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Optimize the parse_attributes method to use Source#match to parse …
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…XML. (#119)

## Why?

Improve maintainability by consolidating processing into `Source#match`.

## Benchmark
```
RUBYLIB= BUNDLER_ORIG_RUBYLIB= /Users/naitoh/.rbenv/versions/3.3.0/bin/ruby -v -S benchmark-driver /Users/naitoh/ghq/github.com/naitoh/rexml/benchmark/parse.yaml
ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [arm64-darwin22]
Calculating -------------------------------------
                         before       after  before(YJIT)  after(YJIT)
                 dom     10.891      10.622        16.356       17.403 i/s -     100.000 times in 9.182130s 9.414177s 6.113806s 5.746133s
                 sax     30.335      29.845        49.749       54.877 i/s -     100.000 times in 3.296483s 3.350595s 2.010071s 1.822259s
                pull     35.514      34.801        61.123       66.908 i/s -     100.000 times in 2.815793s 2.873484s 1.636041s 1.494591s
              stream     35.141      34.475        52.110       56.836 i/s -     100.000 times in 2.845646s 2.900638s 1.919017s 1.759456s

Comparison:
                              dom
         after(YJIT):        17.4 i/s
        before(YJIT):        16.4 i/s - 1.06x  slower
              before:        10.9 i/s - 1.60x  slower
               after:        10.6 i/s - 1.64x  slower

                              sax
         after(YJIT):        54.9 i/s
        before(YJIT):        49.7 i/s - 1.10x  slower
              before:        30.3 i/s - 1.81x  slower
               after:        29.8 i/s - 1.84x  slower

                             pull
         after(YJIT):        66.9 i/s
        before(YJIT):        61.1 i/s - 1.09x  slower
              before:        35.5 i/s - 1.88x  slower
               after:        34.8 i/s - 1.92x  slower

                           stream
         after(YJIT):        56.8 i/s
        before(YJIT):        52.1 i/s - 1.09x  slower
              before:        35.1 i/s - 1.62x  slower
               after:        34.5 i/s - 1.65x  slower

```

- YJIT=ON : 1.06x - 1.10x faster
- YJIT=OFF : 0.97x - 0.98x faster
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@naitoh
naitoh authored Mar 18, 2024
1 parent d4e79f2 commit 0496940
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Showing 3 changed files with 64 additions and 76 deletions.
116 changes: 44 additions & 72 deletions lib/rexml/parsers/baseparser.rb
View file
Original file line number Diff line number Diff line change
Expand Up @@ -114,7 +114,7 @@ class BaseParser

module Private
INSTRUCTION_END = /#{NAME}(\s+.*?)?\?>/um
TAG_PATTERN = /((?>#{QNAME_STR}))/um
TAG_PATTERN = /((?>#{QNAME_STR}))\s*/um
CLOSE_PATTERN = /(#{QNAME_STR})\s*>/um
ATTLISTDECL_END = /\s+#{NAME}(?:#{ATTDEF})*\s*>/um
NAME_PATTERN = /\s*#{NAME}/um
Expand All @@ -128,7 +128,6 @@ module Private
def initialize( source )
self.stream = source
@listeners = []
@attributes_scanner = StringScanner.new('')
end

def add_listener( listener )
Expand Down Expand Up @@ -614,87 +613,60 @@ def process_instruction(start_position)
def parse_attributes(prefixes, curr_ns)
attributes = {}
closed = false
match_data = @source.match(/^(.*?)(\/)?>/um, true)
if match_data.nil?
message = "Start tag isn't ended"
raise REXML::ParseException.new(message, @source)
end

raw_attributes = match_data[1]
closed = !match_data[2].nil?
return attributes, closed if raw_attributes.nil?
return attributes, closed if raw_attributes.empty?

@attributes_scanner.string = raw_attributes
scanner = @attributes_scanner
until scanner.eos?
if scanner.scan(/\s+/)
break if scanner.eos?
end

start_position = scanner.pos
while true
break if scanner.scan(ATTRIBUTE_PATTERN)
unless scanner.scan(QNAME)
message = "Invalid attribute name: <#{scanner.rest}>"
raise REXML::ParseException.new(message, @source)
end
name = scanner[0]
unless scanner.scan(/\s*=\s*/um)
while true
if @source.match(">", true)
return attributes, closed
elsif @source.match("/>", true)
closed = true
return attributes, closed
elsif match = @source.match(QNAME, true)
name = match[1]
prefix = match[2]
local_part = match[3]

