custom_syntax.md

Custom Types Json

Custom syntax for Unreal Engine4 configures the C++ output to use these types for vectors, strings, and shared references.

https://docs.unrealengine.com/latest/INT/API/Runtime/Core/Containers/FString/index.html

@unrealtypes.json

{
	"vector"   : {
		"template": "TArray<%s>",
		"append"  : "Emplace",
		"len"     : "Num",
		"pop"     : "Pop"
	},
	"string" : {
		"type": "FString",
		"new" : "TEXT(%s)",
		"len" : "Len"
	},
	"shared" : {
		"template" : "TSharedRef<%s>",
		"type"     : "TSharedRef",
		"reset"    : "Reset"
	},
	"map"    : {
		"template" : "TMap<%s, %s>"
	}
}

The code below inside the with syntax block uses the custom template above. Instead of the default std::vector the vectors below will be constructed as TArray from the UnrealEngine C++ API.

https://docs.unrealengine.com/latest/INT/API/Runtime/Core/Containers/TArray/index.html

Unreal's template arrays, maps, and sets work with c++11 range based for loops. https://www.unrealengine.com/blog/ranged-based-for-loops

#backend:c++


with syntax('unrealtypes.json'):
	class A:
		def __init__(self, x:int, y:string):
			self.x = x
			self.y = y

	def foo( s:string, ob:A ) ->A:
		print s
		return ob

	def main():
		v1 = []int(1,2,3,4,5,6)
		v2 = []string( "hello", "world" )
		v1.append( 100 )
		v2.append( "xxx" )
		len(v1)
		s = "foobar"
		len(s)
		v1.pop()

		a = A()
		foo( v2[0], a )
		v3 = []A( a, a, a )
		for ob in v3:
			print ob
		for i in range(len(v3)):
			print i

		m = map[string]int{
			'foo' : 100,
			'bar' : 200,
		}