circuitpython/mpy-cross
Jim Mussared 692d36d779 py: Implement partial PEP-498 (f-string) support.
This implements (most of) the PEP-498 spec for f-strings and is based on
https://github.com/micropython/micropython/pull/4998 by @klardotsh.

It is implemented in the lexer as a syntax translation to `str.format`:
  f"{a}" --> "{}".format(a)

It also supports:
  f"{a=}" --> "a={}".format(a)

This is done by extracting the arguments into a temporary vstr buffer,
then after the string has been tokenized, the lexer input queue is saved
and the contents of the temporary vstr buffer are injected into the lexer
instead.

There are four main limitations:
- raw f-strings (`fr` or `rf` prefixes) are not supported and will raise
  `SyntaxError: raw f-strings are not supported`.

- literal concatenation of f-strings with adjacent strings will fail
    "{}" f"{a}" --> "{}{}".format(a)    (str.format will incorrectly use
                                         the braces from the non-f-string)
    f"{a}" f"{a}" --> "{}".format(a) "{}".format(a) (cannot concatenate)

- PEP-498 requires the full parser to understand the interpolated
  argument, however because this entirely runs in the lexer it cannot
  resolve nested braces in expressions like
    f"{'}'}"

- The !r, !s, and !a conversions are not supported.

Includes tests and cpydiffs.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-08-14 16:58:40 +10:00
..
.gitignore mpy-cross: Add new component, a cross compiler for MicroPython bytecode. 2016-02-25 10:12:21 +00:00
Makefile all: Update to point to files in new shared/ directory. 2021-07-12 17:08:10 +10:00
README.md mpy-cross/README.md: Add notes about -march and -O. 2019-12-09 14:23:04 +11:00
gccollect.c all: Update to point to files in new shared/ directory. 2021-07-12 17:08:10 +10:00
main.c all: Rename BYTES_PER_WORD to MP_BYTES_PER_OBJ_WORD. 2021-02-04 22:46:42 +11:00
mpconfigport.h py: Implement partial PEP-498 (f-string) support. 2021-08-14 16:58:40 +10:00
mphalport.h mpy-cross: Make build independent of extmod directory. 2018-07-10 14:11:28 +10:00
mpy-cross.vcxproj all: Update to point to files in new shared/ directory. 2021-07-12 17:08:10 +10:00
qstrdefsport.h mpy-cross: Add new component, a cross compiler for MicroPython bytecode. 2016-02-25 10:12:21 +00:00

README.md

MicroPython cross compiler

This directory contains the MicroPython cross compiler, which runs under any Unix-like system and compiles .py scripts into .mpy files.

Build it as usual:

$ make

The compiler is called mpy-cross. Invoke it as:

$ ./mpy-cross foo.py

This will create a file foo.mpy which can then be copied to a place accessible by the target MicroPython runtime (eg onto a pyboard's filesystem), and then imported like any other Python module using import foo.

Different target runtimes may require a different format of the compiled bytecode, and such options can be passed to the cross compiler. For example, the unix port of MicroPython requires the following:

$ ./mpy-cross -mcache-lookup-bc foo.py

If the Python code contains @native or @viper annotations, then you must specify -march to match the target architecture.

Run ./mpy-cross -h to get a full list of options.

The optimisation level is 0 by default. Optimisation levels are detailed in https://docs.micropython.org/en/latest/library/micropython.html#micropython.opt_level