A tool to generate Java bytecode in Python.
More information on bytecode can be found here: Oracle docs, Wikipedia class file, Wikipedia instruction listings
from bytecompiler import ClassFile
cf = ClassFile("Main") #Make a ClassFile with name "Main". Try to match the file name. (i.e. Main.class)
cf.addpool("long", 50000) #Add a long entry to the constant pool and return the index
cf.qpool("class", "java/lang/System") #this quick shorthand is equivalent to
cf.addpool("class", cf.addpool("utf8", "java/lang/System"))
x = cf.qpool("class", "java/lang/System")
f = cf.qpool("field", x, "out", "Ljava/io/PrintStream;") #Get System.out, again shorthand to
f = cf.addpool("field", x, cf.addpool("name_type", cf.addpool("utf8", "out"), cf.addpool("utf8", "Ljava/io/PrintStream;")))
cf.field("myfield", "Ljava/lang/Object;", ["private"]) #Create a private field called "myfield" of type java/lang/Object
from bytecompiler import CodeAttribute
code = CodeAttribute(b"Insert bytecode in bytes format")
cf.method("main", "([Ljava/lang/String;)V", ["public", "static"], [code]) #Standart main method
f = open("Main.class", "wb")
f.write(cf.serialize()) #Serialize the classfile
f.close()name - The name of the classfile. Match this to the output file
access - Access flags. Default: ["public"]
sname - The name of the super class. Default: "java/lang/Object"
version - The version. Default: (49, 0)
from byteassembler import assemble
assemble( #Returns the bytecode instructions of this assembly code
f"""
iconst_3
istore_2
loop:
iinc 2 -1
iload_2
ifgt loop
"""
)