====================================================== Generating Python Bytecode with ``dispatch.assembler`` ====================================================== >>> from dispatch.assembler import * >>> from dis import dis Line number tracking: >>> def simple_code(flno, slno, consts=1, ): ... c = Code() ... c.set_lineno(flno) ... for i in range(consts): c.LOAD_CONST(None) ... c.set_lineno(slno) ... c.RETURN_VALUE() ... return c.code() >>> dis(simple_code(1,1)) 1 0 LOAD_CONST 0 (None) 3 RETURN_VALUE >>> simple_code(1,1).co_stacksize 1 >>> dis(simple_code(13,414)) 13 0 LOAD_CONST 0 (None) 414 3 RETURN_VALUE >>> dis(simple_code(13,14,100)) 13 0 LOAD_CONST 0 (None) 3 LOAD_CONST 0 (None) ... 14 300 RETURN_VALUE >>> simple_code(13,14,100).co_stacksize 100 >>> dis(simple_code(13,572,120)) 13 0 LOAD_CONST 0 (None) 3 LOAD_CONST 0 (None) ... 572 360 RETURN_VALUE Stack size tracking: >>> c = Code() >>> c.LOAD_CONST(1) >>> c.POP_TOP() >>> c.LOAD_CONST(2) >>> c.LOAD_CONST(3) >>> c.co_stacksize 2 >>> c.BINARY_ADD() >>> c.LOAD_CONST(4) >>> c.co_stacksize 2 >>> c.LOAD_CONST(5) >>> c.LOAD_CONST(6) >>> c.co_stacksize 4 >>> c.POP_TOP() >>> c.stack_size 3 Stack underflow detection/recovery, and global/local variable names: >>> c = Code() >>> c.LOAD_GLOBAL('foo') >>> c.stack_size 1 >>> c.STORE_ATTR('bar') # drops stack by 2 Traceback (most recent call last): ... AssertionError: Stack underflow >>> c.co_names # 'bar' isn't added unless success ['foo'] >>> c.LOAD_ATTR('bar') >>> c.co_names ['foo', 'bar'] >>> c.DELETE_FAST('baz') >>> c.co_varnames ['baz'] >>> dis(c.code()) 0 0 LOAD_GLOBAL 0 (foo) 3 LOAD_ATTR 1 (bar) 6 DELETE_FAST 0 (baz) Sequence operators and stack tracking: Function calls and raise: >>> c = Code() >>> c.LOAD_GLOBAL('locals') >>> c.CALL_FUNCTION() # argc/kwargc default to 0 >>> c.POP_TOP() >>> c.LOAD_GLOBAL('foo') >>> c.LOAD_CONST(1) >>> c.LOAD_CONST('x') >>> c.LOAD_CONST(2) >>> c.CALL_FUNCTION(1,1) # argc, kwargc >>> c.POP_TOP() >>> dis(c.code()) 0 0 LOAD_GLOBAL 0 (locals) 3 CALL_FUNCTION 0 6 POP_TOP 7 LOAD_GLOBAL 1 (foo) 10 LOAD_CONST 0 (1) 13 LOAD_CONST 1 ('x') 16 LOAD_CONST 2 (2) 19 CALL_FUNCTION 257 22 POP_TOP >>> c = Code() >>> c.LOAD_GLOBAL('foo') >>> c.LOAD_CONST(1) >>> c.LOAD_CONST('x') >>> c.LOAD_CONST(2) >>> c.BUILD_MAP(0) >>> c.stack_size 5 >>> c.CALL_FUNCTION_KW(1,1) >>> c.POP_TOP() >>> c.stack_size 0 >>> c = Code() >>> c.LOAD_GLOBAL('foo') >>> c.LOAD_CONST(1) >>> c.LOAD_CONST('x') >>> c.LOAD_CONST(1) >>> c.BUILD_TUPLE(1) >>> c.CALL_FUNCTION_VAR(0,1) >>> c.POP_TOP() >>> c.stack_size 0 >>> c = Code() >>> c.LOAD_GLOBAL('foo') >>> c.LOAD_CONST(1) >>> c.LOAD_CONST('x') >>> c.LOAD_CONST(1) >>> c.BUILD_TUPLE(1) >>> c.BUILD_MAP(0) >>> c.CALL_FUNCTION_VAR_KW(0,1) >>> c.POP_TOP() >>> c.stack_size 0 >>> c = Code() >>> c.RAISE_VARARGS(0) >>> c.RAISE_VARARGS(1) Traceback (most recent call last): ... AssertionError: Stack underflow >>> c.LOAD_CONST(1) >>> c.RAISE_VARARGS(1) >>> dis(c.code()) 0 0 RAISE_VARARGS 0 3 LOAD_CONST 0 (1) 6 RAISE_VARARGS 1 Sequence building, unpacking, dup'ing: >>> c = Code() >>> c.LOAD_CONST(1) >>> c.LOAD_CONST(2) >>> c.BUILD_TUPLE(3) Traceback (most recent call last): ... AssertionError: Stack underflow >>> c.BUILD_LIST(3) Traceback (most recent call last): ... AssertionError: Stack underflow >>> c.BUILD_TUPLE(2) >>> c.stack_size 1 >>> c.UNPACK_SEQUENCE(2) >>> c.stack_size 2 >>> c.DUP_TOPX(3) Traceback (most recent call last): ... AssertionError: Stack underflow >>> c.DUP_TOPX(2) >>> c.stack_size 4 >>> c.LOAD_CONST(3) >>> c.BUILD_LIST(5) >>> c.stack_size 1 >>> c.UNPACK_SEQUENCE(5) >>> c.BUILD_SLICE(3) >>> c.stack_size 3 >>> c.BUILD_SLICE(3) >>> c.stack_size 1 >>> c.BUILD_SLICE(2) Traceback (most recent call last): ... AssertionError: Stack underflow >>> dis(c.code()) 0 0 LOAD_CONST 0 (1) 3 LOAD_CONST 1 (2) 6 BUILD_TUPLE 2 9 UNPACK_SEQUENCE 2 12 DUP_TOPX 2 15 LOAD_CONST 2 (3) 18 BUILD_LIST 5 21 UNPACK_SEQUENCE 5 24 BUILD_SLICE 3 27 BUILD_SLICE 3 XXX Need tests for MAKE_CLOSURE/MAKE_FUNCTION Labels and backpatching forward references: >>> c = Code() >>> ref = c.JUMP_ABSOLUTE() >>> c.LOAD_CONST(1) >>> ref() >>> c.RETURN_VALUE() >>> dis(c.code()) 0 0 JUMP_ABSOLUTE 6 3 LOAD_CONST 0 (1) >> 6 RETURN_VALUE >>> c = Code() >>> ref = c.JUMP_FORWARD() >>> c.LOAD_CONST(1) >>> ref() >>> c.RETURN_VALUE() >>> dis(c.code()) 0 0 JUMP_FORWARD 3 (to 6) 3 LOAD_CONST 0 (1) >> 6 RETURN_VALUE >>> c = Code() >>> lbl = c.label() >>> c.LOAD_CONST(1) >>> c.JUMP_IF_TRUE(lbl) Traceback (most recent call last): ... AssertionError: Relative jumps can't go backwards >>> c = Code() >>> lbl = c.label() >>> c.LOAD_CONST(1) >>> ref = c.JUMP_ABSOLUTE(lbl) >>> dis(c.code()) 0 >> 0 LOAD_CONST 0 (1) 3 JUMP_ABSOLUTE 0