Escape characters in Strings

[RieksJ]

I used Ampersand-v3.9.1 [development:b051de7] when compiling the following script:

CONTEXT KvK_ZZPRegForms
INCLUDE "..\SSIF-Generic\SSIF_FormTemplates.adl"
-- etc...
ENDCONTEXT

I expected that the texts between quotes after the INCLUDE statement would be recognized as a string literal. However, It resulted in the following error message:

Lexer error at line 3:9, file C:\Ampersand\Git\tno-models\SSIF-KvK\KvK_ZZPRegistrationForms.adl
  Unterminated string literal
    Correct examples of Strings: "Ampersand (&) is cool" "Helium is cool too!" "abc\ndef" ""
Terminated at ...: 15:57:43,67

Diagnosis

After some tinkering, it turned out that I needed to replace the \ characters with /. Perhaps the \S is treated as a separator that terminates the parsing of a literal, because I also tried the example "abc\ndef" as given in the error message.

It seems to me that if beginners get this error, they would have no clue where to look, let alone where to fix this.

[hanjoosten]

Since we like to be able to represent all imaginable strings, we need some way to denote a string that holds a double quote. If nothing was done, the first double quote in the string would be interpreted as the end of the string. Also, we want some way to represent multi-line strings.
To do so, we have \ as an escape character, as is done in C, in Haskell and in many other computer languages. For those interested, we use the same as Haskell does. (documentation is here).

In the above case, I would recommend to write:

CONTEXT KvK_ZZPRegForms
INCLUDE "../SSIF-Generic/SSIF_FormTemplates.adl"
-- etc...
ENDCONTEXT

but you could also write:

CONTEXT KvK_ZZPRegForms
INCLUDE "..\\SSIF-Generic\\SSIF_FormTemplates.adl"
-- etc...
ENDCONTEXT

In the latter case, the escape character is escaped itself!

Feel free to update the documentation if you find that useful.

[RieksJ]

The bug is not the fact that the parsing is wrong, but that the error message does not help the user - particularly if they are beginners. As I have mentioned before, error messages are there to help the user, and I consider it a bug if they do not. In this example, that is the case.

It would be nice if the error message could be extended to include the text This error may be caused by a missing quote-character ('"'), or by the inadvertent use of the escape character ('\'). Would you be so kind as to grant me this wish?

[hanjoosten]

Poof! Wish granted 😁