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Tree-shaking for compiled output from the Opal compiler
#!/usr/bin/env ruby
require 'set'
def get_stubs code
code
.scan(/\.add_stubs\(.*\)/)
.map { |call| call.scan(/"\$?(\w+)"/) }
.flatten
.to_set
end
code = ARGF.read
whitelisted_calls = Set.new(%w(
new
))
all_filtered = Set.new
original_stubs = get_stubs(code)
difference = -1
method_def = /\w+\.defn\(\w+,"\$([\w\*%]+)"/
method_call = /\.\$(\w+)|\["\$([\w\*%])"\]/
method_alias = /\w+\.alias\(\w+,"\w+","([\w\*%]+)"/
method_object = /\w+\.\$method\("([\w\*%]+)"\)/
while difference != 0
calls = (
code.scan(method_call) +
code.scan(method_alias) +
code.scan(method_object) +
[]
)
calls = calls
.flatten
.to_set
method_defs = code
.scan(method_def)
.flatten
.to_set
filtered = method_defs - (calls + whitelisted_calls)
all_filtered |= filtered
# STDERR.puts(
# method_defs: method_defs.count,
# calls: calls.count,
# whitelisted_calls: whitelisted_calls.count,
# filtered: filtered.count,
# )
difference = filtered.count
position = 0
while position
position = code.index(method_def, position)
method_name = $1
if filtered.include? method_name
eom = position + 1
char = nil
nesting = 0
until char == ')' && nesting.zero?
char = code[eom]
case char
when '('
nesting += 1
when ')'
nesting -= 1
end
eom += 1
end
if code[eom] == ','
code[position..eom] = ''
else
code[position...eom] = ''
end
else
if position
position += 1
else
break
end
end
end
end
code = code.gsub(/,([\)\}])/, '\1')
code.gsub!(/\.add_stubs\(.*?\)/) do |match|
methods = match.scan(/\$([^"]+)/).flatten
stubs = (methods.to_set - all_filtered)
.map { |stub| "$#{stub}".inspect }
.join(',')
".add_stubs([#{stubs}])"
end
new_stubs = get_stubs(code)
STDERR.puts "Filtered methods:"
STDERR.puts all_filtered.sort.map { |m| "- #{m}" }
STDERR.puts "Eliminated #{all_filtered.count} method definitions"
STDERR.puts "Eliminated %d/%d stubs (%d%%)" % [
(original_stubs - new_stubs).count,
original_stubs.count,
(original_stubs - new_stubs).count.to_f * 100 / original_stubs.count,
]
puts code
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