I have code that uses the cl-json library to add a line, {"main" : "build/electron.js"} to a package.json file:
(let ((package-json-pathname (merge-pathnames *app-pathname* "package.json")))
(let
((new-json (with-open-file (package-json package-json-pathname :direction :input :if-does-not-exist :error)
(let ((decoded-package (json:decode-json package-json)))
(let ((main-entry (assoc :main decoded-package)))
(if (null main-entry)
(push '(:main . "build/electron.js") decoded-package)
(setf (cdr main-entry) "build/electron.js"))
decoded-package)))))
(with-open-file (package-json package-json-pathname :direction :output :if-exists :supersede)
(json:encode-json new-json package-json))
)
)
The code works, but the result has an escaped slash:
"main":"build\/electron.js"
I'm sure this is a simple thing, but no matter which inputs I try -- "//", "/", "#//" -- I still get the escaped slash.
How do I just get a normal slash in my output?
Also, I'm not sure if there's a trivial way for me to get pretty-printed output, or if I need to write a function that does this; right now the output prints the entire package.json file to a single line.
Special characters
The JSON Spec indicates that "Any character may be escaped.", but some of them MUST be escaped: "quotation mark, reverse solidus, and the control characters". The linked section is followed by a grammar that show "solidus" (/) in the list of escaped characters. I don't think it is really important in practice (typically it needs not be escaped), but that may explain why the library escapes this character.
How to avoid escaping
cl-json relies on an internal list of escaped characters named +json-lisp-escaped-chars+, namely:
(defparameter +json-lisp-escaped-chars+
'((#\" . #\")
(#\\ . #\\)
(#\/ . #\/)
(#\b . #\Backspace)
(#\f . #\ )
(#\n . #\Newline)
(#\r . #\Return)
(#\t . #\Tab)
(#\u . (4 . 16)))
"Mapping between JSON String escape sequences and Lisp chars.")
The symbol is not exported, but you can still refer to it externally with ::. You can dynamically rebind the parameter around the code that needs to use a different list of escaped characters; for example, you can do as follows:
(let ((cl-json::+json-lisp-escaped-chars+
(remove #\/ cl-json::+json-lisp-escaped-chars+ :key #'car)))
(cl-json:encode-json-plist '("x" "1/5")))
This prints:
{"x":"1/5"}
Related
Here is my code that does CSV parsing, using the text and attoparsec
libraries:
import qualified Data.Attoparsec.Text as A
import qualified Data.Text as T
-- | Parse a field of a record.
field :: A.Parser T.Text -- ^ parser
field = fmap T.concat quoted <|> normal A.<?> "field"
where
normal = A.takeWhile (A.notInClass "\n\r,\"") A.<?> "normal field"
quoted = A.char '"' *> many between <* A.char '"' A.<?> "quoted field"
between = A.takeWhile1 (/= '"') <|> (A.string "\"\"" *> pure "\"")
-- | Parse a block of text into a CSV table.
comma :: T.Text -- ^ CSV text
-> Either String [[T.Text]] -- ^ error | table
comma text
| T.null text = Right []
| otherwise = A.parseOnly table text
where
table = A.sepBy1 record A.endOfLine A.<?> "table"
record = A.sepBy1 field (A.char ',') A.<?> "record"
This works well for a variety of inputs but is not working in case that there
is a trailing \n at the end of the input.
Current behaviour:
> comma "hello\nworld"
Right [["hello"],["world"]]
> comma "hello\nworld\n"
Right [["hello"],["world"],[""]]
Wanted behaviour:
> comma "hello\nworld"
Right [["hello"],["world"]]
> comma "hello\nworld\n"
Right [["hello"],["world"]]
I have been trying to fix this issue but I ran out of idaes. I am almost
certain that it will have to be something with A.endOfInput as that is the
significant anchor and the only "bonus" information we have. Any ideas on how
to work that into the code?
One possible idea is to look at the end of the string before running the
Attoparsec parser and removing the last character (or two in case of \r\n)
but that seems to be a hacky solution that I would like avoid in my code.
