therubyrhino
DESCRIPTION:
Embed the Mozilla Rhino JavaScript interpreter into Ruby
FEATURES/PROBLEMS:
-
Evaluate JavaScript from with in Ruby
-
Embed your Ruby objects into the JavaScript world
SYNOPSIS:
-
JavaScript goes into Ruby
-
Ruby Objects goes into JavaScript
-
Our shark’s in the JavaScript!
require 'rhino'
# evaluate some simple javascript
eval_js "7 * 6" #=> 42
# that’s quick and dirty, but if you want more control over your # environment, use a Context:
Rhino::Context.open do |cxt|
cxt['foo'] = "bar"
cxt.eval('foo') # => "bar"
end
# evaluate a ruby function from JS
Rhino::Context.open do |context|
context["say"] = lambda {|word, times| word * times}
context.eval("say("Hello", 3)") #=> HelloHelloHello
end
# embed a ruby object into your JS environment
class MyMath
def plus(lhs, rhs)
lhs + rhs
end
end
Rhino::Context.open do |context|
context["math"] = MyMath.new
context.eval("math.plus(20, 22)") #=> 42
end
# make a ruby object be your JS environment
math = MyMath.new
Rhino::Context.open(:with => math) do |context|
context.eval("plus(20, 22)") #=> 42
end
#or the equivalent
math.eval_js("plus(20, 22)")
# Configure your embedding setup
# Make your standard objects (Object, String, etc...) immutable
Rhino::Context.open(:sealed => true) do |context|
context.eval("Object.prototype.toString = function() {}") # this is an error!
end
#Turn on Java integration from javascript (probably a bad idea)
Rhino::Context.open(:java => true) do |context|
context.eval("java.lang.System.exit()") # it's dangerous!
end
#limit the number of instructions that can be executed in order to prevent
#rogue scripts
Rhino::Context.open(:restrictable => true) do |context|
context.instruction_limit = 100000
context.eval("while (true);") # => Rhino::RunawayScriptError
end
#limit the time a script executes
#rogue scripts
Rhino::Context.open(:restrictable => true, :java => true) do |context|
context.timeout_limit = 1.5 # seconds
context.eval %Q{
for (var i = 0; i < 100; i++) {
java.lang.Thread.sleep(100);
}
} # => Rhino::ScriptTimeoutError
end
Different ways of loading JavaScript source
In addition to just evaluating strings, you can also use streams such as files.
# evaluate bytes read from any File/IO object:
File.open("mysource.js") do |file|
eval_js file, "mysource.js"
end
# or load it by filename
Rhino::Context.open do |context|
context.load("mysource.js")
end
Configurable Ruby access
By default accessing Ruby objects from JavaScript is compatible with therubyracer: github.com/cowboyd/therubyracer/wiki/Accessing-Ruby-Objects-From-JavaScript
Thus you end-up calling arbitrary no-arg methods as if they were JavaScript properties, since instance accessors (properties) and methods (functions) are indistinguishable:
Rhino::Context.open do |context|
context['Time'] = Time
context.eval('Time.now')
end
However, you can customize this behavior and there’s another access implementation that attempts to mirror only attributes as properties as close as possible:
class Foo
attr_accessor :bar
def initialize
@bar = "bar"
end
def
== "bar"
end
end
Rhino::Ruby::Scriptable.access = :attribute
Rhino::Context.open do |context|
context['Foo'] = Foo
context.eval('var foo = new Foo()')
context.eval('foo.bar') # get property using reader
context.eval('foo.bar = null') # set property using writer
context.eval('foo.check_bar()') # called like a function
end
If you happen to come up with your own access strategy, just set it directly :
Rhino::Ruby::Scriptable.access = FooApp::BarAccess.instance
Safe by default
The Ruby Rhino is designed to let you evaluate JavaScript as safely as possible unless you tell it to do something more dangerous. The default context is a hermetically sealed JavaScript environment with only the standard objects and functions. Nothing from the Ruby world is accessible at all.
For Ruby objects that you explicitly embed into JavaScript, only the public
methods “defined in their classes” are exposed by default e.g.
class A
def a
"a"
end
end
class B < A
def b
"b"
end
end
Rhino::Context.open do |cxt|
cxt['a'] = A.new
cxt['b'] = B.new
cxt.eval("a.a()") # => 'a'
cxt.eval("b.b()") # => 'b'
cxt.eval("b.a()") # => 'TypeError: undefined property 'a' is not a function'
end
Rhino
Rhino is currently maintained at github.com/mozilla/rhino Release downloads are available at www.mozilla.org/rhino/download.html Rhino is licensed under the MPL 1.1/GPL 2.0 license.
REQUIREMENTS:
-
JRuby >= 1.5.6
INSTALL:
-
jgem install therubyrhino
LICENSE:
(The MIT License)
Copyright © 2009-2012 Charles Lowell
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ‘Software’), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED ‘AS IS’, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.