Re: pattern matching problem

[Andrew Starks <andrew.starks@...>]

Cue the zealot with the LPeg answer in 3...2...1..

local lpeg = require"lpeg"

local P, R, C = lpeg.P, lpeg.R, lpeg.C

local integer = R("09")^1

local mant  = P"." * integer

local number = C(integer * (mant + -1))

local trimmed_mant = P"." * (R"09"^1 - (P"0"^0 * -1))

local trimmed_number = C(integer * (P"." * R"09" * (R"09"- (P"0"^0 * -1))^0)^-1)

local n1 = "123.450000000" 

local n2 = "1234500"

local n3 = "12345.00" 

print(trimmed_number:match(n1))

--> 123.45

print(trimmed_number:match(n2))

--> 1234500

print(trimmed_number:match(n3))

--> 12345.0

On Fri, Aug 30, 2013 at 4:10 PM, Geoff Smith <spammealot1@live.co.uk> wrote:

Hi
 
Wow, you guys are quick. Three working solutions and a debate about the subtleties of a solution, all in the time I would be chewing my pencil and staring at a blank sheet of paper
 
I tried all 3 solutions, they all work fine.  I am still trying to digest how they all work though. Its a very useful example in learning how pattern matching works,  it would be a good and practical example problem for the Lua wiki page.
 
Thanks to everyone for your help
 
Regards Geoff