518 lines
17 KiB
Ruby
518 lines
17 KiB
Ruby
require 'sass/scss/rx'
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module Sass
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module Script
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# The lexical analyzer for SassScript.
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# It takes a raw string and converts it to individual tokens
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# that are easier to parse.
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class Lexer
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include Sass::SCSS::RX
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# A struct containing information about an individual token.
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#
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# `type`: \[`Symbol`\]
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# : The type of token.
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#
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# `value`: \[`Object`\]
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# : The Ruby object corresponding to the value of the token.
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#
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# `source_range`: \[`Sass::Source::Range`\]
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# : The range in the source file in which the token appeared.
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#
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# `pos`: \[`Integer`\]
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# : The scanner position at which the SassScript token appeared.
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Token = Struct.new(:type, :value, :source_range, :pos)
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# The line number of the lexer's current position.
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#
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# @return [Integer]
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def line
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return @line unless @tok
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@tok.source_range.start_pos.line
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end
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# The number of bytes into the current line
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# of the lexer's current position (1-based).
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#
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# @return [Integer]
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def offset
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return @offset unless @tok
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@tok.source_range.start_pos.offset
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end
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# A hash from operator strings to the corresponding token types.
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OPERATORS = {
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'+' => :plus,
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'-' => :minus,
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'*' => :times,
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'/' => :div,
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'%' => :mod,
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'=' => :single_eq,
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':' => :colon,
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'(' => :lparen,
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')' => :rparen,
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'[' => :lsquare,
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']' => :rsquare,
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',' => :comma,
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'and' => :and,
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'or' => :or,
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'not' => :not,
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'==' => :eq,
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'!=' => :neq,
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'>=' => :gte,
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'<=' => :lte,
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'>' => :gt,
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'<' => :lt,
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'#{' => :begin_interpolation,
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'}' => :end_interpolation,
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';' => :semicolon,
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'{' => :lcurly,
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'...' => :splat,
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}
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OPERATORS_REVERSE = Sass::Util.map_hash(OPERATORS) {|k, v| [v, k]}
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TOKEN_NAMES = Sass::Util.map_hash(OPERATORS_REVERSE) {|k, v| [k, v.inspect]}.merge(
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:const => "variable (e.g. $foo)",
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:ident => "identifier (e.g. middle)")
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# A list of operator strings ordered with longer names first
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# so that `>` and `<` don't clobber `>=` and `<=`.
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OP_NAMES = OPERATORS.keys.sort_by {|o| -o.size}
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# A sub-list of {OP_NAMES} that only includes operators
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# with identifier names.
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IDENT_OP_NAMES = OP_NAMES.select {|k, _v| k =~ /^\w+/}
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PARSEABLE_NUMBER = /(?:(\d*\.\d+)|(\d+))(?:[eE]([+-]?\d+))?(#{UNIT})?/
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# A hash of regular expressions that are used for tokenizing.
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REGULAR_EXPRESSIONS = {
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:whitespace => /\s+/,
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:comment => COMMENT,
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:single_line_comment => SINGLE_LINE_COMMENT,
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:variable => /(\$)(#{IDENT})/,
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:ident => /(#{IDENT})(\()?/,
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:number => PARSEABLE_NUMBER,
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:unary_minus_number => /-#{PARSEABLE_NUMBER}/,
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:color => HEXCOLOR,
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:id => /##{IDENT}/,
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:selector => /&/,
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:ident_op => /(#{Regexp.union(*IDENT_OP_NAMES.map do |s|
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Regexp.new(Regexp.escape(s) + "(?!#{NMCHAR}|\Z)")
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end)})/,
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:op => /(#{Regexp.union(*OP_NAMES)})/,
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}
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class << self
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private
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def string_re(open, close)
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/#{open}((?:\\.|\#(?!\{)|[^#{close}\\#])*)(#{close}|#\{)/m
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end
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end
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# A hash of regular expressions that are used for tokenizing strings.
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#
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# The key is a `[Symbol, Boolean]` pair.
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# The symbol represents which style of quotation to use,
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# while the boolean represents whether or not the string
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# is following an interpolated segment.
