Is there a way to escape an iterate loop in helper like break in Java , in my example :
helper context activity!Activity def : print(s : String,s1:OrderedSet(String)) : String =
s1->iterate(a; acc1 : String = '' | acc1+
if ((a.target.name = b.target.name)and (a.source <> b.source))then
'print'
--break
else ''
endif
);
Related
I am trying to write a small parser with golang target, but not using visitors or walkers, but I am not able to find any sample code to build my parser upon.
For example, the following is the grammar code which I am trying to replicate with golang:
# Expr.g4:
grammar Expr;
#header {
}
#parser::members {
def eval(self, left, op, right):
if ExprParser.MUL == op.type:
return left * right
elif ExprParser.DIV == op.type:
return left / right
elif ExprParser.ADD == op.type:
return left + right
elif ExprParser.SUB == op.type:
return left - right
else:
return 0
}
stat: e NEWLINE {print($e.v);}
| ID '=' e NEWLINE {self.memory[$ID.text] = $e.v}
| NEWLINE
;
e returns [int v]
: a=e op=('*'|'/') b=e {$v = self.eval($a.v, $op, $b.v)}
| a=e op=('+'|'-') b=e {$v = self.eval($a.v, $op, $b.v)}
| INT {$v = $INT.int}
| ID
{
id = $ID.text
$v = self.memory.get(id, 0)
}
| '(' e ')' {$v = $e.v}
;
MUL : '*' ;
DIV : '/' ;
ADD : '+' ;
SUB : '-' ;
ID : [a-zA-Z]+ ; // match identifiers
INT : [0-9]+ ; // match integers
NEWLINE:'\r'? '\n' ; // return newlines to parser (is end-statement signal)
WS : [ \t]+ -> skip ; // toss out whitespace
And this is the python tester code for it:
# test_expr.py:
import sys
from antlr4 import *
from antlr4.InputStream import InputStream
from ExprLexer import ExprLexer
from ExprParser import ExprParser
if __name__ == '__main__':
parser = ExprParser(None)
parser.buildParseTrees = False
parser.memory = {} # how to add this to generated constructor?
line = sys.stdin.readline()
lineno = 1
while line != '':
line = line.strip()
istream = InputStream(line + "\n")
lexer = ExprLexer(istream)
lexer.line = lineno
lexer.column = 0
token_stream = CommonTokenStream(lexer)
parser.setInputStream(token_stream)
parser.stat()
line = sys.stdin.readline()
lineno += 1
Can anybody please post a sample golang code which is equivalent to the above python and inlined code?
I need to change the output of a method a bit: Execute the function, and if it's a empty string, then convert it to a "1". How can i write this short on just one line?
var = some_really_long_method(foo)
var = "1" if var == ""
I tried below, but that does call the method twice, right?
var = some_really_long_method(foo) == "" ? "1" : some_really_long_method(foo)
You could use Object#then:
def some_really_long_method
p 'called'
p res = ["", "10"].sample
res
end
var = some_really_long_method.then { |m| m == "" ? '1' : m }
You can check for yourself that the method is called once.
Newlines are optional in Ruby, they can always be replaced with either an expression separator (;), a keyword (e.g. then, do), or sometimes just whitespace.
Therefore, every program, no matter how complex, can always be written in one line, just by removing the linebreaks:
var = some_really_long_method(foo); var = "1" if var == ""
var = "1" if (var = some_really_long_method(foo)) == ""
I'm making a JSON parser and I am looking for an algorithm that can find all of the matching brackets ([]) and braces ({}) and put them into a table with the positions of the pair.
Examples of returned values:
table[x][firstPos][secondPos] = type
table[x] = {firstPos, secondPos, bracketType}
EDIT: Let parse() be the function that returns the bracket pairs. Let table be the value returned by the parse() function. Let codeString be the string containing the brackets that I want to detect. Let firstPos be the position of the first bracket in the Nth pair of brackets. Let secondPos be the position of the second bracket in the Nth pair of brackets. Let bracketType be the type of the bracket pair ("bracket" or "brace").
Example:
If you called:
table = parse(codeString)
table[N][firstPos][secondPos] would be equal to type.
Well, In plain Lua, you could do something like this, also taking into account nested brackets:
function bm(s)
local res ={}
if not s:match('%[') then
return s
end
for k in s:gmatch('%b[]') do
res[#res+1] = bm(k:sub(2,-2))
end
return res
end
Of course you can generalize this easy enough to braces, parentheses, whatever (do keep in mind the necessary escaping of [] in patterns , except behind the %b pattern).
