lib/csv/row.rb
# frozen_string_literal: true
require "forwardable"
class CSV
# = \CSV::Row
# A \CSV::Row instance represents a \CSV table row.
# (see {class CSV}[../CSV.html]).
#
# The instance may have:
# - Fields: each is an object, not necessarily a \String.
# - Headers: each serves a key, and also need not be a \String.
#
# === Instance Methods
#
# \CSV::Row has three groups of instance methods:
# - Its own internally defined instance methods.
# - Methods included by module Enumerable.
# - Methods delegated to class Array.:
# * Array#empty?
# * Array#length
# * Array#size
#
# == Creating a \CSV::Row Instance
#
# Commonly, a new \CSV::Row instance is created by parsing \CSV source
# that has headers:
# source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
# table = CSV.parse(source, headers: true)
# table.each {|row| p row }
# Output:
# #<CSV::Row "Name":"foo" "Value":"0">
# #<CSV::Row "Name":"bar" "Value":"1">
# #<CSV::Row "Name":"baz" "Value":"2">
#
# You can also create a row directly. See ::new.
#
# == Headers
#
# Like a \CSV::Table, a \CSV::Row has headers.
#
# A \CSV::Row that was created by parsing \CSV source
# inherits its headers from the table:
# source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
# table = CSV.parse(source, headers: true)
# row = table.first
# row.headers # => ["Name", "Value"]
#
# You can also create a new row with headers;
# like the keys in a \Hash, the headers need not be Strings:
# row = CSV::Row.new([:name, :value], ['foo', 0])
# row.headers # => [:name, :value]
#
# The new row retains its headers even if added to a table
# that has headers:
# table << row # => #<CSV::Table mode:col_or_row row_count:5>
# row.headers # => [:name, :value]
# row[:name] # => "foo"
# row['Name'] # => nil
#
#
#
# == Accessing Fields
#
# You may access a field in a \CSV::Row with either its \Integer index
# (\Array-style) or its header (\Hash-style).
#
# Fetch a field using method #[]:
# row = CSV::Row.new(['Name', 'Value'], ['foo', 0])
# row[1] # => 0
# row['Value'] # => 0
#
# Set a field using method #[]=:
# row = CSV::Row.new(['Name', 'Value'], ['foo', 0])
# row # => #<CSV::Row "Name":"foo" "Value":0>
# row[0] = 'bar'
# row['Value'] = 1
# row # => #<CSV::Row "Name":"bar" "Value":1>
#
class Row
# :call-seq:
# CSV::Row.new(headers, fields, header_row = false) -> csv_row
#
# Returns the new \CSV::Row instance constructed from
# arguments +headers+ and +fields+; both should be Arrays;
# note that the fields need not be Strings:
# row = CSV::Row.new(['Name', 'Value'], ['foo', 0])
# row # => #<CSV::Row "Name":"foo" "Value":0>
#
# If the \Array lengths are different, the shorter is +nil+-filled:
# row = CSV::Row.new(['Name', 'Value', 'Date', 'Size'], ['foo', 0])
# row # => #<CSV::Row "Name":"foo" "Value":0 "Date":nil "Size":nil>
#
# Each \CSV::Row object is either a <i>field row</i> or a <i>header row</i>;
# by default, a new row is a field row; for the row created above:
# row.field_row? # => true
# row.header_row? # => false
#
# If the optional argument +header_row+ is given as +true+,
# the created row is a header row:
# row = CSV::Row.new(['Name', 'Value'], ['foo', 0], header_row = true)
# row # => #<CSV::Row "Name":"foo" "Value":0>
# row.field_row? # => false
# row.header_row? # => true
def initialize(headers, fields, header_row = false)
@header_row = header_row
headers.each { |h| h.freeze if h.is_a? String }
# handle extra headers or fields
@row = if headers.size >= fields.size
headers.zip(fields)
else
fields.zip(headers).each(&:reverse!)
end
end
# Internal data format used to compare equality.
attr_reader :row
protected :row
### Array Delegation ###
extend Forwardable
def_delegators :@row, :empty?, :length, :size
# :call-seq:
# row.initialize_copy(other_row) -> self
#
# Calls superclass method.
def initialize_copy(other)
super_return_value = super
@row = @row.collect(&:dup)
super_return_value
end
# :call-seq:
# row.header_row? -> true or false
#
# Returns +true+ if this is a header row, +false+ otherwise.
def header_row?
