E2 string match functions (for LUA's string.Match functions)

[Jeremydeath]

These are just some quick little E2 wrappers for LUA's string.match() function. Pretty easy stuff, but I was surprised that this was not already in the SVN. Useful because the S:find(S) function only return the beginning position of the string, not very useful if you want the actual thing that it found.

Here it is:
[highlight=LUA]--Just wrapers for LUA's string.match
--only uses LUA Patterns and those use "%" instead of "\" like regular expressions
--see String.match - GMod Wiki for more explanarion on the function and
--http://lua-users.org/wiki/PatternsTutorial for more info on patterns
--made by Jeremydeath, 6-30-09

e2function array string:match( string PatternString , number StartIndex )
local InputString = this
if(!InputString or !PatternString or !StartIndex) then return "" end
local Ret = {string.match(InputString,PatternString,StartIndex )}
if(Ret) then
return Ret
else
return ""
end
end

e2function array string:match(string PatternString )
local InputString = this
if(!InputString or !PatternString) then return "" end
local Ret = {string.match(InputString,PatternString)}
if(Ret) then
return Ret
else
return ""
end
end[/highlight]

And a quick use of it would be to get a number from a string.
[highlight=E2]@name match test
@inputs
@outputs Number
@persist
@trigger all

String = "Hello, my name is Jeremydeath and I like the number pi which is approximately 3.141592653589, which is the ratio between the diameter and circumference of a circle."

Number = String:match("[%d%.]+"):toNumber()
#Number = 3.141592653589

Number = String:match("[%d%.]+" , 84):toNumber()
#Number = 592653589
[/highlight]

[TomyLobo]

these patterns aren't regular expressions ^^
regular expressions are like 100 times more useful

also, shouldn't that function return arrays instead?
It returns multiple values for patterns with multiple captures.

[Jeremydeath]

Yeah, I learned that only after I posted this... Oh well, at least LUA's patterns are more useful than just plain text searching.

As to the array, I didn't see any indication of this LUA function ever returning a table instead of a string, even when there are multiple matches.

[TomyLobo]

captures, not matches

string.match("hello world","(%S+)%s+(%S+)")
should return "hello" and "world"

[Jeremydeath]

Hmmm, that should return an array... but it doesn't in LUA. I think this is a LUA or Gmod bug.

This is the test code I used.
[highlight=LUA]
function Capture_Test()
local Matches = string.match("hello world","(%S+)%s+(%S+)")
print(Matches)
end
timer.Create( "Capture_Test", 1, 0, Capture_Test)
[/highlight]

It's in the autorun directory and it just prints:
"hello" to the console every second.

[TomyLobo]

yeah because you discarded the 2nd return value of string.match, which would be the 2nd capture.

lua_run print(string.match("hello world","(%S+)%s+(%S+)"))

print prints all of its arguments, tab-separated.

[Jeremydeath]

Ok, I see what you mean. I'll fix it up and re-post it when I'm done.

[Jeremydeath]

Done.

It took me a while to figure out that string.match() returns multiple arguments, and not an array.

Here it is (also updated the first post):
[highlight=Lua]--Just wrapers for LUA's string.match
--only uses Lua Patterns and those use "%" as an escape character, instead of "\" like regular expressions
--see String.match - GMod Wiki for more explanation on the function and
--http://lua-users.org/wiki/PatternsTutorial for more info on patterns
--made by Jeremydeath, 6-30-09

e2function array string:match( string PatternString, number StartIndex )
local InputString = this
return { string.match(InputString, PatternString, StartIndex) }
end

e2function array string:match(string PatternString )
local InputString = this
return { string.match(InputString, PatternString) }
end
[/highlight]

[TomyLobo]

I edited your code a bit.
strings shouldn't be returned from a function returning arrays
also, { <nothing> } is an empty array already, no need for a check.
E2 strings and numbers can never be nil too, so you don't need to check for that.

Also, maybe make versions for just returning one match, for simplicity?
the names i come up with are shit though:
matchOne
matchFirst

[Jeremydeath]

yeah, actually I was just thinking that it might cause errors if you return a string as an array...

I didn't know about the non-nil numbers/string thing. I'll have to remember that.

I was thinking about doing the find first match thing. It would be easy to implement. I'll make it and test it.

EDIT: Done and tested

[highlight=LUA]--Just wrapers for LUA's string.match
--only uses LUA Patterns and those use "%" instead of "\" like regular expressions
--see String.match - GMod Wiki for more explanarion on the function and
--http://lua-users.org/wiki/PatternsTutorial for more info on patterns
--made by Jeremydeath, 6-30-09

e2function array string:match( string PatternString , number StartIndex )
local InputString = this
return {string.match(InputString,PatternString,StartIndex )}
end

e2function array string:match(string PatternString )
local InputString = this
return {string.match(InputString,PatternString)}
end

e2function string string:matchFirst( string PatternString , number StartIndex )
local InputString = this
return string.match(InputString,PatternString,StartIndex) or ""
end

e2function string string:matchFirst(string PatternString )
local InputString = this
return string.match(InputString,PatternString) or ""
end[/highlight]