Full code of the library can be found here: https://github.com/lovasko/comma
I had a question concerning some basic transformations in Haskell.
Basically, I have a written Input file, named Input.md. This contains some markdown text that is read in my project file, and I want to write a few functions to do transformations on the text. After completing these functions under a function called convertToHTML, I have output the file as an .html file in the correct format.
module Main
(
convertToHTML,
main
) where
import System.Environment (getArgs)
import System.IO
import Data.Char (toLower, toUpper)
process :: String -> String
process s = head $ lines s
convertToHTML :: String -> String
convertToHTML str = do
x <- str
if (x == '#')
then "<h1>"
else return x
--convertToHTML x = map toUpper x
main = do
args <- getArgs -- command line args
let (infile,outfile) = (\(x:y:ys)->(x,y)) args
putStrLn $ "Input file: " ++ infile
putStrLn $ "Output file: " ++ outfile
contents <- readFile infile
writeFile outfile $ convertToHTML contents
So,
How would I read through my input file, and transform any line that starts with a # to an html tag
How would I read through my input file once more and transform any WORD that is surrounded by _word_ (1 underscore) to another html tag
Replace any Character with an html string.
I tried using such functions such as Map, Filter, ZipWith, but could not figure out how to iterate through the text and transform each text. Please if anybody has any suggestions. I've been working on this for 2 days straight and have a bunch of failed code to show for a couple of weeks and have a bunch of failed code to show it.
I tried using such functions such as Map, Filter, ZipWith, but could not figure out how to iterate through the text and transform each text.
Because they work on appropriate element collection. And they don't really "iterate"; you simply have to feed the appropriate data. Let's tackle the # problem as an example.
Our file is one giant String, and what we'd like is to have it nicely split in lines, so [String]. What could do it for us? I have no idea, so let's just search Hoogle for String -> [String].
Ah, there we go, lines function! Its counterpart, unlines, is also going to be useful. Now we can write our line wrapper:
convertHeader :: String -> String
convertHeader [] = [] -- that prevents us from calling head on an empty line
convertHeader x = if head x == '#' then "<h1>" ++ x ++ "</h1>"
else x
and so:
convertHeaders :: String -> String
convertHeaders = unlines . map convertHeader . lines
-- ^String ^[String] ^[String] ^String
As you can see the function first converts the file to lines, maps convertHeader on each line, and the puts the file back together.
See it live on Ideone
Try now doing the same with words to replace your formatting patterns. As a bonus exercise, change convertHeader to count the number of # in front of the line and output <h1>, <h2>, <h3> and so on accordingly.
I have a list:
[[1]]$period
[1] "DAY"
[[1]]$dates
[1] 1.361743e+12 1.362348e+12 1.362953e+12 1.363558e+12 1.364162e+12 1.364764e+12 1.365368e+12 1.365973e+12 1.366578e+12
I want to put this list to json:
toJSON(my_list)
answer:
[
{
\"period\": \"DAY\",
\"dates\": [
1361743200000,
1362348000000,
1362952800000,
1363557600000,
1364162400000,
1364763600000,
1365368400000,
1365973200000,
1366578000000
]
}
]
The answer is with slash symbols "\".
How to get rid of slash symbols? Maybe I should apply another function, to parse my_list to json?
The slash is just R's escape character. Used in this context it allows a quotation mark without closing the string. Although it appears in R console output, it doesn't appear when writing out to a file and it and the character you are escaping are counted as a single character:
x <- "ab\"c"
x
[1] "ab\"c"
writeLines(x)
ab"c
nchar(x)
[1] 4
I am using h helper method in Rails to encode/escape a string that has an apostrophe (') In my view I am using it like this
<%=h "Mike's computer" %>
My understanding is that the html when viewing the source should be Mike%27s computer but the html produced has an apostrophe in it, Mike's computer
Am I missing something obvious?
How do I get my desired result of Mike%27s computer?
Help is always appreciated.
An apostrophe is a valid character in HTML. It is not encoded because it is not needed to be encoded.
