| bytecode instead of on these mechanical issues. |
bytecode instead of on these mechanical issues. |
| |
|
| In addition to a low-level opcode-oriented API for directly generating specific |
In addition to a low-level opcode-oriented API for directly generating specific |
| bytecodes, this module also offers an extensible mini-AST framework for |
Python bytecodes, this module also offers an extensible mini-AST framework for |
| generating code from high-level specifications. This framework does most of |
generating code from high-level specifications. This framework does most of |
| the work needed to transform tree-like structures into linear bytecode |
the work needed to transform tree-like structures into linear bytecode |
| instructions, and includes the ability to do compile-time constant folding. |
instructions, and includes the ability to do compile-time constant folding. |
| |
|
| Changes since version 0.2: |
Changes since version 0.2: |
| |
|
| |
* Added a ``Getattr`` symbol that does static or dynamic attribute access and |
| |
constant folding |
| |
|
| |
* Fixed ``code.from_function()`` not copying the ``co_filename`` attribute when |
| |
``copy_lineno`` was specified. |
| |
|
| * The ``repr()`` of AST nodes doesn't include a trailing comma for 1-argument |
* The ``repr()`` of AST nodes doesn't include a trailing comma for 1-argument |
| node types any more. |
node types any more. |
| |
|
| strings accepted (in the ``cmp_op`` tuple). ``"<>"`` is also accepted as an |
strings accepted (in the ``cmp_op`` tuple). ``"<>"`` is also accepted as an |
| alias for ``"!="``. |
alias for ``"!="``. |
| |
|
| |
* Added code to verify that forward jump offsets don't exceed a 64KB span, and |
| |
support absolute backward jumps to locations >64KB. |
| |
|
| Changes since version 0.1: |
Changes since version 0.1: |
| |
|
| * Constant handling has been fixed so that it doesn't confuse equal values of |
* Constant handling has been fixed so that it doesn't confuse equal values of |
| * Various bug fixes |
* Various bug fixes |
| |
|
| There are a few features that aren't tested yet, and not all opcodes may be |
There are a few features that aren't tested yet, and not all opcodes may be |
| fully supported. Notably, the following features are still NOT reliably |
fully supported. Also note the following limitations: |
| supported yet: |
|
| |
|
| * Wide jump addressing (for generated bytecode>64K in size) |
* Jumps to as-yet-undefined labels cannot span a distance greater than 65,535 |
| |
bytes. |
| |
|
| * The ``dis()`` module in Python 2.3 has a bug that makes it show incorrect |
* The ``dis()`` module in Python 2.3 has a bug that makes it show incorrect |
| line numbers when the difference between two adjacent line numbers is |
line numbers when the difference between two adjacent line numbers is |
| 6 LOAD_DEREF 1 (z) |
6 LOAD_DEREF 1 (z) |
| |
|
| |
|
| |
Obtaining Attributes |
| |
-------------------- |
| |
|
| |
The ``Getattr`` node type takes an expression and an attribute name. The |
| |
attribute name can be a constant string, in which case a ``LOAD_ATTR`` opcode |
| |
is used, and constant folding is done if possible:: |
| |
|
| |
>>> from peak.util.assembler import Getattr |
| |
|
| |
>>> c = Code() |
| |
>>> c(Getattr(Local('x'), '__class__')) |
| |
>>> dis(c.code()) |
| |
0 0 LOAD_FAST 0 (x) |
| |
3 LOAD_ATTR 0 (__class__) |
| |
|
| |
|
| |
>>> Getattr(Const(object), '__class__') # const expression, const result |
| |
Const(<type 'type'>) |
| |
|
| |
Or the attribute name can be an expression, in which case a ``getattr()`` call |
| |
is compiled instead:: |
| |
|
| |
>>> c = Code() |
| |
>>> c(Getattr(Local('x'), Local('y'))) |
| |
>>> dis(c.code()) |
| |
0 0 LOAD_CONST 1 (<built-in function getattr>) |
| |
3 LOAD_FAST 0 (x) |
| |
6 LOAD_FAST 1 (y) |
| |
9 CALL_FUNCTION 2 |
| |
|
| |
|
| Calling Functions and Methods |
Calling Functions and Methods |
| ----------------------------- |
----------------------------- |
| |
|
| implements its ``fold`` argument and the suppression of folding when |
implements its ``fold`` argument and the suppression of folding when |
| the call has no arguments. |
the call has no arguments. |
| |
|
| |
(By the way, this same ``Getattr`` node type is also available |
| |
|
| |
|
| Setting the Code's Calling Signature |
Setting the Code's Calling Signature |
| ==================================== |
==================================== |
| >>> c1 = Code.from_function(f1, copy_lineno=True) |
>>> c1 = Code.from_function(f1, copy_lineno=True) |
| >>> c1.co_firstlineno |
>>> c1.co_firstlineno |
| 1 |
1 |
| |
>>> c1.co_filename is f1.func_code.co_filename |
| |
True |
| |
|
| If you create a ``Code`` instance from a function that has nested positional |
If you create a ``Code`` instance from a function that has nested positional |
| arguments, the returned code object will include a prologue to unpack the |
arguments, the returned code object will include a prologue to unpack the |
| |
|
| >>> c = Code() |
>>> c = Code() |
| >>> c( If(23, 42, 55) ) |
>>> c( If(23, 42, 55) ) |
| >>> dis(c.code()) |
>>> dis(c.code()) # Python 2.3 may peephole-optimize this code |
| 0 0 LOAD_CONST 1 (23) |
0 0 LOAD_CONST 1 (23) |
| 3 JUMP_IF_FALSE 7 (to 13) |
3 JUMP_IF_FALSE 7 (to 13) |
| 6 POP_TOP |
6 POP_TOP |
| |
|
| >>> c = Code() |
>>> c = Code() |
| >>> c( If(23, Return(42), 55) ) |
>>> c( If(23, Return(42), 55) ) |
| >>> dis(c.code()) |
>>> dis(c.code()) # Python 2.3 may peephole-optimize this code |
| 0 0 LOAD_CONST 1 (23) |
0 0 LOAD_CONST 1 (23) |
| 3 JUMP_IF_FALSE 5 (to 11) |
3 JUMP_IF_FALSE 5 (to 11) |
| 6 POP_TOP |
6 POP_TOP |
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