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# # ## ### ##### ######## ############# ######################
## Validation of EAN13 numbers.
## EAN = European Article Number
## now International Article Number, without changing the acronym.
#
# References
# http://www.cut-the-knot.org/Curriculum/Arithmetic/EAN13.shtml
# http://www.barcodeisland.com/ean13.phtml
# http://en.wikipedia.org/wiki/EAN-13
# # ## ### ##### ######## ############# ######################
# The code below implements the interface of a snit validation type,
# making it directly usable with snit's -type option in option
# specifications.
# # ## ### ##### ######## ############# ######################
## Requisites
package require Tcl 8.5 9
package require snit
package require valtype::common
# # ## ### ##### ######## ############# ######################
## Implementation
namespace eval ::valtype::gs1::ean13 {
namespace import ::valtype::common::*
}
snit::type ::valtype::gs1::ean13 {
#-------------------------------------------------------------------
# Type Methods
typemethod validate {value} {
if {![regexp {^[0-9]+[Xx]?$} $value]} {
badchar EAN13 "EAN13 number, expected only digits, and possibly 'X' or 'x' as checkdigit"
} elseif {[string length $value] != 13} {
badlength EAN13 13 "EAN13 number"
}
# FUTURE: Check that the first 3 digits are a valid GS1
# FUTURE: country code (numeric). See also the ISO 3166-1
# FUTURE: country codes. Same purpose, different codings (alpha2
# FUTURE: alpha3, numeric3).
set sum [Sum $value]
if {($sum % 10) != 0} {
badcheck EAN13 "EAN13 number"
}
return $value
}
typemethod checkdigit {value} {
if {![regexp {^[0-9]+[Xx]?$} $value]} {
badchar EAN13 "EAN13 number (without checkdigit), expected only digits"
} elseif {[string length $value] != 12} {
badlength EAN13 12 "EAN13 number (without checkdigit)"
}
set c [expr {10 - ([Sum $value] % 10)}]
if {$c == 10} { set c 0 }
return $c
}
proc Sum {value} {
# i| 0 1 2 3 4 5 6 7 8 9
# *3| 0 3 6 9 12 15 18 21 24 27
set sum 0
set flip 1
foreach d [string map {x 10 X 10} [split $value {}]] {
incr sum [lindex {
{0 1 2 3 4 5 6 7 8 9 10}
{0 3 6 9 12 15 18 21 24 27 30}
} [expr {[incr flip] & 1}] $d]
}
return $sum
}
#-------------------------------------------------------------------
# Constructor
# None needed; no options
#-------------------------------------------------------------------
# Public Methods
method validate {value} {
$type validate $value
}
}
# # ## ### ##### ######## ############# ######################
## Ready
package provide valtype::gs1::ean13 1.1
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