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JavaScript Backend - Basics

To run this example run these commands in your shell:

cd
git clone https://github.com/rusthon/Rusthon.git
cd Rusthon/
./rusthon.py ./examples/javascript_syntax.md

See Also

html

@index.html

<html>
<head>
</head>
<body>
<button onclick="javascript:hello_world()">clickme</button>
<@myscript>
</body>
</html>

rusthon javascript backend

Below @myscript is given on the line just before the fenced rusthon code block. This allows you to insert multiple scripts into your html, in the head or body.

The extra syntax switch and default is also supported.

@myscript

#backend:javascript
from runtime import *


class MyChannel():
	def send(self,ob):
		print 'calling MyChannel.send:' + ob
		return ob
	def keys(self):
		return 420


with webworker:
	class Worker():
		def send(self,ob):
			print 'sending:' + ob
			return ob


def mydecorator( f ):
	f.something = 'decorators ok'
	return f

@mydecorator
def hello_world():
	window.alert(" new hi R arrow -> and L arrow <- and $ $. $(")

assert hello_world is not undefined
print hello_world.something

X = []
Z = None

@debugger
def test():
	global X, Z

	mystring1 = "hello %s" %"world"
	print mystring1

	mystring2 = "%s %s" %("hello", "world")
	print mystring2

	## the runtime provides some fake python libs ##
	J = json.loads( '{"x":1}' )  
	print  J 

	s1 = set( [1,2,3,1,2])
	print s1
	s2 = frozenset( [0,1,1,1,1,20])
	print s2
	s3 = s1.difference(s2)
	print s3

	chan = MyChannel()

	## macros let you inline javascript and compress multiple things into one simple macro function
	with mymacro as "chan.send(JSON.stringify(%s)); console.log('macro test OK');":
		mymacro( s3 )

	print 'chan is an isinstance of MyChannel'
	print isinstance(chan, MyChannel)  ## True
	print isinstance(chan, Array)    ## False

	## as a special case for `isinstance` you can also pass a string as the type to test for ##
	assert isinstance(chan, "MyChannel")
	assert isinstance(1, 'int')
	assert isinstance(1, '𝑰𝒏𝒕𝒆𝒈𝒆𝒓')
	assert isinstance('hi', 'string')
	assert isinstance('hi', 'str')
	assert isinstance('hi', '𝑺𝒕𝒓𝒊𝒏𝒈')

	mydict = {keys:1}
	assert mydict[ 'keys' ] == 1
	print mydict.keys()

	print chan.keys()
	assert chan.keys() == 420

	## using objects as keys ##
	global chan2
	mydict[ chan ] = 'foo'
	chan2 = MyChannel()
	mydict[ chan2 ] = 'bar'
	assert mydict[ chan ] == 'foo'
	assert mydict[ chan2 ] == 'bar'

	#copy = dict(mydict)

	## this is a very rare case, but it still works ##
	def f():
		return 'VERYRARE'
	mydict2 = {keys: f}
	assert mydict2['keys']() == 'VERYRARE'
	assert mydict2.keys()    != 'VERYRARE'

	## the key type of this dict can be determined at translation time as int
	idict = {0:'a', 1:'b', 2:'c'}

	## this returns an array of ints ##
	print idict.keys()
	for k in idict.keys():
		assert isinstance(k, int)

	## having numbers as keys allows you to use `max()` as you normally would in python
	assert max( idict.keys() ) == 2

	## this also restores `k` to type int from the hash keys ##
	for k in idict:
		assert isinstance(k, int)

	## the hash keys are still actually strings and it needs
	## to be this way to stay compatible with external js.
	assert idict['0'] == 'a'

	a = 1
	b = 2
	if a <= b-1:
		print 'ok'
	else:
		print 'error'

	switch a:
		case 0:
			print 'no'
		case 1:
			print 'yes'
			print 'switch syntax ok'

	switch b:
		case 0:
			print 'error'
		case 1 or 10:
			print 'error'
		default:
			print 'switch default ok'

	## get translated to the ternary operator in `test?truevalue:falsevalue`
	print 'testing ternary'
	tertest = a if True else b
	assert tertest==1
	print 'ternay OK'

	with operator_overloading:
		X = [1,2]
		arr = [3,4]
		X += arr

	## `oo` is an alias for `operator_overloading`
	with oo:
		Z = [10,20] + [30,40]


	print X
	print Z
	print X.pop()
	print 'testing enumerate'
	for i,e in enumerate(X):
		print 'index:' + i
		print 'item:'  + e
		if i==0:
			assert e == 1
		elif i==1:
			assert e == 2
		elif i==2:
			assert e == 3
	print '------------------'

	print 'X is list:', isinstance(Z, list)
	print 'X is really a js Array:', isinstance(Z, Array)

	try:
		getattr(X, 'notthere')  ## throws exception
	except AttributeError:
		print 'caught attribute error OK'

	#getattr(X, 'notthere')  ## throws exception


	print "STRING TESTS"
	print 'a b c'.split()
	print 'axbxc'.replace('x', 'Z')

	print dir(X)

	print 'testing isdigit'
	print '1'.isdigit()
	print 'A'.isdigit()
	print len('123')

	## jquery or some external library that uses `$` ##
	def $(w):
		print(w)
	$.bla = $

	if $ is not undefined:
		$('testing calling $')
		$.bla('testing bla')
		$($)
		$ = 1
	else:
		print 'missing jquery'

	test_spawn()


def test_spawn():
	print 'spawn workers'
	worker1 = spawn(
		Worker(),
	)
	worker2 = spawn(
		Worker(),
	)
	window.setTimeout(
		lambda: test_workers(worker1,worker2),
		1500,
	)

def test_workers(worker1, worker2):
	print 'sending data to workers'
	worker1 <- 'msg 1'
	worker1 <- 'msg 2'
	worker1 <- 'msg 3'
	worker1 <- 'msg 4'

	worker2 <- 'msg 5'
	worker2 <- 'msg 6'
	worker2 <- 'msg 7'
	worker2 <- 'msg 8'

	print 'getting data from workers'
	res = <- worker1
	print res
	res = <- worker1
	print res
	res = <- worker1
	print res
	res = <- worker1
	print res

	res = <- worker2
	print res
	res = <- worker2
	print res
	res = <- worker2
	print res
	res = <- worker2
	print res

	#worker1.terminate()  ## TODO



test()