@header_row
end
# :call-seq:
# row.field_row? -> true or false
#
# Returns +true+ if this is a field row, +false+ otherwise.
def field_row?
not header_row?
end
# :call-seq:
# row.headers -> array_of_headers
#
# Returns the headers for this row:
# source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
# table = CSV.parse(source, headers: true)
# row = table.first
# row.headers # => ["Name", "Value"]
def headers
@row.map(&:first)
end
# :call-seq:
# field(index) -> value
# field(header) -> value
# field(header, offset) -> value
#
# Returns the field value for the given +index+ or +header+.
#
# ---
#
# Fetch field value by \Integer index:
# source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.field(0) # => "foo"
# row.field(1) # => "bar"
#
# Counts backward from the last column if +index+ is negative:
# row.field(-1) # => "0"
# row.field(-2) # => "foo"
#
# Returns +nil+ if +index+ is out of range:
# row.field(2) # => nil
# row.field(-3) # => nil
#
# ---
#
# Fetch field value by header (first found):
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.field('Name') # => "Foo"
#
# Fetch field value by header, ignoring +offset+ leading fields:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.field('Name', 2) # => "Baz"
#
# Returns +nil+ if the header does not exist.
def field(header_or_index, minimum_index = 0)
# locate the pair
finder = (header_or_index.is_a?(Integer) || header_or_index.is_a?(Range)) ? :[] : :assoc
pair = @row[minimum_index..-1].public_send(finder, header_or_index)
# return the field if we have a pair
if pair.nil?
nil
else
header_or_index.is_a?(Range) ? pair.map(&:last) : pair.last
end
end
alias_method :[], :field
#
# :call-seq:
# fetch(header) -> value
# fetch(header, default) -> value
# fetch(header) {|row| ... } -> value
#
# Returns the field value as specified by +header+.
#
# ---
#
# With the single argument +header+, returns the field value
# for that header (first found):
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.fetch('Name') # => "Foo"
#
# Raises exception +KeyError+ if the header does not exist.
#
# ---
#
# With arguments +header+ and +default+ given,
# returns the field value for the header (first found)
# if the header exists, otherwise returns +default+:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.fetch('Name', '') # => "Foo"
# row.fetch(:nosuch, '') # => ""
#
# ---
#
# With argument +header+ and a block given,
# returns the field value for the header (first found)
# if the header exists; otherwise calls the block
# and returns its return value:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.fetch('Name') {|header| fail 'Cannot happen' } # => "Foo"
# row.fetch(:nosuch) {|header| "Header '#{header} not found'" } # => "Header 'nosuch not found'"
def fetch(header, *varargs)
raise ArgumentError, "Too many arguments" if varargs.length > 1
pair = @row.assoc(header)
if pair
pair.last
else
if block_given?
yield header
elsif varargs.empty?
raise KeyError, "key not found: #{header}"
else
varargs.first
end
end
end
# :call-seq:
# row.has_key?(header) -> true or false
#
# Returns +true+ if there is a field with the given +header+,
# +false+ otherwise.
def has_key?(header)
!!@row.assoc(header)
end
alias_method :include?, :has_key?
alias_method :key?, :has_key?
alias_method :member?, :has_key?
alias_method :header?, :has_key?
