What is best approach to parsing CSV string to tab-delimited string?

$tr(str,",",$c(9))
or
$replace(str,",",$c(9))

not being verbose in %occ* world I had this solution also allowing to change quoting
 

BTW.
It's an excellent test exercise for new COS programmers
I'll add it to my collection.

Thanks   
 

You could use CSV() like this... (sorry for the weird formatting)

Your output then looks like this

My proposal:

USER>w csv
ABC Company,"123 Main St, Ste 102","Anytown, DC",10001,234-567-8901
USER>s i=0
 
USER>f  s i=$f(csv,",",i) q:'i  i $l($e(csv,1,i-2),"""")#2 s $e(csv,i-1)=$c(9)
 
USER>w csv
ABC Company     "123 Main St, Ste 102"  "Anytown, DC"   10001   234-567-8901
USER>

USER>write csv
ABC Company,"123 Main St, Ste 102","Anytown, DC",10001,234-567-8901
USER>set i=0
 
USER>for  set i=$find(csv,",",i) quit:'i  if $length($extract(csv,1,i-2),"""")#2 set $extract(csv,i-1)=$char(9)
 
USER>write csv
ABC Company     "123 Main St, Ste 102"  "Anytown, DC"   10001   234-567-8901
USER>

/// <p>This Reader is to be used with %ResultSet. It will allow you to scan a CSV file, record by record.
/// There are three queries available for reading:</p>
/// <ol>
/// <li>CSV - comma separated
/// <li>CSV2 - semicolon separated
/// <li>TSV - tab separated
/// </ol>
/// <p>Use the query accordingly to your file type! The reader expects to find a header on the first line with the name of the fields.
/// This will be used to name the columns when you use the method Get().</p>
/// <p>The reader can deal with fields quoted and unquoted automatically.</p>  
///
///    <p>This assumes that your CSV file has a header line.
/// This custom query supports Comman Separated Values (CSV), Semicolumn Separated Values (CSV2)
/// and Tab Separated Values (TSV).</p>    
///
/// <EXAMPLE>
///
///            ; Comma Separated Values
///            ;Set oCSVFileRS=##class(%ResultSet).%New("IRISDemo.Util.FileReader:CSV")
///            ;
///            ; Semicolon Separated Values
///            ;Set oCSVFileRS=##class(%ResultSet).%New("IRISDemo.Util.FileReader:CSV2")
///            ;
///            ; Tab Separated Values
///            Set oCSVFileRS=##class(%ResultSet).%New("IRISDemo.Util.FileReader:TSV")
///            
///            Set tSC = oCSVFileRS.Execute(pFileName)
///            Quit:$System.Status.IsError(tSC)
///            
///            While oCSVFileRS.Next()
///            {
///                Set tDataField1 = oCSVFileRS.Get("Column Name 1")
///                Set tDataField2 = oCSVFileRS.Get("Column Name 2")
///                Set tDataField4 = oCSVFileRS.GetData(3)
///                
///                // Your code goes here            
///            }
///    </EXAMPLE>                    
///

Class IRISDemo.Util.FileReader Extends %RegisteredObject
{

    /// Use this Query with %ResultSet class to read comma (,) separated files.
    Query CSV(pFileName As %String, pFileEncoding As %String = "UTF8") As %Query
    {
    }
    
    /// Use this Query with %ResultSet class to read semicolon (;) separated files.
    Query CSV2(pFileName As %String, pFileEncoding As %String = "UTF8") As %Query
    {
    }
    
    /// Use this Query with %ResultSet class to read tab separated files.
    Query TSV(pFileName As %String, pFileEncoding As %String = "UTF8") As %Query
    {
    }
    
    /// Index a header from a CSV file so we can later get every row of the file
    /// and read every column by it's name. This method supports fields quoted, double 
    /// quoted or not quoted or a mix of the three. The only thing that is required for this to work
    /// is that the correct field separator is specified (Comma, Semicolon or Tab).
    ClassMethod IndexHeader(pHeader As %String, pSeparator As %String = ",", Output pHeaderIndex)
    {
        //How many columns?
        Set pHeaderIndex=$Length(pHeader,pSeparator)
        
        Set tRegexSeparator=pSeparator
        
        If tRegexSeparator=$Char(9)
        {
            Set tRegexSeparator="\x09"
        }
        
        //Let's build a regular expression to read all the data without the quotes...
        Set pHeaderIndex("Regex")=""
        For i=1:1:pHeaderIndex
        {
            Set $Piece(pHeaderIndex("Regex"),tRegexSeparator,i)="\""?'?(.*?)\""?'?"
        }
        Set pHeaderIndex("Regex")="^"_pHeaderIndex("Regex")
        
