ANTLRv4: How to read double quote escaped double quotes in string?

Question

In ANTLR v4, how do we parse this kind of string with double quote escaped double quotes like in VBA?

for text:

"some string with ""john doe"" in it"

the goal would be to identify the string: some string with "john doe" in it

And is it possible to rewrite it to turn double double quotes in single double quotes? "" -> "?

Bart Kiers · Accepted Answer · 2013-07-28T17:59:17.443

17

Like this:

STRING
 : '"' (~[\r\n"] | '""')* '"'
 ;

where ~[\r\n"] | '""' means:

~[\r\n"]    # any char other than '\r', '\n' and double quotes
|           # OR
'""'        # two successive double quotes

And is it possible to rewrite it to turn double double quotes in single double quotes?

Not without embedding custom code. In Java that could look like:

STRING
 : '"' (~[\r\n"] | '""')* '"' 
   {
     String s = getText();
     s = s.substring(1, s.length() - 1); // strip the leading and trailing quotes
     s = s.replace("\"\"", "\""); // replace all double quotes with single quotes
     setText(s);
   }
 ;

edited Jul 28 '13 at 17:59

answered Jul 27 '13 at 12:47

Bart Kiers

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works like a charm. side question, is it possible to rewrite it to turn double double quotes in single double quotes? "" -> "? thanks! – JayDee Jul 28 '13 at 15:40
@JayDee see my revised answer. – Bart Kiers Jul 28 '13 at 18:11
2

For me using ANTLR 4 the following rule worked with both double quoted and single quoted strings: STRING : '"' (~[\r\n"] | '""')* '"' | '\'' (~[\r\n\'] | '\'\'')* '\''; – Sasha Sep 03 '15 at 12:49
@Sasha your string throws "invalid escape sequence \' Exception in thread "main" java.lang.RuntimeException: set is empty" – Alexey Sh. Jul 20 '20 at 23:37
@AlexeySh. I assume that's because I copy-pasted from a C# program and you pasted it into java program where escaping a double-quote is done differently (not through '\') – Sasha Jul 21 '20 at 15:12
Different ANTLR versions might react differently for `~[\r\n\']`. ANTLR 4.8 produces an error. It should be `~[\r\n']` – Bart Kiers Jul 21 '20 at 15:24

ANTLRv4: How to read double quote escaped double quotes in string?

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