How to resolve the algorithm Unix/ls step by step in the Smalltalk programming language

Published on 12 May 2024 09:40 PM
#Smalltalk

How to resolve the algorithm Unix/ls step by step in the Smalltalk programming language

Table of Contents

Problem Statement

Write a program that will list everything in the current folder,   similar to:

The output must be sorted, but printing extended details and producing multi-column output is not required.

For the list of paths:

When the program is executed in   /foo,   it should print: and when the program is executed in   /foo/bar,   it should print:

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Unix/ls step by step in the Smalltalk programming language

Source code in the smalltalk programming language

Stdout printCR: ( PipeStream outputFromCommand:'ls' )


Stdout printCR:('.' asFilename directoryContents sort asStringWith:Character cr)


'.' asFilename directoryContents sort do:#printCR


dir := '.' asFilename.
dir directoryContentsAsFilenames sort do:[:fn |
    |line|
    " 
     generate a line of the form of ls -l:
         drwxrwxrwx    user  group     size  date time name
     where year is printed if not current, time of day otherwise
    " 
    line := String streamContents:[:s |
        |accessRights|

        s nextPut:(fn isDirectory ifTrue:[$d] ifFalse:[$-]).
        accessRights := fn symbolicAccessRights.
        #(  readUser writeUser executeUser 
            readGroup writeGroup executeGroup
            readOthers writeOthers executeOthers
         ) 
        with:'rwxrwxrwx' 
        do:[:eachRight :charToPrint |
            s nextPut:((accessRights includes:eachRight) ifTrue:[charToPrint] ifFalse:[$-])
        ].
        (OperatingSystem getUserNameFromID:fn info uid) printOn:s leftPaddedTo:10.
        (OperatingSystem getGroupNameFromID:fn info gid) printOn:s leftPaddedTo:10.
        fn fileSize printOn:s leftPaddedTo:12.
        fn modificationTime year = Date today year ifTrue:[
            fn modificationTime printOn:s format:' %(dayPadded) %(ShortMonthName) %h:%m'.
        ] ifFalse:[
            fn modificationTime asDate printOn:s format:' %(dayPadded) %(ShortMonthName)  %y'.
        ].
        s space.
        s nextPutAll:fn baseName
    ].
    line printCR
].

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