I've already had a rule that \ should be replaced with \\\\
, so the existed code is
string.gsub(s, '\\', '\\\\\\\\')
but there is some data that should not be converted, such as abc\"cba, which will be replaced with abc\\\\"cba.
How can I constraint that only \ followed without " can be replaced, such like
'abc\abc' -> 'abc\\\\abc'
'abc\"abc' -> 'abc\"abc'
I have used patterns like \\[^\"]- and \\[^\"]+- but none of them works.
Thanks
You can use
string.gsub((s .. ' '), '\\([^"])', '\\\\\\\\%1'):sub(1, -2)
See the online demo:
local s = [[abc\abc abc\"abc\]];
s = string.gsub((s .. ' '), '\\([^"])', '\\\\\\\\%1'):sub(1, -2)
print( s );
-- abc\\\\abc abc\"abc\\\\
Notes:
\\([^"]) - matches two chars, a \ and then any one char other than a " char (that is captured into Group 1)
\\\\\\\\%1 - replacement pattern that replaces each match with 4 backslashes and the value captured in Group 1
(s .. ' ') - a space is appended at the end of the input string so that the pattern could consume a char other than a " char
:sub(1, -2) - removes the last "technical" space that was added.
Related
I'm new in Ruby on rails and I would like to fetch records based on a condition, and I'm passing the condition in a string format. Moreover, I will pass the query in multiple OR and AND conditions. However, right now, I'm stuck that how to pass the query in string format in rails
I have attached the screenshot
#data= CustomAttribute.includes(:custom_attribute_values).where(id: 18, company_id: current_user.company_id).first
The above line executed successfully and gave the output
<CustomAttribute id: 18, data_type: "string", label: "Marital status", code: "marital_status", entity_type: "member", company_id: 1, created_at: "2021-03-10 10:16:15", updated_at: "2021-03-10 10:16:27", is_active: true, is_default: false, rank: nil, is_identifier: false>
but when I executed the below line it gave me the error that
#data.custom_attribute_values.where("\""+"value_string"+"\""+"="+"\""+'Single'+"\"").size
ERROR: column "Single" does not exist
the Single is the value which I would like to count
Here is my code for the dynamic query creation
logical_operator = 'OR'
#custom_attribute = CustomAttribute.includes(:custom_attribute_values).where(id: custom_attribute_ids, company_id: current_user.company_id)
query=""
#custom_attribute.each_with_index do |attribute_object, index|
filter_object= filter_params[:filters].find {|x| x['custom_attribute_id']==attribute_object['id']}
if filter_object.present?
query += "("+ '"' +'value_'+attribute_object.data_type + '"' + ' ' + filter_object['operator'] + ' ' + "'" + filter_object['value'].to_s + "'"+ ")"
end
if index != #custom_attribute.length-1
query+=' '+logical_operator+' '
end
if index == #custom_attribute.length-1
query="'" + " ( " + query + " ) " + "'"
end
end
byebug
puts(#custom_attribute.first.custom_attribute_values.where(query).size)
Any time you're doing a lot of escaping and string addition in Ruby you're doing it wrong. If we clean up how you build your SQL:
"\""+"value_string"+"\""+"="+"\""+'Single'+"\""
things will be clearer. First, put space around your operators for readability:
"\"" + "value_string" + "\"" + "=" + "\"" + 'Single' + "\""
Next, don't use double quotes unless you need them for escape codes (such as \n) or interpolation:
'"' + 'value_string' + '"' + '=' + '"' + 'Single' + '"'
Now we see that we're adding several constant strings so there's no need to add them at all, a single string literal will do:
'"value_string" = "Single"'
Standard SQL uses double quotes for identifiers (such as table and column names) and single quotes for strings. So your query is asking for all rows where the value_string column equals the Single column and there's your error.
You want to use single quotes for the string (and %q(...) to quote the whole thing to avoid adding escapes back in):
#data.custom_attribute_values.where(
%q("value_string" = 'Single')
)
Or better, let ActiveRecord build the query:
# With a positional placeholder:
#data.custom_attribute_values.where('value_string = ?', 'Single')
# Or a named placeholder:
#data.custom_attribute_values.where('value_string = :s', s: 'Single')
# Or most idiomatic:
#data.custom_attribute_values.where(value_string: 'Single')
So I am trying to parse out #define statements out of a C file using Lua patterns, but there is the case on multiline defines, where you might escape the newline character with a backslash.