If you're not restricted to plain Lua, you could use LPeg for more flexibility
If you are not looking for the contents of the brackets, but the locations, the recursive approach is harder to implement, since you should keep track of where you are. Easier is just walking through the string and match them while going:
function bm(s,i)
local res={}
res.par=res -- Root
local lev = 0
for loc=1,#s do
if s:sub(loc,loc) == '[' then
lev = lev+1
local t={par=res,start=loc,lev=lev} -- keep track of the parent
res[#res+1] = t -- Add to the parent
res = t -- make this the current working table
print('[',lev,loc)
elseif s:sub(loc,loc) == ']' then
lev = lev-1
if lev<0 then error('too many ]') end -- more closing than opening.
print(']',lev,loc)
res.stop=loc -- save bracket closing position
res = res.par -- revert to the parent.
end
end
return res
end
Now that you have all matched brackets, you can loop through the table, extracting all locations.
I figured out my own algorithm.
function string:findAll(query)
local firstSub = 1
local lastSub = #query
local result = {}
while lastSub <= #self do
if self:sub(firstSub, lastSub) == query then
result[#result + 1] = firstSub
end
firstSub = firstSub + 1
lastSub = lastSub + 1
end
return result
end
function string:findPair(openPos, openChar, closeChar)
local counter = 1
local closePos = openPos
while closePos <= #self do
closePos = closePos + 1
if self:sub(closePos, closePos) == openChar then
counter = counter + 1
elseif self:sub(closePos, closePos) == closeChar then
counter = counter - 1
end
if counter == 0 then
return closePos
end
end
return -1
end
function string:findBrackets(bracketType)
local openBracket = ""
local closeBracket = ""
local openBrackets = {}
local result = {}
if bracketType == "[]" then
openBracket = "["
closeBracket = "]"
elseif bracketType == "{}" then
openBracket = "{"
closeBracket = "}"
elseif bracketType == "()" then
openBracket = "("
closeBracket = ")"
elseif bracketType == "<>" then
openBracket = "<"
closeBracket = ">"
else
error("IllegalArgumentException: Invalid or unrecognized bracket type "..bracketType.."\nFunction: findBrackets()")
end
local openBrackets = self:findAll(openBracket)
if not openBrackets[1] then
return {}
end
for i, j in pairs(openBrackets) do
result[#result + 1] = {j, self:findPair(j, openBracket, closeBracket)}
end
return result
end
Will output:
5 14
6 13
7 12
8 11
9 10
I have a string of email addresses something like :
string str = abc#gmail.com;ghf < ghf#gmail.com >;xyz < xyz#gmail.com>
Now i wanna do something like this
List<string> test = new List<string>();
Regex.Split(to, ";").ToList().ForEach(x => x.Split(new char[] { '<', '>' }).Select(y => y != "<" || y != ">"));
Now how do i Fill only email addresses like abc#gmail.com , ghf#gmail.com and xyz#gmail.com into the list test in single linq query ?
var result = str.Split(';')
.Select(m => Regex.Replace(m, "([^<]+)<([^>]+)>", "$2")
.Trim()).ToList();
Did you try something like:
var test = Regex.Split(to, ";").ToList().ForEach(x => x.Split(new char[] { '<', '>' }).Select(y => y != "<" || y != ">"));
I would like to replace every blank spaces in a string by a fixnum (which is the number of blank spaces).
Let me give an example:
s = "hello, how are you ?"
omg(s) # => "hello,3how10are2you1?"
Do you see a way (sexy if possible) to update a string like this?
Thank you Rubists :)
gsub can be fed a block for the "replace with" param, the result of the block is inserted into place where the match was found. The argument to the block is the matched string. So to implement this we capture as much whitespace as we can ( /\s+/ ) and feed that into the block each time a section is found, returning that string's length, which gets put back where the whitespace was originally found.
Code:
s = "hello, how are you ?"
res = s.gsub(/\s+/) { |m| m.length }
puts res
# => hello,3how10are2you1?
it is possible to do this via an array split : Javascript example
var s = "hello, how are you ?";
function omg( str ) {
var strArr = str.split('');
var count = 0;
var finalStr = '';
for( var i = 0; i < strArr.length; i++ ) {
if( strArr[i] == ' ' ) {
count++;
}
else
{
if( count > 0 ) {
finalStr += '' + count;
count = 0;
}
finalStr += strArr[i];
}
}
return finalStr
}
alert( omg( s ) ); //"hello,3how10are2you1?"
Lol, this seems the best it can be for javascript