unless @source.match(/\s*=\s*/um, true)
message = "Missing attribute equal: <#{name}>"
raise REXML::ParseException.new(message, @source)
end
quote = scanner.scan(/['"]/)
unless quote
message = "Missing attribute value start quote: <#{name}>"
raise REXML::ParseException.new(message, @source)
end
unless scanner.scan(/.*#{Regexp.escape(quote)}/um)
@source.ensure_buffer
match_data = @source.match(/^(.*?)(\/)?>/um, true)
if match_data
scanner << "/" if closed
scanner << ">"
scanner << match_data[1]
scanner.pos = start_position
closed = !match_data[2].nil?
next
unless match = @source.match(/(['"])(.*?)\1\s*/um, true)
if match = @source.match(/(['"])/, true)
message =
"Missing attribute value end quote: <#{name}>: <#{match[1]}>"
raise REXML::ParseException.new(message, @source)
else
message = "Missing attribute value start quote: <#{name}>"
raise REXML::ParseException.new(message, @source)
end
message =
"Missing attribute value end quote: <#{name}>: <#{quote}>"
raise REXML::ParseException.new(message, @source)
end
end
name = scanner[1]
prefix = scanner[2]
local_part = scanner[3]
# quote = scanner[4]
value = scanner[5]
if prefix == "xmlns"
if local_part == "xml"
if value != "http://www.w3.org/XML/1998/namespace"
msg = "The 'xml' prefix must not be bound to any other namespace "+
value = match[2]
if prefix == "xmlns"
if local_part == "xml"
if value != "http://www.w3.org/XML/1998/namespace"
msg = "The 'xml' prefix must not be bound to any other namespace "+
"(http://www.w3.org/TR/REC-xml-names/#ns-decl)"
raise REXML::ParseException.new( msg, @source, self )
end
elsif local_part == "xmlns"
msg = "The 'xmlns' prefix must not be declared "+
"(http://www.w3.org/TR/REC-xml-names/#ns-decl)"
raise REXML::ParseException.new( msg, @source, self )
raise REXML::ParseException.new( msg, @source, self)
end
elsif local_part == "xmlns"
msg = "The 'xmlns' prefix must not be declared "+
"(http://www.w3.org/TR/REC-xml-names/#ns-decl)"
raise REXML::ParseException.new( msg, @source, self)
curr_ns << local_part
elsif prefix
prefixes << prefix unless prefix == "xml"
end
curr_ns << local_part
elsif prefix
prefixes << prefix unless prefix == "xml"
end

if attributes.has_key?(name)
msg = "Duplicate attribute #{name.inspect}"
raise REXML::ParseException.new(msg, @source, self)
end
if attributes.has_key?(name)
msg = "Duplicate attribute #{name.inspect}"
raise REXML::ParseException.new(msg, @source, self)
end

attributes[name] = value
attributes[name] = value
else
message = "Invalid attribute name: <#{@source.buffer.split(%r{[/>\s]}).first}>"
raise REXML::ParseException.new(message, @source)
end
end
return attributes, closed
end
end
end
Expand Down
4 changes: 2 additions & 2 deletions test/parse/test_element.rb
View file
Original file line number Diff line number Diff line change
Expand Up @@ -41,9 +41,9 @@ def test_empty_namespace_attribute_name
assert_equal(<<-DETAIL.chomp, exception.to_s)
Invalid attribute name: <:a="">
Line: 1
Position: 9
Position: 13
Last 80 unconsumed characters:
:a=""></x>
DETAIL
end

Expand Down
20 changes: 18 additions & 2 deletions test/test_core.rb
View file
Original file line number Diff line number Diff line change
Expand Up @@ -116,11 +116,12 @@ def test_attribute

def test_attribute_namespace_conflict
# https://www.w3.org/TR/xml-names/#uniqAttrs
message = <<-MESSAGE
message = <<-MESSAGE.chomp
Duplicate attribute "a"
Line: 4
Position: 140
Last 80 unconsumed characters:
/>
MESSAGE
assert_raise(REXML::ParseException.new(message)) do
Document.new(<<-XML)
Expand Down Expand Up @@ -1323,11 +1324,26 @@ def test_ticket_21
exception = assert_raise(ParseException) do
Document.new(src)
end
assert_equal(<<-DETAIL, exception.to_s)
assert_equal(<<-DETAIL.chomp, exception.to_s)
Missing attribute value start quote: <bar>
Line: 1
Position: 16
Last 80 unconsumed characters:
value/>
DETAIL
end

def test_parse_exception_on_missing_attribute_end_quote
src = '<foo bar="value/>'
exception = assert_raise(ParseException) do
Document.new(src)
end
assert_equal(<<-DETAIL.chomp, exception.to_s)
Missing attribute value end quote: <bar>: <">
Line: 1
Position: 17
Last 80 unconsumed characters:
value/>
DETAIL
end

Expand Down

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