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STRING_REGULAR_EXPRESSIONS = {
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:double => {
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false => string_re('"', '"'),
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true => string_re('', '"')
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},
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:single => {
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false => string_re("'", "'"),
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true => string_re('', "'")
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},
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:uri => {
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false => /url\(#{W}(#{URLCHAR}*?)(#{W}\)|#\{)/,
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true => /(#{URLCHAR}*?)(#{W}\)|#\{)/
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},
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# Defined in https://developer.mozilla.org/en/CSS/@-moz-document as a
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# non-standard version of http://www.w3.org/TR/css3-conditional/
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:url_prefix => {
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false => /url-prefix\(#{W}(#{URLCHAR}*?)(#{W}\)|#\{)/,
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true => /(#{URLCHAR}*?)(#{W}\)|#\{)/
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},
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:domain => {
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false => /domain\(#{W}(#{URLCHAR}*?)(#{W}\)|#\{)/,
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true => /(#{URLCHAR}*?)(#{W}\)|#\{)/
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}
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}
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# @param str [String, StringScanner] The source text to lex
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# @param line [Integer] The 1-based line on which the SassScript appears.
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# Used for error reporting and sourcemap building
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# @param offset [Integer] The 1-based character (not byte) offset in the line in the source.
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# Used for error reporting and sourcemap building
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# @param options [{Symbol => Object}] An options hash;
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# see {file:SASS_REFERENCE.md#Options the Sass options documentation}
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def initialize(str, line, offset, options)
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@scanner = str.is_a?(StringScanner) ? str : Sass::Util::MultibyteStringScanner.new(str)
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@line = line
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@offset = offset
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@options = options
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@interpolation_stack = []
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@prev = nil
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@tok = nil
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@next_tok = nil
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end
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# Moves the lexer forward one token.
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#
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# @return [Token] The token that was moved past
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def next
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@tok ||= read_token
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@tok, tok = nil, @tok
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@prev = tok
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tok
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end
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# Returns whether or not there's whitespace before the next token.
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#
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# @return [Boolean]
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def whitespace?(tok = @tok)
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if tok
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@scanner.string[0...tok.pos] =~ /\s\Z/
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else
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@scanner.string[@scanner.pos, 1] =~ /^\s/ ||
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@scanner.string[@scanner.pos - 1, 1] =~ /\s\Z/
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end
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end
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# Returns the given character.
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#
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# @return [String]
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def char(pos = @scanner.pos)
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@scanner.string[pos, 1]
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end
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# Consumes and returns single raw character from the input stream.
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#
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# @return [String]
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def next_char
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unpeek!
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scan(/./)
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end
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# Returns the next token without moving the lexer forward.
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#
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# @return [Token] The next token
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def peek
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@tok ||= read_token
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end
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# Rewinds the underlying StringScanner
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# to before the token returned by \{#peek}.
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def unpeek!
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raise "[BUG] Can't unpeek before a queued token!" if @next_tok
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return unless @tok
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@scanner.pos = @tok.pos
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@line = @tok.source_range.start_pos.line
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@offset = @tok.source_range.start_pos.offset
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end
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# @return [Boolean] Whether or not there's more source text to lex.
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def done?
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return if @next_tok
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whitespace unless after_interpolation? && !@interpolation_stack.empty?
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@scanner.eos? && @tok.nil?
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end
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# @return [Boolean] Whether or not the last token lexed was `:end_interpolation`.
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def after_interpolation?
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@prev && @prev.type == :end_interpolation
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end
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# Raise an error to the effect that `name` was expected in the input stream
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# and wasn't found.
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#
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# This calls \{#unpeek!} to rewind the scanner to immediately after
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# the last returned token.
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#
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# @param name [String] The name of the entity that was expected but not found
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# @raise [Sass::SyntaxError]
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def expected!(name)
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unpeek!
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Sass::SCSS::Parser.expected(@scanner, name, @line)
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end
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# Records all non-comment text the lexer consumes within the block
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# and returns it as a string.
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#
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# @yield A block in which text is recorded
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# @return [String]
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def str
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old_pos = @tok ? @tok.pos : @scanner.pos
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yield
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new_pos = @tok ? @tok.pos : @scanner.pos
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@scanner.string[old_pos...new_pos]
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end
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# Runs a block, and rewinds the state of the lexer to the beginning of the
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# block if it returns `nil` or `false`.
