.next
    else
      break
    end
  end

  # 3.
  case tokens.peek
  in IdentToken
    # do nothing
  in EOFToken
    return ParseError.new("Unexpected end of input parsing declaration")
  else
    return ParseError.new("Expected an identifier at #{tokens.peek.location.start_char}")
  end

  # 4.
  if (declaration = consume_declaration(tokens))
    declaration
  else
    ParseError.new("Expected a declaration at #{tokens.peek.location.start_char}")
  end
end

#parse_declaration_list ⇒ Object

5.3.8. Parse a list of declarations www.w3.org/TR/css-syntax-3/#parse-list-of-declarations



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# File 'lib/syntax_tree/css/parser.rb', line 183

def parse_declaration_list
  consume_declaration_list(tokenize)
end

#parse_rule ⇒ Object

5.3.5. Parse a rule www.w3.org/TR/css-syntax-3/#parse-rule



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# File 'lib/syntax_tree/css/parser.rb', line 101

def parse_rule
  # 1.
  tokens = tokenize

  # 2.
  loop do
    case tokens.peek
    in CommentToken | WhitespaceToken
      tokens.next
    else
      break
    end
  end

  # 3.
  rule = nil

  case tokens.peek
  in EOFToken
    return ParseError.new("Unexpected end of input parsing rule")
  in AtKeywordToken
    rule = consume_at_rule(tokens)
  else
    rule = consume_qualified_rule(tokens)
    return ParseError.new("Expected a rule at #{tokens.peek.location.start_char}") unless rule
  end

  # 4.
  loop do
    case tokens.peek
    in CommentToken | WhitespaceToken
      tokens.next
    else
      break
    end
  end

  # 5.
  case tokens.peek
  in EOFToken
    rule
  else
    ParseError.new("Expected end of input parsing rule")
  end
end

#parse_rule_list ⇒ Object

5.3.4. Parse a list of rules www.w3.org/TR/css-syntax-3/#parse-list-of-rules



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# File 'lib/syntax_tree/css/parser.rb', line 95

def parse_rule_list
  consume_rule_list(tokenize, top_level: false)
end

#parse_stylesheet ⇒ Object

5.3.3. Parse a stylesheet www.w3.org/TR/css-syntax-3/#parse-stylesheet



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# File 'lib/syntax_tree/css/parser.rb', line 79

def parse_stylesheet
  tokens = tokenize
  rules = consume_rule_list(tokens, top_level: true)

  location =
    if rules.any?
      rules.first.location.to(rules.last.location)
    else
      tokens.reverse_each.first.location
    end

  StyleSheet.new(rules: rules, location: location)
end