Handling of csv-files for GemStone/S
# GsCsvSupport
Handling of csv-files for GemStone/S
This package currently contains the classes CsvReader and CsvWriter.
## CsvReader
CsvReader is a self-contained class with no dependencies other than GemStone/S kernel classes.
It allows performant reading of very large amount of csv-data from a file stream.
CsvReader will auto-detect the used line-ending from either lf (Unix style), cr (Classic Mac style) or crlf (Windows style). However, consitent line-endings within a single file are expected.
The used delimiter can optionally be specified with useDelimiter:, otherwise an auto-detection is tried from the commonly used separators tab, comma, semicolon, pipe, tilde or colon.
CsvReader auto-detects the encoding of the file. UTF-8 and ANSI encoding is supported. If the file starts with an [UTF-8 BOM](https://en.wikipedia.org/wiki/Byte_order_mark), the file is clearly detected as UTF-8 encoded. If no UTF-8 BOM is given, auto-detection will be done based on the file's content, paying special attention to german umlauts and the Euro sign €. In case of an ANSI file, Windows-1252 is assumed rather than ISO-8859-1, therefore octet 0x80 will be interpreted as Euro sign € and automatically transcoded to its unicode.
CsvReader respects [RFC 4180](https://tools.ietf.org/html/rfc4180) and can handle properly escaped files, hence double-quotes, the used separator and line breaks can be part of the file's content without harming the file's structue.
Usage of CsvReader is very straightforward and illustrated by the following example:
```smalltalk
| reader lines headerArray |
lines := OrderedCollection new.
reader := CsvReader newOnServerFile: '/path/to/file.csv'.
"optional: Set the delimiter to omit auto-detection."
reader useDelimiter: $;.
"optional: Read a single (header) line, e.g. to verify existence of expected column headers."
headerArray := reader readHeaderFromLine: 1.
"optional: Specify the first line to read. Default is 1."
reader firstLineToRead: 2.
"Specify a two-argument-block, which will be evaluated for each read line.
First argument is an array holding the cells of the line; second argument is the line number."
reader linesWithIndexDo: [:lineArray :index | lines add: index -> lineArray].
"Start reading the file."
reader read.
^lines
```
## CsvWriter
CsvWriter is a self-contained class with no dependencies other than GemStone/S kernel classes.
```smalltalk
| csvWriter |
csvWriter := CsvWriter newOnServerFile: '~/CsvWriterTest.csv'.
csvWriter
delimiter: $;; "optional; default is comma"
nilString: 'I represent a nil value'; "optional; default is an empty string"
beUtf8; "optional; default is not to encode to utf8"
openFile.
csvWriter addLineArray: #('col1' 'col2' 'col3' 4 5 nil 'Text containing " a quotaion mark').
csvWriter closeFile
```