Cursive throws an exception when entering {:12345 :abc}

[danielcompton]

I think this exists in the grey regions of undefined Clojure Reader behaviour.

Typing {:12345 :abc} at the REPL throws this exception in the editor window error box

String index out of range: -1
java.lang.StringIndexOutOfBoundsException: String index out of range: -1
    at java.lang.String.substring(String.java:1937)
    at clojure.core$subs.invoke(core.clj:4781)
    at cursive.filters$fold_line_QMARK_.invoke(filters.clj:146)
    at cursive.filters$stacktrace_folder$fn__8366.invoke(filters.clj:156)
    at cursive.repl.StyledOutputBuffer.addFolding(StyledOutputBuffer.java:456)
    at cursive.repl.StyledOutputBuffer.updateFoldings(StyledOutputBuffer.java:388)
    at cursive.repl.StyledOutputBuffer.access$2700(StyledOutputBuffer.java:40)
    at cursive.repl.StyledOutputBuffer$Text.execute(StyledOutputBuffer.java:338)
    at cursive.repl.StyledOutputBuffer$1.run(StyledOutputBuffer.java:92)
    at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:332)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:715)
    at java.awt.EventQueue.access$400(EventQueue.java:82)

and the repl returns

=> {:12345 :abc}

I'm not really sure what the right behaviour is here. Clojure explicitly says that keywords (all symbols really) must start with a non numeric character, but it goes right ahead and allows it anyway.

This works fine though:

{:12345-12 :abc}
=> {:12345-12 :abc}

[cursive-ide]

Actually, this is a different error due to the regexps used for Cursive's stacktrace folding erroneously matching that line. I'll fix that.

[cursive-ide]

Reopening this since the fix causes IntelliJ to freeze on some REPL output, presumably because of exponential regular expression matching (#1041).