Commit 8c6b3c80 authored by Rene Saarsoo's avatar Rene Saarsoo
Browse files

Detection of undefined return value.

parent aca60237

lib/jsduck/function_ast.rb

+37 −11
Original line number Diff line number Diff line
@@ -12,12 +12,24 @@ module JsDuck 
    #

    # For now there are three possible detected return values:

    #

    # * :void - the code can finish without explicitly returning anything

    # * :this - the code contins 'return this;'

    #

    # * "undefined" - the code finishes by returning undefined or

    #   without explicitly returning anything

    #

    # * :other - some other value is returned.

    #

    def return_types(ast)

      return_types_hash(ast["body"]["body"]).keys

      h = return_types_hash(ast["body"]["body"])



      # Replace the special :void value that signifies possibility of

      # exiting without explicitly returning anything

      if h[:void]

        h["undefined"] = true

        h.delete(:void)

      end



      h.keys

    end



    private
@@ -25,11 +37,9 @@ module JsDuck 
    def return_types_hash(body)

      rvalues = {}

      body.each do |ast|

        if return_this?(ast)

          rvalues[:this] = true

          return rvalues

        elsif return?(ast)

          rvalues[:other] = true

        if return?(ast)

          type = value_type(ast["argument"])

          rvalues[type] = true

          return rvalues

        elsif possibly_blocking?(ast)

          extract_bodies(ast).each do |b|
@@ -52,14 +62,30 @@ module JsDuck 
      return rvalues

    end



    def return_this?(ast)

      return?(ast) && !!ast["argument"] && this?(ast["argument"])

    end



    def return?(ast)

      ast["type"] == "ReturnStatement"

    end



    def value_type(ast)

      if !ast

        :void

      elsif undefined?(ast) || void?(ast)

        "undefined"

      elsif this?(ast)

        :this

      else

        :other

      end

    end



    def undefined?(ast)

      ast["type"] == "Identifier" && ast["name"] == "undefined"

    end



    def void?(ast)

      ast["type"] == "UnaryExpression" && ast["operator"] == "void"

    end



    def this?(ast)

      ast["type"] == "ThisExpression"

    end

spec/function_ast_spec.rb

+23 −1
Original line number Diff line number Diff line
@@ -161,7 +161,7 @@ describe "JsDuck::FunctionAst#return_types" do 
  end



  describe "doesn't return [:this] when function body" do

    it "has no return statement." do

    it "is empty" do

      returns("/** */ function foo() {}").should_not == [:this]

    end
@@ -209,4 +209,26 @@ describe "JsDuck::FunctionAst#return_types" do 
    end

  end



  describe "returns ['undefined'] when function body" do

    it "is empty" do

      returns("/** */ function foo() {}").should == ["undefined"]

    end



    it "has no return statement" do

      returns("/** */ function foo() { bar(); baz(); }").should == ["undefined"]

    end



    it "has empty return statement" do

      returns("/** */ function foo() { return; }").should == ["undefined"]

    end



    it "has RETURN UNDEFINED statement" do

      returns("/** */ function foo() { return undefined; }").should == ["undefined"]

    end



    it "has RETURN VOID statement" do

      returns("/** */ function foo() { return void(blah); }").should == ["undefined"]

    end

  end



end