Feature #19070: Enhance keep_tokens option for RubyVM::AbstractSyntaxTree parsing methods

• Status: Closed
• Assignee: -
• Target version: -

[yui-knk (Kaneko Yuichiro)]

Background

Implementation for Language Server Protocol (LSP) sometimes needs token information. For example both m(1) and m(1, ) has same AST structure other than node locations then it's impossible to check the existence of , from AST. However in later case, it might be better to suggest variables list for the second argument. Token information is important for such case.

Example

require "pp"

node = RubyVM::AbstractSyntaxTree.parse(<<~STR, keep_tokens: true)
def m(a, b = 1, *rest, &block)
end

m(1, )
STR
defn  = node.children[2].children[0]
fcall = node.children[2].children[1]

puts "defn.tokens"
pp defn.tokens
puts "\n\n"

puts "fcall.tokens"
pp fcall.tokens
puts "\n\n"

puts defn.tokens.map{_1[2]}.join
puts fcall.tokens.map{_1[2]}.join

shows below, where token is [sequence_id, token_type, token_string, [first_line, first_column, last_line, last_column]]

defn.tokens
[[0, :kw, "def", [1, 0, 1, 3]],
 [1, :sp, " ", [1, 3, 1, 4]],
 [2, :ident, "m", [1, 4, 1, 5]],
 [3, :lparen, "(", [1, 5, 1, 6]],
 [4, :ident, "a", [1, 6, 1, 7]],
 [5, :comma, ",", [1, 7, 1, 8]],
 [6, :sp, " ", [1, 8, 1, 9]],
 [7, :ident, "b", [1, 9, 1, 10]],
 [8, :sp, " ", [1, 10, 1, 11]],
 [9, :op, "=", [1, 11, 1, 12]],
 [10, :sp, " ", [1, 12, 1, 13]],
 [11, :int, "1", [1, 13, 1, 14]],
 [12, :comma, ",", [1, 14, 1, 15]],
 [13, :sp, " ", [1, 15, 1, 16]],
 [14, :op, "*", [1, 16, 1, 17]],
 [15, :ident, "rest", [1, 17, 1, 21]],
 [16, :comma, ",", [1, 21, 1, 22]],
 [17, :sp, " ", [1, 22, 1, 23]],
 [18, :op, "&", [1, 23, 1, 24]],
 [19, :ident, "block", [1, 24, 1, 29]],
 [20, :rparen, ")", [1, 29, 1, 30]],
 [21, :ignored_nl, "\n", [1, 30, 1, 31]],
 [22, :kw, "end", [2, 0, 2, 3]]]


fcall.tokens
[[25, :ident, "m", [4, 0, 4, 1]],
 [26, :lparen, "(", [4, 1, 4, 2]],
 [27, :int, "1", [4, 2, 4, 3]],
 [28, :comma, ",", [4, 3, 4, 4]],
 [29, :sp, " ", [4, 4, 4, 5]],
 [30, :rparen, ")", [4, 5, 4, 6]]]


def m(a, b = 1, *rest, &block)
end
m(1, )

Interface

• Add keep_tokens option for RubyVM::AbstractSyntaxTree.parse, .parse_file and .of
• Add RubyVM::AbstractSyntaxTree::Node#tokens which returns tokens for the node including tokens for descendants nodes.
• Add RubyVM::AbstractSyntaxTree::Node#all_tokens which returns all tokens for the input script regardless the receiver node.

Implementation

https://github.com/yui-knk/ruby/tree/cst5

[Eregon (Benoit Daloze)]

Doesn't Ripper.lex already provide this information?

[matz (Yukihiro Matsumoto)]

Sounds OK.

Matz.

[yui-knk (Kaneko Yuichiro)]

• Status changed from Open to Closed

Applied in changeset git|d8601621edcf29e3323b90dcf04b774edd9fb45e.

---

Enhance keep_tokens option for RubyVM::AbstractSyntaxTree parsing methods

Implementation for Language Server Protocol (LSP) sometimes needs token information.
For example both m(1) and m(1, ) has same AST structure other than node locations
then it's impossible to check the existence of , from AST. However in later case,
it might be better to suggest variables list for the second argument.
Token information is important for such case.

This commit adds these methods.

• Add keep_tokens option for RubyVM::AbstractSyntaxTree.parse, .parse_file and .of
• Add RubyVM::AbstractSyntaxTree::Node#tokens which returns tokens for the node including tokens for descendants nodes.
• Add RubyVM::AbstractSyntaxTree::Node#all_tokens which returns all tokens for the input script regardless the receiver node.

[Feature #19070]

Impacts on memory usage and performance are below:

Memory usage:

$ cat test.rb
root = RubyVM::AbstractSyntaxTree.parse_file(File.expand_path('../test/ruby/test_keyword.rb', __FILE__), keep_tokens: true)

$ /usr/bin/time -f %Mkb /usr/local/bin/ruby -v
ruby 3.2.0dev (2022-11-19T09:41:54Z 19070-keep_tokens d3af1b8057) [x86_64-linux]
11408kb

# keep_tokens :false
$ /usr/bin/time -f %Mkb /usr/local/bin/ruby test.rb
17508kb

# keep_tokens :true
$ /usr/bin/time -f %Mkb /usr/local/bin/ruby test.rb
30960kb

Performance:

$ cat ../ast_keep_tokens.yml
prelude: |
  src = <<~SRC
    module M
      class C
        def m1(a, b)
          1 + a + b
        end
      end
    end
  SRC
benchmark:
  without_keep_tokens: |
    RubyVM::AbstractSyntaxTree.parse(src, keep_tokens: false)
  with_keep_tokens: |
    RubyVM::AbstractSyntaxTree.parse(src, keep_tokens: true)

$ make benchmark COMPARE_RUBY="./ruby" ARGS=../ast_keep_tokens.yml
/home/kaneko.y/.rbenv/shims/ruby --disable=gems -rrubygems -I../benchmark/lib ../benchmark/benchmark-driver/exe/benchmark-driver \
            --executables="compare-ruby::./ruby -I.ext/common --disable-gem" \
            --executables="built-ruby::./miniruby -I../lib -I. -I.ext/common  ../tool/runruby.rb --extout=.ext  -- --disable-gems --disable-gem" \
            --output=markdown --output-compare -v ../ast_keep_tokens.yml
compare-ruby: ruby 3.2.0dev (2022-11-19T09:41:54Z 19070-keep_tokens d3af1b8057) [x86_64-linux]
built-ruby: ruby 3.2.0dev (2022-11-19T09:41:54Z 19070-keep_tokens d3af1b8057) [x86_64-linux]
warming up..

|                     |compare-ruby|built-ruby|
|:--------------------|-----------:|---------:|
|without_keep_tokens  |     21.659k|   21.303k|
|                     |       1.02x|         -|
|with_keep_tokens     |      6.220k|    5.691k|
|                     |       1.09x|         -|