#
# :call-seq:
# row[index] = value -> value
# row[header, offset] = value -> value
# row[header] = value -> value
#
# Assigns the field value for the given +index+ or +header+;
# returns +value+.
#
# ---
#
# Assign field value by \Integer index:
# source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row[0] = 'Bat'
# row[1] = 3
# row # => #<CSV::Row "Name":"Bat" "Value":3>
#
# Counts backward from the last column if +index+ is negative:
# row[-1] = 4
# row[-2] = 'Bam'
# row # => #<CSV::Row "Name":"Bam" "Value":4>
#
# Extends the row with <tt>nil:nil</tt> if positive +index+ is not in the row:
# row[4] = 5
# row # => #<CSV::Row "Name":"bad" "Value":4 nil:nil nil:nil nil:5>
#
# Raises IndexError if negative +index+ is too small (too far from zero).
#
# ---
#
# Assign field value by header (first found):
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row['Name'] = 'Bat'
# row # => #<CSV::Row "Name":"Bat" "Name":"Bar" "Name":"Baz">
#
# Assign field value by header, ignoring +offset+ leading fields:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row['Name', 2] = 4
# row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":4>
#
# Append new field by (new) header:
# source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row['New'] = 6
# row# => #<CSV::Row "Name":"foo" "Value":"0" "New":6>
def []=(*args)
value = args.pop
if args.first.is_a? Integer
if @row[args.first].nil? # extending past the end with index
@row[args.first] = [nil, value]
@row.map! { |pair| pair.nil? ? [nil, nil] : pair }
else # normal index assignment
@row[args.first][1] = value
end
else
index = index(*args)
if index.nil? # appending a field
self << [args.first, value]
else # normal header assignment
@row[index][1] = value
end
end
end
#
# :call-seq:
# row << [header, value] -> self
# row << hash -> self
# row << value -> self
#
# Adds a field to +self+; returns +self+:
#
# If the argument is a 2-element \Array <tt>[header, value]</tt>,
# a field is added with the given +header+ and +value+:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row << ['NAME', 'Bat']
# row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" "NAME":"Bat">
#
# If the argument is a \Hash, each <tt>key-value</tt> pair is added
# as a field with header +key+ and value +value+.
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row << {NAME: 'Bat', name: 'Bam'}
# row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" NAME:"Bat" name:"Bam">
#
# Otherwise, the given +value+ is added as a field with no header.
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row << 'Bag'
# row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" nil:"Bag">
def <<(arg)
if arg.is_a?(Array) and arg.size == 2 # appending a header and name
@row << arg
elsif arg.is_a?(Hash) # append header and name pairs
arg.each { |pair| @row << pair }
else # append field value
@row << [nil, arg]
end
self # for chaining
end
# :call-seq:
# row.push(*values) -> self
#
# Appends each of the given +values+ to +self+ as a field; returns +self+:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.push('Bat', 'Bam')
# row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" nil:"Bat" nil:"Bam">
def push(*args)
args.each { |arg| self << arg }
self # for chaining
end
#
# :call-seq:
# delete(index) -> [header, value] or nil
# delete(header) -> [header, value] or empty_array
# delete(header, offset) -> [header, value] or empty_array
#
# Removes a specified field from +self+; returns the 2-element \Array
# <tt>[header, value]</tt> if the field exists.
#
# If an \Integer argument +index+ is given,
# removes and returns the field at offset +index+,
# or returns +nil+ if the field does not exist:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.delete(1) # => ["Name", "Bar"]
# row.delete(50) # => nil
#
# Otherwise, if the single argument +header+ is given,
# removes and returns the first-found field with the given header,
# of returns a new empty \Array if the field does not exist:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.delete('Name') # => ["Name", "Foo"]
# row.delete('NAME') # => []
#
# If argument +header+ and \Integer argument +offset+ are given,
# removes and returns the first-found field with the given header
# whose +index+ is at least as large as +offset+:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.delete('Name', 1) # => ["Name", "Bar"]
# row.delete('NAME', 1) # => []
def delete(header_or_index, minimum_index = 0)
if header_or_index.is_a? Integer # by index
@row.delete_at(header_or_index)
elsif i = index(header_or_index, minimum_index) # by header
@row.delete_at(i)
else
[ ]
