Commit 52119866 authored by Megax's avatar Megax
Browse files

bridge from LuaInterface(capresti) to LuaInterface (megax)

parent 99dc49f7
-- bare-bones luac in Lua
-- usage: lua luac.lua file.lua
assert(arg[1]~=nil and arg[2]==nil,"usage: lua luac.lua file.lua")
f=assert(io.open("luac.out","wb"))
assert(f:write(string.dump(assert(loadfile(arg[1])))))
assert(f:close())
-- an implementation of printf
function printf(...)
io.write(string.format(...))
end
printf("Hello %s from %s on %s\n",os.getenv"USER" or "there",_VERSION,os.date())
-- make global variables readonly
local f=function (t,i) error("cannot redefine global variable `"..i.."'",2) end
local g={}
local G=getfenv()
setmetatable(g,{__index=G,__newindex=f})
setfenv(1,g)
-- an example
rawset(g,"x",3)
x=2
y=1 -- cannot redefine `y'
-- the sieve of of Eratosthenes programmed with coroutines
-- typical usage: lua -e N=1000 sieve.lua | column
-- generate all the numbers from 2 to n
function gen (n)
return coroutine.wrap(function ()
for i=2,n do coroutine.yield(i) end
end)
end
-- filter the numbers generated by `g', removing multiples of `p'
function filter (p, g)
return coroutine.wrap(function ()
while 1 do
local n = g()
if n == nil then return end
if math.mod(n, p) ~= 0 then coroutine.yield(n) end
end
end)
end
N=N or 1000 -- from command line
x = gen(N) -- generate primes up to N
while 1 do
local n = x() -- pick a number until done
if n == nil then break end
print(n) -- must be a prime number
x = filter(n, x) -- now remove its multiples
end
-- two implementations of a sort function
-- this is an example only. Lua has now a built-in function "sort"
-- extracted from Programming Pearls, page 110
function qsort(x,l,u,f)
if l<u then
local m=math.random(u-(l-1))+l-1 -- choose a random pivot in range l..u
x[l],x[m]=x[m],x[l] -- swap pivot to first position
local t=x[l] -- pivot value
m=l
local i=l+1
while i<=u do
-- invariant: x[l+1..m] < t <= x[m+1..i-1]
if f(x[i],t) then
m=m+1
x[m],x[i]=x[i],x[m] -- swap x[i] and x[m]
end
i=i+1
end
x[l],x[m]=x[m],x[l] -- swap pivot to a valid place
-- x[l+1..m-1] < x[m] <= x[m+1..u]
qsort(x,l,m-1,f)
qsort(x,m+1,u,f)
end
end
function selectionsort(x,n,f)
local i=1
while i<=n do
local m,j=i,i+1
while j<=n do
if f(x[j],x[m]) then m=j end
j=j+1
end
x[i],x[m]=x[m],x[i] -- swap x[i] and x[m]
i=i+1
end
end
function show(m,x)
io.write(m,"\n\t")
local i=1
while x[i] do
io.write(x[i])
i=i+1
if x[i] then io.write(",") end
end
io.write("\n")
end
function testsorts(x)
local n=1
while x[n] do n=n+1 end; n=n-1 -- count elements
show("original",x)
qsort(x,1,n,function (x,y) return x<y end)
show("after quicksort",x)
selectionsort(x,n,function (x,y) return x>y end)
show("after reverse selection sort",x)
qsort(x,1,n,function (x,y) return x<y end)
show("after quicksort again",x)
end
-- array to be sorted
x={"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"}
testsorts(x)
-- make table, grouping all data for the same item
-- input is 2 columns (item, data)
local A
while 1 do
local l=io.read()
if l==nil then break end
local _,_,a,b=string.find(l,'"?([_%w]+)"?%s*(.*)$')
if a~=A then A=a io.write("\n",a,":") end
io.write(" ",b)
end
io.write("\n")
-- trace calls
-- example: lua -ltrace-calls bisect.lua
local level=0
local function hook(event)
local t=debug.getinfo(3)
io.write(level," >>> ",string.rep(" ",level))
if t~=nil and t.currentline>=0 then io.write(t.short_src,":",t.currentline," ") end
t=debug.getinfo(2)
if event=="call" then
level=level+1
else
level=level-1 if level<0 then level=0 end
end
if t.what=="main" then
if event=="call" then
io.write("begin ",t.short_src)
else
io.write("end ",t.short_src)
end
elseif t.what=="Lua" then
-- table.foreach(t,print)
io.write(event," ",t.name or "(Lua)"," <",t.linedefined,":",t.short_src,">")
else
io.write(event," ",t.name or "(C)"," [",t.what,"] ")
end
io.write("\n")
end
debug.sethook(hook,"cr")
level=0
-- trace assigments to global variables
do
-- a tostring that quotes strings. note the use of the original tostring.
local _tostring=tostring
local tostring=function(a)
if type(a)=="string" then
return string.format("%q",a)
else
return _tostring(a)
end
end
local log=function (name,old,new)
local t=debug.getinfo(3,"Sl")
local line=t.currentline
io.write(t.short_src)
if line>=0 then io.write(":",line) end
io.write(": ",name," is now ",tostring(new)," (was ",tostring(old),")","\n")
end
local g={}
local set=function (t,name,value)
log(name,g[name],value)
g[name]=value
end
setmetatable(getfenv(),{__index=g,__newindex=set})
end
-- an example
a=1
b=2
a=10
b=20
b=nil
b=200
print(a,b,c)
-- hex dump
-- usage: lua xd.lua < file
local offset=0
while true do
local s=io.read(16)
if s==nil then return end
io.write(string.format("%08X ",offset))
string.gsub(s,"(.)",
function (c) io.write(string.format("%02X ",string.byte(c))) end)
io.write(string.rep(" ",3*(16-string.len(s))))
io.write(" ",string.gsub(s,"%c","."),"\n")
offset=offset+16
end
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment