[ruby/csv] Enhanced Rdoc for CSV (ruby#122)

ruby/csv@cd670595d5

doc/csv/col_sep.rdoc

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+====== Option +col_sep+
+
+Specifies the \String field separator to be used
+for both parsing and generating.
+The \String will be transcoded into the data's \Encoding before use.
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:col_sep) # => "," (comma)
+
+For examples in this section:
+  ary = ['a', 'b', 'c']
+
+Using the default:
+  str = CSV.generate_line(line)
+  str # => "a,b,c\n"
+  ary = CSV.parse_line(str)
+  ary # => ["a", "b", "c"]
+
+Using +:+ (colon):
+  col_sep = ':'
+  str = CSV.generate_line(ary, col_sep: col_sep)
+  str # => "a:b:c\n"
+  ary = CSV.parse_line(str, col_sep: col_sep)
+  ary # => [["a", "b", "c"]]
+
+Using +::+ (two colons):
+  col_sep = '::'
+  str = CSV.generate_line(ary, col_sep: col_sep)
+  str # => "a::b::c\n"
+  ary = CSV.parse_line(str, col_sep: col_sep)
+  ary # => [["a", "b", "c"]]
+
+---
+
+Raises an exception if given the empty \String:
+  col_sep = ''
+  # Raises ArgumentError (:col_sep must be 1 or more characters: "")
+  CSV.parse_line("a:b:c\n", col_sep: col_sep)
+
+Raises an exception if the given value is not String-convertible:
+  col_sep = BasicObject.new
+  # Raises NoMethodError (undefined method `to_s' for #<BasicObject:>)
+  CSV.generate_line(line, col_sep: col_sep)
+  # Raises NoMethodError (undefined method `to_s' for #<BasicObject:>)
+  CSV.parse(str, col_sep: col_sep)

doc/csv/converters.rdoc

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+====== Option +converters+
+
+Specifies a single field converter name or \Proc,
+or an \Array of field converter names and Procs.
+
+See {Field Converters}[#class-CSV-label-Field+Converters]
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:converters) # => nil
+
+The value may be a single field converter name:
+  str = '1,2,3'
+  # Without a converter
+  ary = CSV.parse_line(str)
+  ary # => ["1", "2", "3"]
+  # With built-in converter :integer
+  ary = CSV.parse_line(str, converters: :integer)
+  ary # => [1, 2, 3]
+
+The value may be an \Array of field converter names:
+  str = '1,3.14159'
+  # Without converters
+  ary = CSV.parse_line(str)
+  ary # => ["1", "3.14159"]
+  # With built-in converters
+  ary = CSV.parse_line(str, converters: [:integer, :float])
+  ary # => [1, 3.14159]
+
+The value may be a \Proc custom converter:
+  str = ' foo  ,  bar  ,  baz  '
+  # Without a converter
+  ary = CSV.parse_line(str)
+  ary # => [" foo  ", "  bar  ", "  baz  "]
+  # With a custom converter
+  ary = CSV.parse_line(str, converters: proc {|field| field.strip })
+  ary # => ["foo", "bar", "baz"]
+
+See also {Custom Converters}[#class-CSV-label-Custom+Converters]
+
+---
+
+Raises an exception if the converter is not a converter name or a \Proc:
+  str = 'foo,0'
+  # Raises NoMethodError (undefined method `arity' for nil:NilClass)
+  CSV.parse(str, converters: :foo)

doc/csv/empty_value.rdoc

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+====== Option +empty_value+
+
+Specifies the object that is to be substituted
+for each field that has an empty \String.
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:empty_value) # => "" (empty string)
+
+With the default, <tt>""</tt>:
+  CSV.parse_line('a,"",b,"",c') # => ["a", "", "b", "", "c"]
+
+With a different object:
+  CSV.parse_line('a,"",b,"",c', empty_value: 'x') # => ["a", "x", "b", "x", "c"]