        //Let's use this regular expression to index the column names...
        Set oMatcher = ##class(%Regex.Matcher).%New(pHeaderIndex("Regex"))
        Do oMatcher.Match(pHeader)
        
        //Now let's index the colum names
        For i=1:1:oMatcher.GroupCount
        {
            Set pHeaderIndex("Columns",i)=$ZStrip(oMatcher.Group(i),"<>W")
        }
    }

    ClassMethod IndexRow(pRow As %String, ByRef pHeaderIndex As %String, Output pIndexedRow As %String)
    {
        Set oMatcher = ##class(%Regex.Matcher).%New(pHeaderIndex("Regex"))
        Do oMatcher.Match(pRow)
        
        //Now let's index the colum names
        For i=1:1:oMatcher.GroupCount
        {
            Set $List(pIndexedRow,i)=oMatcher.Group(i)
        }
    }

    ClassMethod CSVGetInfo(colinfo As %List, parminfo As %List, idinfo As %List, qHandle As %Binary, extoption As %Integer = 0, extinfo As %List) As %Status
    {
            Quit ..FileGetInfo(.colinfo, .parminfo, .idinfo, .qHandle, .extoption, .extinfo)
    }
    
    ClassMethod CSV2GetInfo(colinfo As %List, parminfo As %List, idinfo As %List, qHandle As %Binary, extoption As %Integer = 0, extinfo As %List) As %Status
    {
            Quit ..FileGetInfo(.colinfo, .parminfo, .idinfo, .qHandle, .extoption, .extinfo)
    }
    
    ClassMethod TSVGetInfo(colinfo As %List, parminfo As %List, idinfo As %List, qHandle As %Binary, extoption As %Integer = 0, extinfo As %List) As %Status
    {
            Quit ..FileGetInfo(.colinfo, .parminfo, .idinfo, .qHandle, .extoption, .extinfo)
    }
    
    ClassMethod FileGetInfo(colinfo As %List, parminfo As %List, idinfo As %List, qHandle As %Binary, extoption As %Integer = 0, extinfo As %List) As %Status
    {
        Merge tHeaderIndex = qHandle("HeaderIndex")
        Set colinfo = ""
        For i=1:1:tHeaderIndex
        {
            Set tColName = tHeaderIndex("Columns",i)
            Set colinfo=colinfo_$LB($LB(tColName))    
        }
        
        Set parminfo=$ListBuild("pFileName","pFileEncoding")
        Set extinfo=""
        Set idinfo=""
        Quit $$$OK
    }

    ClassMethod CSVExecute(ByRef qHandle As %Binary, pFileName As %String, pFileEncoding As %String = "UTF8") As %Status
    {
        Set qHandle("Separator")=","
        Quit ..FileExecute(.qHandle, pFileName, pFileEncoding)
    }

    ClassMethod CSV2Execute(ByRef qHandle As %Binary, pFileName As %String, pFileEncoding As %String = "UTF8") As %Status
    {
        Set qHandle("Separator")=";"
        Quit ..FileExecute(.qHandle, pFileName, pFileEncoding)
    }

    ClassMethod TSVExecute(ByRef qHandle As %Binary, pFileName As %String, pFileEncoding As %String = "UTF8") As %Status
    {
        Set qHandle("Separator")=$Char(9)
        Quit ..FileExecute(.qHandle, pFileName, pFileEncoding)
    }

    ClassMethod FileExecute(ByRef qHandle As %Binary, pFileName As %String, pFileEncoding As %String = "UTF8") As %Status
    {
        Set tSC = $System.Status.OK()
        Try
        {
            Set oFile = ##class(%Stream.FileCharacter).%New()
            If pFileEncoding'="" Set oFile.TranslateTable=pFileEncoding
            Set oFile.Filename=pFileName
            
            Set tHeader=oFile.ReadLine()
            Do ..IndexHeader(tHeader, qHandle("Separator"), .tHeaderIndex)
            
            Merge qHandle("HeaderIndex")=tHeaderIndex
            Set qHandle("File")=oFile
        }
        Catch (oException)
        {
            Set tSC = oException.AsStatus()
        }
        
        Quit tSC
    }

    ClassMethod CSVClose(ByRef qHandle As %Binary) As %Status [ PlaceAfter = FileExecute ]
    {
        Quit ..FileClose(.qHandle)
    }

    ClassMethod CSV2Close(ByRef qHandle As %Binary) As %Status [ PlaceAfter = FileExecute ]
    {
        Quit ..FileClose(.qHandle)
    }

    ClassMethod TSVClose(ByRef qHandle As %Binary) As %Status [ PlaceAfter = FileExecute ]
    {
        Quit ..FileClose(.qHandle)
    }