In order for me to know where the define ends, I need to be able to define backslash + linebreak as if it were a single character so I can get the complement of that and then use the * quantifier on it and then count until the first non-escaped linebreak.
How do I do that?
You cannot simply replace all occurrences of "\\\n" with some temporary symbol, because a problem will arise with the line "c\\\\\n" in the following example.
Instead, you should implement mini-scanner for C source files:
local str = [[
#define x y
#define a b\
c\\
d();
#define z
]]
-- Print all #defines found in the text
local line = ""
for char in str:gmatch"\\?." do
if char == "\n" then
if line:sub(1, #"#define") == "#define" then
print(line)
end
line = ""
else
line = line..char
end
end
Output:
#define x y
#define a b\
c\\
#define z
Hello experienced pythoners.
The goal is simply to read in my own files which have the following format, and to then apply mathematical operations to these values and polynomials. The files have the following format:
m1:=10:
m2:=30:
Z1:=1:
Z2:=-1:
...
Some very similar variables, next come the laguerre polynomials
...
F:= (12.58295)*L(0,x)*L(1,y)*L(6,z) + (30.19372)*L(0,x)*L(2,y)*L(2,z) - ...:
Where L stands for a laguerre polynomial and takes two arguments.
I have written a procedure in Python which splits apart each line into a left and right hand side split using the "=" character as a divider. The format of these files is always the same, but the number of laguerre polynomials in F can vary.
import re
linestring = open("file.txt", "r").read()
linestring = re.sub("\n\n","\n",str(linestring))
linestring = re.sub(",\n",",",linestring)
linestring = re.sub("\\+\n","+",linestring)
linestring = re.sub(":=\n",":=",linestring)
linestring = re.sub(":\n","\n",linestring)
linestring = re.sub(":","",linestring)
LINES = linestring.split("\n")
for LINE in LINES:
LINE = re.sub(" ","",LINE)
print "LINE=", LINE
if len(LINE) <=0:
next
PAIR = LINE.split("=")
print "PAIR=", PAIR
LHS = PAIR[0]
RHS = PAIR[1]
print "LHS=", LHS
print "RHS=", RHS
The first re.sub block just deals with formatting the file and discarding characters that python will not be able to process; then a loop is performed to print 4 things, LINE, PAIR, LHS and RHS, and it does this nicely. using the example file from above the procedure will print the following:
LINE= m1=1
PAIR= ['m1', '1']
LHS= m1
RHS= 1
LINE= m2=1
PAIR= ['m2', '1']
LHS= m2
RHS= 1
LINE= Z1=-1
PAIR= ['Z1', '-1']
LHS= Z1
RHS= -1
LINE= Z2=-1
PAIR= ['Z2', '-1']
LHS= Z2
RHS= -1
LINE= F= 12.5*L(0,x)L(1,y) + 30*L(0,x)L(2,y)L(2,z)
PAIR=['F', '12.5*L(0,x)L(1,y) + 30*L(0,x)L(2,y)L(2,z)']
LHS= F
RHS= 12.5*L(0,x)L(1,y) + 30*L(0,x)L(2,y)L(2,z)
My question is what is the next best step to process this output and use it in a mathematical script, especially assigning the L to mean a laguerre polynomial? I tried putting the LHS and RHS into a dictionary, but found it troublesome to put F in it due to the laguerre polynomials.
Any ideas are welcome. Perhaps I am overcomplicating this and there is a much simpler way to parse this file.
Many thanks in advance
Your parsing algorithm doesn't seem to work correctly, as the RHS of your variables dont produce the expected result.