doc/csv/field_size_limit.rdoc

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+====== Option +field_size_limit+
+
+Specifies the \Integer field size limit.
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:field_size_limit) # => nil
+
+This is a maximum size CSV will read ahead looking for the closing quote for a field.
+(In truth, it reads to the first line ending beyond this size.)
+If a quote cannot be found within the limit CSV will raise a MalformedCSVError,
+assuming the data is faulty.
+You can use this limit to prevent what are effectively DoS attacks on the parser.
+However, this limit can cause a legitimate parse to fail;
+therefore the default value is +nil+ (no limit).
+
+For the examples in this section:
+  str = <<~EOT
+    "a","b"
+    "
+    2345
+    ",""
+  EOT
+  str # => "\"a\",\"b\"\n\"\n2345\n\",\"\"\n"
+
+Using the default +nil+:
+  ary = CSV.parse(str)
+  ary # => [["a", "b"], ["\n2345\n", ""]]
+
+Using <tt>50</tt>:
+  field_size_limit = 50
+  ary = CSV.parse(str, field_size_limit: field_size_limit)
+  ary # => [["a", "b"], ["\n2345\n", ""]]
+
+---
+
+Raises an exception if a field is too long:
+  big_str = "123456789\n" * 1024
+  # Raises CSV::MalformedCSVError (Field size exceeded in line 1.)
+  CSV.parse('valid,fields,"' + big_str + '"', field_size_limit: 2048)

doc/csv/force_quotes.rdoc

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+====== Option +force_quotes+
+
+Specifies the boolean that determines whether each output field is to be double-quoted.
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:force_quotes) # => false
+
+For examples in this section:
+  ary = ['foo', 0, nil]
+
+Using the default, +false+:
+  str = CSV.generate_line(ary)
+  str # => "foo,0,\n"
+
+Using +true+:
+  str = CSV.generate_line(ary, force_quotes: true)
+  str # => "\"foo\",\"0\",\"\"\n"

doc/csv/header_converters.rdoc

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+====== Option +header_converters+
+
+Specifies a \String converter name or an \Array of converter names.
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:header_converters) # => nil
+
+Identical in functionality to option {converters}[#class-CSV-label-Option+converters]
+except that:
+- The converters apply only to the header row.
+- The built-in header converters are +:downcase+ and +:symbol+.
+
+Examples:
+  str = <<-EOT
+  foo,0
+  bar,1
+  baz,2
+  EOT
+  headers = ['Name', 'Value']
+  # With no header converter
+  csv = CSV.parse(str, headers: headers)
+  csv.headers # => ["Name", "Value"]
+  # With header converter :downcase
+  csv = CSV.parse(str, headers: headers, header_converters: :downcase)
+  csv.headers # => ["name", "value"]
+  # With header converter :symbol
+  csv = CSV.parse(str, headers: headers, header_converters: :symbol)
+  csv.headers # => [:name, :value]
+  # With both
+  csv = CSV.parse(str, headers: headers, header_converters: [:downcase, :symbol])
+  csv.headers # => [:name, :value]

doc/csv/headers.rdoc

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+====== Option +headers+
+
+Specifies a boolean, \Symbol, \Array, or \String to be used
+to define column headers.
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:headers) # => false
+
+---
+
+Without +headers+:
+  str = <<-EOT
+  Name,Count
+  foo,0
+  bar,1
+  bax,2
+  EOT
+  csv = CSV.new(str)
+  csv # => #<CSV io_type:StringIO encoding:UTF-8 lineno:0 col_sep:"," row_sep:"\n" quote_char:"\"">
+  csv.headers # => nil
+  csv.shift # => ["Name", "Count"]
+
+---
+
+If set to +true+ or the \Symbol +:first_row+,
+the first row of the data is treated as a row of headers:
+  str = <<-EOT
+  Name,Count
+  foo,0
+  bar,1
+  bax,2
+  EOT
+  csv = CSV.new(str, headers: true)
+  csv # => #<CSV io_type:StringIO encoding:UTF-8 lineno:2 col_sep:"," row_sep:"\n" quote_char:"\"" headers:["Name", "Count"]>
+  csv.headers # => ["Name", "Count"]
+  csv.shift # => #<CSV::Row "Name":"bar" "Count":"1">
+
+---
+
+If set to an \Array, the \Array elements are treated as headers:
+  str = <<-EOT
+  foo,0
+  bar,1
+  bax,2
+  EOT
+  csv = CSV.new(str, headers: ['Name', 'Count'])
+  csv
+  csv.headers # => ["Name", "Count"]
+  csv.shift # => #<CSV::Row "Name":"bar" "Count":"1">
+
+---
+
+If set to a \String +str+, method <tt>CSV::parse_line(str, options)</tt> is called
+with the current +options+, and the returned \Array is treated as headers:
+  str = <<-EOT
+  foo,0
+  bar,1
+  bax,2
+  EOT
+  csv = CSV.new(str, headers: 'Name,Count')
+  csv
+  csv.headers # => ["Name", "Count"]
+  csv.shift # => #<CSV::Row "Name":"bar" "Count":"1">

