On Saturday, 24 June 2023 at 15:12:14 UTC, Jonathan M Davis wrote:
On Saturday, June 24, 2023 8:43:00 AM MDT Cecil Ward via
Digitalmars-d-learn wrote:
I started out looking into a number of runtime library
routines, but in the end it seemed quicker to roll my own code
for a crude recursive descent parser/lexer that parses part of
D’s grammar for expressions, and (again partial grammar)
parser for string literal expressions and so on. I find
certain special elements and execute actions which involve
doing the AA lookup and replacing variable names with ordinal
numbers in decimal in the output stream. Admission: The
parsing is the thing that has to be fast, even though again
the size of the D language text is not likely to be huge at
all. But 40 years ago, I came from a world with 2k RAM and 0.9
MHz clock rates so I have developed a habit of always thinking
about speed before I do anything, needful or not, to be
honest. I once wrote a program that took 35 mins to evaluate
2+2 and print out the answer, so I’m now ashamed of writing
slow code. Those were bad days, to be honest. 4 GHz+ and ILP
is nicer.
Well, dmd is open source (and Boost-licensed, so it doesn't
really have any restrictions), so depending on what you're
doing, it might make sense to just take code from that (and
it's very fast). IIRC, it pulls some fun tricks like replacing
identical strings with pointers to the same string so that it
can just compare pointers.
- Jonathan M Davis
Yeah, it would take me forever to get my head around that, and I
only want a crude toy partial parser for certain portions of the
grammar, and the parsing code is done now. A hand-written
recursive descent type thing mainly dealing with things like
comments and literal string that have to be taken account of as
they prevent hazards to naive straight string searching for what
you want to find, as comments and eg double-quoted strings could
have things in them that are red-herrings or the things that you
want to find items in, depending on circumstances.
I’m trying to get my head round the differences between OSX tools
and those for Linux relating to LDC and GDC which seems slightly
inferior in some situations. I’m a serious professional asm
programmer of old, before compilers were of usable output quality
for
git-hard applications. (‘a git’ a disreputable person, colloquial
English English. ‘git hard’ - brain-meltingly hard, like quantum
gravity.)