If you want to encode a URL, use u helper:
>> fer#:~/$ script/console
Loading development environment (Rails 2.3.8)
>> include ERB::Util
=> Object
>> h "Mike's computer"
=> "Mike's computer"
>> u "Mike's computer"
=> "Mike%27s%20computer"
>>
If we look at the source code of the h method (it is an alias for html_escape), it is not that hard to just open the file and add the single quote (') to the HTML_ESCAPE constant in the file.
Below is the source code of the method with the location of the method in the file. Find the constant and and the quote in. You can even add more things inside as you want it.
HTML_ESCAPE = { '&' => '&', '>' => '>', '<' => '<', '"' => '"' }
File actionpack/lib/action_view/template_handlers/erb.rb, line 17
17: def html_escape(s)
18: s.to_s.gsub(/[&"><]/) { |special| HTML_ESCAPE[special] }
19: end
CAVEAT: This modification will affect all projects that uses the library.
OR an alternative will be to create a view helper method say in ApplicationHelper
def h_with_quote(s)
HTML_ESCAPE = { "'" => "%27"}
h(s).gsub(/[']/) {|special| HTML_ESCAPE[special]}
end
That approach should be safer.
When I use emacs python-mode, if the last character of a line is an open parenthesis it indents the next line just one step in from the indentation of the previous line.
call_some_function(
some_very_long_argument_that_I_want_to_put_on_its_own_line)
I like that. Now in ecmascript-mode (which I am using for actionscript 3), it always indents to the level of the previous parenthesis.
call_some_function(
this_is_not_really_saving_me_any_horizontal_space);
How can I make ecmascript-mode indent like python-mode in this respect?
Since ecmascript-mode is based on cc-mode, you can use c-set-offset which allows you to customize any syntactic symbol's offset with the preferred value.
In your case, go to the point which is indented in the wrong level, hit C-c C-o (or type M-x c-set-offset), accept the suggested symbol (arglist-intro), and set it a new value (e.g. +, the default offset).
You can also do it programmatically in your dotemacs, for instance, with:
(add-hook 'ecmascript-mode-hook
(lambda ()
(c-set-offset 'arglist-intro '+)
(c-set-offset 'arglist-close 0)))
ecmascript-mode seems to be based on cc-mode. If you set the indentation style for cc-mode,
it will also work for ecmascript-mode. I have the following code in my .emacs. When I use
ecmascript-mode it indents as desired:
;;{{{ c/c++ indent style variables
(require 'cc-mode)
(defconst my-c-style
'(
(c-electric-pound-behavior . 'alignleft)
(c-tab-always-indent . t)
(c-hanging-braces-alist . ((block-open)
(brace-list-open)
(substatement-open)
(defun-open before after)
(defun-close before after)
))
(c-hanging-colons-alist . ((member-init-intro before)
(inher-intro)
(case-label)
(access-label after)
(label after)
(access-key after)))
(c-cleanup-list . (scope-operator
empty-defun-braces
defun-close-semi))
(c-offsets-alist . ((arglist-close . c-lineup-arglist)
(case-label . 4)
(statement-case-intro . 4)
(access-label . -4)
(label . -)
(substatement-open . 0)
(block-open . 0)
(knr-argdecl-intro . -)))
)
"My C++/C Programming Style")
; Customizations for both c-mode and c++-mode
(defun my-c-mode-common-hook ()
; set up for my perferred indentation style, but only do it once
(c-add-style "My" my-c-style 'set-this-style)
; we like auto-newline and hungry-delete
(c-toggle-auto-hungry-state 1)
; keybindings for both C and C++. We can put these in c-mode-map
; because c++-mode-map inherits it
(define-key c-mode-map "\C-m" 'newline-and-indent)
; insert 8 tabs
(setq tab-width 8)
)
;;}}}
Thank you Török Gábor, in my case I prefered to set
(add-hook 'XXX-mode-hook
(lambda ()
(c-set-offset 'arglist-cont-nonempty '+)))
I was looking for something like this :
veryLongFunctionName (bar,
bar,
bar)
For a more exhaustive list of variables : read emacs documentation