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def try
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old_pos = @scanner.pos
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old_line = @line
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old_offset = @offset
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old_interpolation_stack = @interpolation_stack.dup
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old_prev = @prev
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old_tok = @tok
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old_next_tok = @next_tok
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result = yield
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return result if result
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@scanner.pos = old_pos
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@line = old_line
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@offset = old_offset
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@interpolation_stack = old_interpolation_stack
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@prev = old_prev
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@tok = old_tok
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@next_tok = old_next_tok
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nil
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end
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private
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def read_token
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if (tok = @next_tok)
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@next_tok = nil
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return tok
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end
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return if done?
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start_pos = source_position
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value = token
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return unless value
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type, val = value
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Token.new(type, val, range(start_pos), @scanner.pos - @scanner.matched_size)
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end
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def whitespace
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nil while scan(REGULAR_EXPRESSIONS[:whitespace]) ||
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scan(REGULAR_EXPRESSIONS[:comment]) ||
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scan(REGULAR_EXPRESSIONS[:single_line_comment])
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end
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def token
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if after_interpolation?
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interp_type, interp_value = @interpolation_stack.pop
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if interp_type == :special_fun
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return special_fun_body(interp_value)
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elsif interp_type.nil?
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if @scanner.string[@scanner.pos - 1] == '}' && scan(REGULAR_EXPRESSIONS[:ident])
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return [@scanner[2] ? :funcall : :ident, Sass::Util.normalize_ident_escapes(@scanner[1], start: false)]
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end
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else
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raise "[BUG]: Unknown interp_type #{interp_type}" unless interp_type == :string
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return string(interp_value, true)
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end
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end
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variable || string(:double, false) || string(:single, false) || number || id || color ||
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selector || string(:uri, false) || raw(UNICODERANGE) || special_fun || special_val ||
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ident_op || ident || op
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end
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def variable
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_variable(REGULAR_EXPRESSIONS[:variable])
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end
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def _variable(rx)
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return unless scan(rx)
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[:const, Sass::Util.normalize_ident_escapes(@scanner[2])]
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end
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def ident
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return unless scan(REGULAR_EXPRESSIONS[:ident])
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[@scanner[2] ? :funcall : :ident, Sass::Util.normalize_ident_escapes(@scanner[1])]
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end
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def string(re, open)
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line, offset = @line, @offset
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return unless scan(STRING_REGULAR_EXPRESSIONS[re][open])
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if @scanner[0] =~ /([^\\]|^)\n/
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filename = @options[:filename]
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Sass::Util.sass_warn <<MESSAGE
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DEPRECATION WARNING on line #{line}, column #{offset}#{" of #{filename}" if filename}:
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Unescaped multiline strings are deprecated and will be removed in a future version of Sass.
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To include a newline in a string, use "\\a" or "\\a " as in CSS.
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MESSAGE
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end
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if @scanner[2] == '#{' # '
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@interpolation_stack << [:string, re]
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start_pos = Sass::Source::Position.new(@line, @offset - 2)
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@next_tok = Token.new(:string_interpolation, range(start_pos), @scanner.pos - 2)
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end
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str =
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if re == :uri
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url = "#{'url(' unless open}#{@scanner[1]}#{')' unless @scanner[2] == '#{'}"
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Script::Value::String.new(url)
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else
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Script::Value::String.new(Sass::Script::Value::String.value(@scanner[1]), :string)
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end
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[:string, str]
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end
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def number
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# Handling unary minus is complicated by the fact that whitespace is an
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# operator in SassScript. We want "1-2" to be parsed as "1 - 2", but we
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# want "1 -2" to be parsed as "1 (-2)". To accomplish this, we only
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# parse a unary minus as part of a number literal if there's whitespace
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# before and not after it. Cases like "(-2)" are handled by the unary
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# minus logic in the parser instead.
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if @scanner.peek(1) == '-'
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return if @scanner.pos == 0
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unary_minus_allowed =
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case @scanner.string[@scanner.pos - 1, 1]
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when /\s/; true
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when '/'; @scanner.pos != 1 && @scanner.string[@scanner.pos - 2, 1] == '*'
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else; false
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end
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return unless unary_minus_allowed
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return unless scan(REGULAR_EXPRESSIONS[:unary_minus_number])
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minus = true
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else
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return unless scan(REGULAR_EXPRESSIONS[:number])
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minus = false
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end
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value = (@scanner[1] ? @scanner[1].to_f : @scanner[2].to_i) * (minus ? -1 : 1)
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value *= 10**@scanner[3].to_i if @scanner[3]
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units = @scanner[4]
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units = Sass::Util::normalize_ident_escapes(units) if units
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script_number = Script::Value::Number.new(value, Array(units))
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[:number, script_number]
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end
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def id
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# Colors and ids are tough to tell apart, because they overlap but
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# neither is a superset of the other. "#xyz" is an id but not a color,
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# "#000" is a color but not an id, "#abc" is both, and "#0" is neither.
