Class: Opal::Nodes::IfNode

Inherits:
Base
  • Object
show all
Defined in:
opal/lib/opal/nodes/if.rb

Instance Attribute Summary

Attributes inherited from Base

#compiler, #sexp, #type

Instance Method Summary collapse

Methods inherited from Base

#add_gvar, #add_ivar, #add_local, #add_temp, #children, children, #class_variable_owner, #class_variable_owner_nesting_level, #comments, #compile_to_fragments, #error, #expr, #expr?, #expr_or_nil, #fragment, handle, handlers, #has_rescue_else?, #helper, #in_ensure, #in_ensure?, #in_resbody, #in_resbody?, #in_rescue, #in_while?, #initialize, #process, #push, #recv, #recv?, #s, #scope, #source_location, #stmt, #stmt?, #top_scope, truthy_optimize?, #unshift, #while_loop, #with_temp, #wrap

Methods included from Helpers

#conditional_send, #current_indent, #empty_line, #indent, #js_truthy, #js_truthy_optimize, #line, #mid_to_jsid, #property, #valid_name?

Constructor Details

This class inherits a constructor from Opal::Nodes::Base

Instance Method Details

#compile ⇒ Object 



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# File 'opal/lib/opal/nodes/if.rb', line 12

def compile
  if should_compile_as_simple_expression?
    if true_body == s(:true)
      compile_with_binary_or
    elsif false_body == s(:false)
      compile_with_binary_and
    else
      compile_with_ternary
    end
  else
    compile_with_if
  end
end

#compile_with_binary_and ⇒ Object 



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# File 'opal/lib/opal/nodes/if.rb', line 117

def compile_with_binary_and
  if sexp.meta[:do_js_truthy_on_true_body]
    truthy = js_truthy(true_body || s(:nil))
  else
    truthy = expr(true_body || s(:nil))
  end

  push '('
  push js_truthy(test), ' && '
  push '(', truthy, ')'
  push ')'
end

#compile_with_binary_or ⇒ Object 



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# File 'opal/lib/opal/nodes/if.rb', line 130

def compile_with_binary_or
  if sexp.meta[:do_js_truthy_on_false_body]
    falsy = js_truthy(false_body || s(:nil))
  else
    falsy = expr(false_body || s(:nil))
  end

  push '('
  push js_truthy(test), ' || '
  push '(', falsy, ')'
  push ')'
end

#compile_with_if ⇒ Object 



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# File 'opal/lib/opal/nodes/if.rb', line 26

def compile_with_if
  truthy = self.truthy
  falsy = self.falsy

  if falsy && !truthy
    # Let's optimize a little bit `unless` calls.
    push 'if (!', js_truthy(test), ') {'
    falsy, truthy = truthy, falsy
  else
    push 'if (', js_truthy(test), ') {'
  end

  # skip if-body if no truthy sexp
  indent { line stmt(truthy) } if truthy

  if falsy
    if falsy.type == :if
      line '} else ', stmt(falsy)
    else
      line '} else {'
      indent do
        line stmt(falsy)
      end

      line '}'
    end
  else
    line '}'

    # This resolution isn't finite. Let's ensure this block
    # always return something if we expect a return
    line 'return nil;' if expects_expression?
  end

  if expects_expression?
    if scope.await_encountered
      wrap '(await (async function() {', '})())'
    else
      wrap '(function() {', '})()'
    end
  end
end

#compile_with_ternary ⇒ Object 



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# File 'opal/lib/opal/nodes/if.rb', line 99

def compile_with_ternary
  truthy = true_body
  falsy = false_body

  push '('

  push js_truthy(test), ' ? '

  push '(', expr(truthy || s(:nil)), ') : '
  if !falsy || falsy.type == :if
    push expr(falsy || s(:nil))
  else
    push '(', expr(falsy || s(:nil)), ')'
  end

  push ')'
end

#expects_expression? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'opal/lib/opal/nodes/if.rb', line 85

def expects_expression?
  expr? || recv?
end

#falsy ⇒ Object 



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# File 'opal/lib/opal/nodes/if.rb', line 73

def falsy
  returnify(false_body)
end

#returnify(body) ⇒ Object 



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# File 'opal/lib/opal/nodes/if.rb', line 77

def returnify(body)
  if expects_expression? && body
    compiler.returns(body)
  else
    body
  end
end

#should_compile_as_simple_expression? ⇒ Boolean

There was a particular case in the past, that when we expected an expression from if, we always had to closure it. This produced an ugly code that was hard to minify. This addition tries to make a few cases compiled with a ternary operator instead and possibly a binary operator even?

Returns:

  • (Boolean) 


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# File 'opal/lib/opal/nodes/if.rb', line 95

def should_compile_as_simple_expression?
  expects_expression? && simple?(true_body) && simple?(false_body)
end

#simple?(body) ⇒ Boolean

Let's ensure there are no control flow statements inside.

Returns:

  • (Boolean) 


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# File 'opal/lib/opal/nodes/if.rb', line 144

def simple?(body)
  case body
  when AST::Node
    case body.type
    when :return, :js_return, :break, :next, :redo, :retry
      false
    when :xstr
      XStringNode.single_line?(
        XStringNode.strip_empty_children(body.children)
      )
    else
      body.children.all? { |i| simple?(i) }
    end
  else
    true
  end
end

#truthy ⇒ Object 



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# File 'opal/lib/opal/nodes/if.rb', line 69

def truthy
  returnify(true_body)
end