Also the first re.sub block where you want to format the file seems overly complicated. Assuming every statement in your input file is terminated by a colon, you could get rid of all whitespace and newlines and seperate the statements using the following code:
linestring = open('file.txt','r').read()
strippedstring = linestring.replace('\n','').replace(' ','')
statements = re.split(':(?!=)',strippedstring)[:-1]
Then you iterate over the statements and split each one in LHS and RHS:
for st in statements:
lhs,rhs = re.split(':=',st)
print 'lhs=',lhs
print 'rhs=',rhs
In the next step, try to distinguish normal float variables and polynomials:
#evaluate rhs
try:
#interpret as numeric constant
f = float(rhs)
print " ",f
except ValueError:
#interpret as laguerre-polynomial
summands = re.split('\+', re.sub('-','+-',rhs))
for s in summands:
m = re.match("^(?P<factor>-?[0-9]*(\.[0-9]*)?)(?P<poly>(\*?L\([0-9]+,[a-z]\))*)", s)
if not m:
print ' polynomial misformatted'
continue
f = m.group('factor')
print ' factor: ',f
p = m.group('poly')
for l in re.finditer("L\((?P<a>[0-9]+),(?P<b>[a-z])\)",p):
print ' poly: L(%s,%s)' % (l.group("a"),l.group("b"))
This should work for your given example file.
I'm writing a grep utility in Lua for our mobile devices running Windows CE 6/7, but I've run into some issues implementing case-insensitive match patterns. The obvious solution of converting everything to uppercase (or lower) does not work so simply due to the character classes.
The only other thing I can think of is converting the literals in the pattern itself to uppercase.
Here's what I have so far:
function toUpperPattern(instr)
-- Check first character
if string.find(instr, "^%l") then
instr = string.upper(string.sub(instr, 1, 1)) .. string.sub(instr, 2)
end
-- Check the rest of the pattern
while 1 do
local a, b, str = string.find(instr, "[^%%](%l+)")
if not a then break end
if str then
instr = string.sub(instr, 1, a) .. string.upper(string.sub(instr, a+1, b)) .. string.sub(instr, b + 1)
end
end
return instr
end
I hate to admit how long it took to get even that far, and I can still see right away there are going to be problems with things like escaped percent signs '%%'
I figured this must be a fairly common issue, but I can't seem to find much on the topic.
Are there any easier (or at least complete) ways to do this? I'm starting to go crazy here...
Hoping you Lua gurus out there can enlighten me!
Try something like this:
function case_insensitive_pattern(pattern)
-- find an optional '%' (group 1) followed by any character (group 2)
local p = pattern:gsub("(%%?)(.)", function(percent, letter)
if percent ~= "" or not letter:match("%a") then
-- if the '%' matched, or `letter` is not a letter, return "as is"
return percent .. letter
else
-- else, return a case-insensitive character class of the matched letter
return string.format("[%s%s]", letter:lower(), letter:upper())
end
end)
return p
end
print(case_insensitive_pattern("xyz = %d+ or %% end"))
which prints:
[xX][yY][zZ] = %d+ [oO][rR] %% [eE][nN][dD]
Lua 5.1, LPeg v0.12
do
local p = re.compile([[
pattern <- ( {b} / {escaped} / brackets / other)+
b <- "%b" . .
escaped <- "%" .
brackets <- { "[" ([^]%]+ / escaped)* "]" }
other <- [^[%]+ -> cases
]], {
cases = function(str) return (str:gsub('%a',function(a) return '['..a:lower()..a:upper()..']' end)) end
})
local pb = re.compile([[
pattern <- ( {b} / {escaped} / brackets / other)+
b <- "%b" . .
escaped <- "%" .
brackets <- {: {"["} ({escaped} / bcases)* {"]"} :}
bcases <- [^]%]+ -> bcases
other <- [^[%]+ -> cases
]], {
cases = function(str) return (str:gsub('%a',function(a) return '['..a:lower()..a:upper()..']' end)) end
, bcases = function(str) return (str:gsub('%a',function(a) return a:lower()..a:upper() end)) end
})
function iPattern(pattern,brackets)
('sanity check'):find(pattern)
return table.concat({re.match(pattern, brackets and pb or p)})
end
end
local test = '[ab%c%]d%%]+ o%%r %bnm'
print(iPattern(test)) -- [ab%c%]d%%]+ [oO]%%[rR] %bnm
print(iPattern(test,true)) -- [aAbB%c%]dD%%]+ [oO]%%[rR] %bnm
print(('qwe [%D]% O%r n---m asd'):match(iPattern(test, true))) -- %D]% O%r n---m
Pure Lua version:
It is necessary to analyze all the characters in the string to convert it into a correct pattern because Lua patterns do not have alternations like in regexps (abc|something).
