Class: Dommy::Js::Quickjs::SourceGuard::Rewriter

Inherits:
Object
  • Object
show all
Defined in:
lib/dommy/js/quickjs/source_guard.rb

Overview

Walks source once, copying literals/comments verbatim and rewriting a for-of-with-yield-in-iterable found at a statement boundary.

Constant Summary collapse

HEAD_SCAN_LIMIT =

Upper bound on a ‘for (…)` head length we will consider (well above any real for-of header, including a large iterable expression).

64 * 1024

Instance Method Summary collapse

Constructor Details

#initialize(src) ⇒ Rewriter

Returns a new instance of Rewriter.



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# File 'lib/dommy/js/quickjs/source_guard.rb', line 230

def initialize(src)
  @src = src
  @n = src.length
end

Instance Method Details

#run ⇒ Object 



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# File 'lib/dommy/js/quickjs/source_guard.rb', line 235

def run
  out = +""
  i = 0
  prev = nil  # previous significant code char
  counter = 0
  while i < @n
    stop = SourceGuard.atom_end(@src, i, prev)
    if stop
      out << @src[i...stop]
      prev = @src[stop - 1]
      i = stop
      next
    end

    ch = @src[i]
    if ch == "f" && @src[i, 3] == "for" &&
       !SourceGuard.ident_char?(i.zero? ? nil : @src[i - 1]) &&
       !SourceGuard.ident_char?(@src[i + 3]) &&
       boundary?(prev)
      rewrite = transform_for(i, counter)
      if rewrite
        out << rewrite[:text]
        i = rewrite[:next]
        counter += 1
        prev = ")"
        next
      end
    end

    out << ch
    prev = ch unless ch =~ /\s/
    i += 1
  end
  out
end