#
#
# Nim's Runtime Library
# (c) Copyright 2009 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## This module implements a simple high performance `CSV`:idx:
## (`comma separated value`:idx:) parser.
##
## Example: How to use the parser
## ==============================
##
## .. code-block:: nim
## import os, parsecsv, streams
## var s = newFileStream(paramStr(1), fmRead)
## if s == nil: quit("cannot open the file" & paramStr(1))
## var x: CsvParser
## open(x, s, paramStr(1))
## while readRow(x):
## echo "new row: "
## for val in items(x.row):
## echo "##", val, "##"
## close(x)
##
import
lexbase, streams
type
CsvRow* = seq[string] ## a row in a CSV file
CsvParser* = object of BaseLexer ## the parser object.
row*: CsvRow ## the current row
filename: string
sep, quote, esc: char
skipWhite: bool
currRow: int
CsvError* = object of IOError ## exception that is raised if
## a parsing error occurs
{.deprecated: [TCsvRow: CsvRow, TCsvParser: CsvParser, EInvalidCsv: CsvError].}
proc raiseEInvalidCsv(filename: string, line, col: int,
msg: string) {.noreturn.} =
var e: ref CsvError
new(e)
e.msg = filename & "(" & $line & ", " & $col & ") Error: " & msg
raise e
proc error(my: CsvParser, pos: int, msg: string) =
raiseEInvalidCsv(my.filename, my.lineNumber, getColNumber(my, pos), msg)
proc open*(my: var CsvParser, input: Stream, filename: string,
separator = ',', quote = '"', escape = '\0',
skipInitialSpace = false) =
## initializes the parser with an input stream. `Filename` is only used
## for nice error messages. The parser's behaviour can be controlled by
## the diverse optional parameters:
## - `separator`: character used to separate fields
## - `quote`: Used to quote fields containing special characters like
## `separator`, `quote` or new-line characters. '\0' disables the parsing
## of quotes.
## - `escape`: removes any special meaning from the following character;
## '\0' disables escaping; if escaping is disabled and `quote` is not '\0',
## two `quote` characters are parsed one literal `quote` character.
## - `skipInitialSpace`: If true, whitespace immediately following the
## `separator` is ignored.
lexbase.open(my, input)
my.filename = filename
my.sep = separator
my.quote = quote
my.esc = escape
my.skipWhite = skipInitialSpace
my.row = @[]
my.currRow = 0
proc parseField(my: var CsvParser, a: var string) =
var pos = my.bufpos
var buf = my.buf
if my.skipWhite:
while buf[pos] in {' ', '\t'}: inc(pos)
setLen(a, 0) # reuse memory
if buf[pos] == my.quote and my.quote != '\0':
inc(pos)
while true:
var c = buf[pos]
if c == '\0':
my.bufpos = pos # can continue after exception?
error(my, pos, my.quote & " expected")
break
elif c == my.quote:
if my.esc == '\0' and buf[pos+1] == my.quote:
add(a, my.quote)
inc(pos, 2)
else:
inc(pos)
break
elif c == my.esc:
add(a, buf[pos+1])
inc(pos, 2)
else:
case c
of '\c':
pos = handleCR(my, pos)
buf = my.buf
add(a, "\n")
of '\l':
pos = handleLF(my, pos)
buf = my.buf
add(a, "\n")
else:
add(a, c)
inc(pos)
else:
while true:
var c = buf[pos]
if c == my.sep: break
if c in {'\c', '\l', '\0'}: break
add(a, c)
inc(pos)
my.bufpos = pos
proc processedRows*(my: var CsvParser): int =
## returns number of the processed rows
return my.currRow
proc readRow*(my: var CsvParser, columns = 0): bool =
## reads the next row; if `columns` > 0, it expects the row to have
## exactly this many columns. Returns false if the end of the file
## has been encountered else true.
var col = 0 # current column
var oldpos = my.bufpos
while my.buf[my.bufpos] != '\0':
var oldlen = my.row.len
if oldlen < col+1:
setLen(my.row, col+1)
my.row[col] = ""
parseField(my, my.row[col])
inc(col)
if my.buf[my.bufpos] == my.sep:
inc(my.bufpos)
else:
case my.buf[my.bufpos]
of '\c', '\l':
# skip empty lines:
while true:
case my.buf[my.bufpos]
of '\c': my.bufpos = handleCR(my, my.bufpos)
of '\l': my.bufpos = handleLF(my, my.bufpos)
else: break
of '\0': discard
else: error(my, my.bufpos, my.sep & " expected")
break
setLen(my.row, col)
result = col > 0
if result and col != columns and columns > 0:
error(my, oldpos+1, $columns & " columns expected, but found " &
$col & " columns")
inc(my.currRow)
proc close*(my: var CsvParser) {.inline.} =
## closes the parser `my` and its associated input stream.
lexbase.close(my)
when not defined(testing) and isMainModule:
import os
var s = newFileStream(paramStr(1), fmRead)
if s == nil: quit("cannot open the file" & paramStr(1))
var x: CsvParser
open(x, s, paramStr(1))