function iPattern(pattern, brackets)
('sanity check'):find(pattern)
local tmp = {}
local i=1
while i <= #pattern do -- 'for' don't let change counter
local char = pattern:sub(i,i) -- current char
if char == '%' then
tmp[#tmp+1] = char -- add to tmp table
i=i+1 -- next char position
char = pattern:sub(i,i)
tmp[#tmp+1] = char
if char == 'b' then -- '%bxy' - add next 2 chars
tmp[#tmp+1] = pattern:sub(i+1,i+2)
i=i+2
end
elseif char=='[' then -- brackets
tmp[#tmp+1] = char
i = i+1
while i <= #pattern do
char = pattern:sub(i,i)
if char == '%' then -- no '%bxy' inside brackets
tmp[#tmp+1] = char
tmp[#tmp+1] = pattern:sub(i+1,i+1)
i = i+1
elseif char:match("%a") then -- letter
tmp[#tmp+1] = not brackets and char or char:lower()..char:upper()
else -- something else
tmp[#tmp+1] = char
end
if char==']' then break end -- close bracket
i = i+1
end
elseif char:match("%a") then -- letter
tmp[#tmp+1] = '['..char:lower()..char:upper()..']'
else
tmp[#tmp+1] = char -- something else
end
i=i+1
end
return table.concat(tmp)
end
local test = '[ab%c%]d%%]+ o%%r %bnm'
print(iPattern(test)) -- [ab%c%]d%%]+ [oO]%%[rR] %bnm
print(iPattern(test,true)) -- [aAbB%c%]dD%%]+ [oO]%%[rR] %bnm
print(('qwe [%D]% O%r n---m asd'):match(iPattern(test, true))) -- %D]% O%r n---m
I have a text file which has hex values, one value on one separate line. A file has many such values one below another. I need to do some analysis of the values for which i need to but some kind of delimiter/marker say a '#' in this file before line numbers 32,47,62,77... difference between two line numbers in this patterin is 15 always.
I am trying to do it using awk. I tried few things but didnt work.
What is the command in awk to do it?
Any other solution involving some other language/script/tool is also welcome.
Thank you.
-AD
This is how you can use AWK for it,
awk 'BEGIN{ i=0; } \
{if (FNR<31) {print $0} \
else {i++; if (i%15) {print $0} else {printf "#%s\n",$0}}\
}' inputfile.txt > outputfile.txt
How it works,
BEGIN sets an iterator for counting from your starting line 32
FNR<31 starts counting from the 31st record (the next record needs a #)
input lines are called records and FNR is an AWK variable that counts them
Once we start counting, the i%15 prefixes a # on every 15th line
$0 prints the record (the line) as is
You can type all the text with white spaces skipping the trailing '\' on a single command line.
Or, you can use it as an AWK file,
# File: comment.awk
BEGIN{ i=0; }
$0 ~ {\
if (FNR<31) {print $0} \
else {\
i++; \
if (i%15) {\
print $0
}\
else {\
printf "#%s\n",$0
}\
}\
}
And run it as,
awk -f comment.awk inputfile.txt > outputfile.txt
Hope this will help you to use more AWK.
Python:
f_in = open("file.txt")
f_out = open("file_out.txt","w")
offset = 4 # 0 <= offset < 15 ; first marker after fourth line in this example
for num,line in enumerate(f_in):
if not (num-offset) % 15:
f_out.write("#\n")
f_out.write(line)
Haskell:
offset = 31;
chunk_size = 15;
main = do
{
(h, t) <- fmap (splitAt offset . lines) getContents;
mapM_ putStrLn h;
mapM_ ((putStrLn "#" >>) . mapM_ putStrLn) $
map (take chunk_size) $
takeWhile (not . null) $
iterate (drop chunk_size) t;
}