doc/csv/liberal_parsing.rdoc

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+====== Option +liberal_parsing+
+
+Specifies the boolean value that determines whether
+CSV will attempt to parse input not conformant with RFC 4180,
+such as double quotes in unquoted fields.
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:liberal_parsing) # => false
+
+For examples in this section:
+  str = 'is,this "three, or four",fields'
+
+Without +liberal_parsing+:
+  # Raises CSV::MalformedCSVError (Illegal quoting in str 1.)
+  CSV.parse_line(str)
+
+With +liberal_parsing+:
+  ary = CSV.parse_line(str, liberal_parsing: true)
+  ary # => ["is", "this \"three", " or four\"", "fields"]

doc/csv/nil_value.rdoc

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+====== Option +nil_value+
+
+Specifies the object that is to be substituted for each null (no-text) field.
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:nil_value) # => nil
+
+With the default, +nil+:
+  CSV.parse_line('a,,b,,c') # => ["a", nil, "b", nil, "c"]
+
+With a different object:
+  CSV.parse_line('a,,b,,c', nil_value: 0) # => ["a", 0, "b", 0, "c"]

doc/csv/quote_char.rdoc

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+====== Option +quote_char+
+
+Specifies the character (\String of length 1) used used to quote fields
+in both parsing and generating.
+This String will be transcoded into the data's \Encoding before use.
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:quote_char) # => "\"" (backslash)
+
+This is useful for an application that incorrectly uses <tt>'</tt> (single-quote)
+to quote fields, instead of the correct <tt>"</tt> (double-quote).
+
+Using the default:
+  ary = ['a', 'b', '"c"', 'd']
+  str = CSV.generate_line(ary)
+  str # => "a,b,\"\"\"c\"\"\",d\n"
+  ary = CSV.parse_line(str)
+  ary # => ["a", "b", "\"c\"", "d"]
+
+Using <tt>'</tt> (single-quote):
+  quote_char = "'"
+  ary = ['a', 'b', '\'c\'', 'd']
+  str = CSV.generate_line(ary, quote_char: quote_char)
+  str # => "a,b,'''c''',d\n"
+  ary = CSV.parse_line(str, quote_char: quote_char)
+  ary # => [["a", "b", "'c'", "d"]]
+
+---
+
+Raises an exception if the \String length is greater than 1:
+  # Raises ArgumentError (:quote_char has to be nil or a single character String)
+  CSV.new('', quote_char: 'xx')

doc/csv/quote_empty.rdoc

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+====== Option +quote_empty+
+
+Specifies the boolean that determines whether an empty value is to be double-quoted.
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:quote_empty) # => true
+
+With the default +true+:
+  CSV.generate_line(['"', ""]) # => "\"\"\"\",\"\"\n"
+
+With +false+:
+    CSV.generate_line(['"', ""], quote_empty: false) # => "\"\"\"\",\n"

doc/csv/return_headers.rdoc

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+====== Option +return_headers+
+
+Specifies the boolean that determines whether method #shift
+returns or ignores the header row.
+
+Default value:
+  CSV::DEFAULT_OPTIONS.fetch(:return_headers) # => false
+
+Examples:
+  str = <<-EOT
+  Name,Count
+  foo,0
+  bar,1
+  bax,2
+  EOT
+  # Without return_headers first row is str.
+  csv = CSV.new(str, headers: true)
+  csv.shift # => #<CSV::Row "Name":"foo" "Count":"0">
+  # With return_headers first row is headers.
+  csv = CSV.new(str, headers: true, return_headers: true)
+  csv.shift # => #<CSV::Row "Name":"Name" "Count":"Count">
+