1. expression parser (simple) in EU
Here's a snippet I wrote some time ago from what is to be my Euphoria
version of a database program I originally wrote in Forth. This takes a
text string (e.g., a line of commands entered by the user), removes
spaces and tabs and puts the items in that string away in a sequence,
where the program can easily test the string for various criteria (e.g.,
whether the string is grammatically correct; so it can also be used in
programs for processing natural languages, etc.).
I've written a few lines around the function to test / demonstrate its
use.
Maybe this function is useful for all those Euphorians out there who are
writing language interpreters etc. (I've written such functions in
Forth, Pascal, Modula-2, C, Basic, but... Euphoria is Progress. The
Euphorian 'sequence', combined with practically unlimited memory, makes
this kind of thing easy to write.)
---SNIP---
-- exper. for testing the fnc. 'dissect'
sequence invoer
sequence uitkomst
function dissect(sequence entry)
--takes a string 'entry' and returns either {0} or
--{number_of_words,{{word},{word}...}}
--by Robert Zydenbos, Mysore (India)
--version date 29.7.1997
sequence arg --contains the words found in 'entry'
sequence a --word being found
integer wel --boolean: are we in the middle of a word being found?
integer l --length of 'entry'
object kar --character taken from 'entry'
arg = {}
a = {}
wel = 0
l = length(entry)
for x=1 to l-1 do
kar = entry[x]
--the next line was just for debugging:
--printf(1,"kar = %s\n",kar)
if kar=' ' or kar=9 then
if wel then
arg = arg & {a}
wel = 0
a = {}
end if
else
if not wel then
wel = -1
end if
a = a & kar
end if
end for
if length(a) then
arg = arg & {a}
end if
if not length(arg) then
return {0}
else
return {length(arg)} & {arg}
end if
end function
--main portion
clear_screen()
puts(1,"Enter some text: ")
invoer = gets(0)
printf(1,"The entered text was: %s\n\n",{invoer})
--now comes what all this is about:
uitkomst = dissect(invoer)
puts(1,"Result:\n")
? uitkomst
if uitkomst[1] then
puts(1,"I.e. (with a vertical bar after each item):\n")
for x=1 to uitkomst[1] do
printf(1,"%s|\n", {uitkomst[2][x]})
if not compare(uitkomst[2][x],"-") then
puts(1,"This was a dash.\n")
end if
end for
end if
---SNIP---
2. expression parser (simple) in EU
Hi!
EU>Here's a snippet I wrote some time ago from what is to be my Euphoria
EU>version of a database program I originally wrote in Forth. This takes a
Well, may be that this snippet was posted mainly for someone, and not
for me.
But as I tralked about the snippets, could it be included in "my"
magazine?
Bye! :)
Fernando Ariel Gont
Good Stuff! Magazine Editor
3. Re: expression parser (simple) in EU
Fernando Ariel Gont wrote:
> Well, may be that this snippet was posted mainly for someone, and
> not for me.
> But as I tralked about the snippets, could it be included in "my"
> magazine?
Sure. (Can you put me on the mailing list too?)
RZ