end
end
# :call-seq:
# row.delete_if {|header, value| ... } -> self
#
# Removes fields from +self+ as selected by the block; returns +self+.
#
# Removes each field for which the block returns a truthy value:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.delete_if {|header, value| value.start_with?('B') } # => true
# row # => #<CSV::Row "Name":"Foo">
# row.delete_if {|header, value| header.start_with?('B') } # => false
#
# If no block is given, returns a new Enumerator:
# row.delete_if # => #<Enumerator: #<CSV::Row "Name":"Foo">:delete_if>
def delete_if(&block)
return enum_for(__method__) { size } unless block_given?
@row.delete_if(&block)
self # for chaining
end
# :call-seq:
# self.fields(*specifiers) -> array_of_fields
#
# Returns field values per the given +specifiers+, which may be any mixture of:
# - \Integer index.
# - \Range of \Integer indexes.
# - 2-element \Array containing a header and offset.
# - Header.
# - \Range of headers.
#
# For +specifier+ in one of the first four cases above,
# returns the result of <tt>self.field(specifier)</tt>; see #field.
#
# Although there may be any number of +specifiers+,
# the examples here will illustrate one at a time.
#
# When the specifier is an \Integer +index+,
# returns <tt>self.field(index)</tt>L
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.fields(1) # => ["Bar"]
#
# When the specifier is a \Range of \Integers +range+,
# returns <tt>self.field(range)</tt>:
# row.fields(1..2) # => ["Bar", "Baz"]
#
# When the specifier is a 2-element \Array +array+,
# returns <tt>self.field(array)</tt>L
# row.fields('Name', 1) # => ["Foo", "Bar"]
#
# When the specifier is a header +header+,
# returns <tt>self.field(header)</tt>L
# row.fields('Name') # => ["Foo"]
#
# When the specifier is a \Range of headers +range+,
# forms a new \Range +new_range+ from the indexes of
# <tt>range.start</tt> and <tt>range.end</tt>,
# and returns <tt>self.field(new_range)</tt>:
# source = "Name,NAME,name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.fields('Name'..'NAME') # => ["Foo", "Bar"]
#
# Returns all fields if no argument given:
# row.fields # => ["Foo", "Bar", "Baz"]
def fields(*headers_and_or_indices)
if headers_and_or_indices.empty? # return all fields--no arguments
@row.map(&:last)
else # or work like values_at()
all = []
headers_and_or_indices.each do |h_or_i|
if h_or_i.is_a? Range
index_begin = h_or_i.begin.is_a?(Integer) ? h_or_i.begin :
index(h_or_i.begin)
index_end = h_or_i.end.is_a?(Integer) ? h_or_i.end :
index(h_or_i.end)
new_range = h_or_i.exclude_end? ? (index_begin...index_end) :
(index_begin..index_end)
all.concat(fields.values_at(new_range))
else
all << field(*Array(h_or_i))
end
end
return all
end
end
alias_method :values_at, :fields
# :call-seq:
# index(header) -> index
# index(header, offset) -> index
#
# Returns the index for the given header, if it exists;
# otherwise returns +nil+.
#
# With the single argument +header+, returns the index
# of the first-found field with the given +header+:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.index('Name') # => 0
# row.index('NAME') # => nil
#
# With arguments +header+ and +offset+,
# returns the index of the first-found field with given +header+,
# but ignoring the first +offset+ fields:
# row.index('Name', 1) # => 1
# row.index('Name', 3) # => nil
def index(header, minimum_index = 0)
# find the pair
index = headers[minimum_index..-1].index(header)
# return the index at the right offset, if we found one
index.nil? ? nil : index + minimum_index
end
# :call-seq:
# row.field?(value) -> true or false
#
# Returns +true+ if +value+ is a field in this row, +false+ otherwise:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.field?('Bar') # => true
# row.field?('BAR') # => false
def field?(data)
fields.include? data
end
include Enumerable
# :call-seq:
# row.each {|header, value| ... } -> self
#
# Calls the block with each header-value pair; returns +self+:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.each {|header, value| p [header, value] }
# Output:
# ["Name", "Foo"]
# ["Name", "Bar"]
# ["Name", "Baz"]
#
# If no block is given, returns a new Enumerator:
# row.each # => #<Enumerator: #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz">:each>
def each(&block)
return enum_for(__method__) { size } unless block_given?
