I was trying to fix some weird PDF Unicode remapping issues when I was stuck by this issue where adding an ENQ Unicode character to some part of the code prevents you from compiling the code and IDE will present you with what I think is a false alarm(error).
Consider this example of completely valid Kotlin code and let's call it Program A where unfortunately you can't see the actual characters here between apostrophes but believe me there's a character in there (if you copy this code into your IDE you can see those characters).
package yamin
fun main() {
val foo = mutableListOf('')
//val bar = mutableListOf('')
println(foo)
}
However, you can see them in the picture.
But if you decide to compile this code somehow IDE fails to compile it and claims that there are 'Too many characters in a character literal' in line 4.
What is interesting is that the sheer presence of ENQ character even in a comment line prevents the IDE to compile this code and if you remove line 5, therefore, removing the presence of ENQ character then you can compile this code (let's call it Program B), observe:
Anyway if you decide to remove line 4 in Program A and uncomment line 5 then you can compile that code too (let's call it Program C).
So let's recap Program A is invalid and line 4 is the culprit of the invalidity but removing line 5 in that program which leaves us with Program B could be compiled successfully and this situation is repeated for Program C.
What am I missing here?
It looks like a bug in Kotlin compiler, because the error happens even if the code is compiled with command-line:
kotlinc enq.kt -include-runtime -d enq.jar
Also, this simple program gives different results on the playground (correct):
and locally (incorrect):
As a workaround you may use Unicode escape sequence syntax (at least for ENQ symbol):
Playground does the same thing when passing this code to the server, so the compiler gets sanitized code:
Related
I have the following segment of comment in my code file (the last line is intentionally missing the slash characters - that the error):
// * Cube Back Text from Méi guī
// 一颗 心 怕 摔倒 打破
//"yī kē xīn pà shuāi dǎo dǎ pò"
// "It's the heart afraid of breaking"
// 不敢 起舞 欢 歌
// "bù gǎn qǐwǔ huāngē"
// "that never learns to dance."
不敢起舞欢歌 (dance)
But the red error dot appears on the second character of the second line (second slash of the line "// * Cube Back Text from Méi guī".
Stranger, if I remove various quotes in the comment, the character that is hilited changes.
I assume this has something to do with a recursive structure somewhere in the parser that is continuing to parse the quotes inside the comment itself and ultimately figures out where to signal the error.
I suppose this is a bug ("semi-bug") that I should post to the GitHub list - to completely ignore anything past the second slash on a commented line, or some other change so that the error tag shows up on the line where the error actually is?
As it is, I futzed around about 10 minutes wondering if OpenSCAD just didn't like files longer than 575 lines.
I get the same problem when I try your example or modify it slightly but it worked perfectly when I replaced everything with random Latin characters so I think the bug has a lot to do with the Chinese ideographs you used.
In any case, I only copied the small sample you gave so it probably have nothing to do with the length of the file.
I comment some code in my project and don't want these to be built into my app's binary.
Does Xcode build comments code into its binary?
//Obj-C
//- (void)functionName {
//
//}
//Swift
//func functionName() {
//
//}
For Swift: From The Basics in the “The Swift Programming Language” (emphasis mine):
Use comments to include nonexecutable text in your code, as a note or reminder to yourself. Comments are ignored by the Swift compiler when your code is compiled.
For Objective-C: Objective-C is an extension of C, and the C 99 standard specifies in “5.1.1.2 Translation phases” (emphasis added):
3 The source file is decomposed into preprocessing tokens6) and sequences of white-space characters (including comments). A source file shall not end in a partial preprocessing token or in a partial comment. Each comment is replaced by one space character. New-line characters are retained. Whether each nonempty sequence of white-space characters other than new-line is retained or replaced by one space character is implementation-defined.
and in “6.4.9 Comments”:
1 Except within a character constant, a string literal, or a comment, the characters /* introduce a comment. The contents of such a comment are examined only to identify multibyte characters and to find the characters */ that terminate it.
2 Except within a character constant, a string literal, or a comment, the characters // introduce a comment that includes all multibyte characters up to, but not including, the next new-line character. The contents of such a comment are examined only to identify multibyte characters and to find the terminating new-line character.
Short answer: No.
Long answer:
Every single SDK has a compiler that compiles code into machine language (aka, hexadecimal codes for each of the commands). So, all compilers will ignore comments 100%, so that it can compile codes faster.
In terms of Apple's app, it is bundled such way that in it is packed with all the assets (images, sounds, plist, that are able to be viewed by anybody with the .app file. This is the case where hackers were able to create exactly same app but with slightly different graphics/sounds and resubmit as their own.
