selective replacing of printf statements - ruby

Question

I am trying to search for a bunch of print statements that I want to filter as follows:
I want to select all dbg_printfs.
Out of all of those I want to select those that have value.stringValue().
Out of those I only want those that do not have value.stringValue().value().
Finally, I want to replace those lines with value.stringValue() to value.stringValue().value().
I don't know why my current code isn't working?
fileObj = File.new(filepath, "r")
while (line = fileObj.gets)
line.scan(/dbg_printf/) do
line.scan(/value.stringValue()/) do
if !line.scan(/\.value\(\)/)
line.gsub!(/value.stringValue()/, 'value.stringValue().value()')
end
end
end
fileObj.close

Answer 1

Primarily, your problem seems to be that you expect altering the string returned from gets to alter the contents of the file. There isn't actually that kind of relationship between strings and files. You need to explicitly write the modifications to the file. Personally, I would probably write that code like this:
modified_contents = IO.readlines(filepath).map do |line|
if line =~ /dbg_printf/
# This regex just checks for value.stringValue() when not followed by .value()
line.gsub /value\.stringValue\(\)(?!\.value\(\))/, 'value.stringValue().value()'
else
line
end
end
File.open(filepath, 'w') {|file| file.puts modified_contents }

Answer 2

The problem is that you are not writing the changed lines back to the same file or a new file. To write them to the same file, read the file into an array, change the array and then write it back to the same or a different file (the later being the more prudent). Here's one way to do that with few lines of code.
Code
fin_name and fout_name are the names (with paths) of the input and output files, respectively.
def filter_array(fin_name, fout_name)
arr_in = File.readlines(fin_name)
arr_out = arr_in.map { |l| (l.include?('dbg_printfs') &&
l.include?('value.stringValue()') &&
!l.include?('value.stringValue().value()')) ?
'value.stringValue() to value.stringValue().value()' : l }
File.open(fout_name, 'w') { |f| f.puts arr_out }
end
Because you are reading code files, they will not be so large that reading them all at once into memory will be a problem.
Example
First, we'll construct an input file:
array = ["My dbg_printfs was a value.stringValue() as well.",
"Her dbg_printfs was a value.stringValue() but not " +
"a value.stringValue().value()",
"value.stringValue() is one of my favorites"]
fin_name = 'fin'
fout_name = 'fout'
File.open(fin_name, 'w') { |f| f.puts array }
We can confirm its contents with:
File.readlines(fin_name).map { |l| puts l }
Now try it:
filter_array(fin_name, fout_name)
Read the output file to see if it worked:
File.readlines(fout_name).map { |l| puts l }
#=> value.stringValue() to value.stringValue().value()
# Her dbg_printfs was a value.stringValue() but not a value.stringValue().value()
# value.stringValue() is one of my favorites
It looks OK.
Explanation
def filter_array(fin_name, fout_name)
arr_in = File.readlines(fin_name)
arr_out = arr_in.map { |l| (l.include?('dbg_printfs') &&
l.include?('value.stringValue()') &&
!l.include?('value.stringValue().value()')) ?
'value.stringValue() to value.stringValue().value()' : l }
File.open(fout_name, 'w') { |f| f.puts arr_out }
end
For the above example,
arr_in = File.readlines('fin')
#=> ["My dbg_printfs was a value.stringValue() as well.\n",
# "Her dbg_printfs was a value.stringValue() but not a value.stringValue().value()\n",
# "value.stringValue() is one of my favorites\n"]
The first element of arr_in passed to map is:
l = "My dbg_printfs] was a value.stringValue() as well."
We have
l.include?('dbg_printfs') #=> true
l.include?('value.stringValue()') #=> true
!l.include?('value.stringValue().value()') #=> true
so that element is mapped to:
"value.stringValue() to value.stringValue().value()"
Neither of the other two elements are replaced by this string, because
!l.include?('value.stringValue().value()') #=> false
and
l.include?('dbg_printfs') #=> false
respectively. Hence,
arr_out = arr_in.map { |l| (l.include?('dbg_printfs') &&
l.include?('value.stringValue()') &&
!l.include?('value.stringValue().value()')) ?
'value.stringValue() to value.stringValue().value()' : l }
#=> ["value.stringValue() to value.stringValue().value()",
# "Her dbg_printfs was a value.stringValue() but not a value.stringValue().value()\n",
# "value.stringValue() is one of my favorites\n"]
The final step is writing arr_out to the output file.