@row.each(&block)
self # for chaining
end
alias_method :each_pair, :each
# :call-seq:
# row == other -> true or false
#
# Returns +true+ if +other+ is a /CSV::Row that has the same
# fields (headers and values) in the same order as +self+;
# otherwise returns +false+:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# other_row = table[0]
# row == other_row # => true
# other_row = table[1]
# row == other_row # => false
def ==(other)
return @row == other.row if other.is_a? CSV::Row
@row == other
end
# :call-seq:
# row.to_h -> hash
#
# Returns the new \Hash formed by adding each header-value pair in +self+
# as a key-value pair in the \Hash.
# source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.to_h # => {"Name"=>"foo", "Value"=>"0"}
#
# Header order is preserved, but repeated headers are ignored:
# source = "Name,Name,Name\nFoo,Bar,Baz\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.to_h # => {"Name"=>"Foo"}
def to_h
hash = {}
each do |key, _value|
hash[key] = self[key] unless hash.key?(key)
end
hash
end
alias_method :to_hash, :to_h
# :call-seq:
# row.deconstruct_keys(keys) -> hash
#
# Returns the new \Hash suitable for pattern matching containing only the
# keys specified as an argument.
def deconstruct_keys(keys)
if keys.nil?
to_h
else
keys.to_h { |key| [key, self[key]] }
end
end
alias_method :to_ary, :to_a
# :call-seq:
# row.deconstruct -> array
#
# Returns the new \Array suitable for pattern matching containing the values
# of the row.
def deconstruct
fields
end
# :call-seq:
# row.to_csv -> csv_string
#
# Returns the row as a \CSV String. Headers are not included:
# source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.to_csv # => "foo,0\n"
def to_csv(**options)
fields.to_csv(**options)
end
alias_method :to_s, :to_csv
# :call-seq:
# row.dig(index_or_header, *identifiers) -> object
#
# Finds and returns the object in nested object that is specified
# by +index_or_header+ and +specifiers+.
#
# The nested objects may be instances of various classes.
# See {Dig Methods}[rdoc-ref:dig_methods.rdoc].
#
# Examples:
# source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.dig(1) # => "0"
# row.dig('Value') # => "0"
# row.dig(5) # => nil
def dig(index_or_header, *indexes)
value = field(index_or_header)
if value.nil?
nil
elsif indexes.empty?
value
else
unless value.respond_to?(:dig)
raise TypeError, "#{value.class} does not have \#dig method"
end
value.dig(*indexes)
end
end
# :call-seq:
# row.inspect -> string
#
# Returns an ASCII-compatible \String showing:
# - Class \CSV::Row.
# - Header-value pairs.
# Example:
# source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
# table = CSV.parse(source, headers: true)
# row = table[0]
# row.inspect # => "#<CSV::Row \"Name\":\"foo\" \"Value\":\"0\">"
def inspect
str = ["#<", self.class.to_s]
each do |header, field|
str << " " << (header.is_a?(Symbol) ? header.to_s : header.inspect) <<
":" << field.inspect
end
str << ">"
begin
str.join('')
rescue # any encoding error
str.map do |s|
e = Encoding::Converter.asciicompat_encoding(s.encoding)
e ? s.encode(e) : s.force_encoding("ASCII-8BIT")
end.join('')
end
end
end
end