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# Written by Aleksey Cheusov <vle@gmx.net>, public domain
#
# This awk module is a part of RunAWK distribution,
# http://sourceforge.net/projects/runawk
#
############################################################
# =head2 xgetline.awk
#
# =over 2
#
# =item I<xgetline0([FILE])>
#
# Safe analog to 'getline < FILE' or 'getline' (if no FILE is specified).
# 0 at the end means that input line is assigned to $0.
#
# =item I<xgetline([FILE])>
#
# Safe analog to 'getline __input < FILE' and 'getline __input'
# (if no FILE is specified)
#
# =back
#
# In both cases "safe" means that returned value is analysed and
# if it is less than zero (file reading error happens) program will
# be terminated emmidiately with appropriate error message sent to stderr.
# Both functions return zero if end of file is reached or non-zero otherwise.
#
# Example:
# while (xgetline("/etc/passwd")){
# print "user: " __input
# }
#
#use "alt_assert.awk"
function xgetline0 (fn, ret){
if (fn == ""){
ret = getline
assert(ret >= 0, "getline failed")
}else{
ret = (getline < fn)
assert(ret >= 0, "getline < " fn " failed")
}
return (ret > 0)
}
function xgetline (fn, ret){
if (fn == ""){
ret = getline __input
assert(ret >= 0, "getline failed")
}else{
ret = (getline __input < fn)
assert(ret >= 0, "getline < " fn " failed")
}
return (ret > 0)
}
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