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# We need to handle all these cases correctly.
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#
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# To do so, we first try to parse something as an id. If this works and
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# the id is also a valid color, we return the color. Otherwise, we
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# return the id. If it didn't parse as an id, we then try to parse it as
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# a color. If *this* works, we return the color, and if it doesn't we
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# give up and throw an error.
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#
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# IDs in properties are used in the Basic User Interface Module
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# (http://www.w3.org/TR/css3-ui/).
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return unless scan(REGULAR_EXPRESSIONS[:id])
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if @scanner[0] =~ /^\#[0-9a-fA-F]+$/ &&
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(@scanner[0].length == 4 || @scanner[0].length == 5 ||
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@scanner[0].length == 7 || @scanner[0].length == 9)
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return [:color, Script::Value::Color.from_hex(@scanner[0])]
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end
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[:ident, Sass::Util.normalize_ident_escapes(@scanner[0])]
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end
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def color
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return unless @scanner.match?(REGULAR_EXPRESSIONS[:color])
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unless @scanner[0].length == 4 || @scanner[0].length == 5 ||
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@scanner[0].length == 7 || @scanner[0].length == 9
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return
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end
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script_color = Script::Value::Color.from_hex(scan(REGULAR_EXPRESSIONS[:color]))
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[:color, script_color]
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end
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def selector
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start_pos = source_position
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return unless scan(REGULAR_EXPRESSIONS[:selector])
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if @scanner.peek(1) == '&'
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filename = @options[:filename]
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Sass::Util.sass_warn <<MESSAGE
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WARNING on line #{line}, column #{offset}#{" of #{filename}" if filename}:
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In Sass, "&&" means two copies of the parent selector. You probably want to use "and" instead.
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MESSAGE
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end
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script_selector = Script::Tree::Selector.new
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script_selector.source_range = range(start_pos)
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[:selector, script_selector]
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end
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def special_fun
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prefix = scan(/((-[\w-]+-)?(calc|element)|expression|progid:[a-z\.]*)\(/i)
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return unless prefix
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special_fun_body(1, prefix)
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end
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def special_fun_body(parens, prefix = nil)
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str = prefix || ''
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while (scanned = scan(/.*?([()]|\#\{)/m))
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str << scanned
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if scanned[-1] == ?(
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parens += 1
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next
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elsif scanned[-1] == ?)
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parens -= 1
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next unless parens == 0
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else
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raise "[BUG] Unreachable" unless @scanner[1] == '#{' # '
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str.slice!(-2..-1)
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@interpolation_stack << [:special_fun, parens]
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start_pos = Sass::Source::Position.new(@line, @offset - 2)
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@next_tok = Token.new(:string_interpolation, range(start_pos), @scanner.pos - 2)
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end
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return [:special_fun, Sass::Script::Value::String.new(str)]
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end
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scan(/.*/)
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expected!('")"')
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end
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def special_val
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return unless scan(/!#{W}important/i)
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[:string, Script::Value::String.new("!important")]
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end
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def ident_op
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op = scan(REGULAR_EXPRESSIONS[:ident_op])
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return unless op
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[OPERATORS[op]]
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end
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def op
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op = scan(REGULAR_EXPRESSIONS[:op])
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return unless op
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name = OPERATORS[op]
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@interpolation_stack << nil if name == :begin_interpolation
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[name]
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end
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def raw(rx)
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val = scan(rx)
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return unless val
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[:raw, val]
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end
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def scan(re)
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str = @scanner.scan(re)
|
|
return unless str
|
|
c = str.count("\n")
|
|
@line += c
|
|
@offset = (c == 0 ? @offset + str.size : str.size - str.rindex("\n"))
|
|
str
|
|
end
|
|
|
|
def range(start_pos, end_pos = source_position)
|
|
Sass::Source::Range.new(start_pos, end_pos, @options[:filename], @options[:importer])
|
|
end
|
|
|
|
def source_position
|
|
Sass::Source::Position.new(@line, @offset)
|
|
end
|
|
end
|
|
end
|
|
end
|