    ClassMethod FileClose(ByRef qHandle As %Binary) As %Status [ PlaceAfter = FileExecute ]
    {
        #Dim oFile As %Library.FileCharacterStream
        Set tSC = $System.Status.OK()
        Try
        {
            Kill qHandle("File")
            Kill qHandle("HeaderIndex")
        }
        Catch (oException)
        {
            Set tSC = oException.AsStatus()
        }
        
        Quit tSC
    }

    ClassMethod CSVFetch(ByRef qHandle As %Binary, ByRef Row As %List, ByRef AtEnd As %Integer = 0) As %Status [ PlaceAfter = FileExecute ]
    {
        Quit ..FileFetch(.qHandle, .Row, .AtEnd)
    }

    ClassMethod CSV2Fetch(ByRef qHandle As %Binary, ByRef Row As %List, ByRef AtEnd As %Integer = 0) As %Status [ PlaceAfter = FileExecute ]
    {
        Quit ..FileFetch(.qHandle, .Row, .AtEnd)
    }

    ClassMethod TSVFetch(ByRef qHandle As %Binary, ByRef Row As %List, ByRef AtEnd As %Integer = 0) As %Status [ PlaceAfter = FileExecute ]
    {
        Quit ..FileFetch(.qHandle, .Row, .AtEnd)
    }

    ClassMethod FileFetch(ByRef qHandle As %Binary, ByRef Row As %List, ByRef AtEnd As %Integer = 0) As %Status [ PlaceAfter = FileExecute ]
    {
        Set tSC = $System.Status.OK()
        Try
        {
            Set Row = ""
            
            Set oFile = qHandle("File")
            If oFile.AtEnd
            {
                Set AtEnd=1
                Quit
            }
    
            Merge tHeaderIndex=qHandle("HeaderIndex")
            
            While 'oFile.AtEnd
            {
                Set tRow=oFile.ReadLine()
                Continue:tRow=""
                Quit
            }
                    
            Do ..IndexRow(tRow, .tHeaderIndex, .Row)
            
            
        }
        Catch (oException)
        {
            Set tSC = oException.AsStatus()
        }
        
        Quit tSC
    }
}

I've created a Gist containing the source code for a CSV reader.

It will load CSV data from a file, stream or string, exposing each record via a Next() record method and Get() and GetAt() field methods.

It implements various options for changing the field and EOL delimiter, automatic encoding from UTF8 files, quote stripping and normalisation of EOL character(s) to a preferred internal EOL character(s).

https://gist.github.com/SeanConnelly/cb4ff970c2df5266d24c8802d56f48da

I've been using some ugly data and looks to be working good enough, here is output from the  Display() method...

Record No : 1
 address = 1 long street, somewhere, north pole
 poetry =
 
"Poetry"
========
 
From the "Anglo-Saxon" Rune Poem (Rune version):
"ᚠᛇᚻ᛫ᛒᛦᚦ᛫ᚠᚱᚩᚠᚢᚱ᛫ᚠᛁᚱᚪ᛫ᚷᛖᚻᚹᛦᛚᚳᚢᛗ
ᛋᚳᛖᚪᛚ᛫ᚦᛖᚪᚻ᛫ᛗᚪᚾᚾᚪ᛫ᚷᛖᚻᚹᛦᛚᚳ᛫ᛗᛁᚳᛚᚢᚾ᛫ᚻᛦᛏ᛫ᛞᚫᛚᚪᚾ
ᚷᛁᚠ᛫ᚻᛖ᛫ᚹᛁᛚᛖ᛫ᚠᚩᚱ᛫ᛞᚱᛁᚻᛏᚾᛖ᛫ᛞᚩᛗᛖᛋ᛫ᚻᛚᛇᛏᚪᚾ"᛬
 
From Laȝamon's Brut (The Chronicles of England, Middle English, West Midlands):
 
"An preost wes on leoden, Laȝamon was ihoten
He wes Leovenaðes sone -- liðe him be Drihten.
He wonede at Ernleȝe at æðelen are chirechen,
Uppen Sevarne staþe, sel þar him þuhte,
Onfest Radestone, þer he bock radde."
 
(The third letter in the author's name is Yogh, missing from many fonts; CLICK HERE for another Middle English sample with some explanation of letters and encoding).
 
From the Tagelied of Wolfram von Eschenbach (Middle High German):
 
"Sîne klâwen durh die wolken sint geslagen,
er stîget ûf mit grôzer kraft,
ich sih in grâwen tägelîch als er wil tagen,
den tac, der im geselleschaft
erwenden wil, dem werden man,
den ich mit sorgen în verliez.
ich bringe in hinnen, ob ich kan.
sîn vil manegiu tugent michz leisten hiez."
 
