error.jl

# pseudo-definitions to show how everything behaves
#
# throw(label, val) = # throw a value to a dynamically enclosing block
#
# function rethrow(val)
#     global current_exception = val
#     throw(current_handler(), current_exception)
# end
#
# rethrow() = rethrow(current_exception)
#
# function throw(val)
#     global catch_backtrace = backtrace()
#     rethrow(val)
# end

## native julia error handling ##

error(e::Exception) = throw(e)
error{E<:Exception}(::Type{E}) = throw(E())
error(s::String) = throw(ErrorException(s))
error(s...)      = throw(ErrorException(string(s...)))

macro unexpected()
    :(error("unexpected branch reached"))
end

rethrow() = ccall(:jl_rethrow, Void, ())::None
rethrow(e) = ccall(:jl_rethrow_other, Void, (Any,), e)::None
backtrace() = ccall(:jl_backtrace_from_here, Array{Ptr{Void},1}, ())
catch_backtrace() = ccall(:jl_get_backtrace, Array{Ptr{Void},1}, ())

## system error handling ##

errno() = ccall(:jl_errno, Cint, ())
errno(e::Integer) = ccall(:jl_set_errno, Void, (Cint,), e)
strerror(e::Integer) = bytestring(ccall(:strerror, Ptr{Uint8}, (Int32,), e))
strerror() = strerror(errno())
systemerror(p, b::Bool) = b ? throw(SystemError(string(p))) : nothing

## assertion functions and macros ##

assert(x) = x ? nothing : error("assertion failed")
macro assert(ex,msgs...)
    msg = isempty(msgs) ? ex : msgs[1]
    if !isempty(msgs) && isa(msg, Expr)
        # message is an expression needing evaluating
        msg = :(string("assertion failed: ", $(esc(msg))))
    elseif isdefined(Base,:string)
        msg = string("assertion failed: ", msg)
    else
        # string() might not be defined during bootstrap
        msg = :(string("assertion failed: ", $(Expr(:quote,msg))))
    end
    :($(esc(ex)) ? $(nothing) : error($msg))
end