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Lex whitespace preceding CSS axes separately. 

Previously input such as "x > y" would result in the following token sequences:

    T_IDENT, T_CHILD, T_IDENT

This commit changes this to the following:

    T_IDENT, T_SPACE, T_CHILD, T_IDENT

This allows the parser to use T_SPACE as a terminal token, this in turn prevents
around 16 shift/reduce conflicts from arising.

This does mean that input such as " > y" or " x > y" is now invalid. This
however can be solved by simply _not_ adding leading/trailing whitespace to CSS
queries.
This commit is contained in:
Yorick Peterse 2014-10-21 23:16:25 +02:00
parent e2b4f51e64
commit e3de65a258
2 changed files with 40 additions and 9 deletions
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10
lib/oga/css/lexer.rl
View File

@ -175,9 +175,13 @@ module Oga
op_ends_with = '$=';
op_in = '*=';
op_hyphen_in = '|=';
op_child = whitespace* '>' whitespace*;
op_fol_direct = whitespace* '+' whitespace*;
op_fol = whitespace* '~' whitespace*;
# Whitespace preceding these tokens is _not_ matched to make the parser
# rules more consistent. As such input such as " > x" will result in
# tokens [T_SPACE, T_CHILD, T_IDENT].
op_child = '>' whitespace*;
op_fol_direct = '+' whitespace*;
op_fol = '~' whitespace*;
# Numbers
#

39
spec/oga/css/lexer/axes_spec.rb
View File

@ -6,24 +6,51 @@ describe Oga::CSS::Lexer do
lex_css('>').should == [[:T_CHILD, nil]]
end
example 'lex the > axis with surrounding whitespace' do
lex_css('>').should == [[:T_CHILD, nil]]
example 'lex the expression "> y"' do
lex_css('> y').should == [[:T_CHILD, nil], [:T_IDENT, 'y']]
end
example 'lex the expression "x > y"' do
lex_css('x > y').should == [
[:T_IDENT, 'x'],
[:T_SPACE, nil],
[:T_CHILD, nil],
[:T_IDENT, 'y']
]
end
example 'lex the + axis' do
lex_css('+').should == [[:T_FOLLOWING_DIRECT, nil]]
end
example 'lex the + axis with surrounding whitespace' do
lex_css(' + ').should == [[:T_FOLLOWING_DIRECT, nil]]
example 'lex the expression "+ y"' do
lex_css('+ y').should == [[:T_FOLLOWING_DIRECT, nil], [:T_IDENT, 'y']]
end
example 'lex the expression "x + y"' do
lex_css('x + y').should == [
[:T_IDENT, 'x'],
[:T_SPACE, nil],
[:T_FOLLOWING_DIRECT, nil],
[:T_IDENT, 'y']
]
end
example 'lex the ~ axis' do
lex_css('~').should == [[:T_FOLLOWING, nil]]
end
example 'lex the ~ axis with surrounding whitespace' do
lex_css(' ~ ').should == [[:T_FOLLOWING, nil]]
example 'lex the expression "~ y"' do
lex_css('~ y').should == [[:T_FOLLOWING, nil], [:T_IDENT, 'y']]
end
example 'lex the expression "x ~ y"' do
lex_css('x ~ y').should == [
[:T_IDENT, 'x'],
[:T_SPACE, nil],
[:T_FOLLOWING, nil],
[:T_IDENT, 'y']
]
end
end
end