Some lines of Odysseus Elytis (Greek):
 
Monotonic:
 
"Τη γλώσσα μου έδωσαν ελληνική
το σπίτι φτωχικό στις αμμουδιές του Ομήρου.
Μονάχη έγνοια η γλώσσα μου στις αμμουδιές του Ομήρου.
από το Άξιον Εστί
του Οδυσσέα Ελύτη"
 
Polytonic:
 
"Τὴ γλῶσσα μοῦ ἔδωσαν ἑλληνικὴ
τὸ σπίτι φτωχικὸ στὶς ἀμμουδιὲς τοῦ Ὁμήρου.
Μονάχη ἔγνοια ἡ γλῶσσα μου στὶς ἀμμουδιὲς τοῦ Ὁμήρου.
ἀπὸ τὸ Ἄξιον ἐστί
τοῦ Ὀδυσσέα Ἐλύτη
The first stanza of Pushkin's Bronze Horseman (Russian):
На берегу пустынных волн
Стоял он, дум великих полн,
И вдаль глядел. Пред ним широко
Река неслася; бедный чёлн
По ней стремился одиноко.
По мшистым, топким берегам
Чернели избы здесь и там,
Приют убогого чухонца;
И лес, неведомый лучам
В тумане спрятанного солнца,
Кругом шумел."
 
Šota Rustaveli's Veṗxis Ṭq̇aosani, ̣︡Th, The Knight in the Tiger's Skin (Georgian):
 
"ვეპხის ტყაოსანი შოთა რუსთაველი
ღმერთსი შემვედრე, ნუთუ კვლა დამხსნას სოფლისა შრომასა, ცეცხლს, წყალსა და მიწასა, ჰაერთა თანა მრომასა; მომცნეს ფრთენი და აღვფრინდე, მივჰხვდე მას ჩემსა ნდომასა, დღისით და ღამით ვჰხედვიდე მზისა ელვათა კრთომაასა."
 
Tamil poetry of Subramaniya Bharathiyar: சுப்ரமணிய பாரதியார் (1882-1921):
 
"யாமறிந்த மொழிகளிலே தமிழ்மொழி போல் இனிதாவது எங்கும் காணோம்,
பாமரராய் விலங்குகளாய், உலகனைத்தும் இகழ்ச்சிசொலப் பான்மை கெட்டு,
நாமமது தமிழரெனக் கொண்டு இங்கு வாழ்ந்திடுதல் நன்றோ? சொல்லீர்!
தேமதுரத் தமிழோசை உலகமெலாம் பரவும்வகை செய்தல் வேண்டும்."
 
Kannada poetry by Kuvempu — ಬಾ ಇಲ್ಲಿ ಸಂಭವಿಸು
 
"ಬಾ ಇಲ್ಲಿ ಸಂಭವಿಸು ಇಂದೆನ್ನ ಹೃದಯದಲಿ
ನಿತ್ಯವೂ ಅವತರಿಪ ಸತ್ಯಾವತಾರ
ಮಣ್ಣಾಗಿ ಮರವಾಗಿ ಮಿಗವಾಗಿ ಕಗವಾಗೀ...
ಮಣ್ಣಾಗಿ ಮರವಾಗಿ ಮಿಗವಾಗಿ ಕಗವಾಗಿ
ಭವ ಭವದಿ ಭತಿಸಿಹೇ ಭವತಿ ದೂರ
ನಿತ್ಯವೂ ಅವತರಿಪ ಸತ್ಯಾವತಾರ || ಬಾ ಇಲ್ಲಿ ||"
 
 spaceship =
 
 
       _________
      (=========)
      |=========|
      |====_====|
      |== / \ ==|
      |= / _ \ =|
   _  |=| ( ) |=|
  /=\ |=|,,,,,|=| /=\
  |=| |=| USA |=| |=|
  |=| |=|,,,,,|=| |=|
  |=| |=| | | |=| |=|
  |=| |=| | | |=| |=|
  |=| |=| | | |=| |=|
  |=| |/  | |  \| |=|
  |=|/    | |    \|=|
  |=/NASA |_| NASA\=|
  |(_______________)|
  |=| |_|__|__|_| |=|
  |=|   ( ) ( )   |=|
 /===\           /===\
|||||||         |||||||
-------         -------
 (""")           (""")
 
 size = Big
 qty = 5.7

Still another approach using your original "solution" in PHP following the idea of a Micro-Service.

Instead of a mimic of what PHP might do I use it directly for this purpose.
That way more sophisticated functionalities that can be used without recoding.

I extended your test to include doubled double quotes

*

and here the code: