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parser.cr
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parser.cr
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require "csv"
# A CSV parser. It lets you consume a CSV row by row.
#
# Most of the time `CSV#parse` and `CSV#each_row` are more convenient.
class CSV::Parser
# Creates a parser from a `String` or `IO`.
# Optionally takes the optional *separator* and *quote_char* arguments for
# specifying non-standard cell separators and quote characters
def initialize(string_or_io : String | IO, separator : Char = DEFAULT_SEPARATOR, quote_char : Char = DEFAULT_QUOTE_CHAR)
@lexer = CSV::Lexer.new(string_or_io, separator, quote_char)
@max_row_size = 3
end
# Returns the remaining rows.
def parse : Array(Array(String))
rows = [] of Array(String)
each_row { |row| rows << row }
rows
end
# Yields each of the remaining rows as an `Array(String)`.
def each_row : Nil
while row = next_row
yield row
end
end
# Returns an `Iterator` of `Array(String)` for the remaining rows.
def each_row
RowIterator.new(self)
end
# Returns the next row in the CSV, if any, or `nil`.
def next_row : Array(String) | Nil
token = @lexer.next_token
if token.kind == Token::Kind::Eof
return nil
end
row = Array(String).new(@max_row_size)
next_row_internal(token, row)
end
# Reads the next row into the given *array*.
# Returns that same array, if a row was found, or `nil`.
def next_row(array : Array(String)) : Array(String) | Nil
token = @lexer.next_token
if token.kind == Token::Kind::Eof
return nil
end
next_row_internal(token, array)
end
private def next_row_internal(token, row)
while true
case token.kind
when Token::Kind::Cell
row << token.value
token = @lexer.next_token
else # :newline, :eof
@max_row_size = row.size if row.size > @max_row_size
return row
end
end
end
private struct RowIterator
include Iterator(Array(String))
@parser : Parser
def initialize(@parser)
end
def next
@parser.next_row || stop
end
end
end