Together with those assets, is the BINARY UNIX EXECUTABLE file, which if you open in a notepad, you will see gibberish (machine code cant be read by notepad). Example below is one of my app:
I've been trying to write a simple script compiler for a custom language used by the Game Boy Advance's Z80 processor.
All I want it to do is look at a human-readable command, take it and its arguments and convert it into a hexadecimal value into a ROM file. That's it. Each command is a byte, and each may take a different number of arguments - arguments can be either 8, 16, or 32 bits and each command has a specific number of arguments that it takes.
All of this sort of code is handled by the game and converted into workable machine code within the game's memory, so I'm not writing a full-on assembly compiler if you will. The game automatically knows how many args a command has, what each command does, exactly how to execute it as it is, etc.
For instance, you have command 0x4E, which takes in one 8-bit argument and another 32-bit argument. In hex that would obviously be 4E XX YY YY YY YY. I want my compiler to read it from text as foo 0xXX 0xYYYYYYYY and directly write it into a file as the former.
My question is, how would I do that in VB.NET? I know it's probably a very simple answer, but I see a lot of different options to write it to a file--some work and most don't for me. Could you give me some sample code as to how I would do this?
Writing an assembly compiler as I understand it is not so simple. I recomed you to use one already written see: Software Development Tools for Z80 Family
If you are still interested in writing it here are instructions:
Write the text you want to translate to some file (or memory stream)
Read it line by line
Parse the line either splitting it to an array or with regular
expressions
Identify command and arguments (as far as I remember it some commands
does not have arguments)
Translate the command to Hex (with a collection or dictionary of
commands)
Write results to an array remembering the references for jump
addresses
When everything is translated resolve addresses and write them to
right places.
I think that the most tricky part is to deal with symbolic addressees.
If you are still interested write a first piece of code (or ask how to do it) and continue with next ones.
This sounds like an assembler, even if it for a 'custom language'.
Start by parsing the command lines. use string.split method to convert the string to an array of strings. the first element in the array is your foo, you can then look that up and output 4E, then convert the subsequent elements to bytes.
I'm implementing a small shell, and using lex&yacc to parse command. Lex reads command from stdin and yacc execute the command after yyparse.
The problem is, when there is a syntax error, yacc prompt an error and parse from the begining. In this case, cmd1 >>> cmd2 leads to running cmd2 becuase >>> is a syntax error.
My question is how to discard the rest of current command after encounting a syntax error?
If you want to write an interactive language with a prompt that lets users enter expressions, it's a bad idea to simply use yacc on the entire input stream. Yacc might get confused about something on one line and then misinterpret subsequent lines. For instance, the user might have an unbalanced parenthesis on the first line. or a string literal which is not closed, and then yacc will just keep consuming subsequent lines of the input, looking to close the construct.
It's better to gather the line of input from the user, and then parse that as one unit. The end of the line then simply the end of the input as far as Yacc is concerned.
If you're using lex, there are ways to redirect lex to read characters from a buffer in memory instead of from a FILE * stream. Look for documentation on the YY_INPUT macro, which you can define in a Lex file to basically specify the code that Lex uses for obtaining input characters.
Analogy time: Using a scanner developed with lex/yacc for directly handling interactive user input is a little bit like using scanf for handling user input. Whereas capturing a line into a buffer and then parsing it is more like using sscanf. Quote:
It's perfectly appropriate to parse strings with sscanf (as long as the return value is checked), because it's so easy to regain control, restart the scan, discard the input if it didn't match, etc. [comp.lang.c FAQ, 12.20].
I've made some function that generates an email template. Code it generates is pure HTML with CSS. Problem is compiler does this odd error and highlights each time '#' sign appears which is needed to define colors in CSS. I did try to change '#' to '/pound/' and then string.Replace() on RETURN but no luck. I'm more into C# so there i can escape special characters by using '\' before them but something f$#$ed up there... Once i remove '#' all back to normal and compiles well.
Any guesses ?
btw, i'm using StringBuilder to generate lines of code with sb.Append().
ie.
sb.Append("<div style=""color:#333"">some text</div>")
I think it's a bug,
to reproduce it I used VB.NET 2 (VS 2005), I wrote your instruction:
sb.Append("<div style=""color:#333"">some text</div>")
no problem,
I added some extra " to have the error message you got,
I then fixed everything, all errors disappeared except yours.
Solution: Delete that line, error disappeared, ctrl-z (undo) --> all ok!
I was receiving this same exact error and was able to simply copy the line, delete the line out, re-add a new line, and paste.