factor/library/errors.factor

! :folding=indent:collapseFolds=1:

! $Id$
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! Copyright (C) 2004 Slava Pestov.
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IN: kernel
DEFER: callcc1

IN: errors
USE: kernel
USE: kernel-internals
USE: lists
USE: math
USE: namespaces
USE: strings
USE: vectors

: undefined-method ( object generic -- )
    #! This word is redefined in tools/debugger.factor with a
    #! more useful definition once unparse is available.
    "No suitable method" throw ;

! This is a very lightweight exception handling system.

: catchstack ( -- cs ) 6 getenv ;
: set-catchstack ( cs -- ) 6 setenv ;

: >c ( catch -- ) catchstack cons set-catchstack ;
: c> ( catch -- ) catchstack uncons set-catchstack ;

: save-error ( error -- )
    #! Save the stacks and parser state for post-mortem
    #! inspection after an error.
    namespace [
        "col" get
        "line" get
        "line-number" get
        "file" get
        global [
            "error-file" set
            "error-line-number" set
            "error-line" set
            "error-col" set
            "error" set
            datastack "error-datastack" set
            callstack "error-callstack" set
            namestack "error-namestack" set
            catchstack "error-catchstack" set
        ] bind
    ] when ;

: catch ( try catch -- )
    #! Call the try quotation. If an error occurs restore the
    #! datastack, push the error, and call the catch block.
    #! If no error occurs, push f and call the catch block.
    [ >c >r call c> drop f r> f ] callcc1 rot drop swap call ;

: rethrow ( error -- )
    #! Use rethrow when passing an error on from a catch block.
    #! For convinience, this word is a no-op if error is f.
    [ c> call ] when* ;