How to detect encoding of a file
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How to detect encoding of a file
 
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Hello,
We have a problem using Moose because we have files which we don't know the encoding. Currently we have this implementation to get the content of a file: completeText self fileReference exists ifFalse: [ ^ '' ]. ^ self fileReference readStreamDo: [ :s | [ s contents ] on: Error do: [ [ s converter: Latin1TextConverter new; contents ] on: Error do: [ '' ] ] ] But, we have a problem because we have currently some files at Synectique in ISO-8859-1. The problem is that #contents is able to read some of the files without throwing an error, but the content is not right because it is not the good encoding. Thus I wonder if it is possible to get the Encoding of a FileReference in Pharo to be able to read the file with the right encoding? Something like the bash command `file -I myFile.txt`. -- Cyril Ferlicot https://ferlicot.fr http://www.synectique.eu 2 rue Jacques Prévert 01, 59650 Villeneuve d'ascq France |
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Re: How to detect encoding of a file
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Re: How to detect encoding of a file
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Re: How to detect encoding of a file
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Re: How to detect encoding of a file
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Le 03/05/2017 à 16:41, Sven Van Caekenberghe a écrit :
> >> On 3 May 2017, at 12:18, Sven Van Caekenberghe <[hidden email]> wrote: >> >> Hi Cyril, >> >> I want to try to write such a detector. I'll get back to you. > > I added the following (Zn #bleedingEdge): > > === > Name: Zinc-Character-Encoding-Core-SvenVanCaekenberghe.49 > Author: SvenVanCaekenberghe > Time: 3 May 2017, 4:30:44.081888 pm > UUID: fe8b083d-010b-0d00-9df5-fde304bccfdc > Ancestors: Zinc-Character-Encoding-Core-SvenVanCaekenberghe.48 > > Add ZnCharacterEncoder class>>#detectEncoding: to try to heuristically and unreliably guess the encoding used by a collection of bytes > > Add ZnCharacterEncoderTests>>#testDetectEncoding > > Add #= and #hash to ZnSimplifiedByteEncoder and ZnEndianSensitiveUTFEncoder > > Always use canonical name in ZnSimplifiedByteEncoder class>>#newForEncoding: > === > Name: Zinc-Character-Encoding-Tests-SvenVanCaekenberghe.31 > Author: SvenVanCaekenberghe > Time: 3 May 2017, 4:31:09.469852 pm > UUID: 30ef8b3e-010b-0d00-9df6-4a9304bccfdc > Ancestors: Zinc-Character-Encoding-Tests-SvenVanCaekenberghe.30 > > Add ZnCharacterEncoder class>>#detectEncoding: to try to heuristically and unreliably guess the encoding used by a collection of bytes > > Add ZnCharacterEncoderTests>>#testDetectEncoding > > Add #= and #hash to ZnSimplifiedByteEncoder and ZnEndianSensitiveUTFEncoder > > Always use canonical name in ZnSimplifiedByteEncoder class>>#newForEncoding: > === > > > Now you can do the following: > > ZnCharacterEncoder detectEncoding: ((FileLocator desktop / 'some.data') binaryReadStreamDo: [ :in | in upToEnd ]). > > (FileLocator desktop / 'some.data') binaryReadStreamDo: [ :in | > | bytes encoder | > bytes := in upToEnd. > encoder := ZnCharacterEncoder detectEncoding: bytes. > encoder decodeBytes: bytes ]. > > It works on the test file you gave me, but this process is just a guess, a heuristic that is unreliable and often wrong (especially for very similar byte encodings), see https://en.wikipedia.org/wiki/Charset_detection. > > You can give the whole contents to the detector, or just a header. > > I was a bit too optimistic though, this is basically an unsolvable problem. It is MUCH better to somehow know up front what the encoding used is, or to know something useable about the contents (like the header of HTML or XML). > > Sven > still includes it in Pharo6. Since it's only a little feature unused in Pharo it should not break anything but it would be cool addition for Moose. But since it is feature freeze if people do not want I'll not push it for Pharo 6 :) -- Cyril Ferlicot https://ferlicot.fr http://www.synectique.eu 2 rue Jacques Prévert 01, 59650 Villeneuve d'ascq France |
Re: How to detect encoding of a file
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Re: How to detect encoding of a file
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Re: How to detect encoding of a file
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In reply to this post by Sven Van Caekenberghe-2
On 03/05/2017 16:41, Sven Van Caekenberghe wrote:
> I added the following (Zn #bleedingEdge): > > === > Name: Zinc-Character-Encoding-Core-SvenVanCaekenberghe.49 > Author: SvenVanCaekenberghe > Time: 3 May 2017, 4:30:44.081888 pm > UUID: fe8b083d-010b-0d00-9df5-fde304bccfdc > Ancestors: Zinc-Character-Encoding-Core-SvenVanCaekenberghe.48 > > Add ZnCharacterEncoder class>>#detectEncoding: to try to heuristically and unreliably guess the encoding used by a collection of bytes > > Add ZnCharacterEncoderTests>>#testDetectEncoding > > Add #= and #hash to ZnSimplifiedByteEncoder and ZnEndianSensitiveUTFEncoder > > Always use canonical name in ZnSimplifiedByteEncoder class>>#newForEncoding: > === > Name: Zinc-Character-Encoding-Tests-SvenVanCaekenberghe.31 > Author: SvenVanCaekenberghe > Time: 3 May 2017, 4:31:09.469852 pm > UUID: 30ef8b3e-010b-0d00-9df6-4a9304bccfdc > Ancestors: Zinc-Character-Encoding-Tests-SvenVanCaekenberghe.30 > > Add ZnCharacterEncoder class>>#detectEncoding: to try to heuristically and unreliably guess the encoding used by a collection of bytes > > Add ZnCharacterEncoderTests>>#testDetectEncoding > > Add #= and #hash to ZnSimplifiedByteEncoder and ZnEndianSensitiveUTFEncoder > > Always use canonical name in ZnSimplifiedByteEncoder class>>#newForEncoding: > === > > > Now you can do the following: > > ZnCharacterEncoder detectEncoding: ((FileLocator desktop / 'some.data') binaryReadStreamDo: [ :in | in upToEnd ]). > > (FileLocator desktop / 'some.data') binaryReadStreamDo: [ :in | > | bytes encoder | > bytes := in upToEnd. > encoder := ZnCharacterEncoder detectEncoding: bytes. > encoder decodeBytes: bytes ]. > > It works on the test file you gave me, but this process is just a guess, a heuristic that is unreliable and often wrong (especially for very similar byte encodings), see https://en.wikipedia.org/wiki/Charset_detection. > > You can give the whole contents to the detector, or just a header. > > I was a bit too optimistic though, this is basically an unsolvable problem. It is MUCH better to somehow know up front what the encoding used is, or to know something useable about the contents (like the header of HTML or XML). > > Sven > It seems to guess right in our case and it correct the problems we saw. Thank you for this! We will integrate it to our tools when the configuration will be updated. -- Cyril Ferlicot https://ferlicot.fr http://www.synectique.eu 2 rue Jacques Prévert 01, 59650 Villeneuve d'ascq France |
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