Previous to this patch, a big-int, float or imag constant was interned
(made into a qstr) and then parsed at runtime to create an object each
time it was needed. This is wasteful in RAM and not efficient. Now,
these constants are parsed straight away in the parser and turned into
objects. This allows constants with large numbers of digits (so
addresses issue #1103) and takes us a step closer to #722.
To enable parsing constants more efficiently, mp_parse should be allowed
to raise an exception, and mp_compile can already raise a MemoryError.
So these functions need to be protected by an nlr push/pop block.
This patch adds that feature in all places. This allows to simplify how
mp_parse and mp_compile are called: they now raise an exception if they
have an error and so explicit checking is not needed anymore.
Previously to this patch all constant string/bytes objects were
interned by the compiler, and this lead to crashes when the qstr was too
long (noticeable now that qstr length storage defaults to 1 byte).
With this patch, long string/bytes objects are never interned, and are
referenced directly as constant objects within generated code using
load_const_obj.
mp_lexer_t type is exposed, mp_token_t type is removed, and simple lexer
functions (like checking current token kind) are now inlined.
This saves 784 bytes ROM on 32-bit unix, 348 bytes on stmhal, and 460
bytes on bare-arm. It also saves a tiny bit of RAM since mp_lexer_t
is a bit smaller. Also will run a bit more efficiently.
mp_parse_node_free now frees the memory associated with non-interned
strings. And the parser calls mp_parse_node_free when discarding a
non-used node (such as a doc string).
Also, the compiler now frees the parse tree explicitly just before it
exits (as opposed to relying on the caller to do this).
Addresses issue #708 as best we can.
This completes non-automatic interning of strings in the parser, so that
doc strings don't take up RAM. It complicates the parser and compiler,
and bloats stmhal by about 300 bytes. It's complicated because now
there are 2 kinds of parse-nodes that can be strings: interned leaves
and non-interned structs.
Damien George
nhtshot
Paul Sokolovsky