| """ |
| Compile Python to Bytecode |
| ========================== |
| |
| A toy example that compiles Python directly to bytecode, without generating an AST. |
| It currently only works for very very simple Python code. |
| |
| It requires the 'bytecode' library. You can get it using |
| :: |
| |
| $ pip install bytecode |
| |
| """ |
| from lark import Lark, Transformer, v_args |
| from lark.indenter import Indenter |
|
|
| from bytecode import Instr, Bytecode |
|
|
| class PythonIndenter(Indenter): |
| NL_type = '_NEWLINE' |
| OPEN_PAREN_types = ['LPAR', 'LSQB', 'LBRACE'] |
| CLOSE_PAREN_types = ['RPAR', 'RSQB', 'RBRACE'] |
| INDENT_type = '_INDENT' |
| DEDENT_type = '_DEDENT' |
| tab_len = 8 |
|
|
|
|
| @v_args(inline=True) |
| class Compile(Transformer): |
| def number(self, n): |
| return [Instr('LOAD_CONST', int(n))] |
| def string(self, s): |
| return [Instr('LOAD_CONST', s[1:-1])] |
| def var(self, n): |
| return [Instr('LOAD_NAME', n)] |
|
|
| def arith_expr(self, a, op, b): |
| |
| assert op == '+' |
| return a + b + [Instr('BINARY_ADD')] |
|
|
| def arguments(self, args): |
| return args |
|
|
| def funccall(self, name, args): |
| return name + args + [Instr('CALL_FUNCTION', 1)] |
|
|
| @v_args(inline=False) |
| def file_input(self, stmts): |
| return sum(stmts, []) + [Instr("RETURN_VALUE")] |
|
|
| def expr_stmt(self, lval, rval): |
| |
| name ,= lval |
| assert name.name == 'LOAD_NAME' |
| return rval + [Instr("STORE_NAME", name.arg)] |
|
|
| def __default__(self, *args): |
| assert False, args |
|
|
|
|
| python_parser3 = Lark.open('python3.lark', rel_to=__file__, start='file_input', |
| parser='lalr', postlex=PythonIndenter(), |
| transformer=Compile(), propagate_positions=False) |
|
|
| def compile_python(s): |
| insts = python_parser3.parse(s+"\n") |
| return Bytecode(insts).to_code() |
|
|
| code = compile_python(""" |
| a = 3 |
| b = 5 |
| print("Hello World!") |
| print(a+(b+2)) |
| print((a+b)+2) |
| """) |
| exec(code) |
| |
| |
| |
| |
|
|
