403 lines
13 KiB
Ruby
403 lines
13 KiB
Ruby
# frozen_string_literal: true
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require "forwardable"
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class CSV
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#
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# A CSV::Table is a two-dimensional data structure for representing CSV
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# documents. Tables allow you to work with the data by row or column,
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# manipulate the data, and even convert the results back to CSV, if needed.
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#
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# All tables returned by CSV will be constructed from this class, if header
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# row processing is activated.
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#
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class Table
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#
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# Construct a new CSV::Table from +array_of_rows+, which are expected
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# to be CSV::Row objects. All rows are assumed to have the same headers.
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#
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# The optional +headers+ parameter can be set to Array of headers.
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# If headers aren't set, headers are fetched from CSV::Row objects.
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# Otherwise, headers() method will return headers being set in
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# headers argument.
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#
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# A CSV::Table object supports the following Array methods through
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# delegation:
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#
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# * empty?()
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# * length()
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# * size()
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#
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def initialize(array_of_rows, headers: nil)
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@table = array_of_rows
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@headers = headers
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unless @headers
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if @table.empty?
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@headers = []
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else
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@headers = @table.first.headers
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end
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end
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@mode = :col_or_row
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end
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# The current access mode for indexing and iteration.
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attr_reader :mode
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# Internal data format used to compare equality.
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attr_reader :table
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protected :table
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### Array Delegation ###
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extend Forwardable
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def_delegators :@table, :empty?, :length, :size
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#
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# Returns a duplicate table object, in column mode. This is handy for
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# chaining in a single call without changing the table mode, but be aware
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# that this method can consume a fair amount of memory for bigger data sets.
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#
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# This method returns the duplicate table for chaining. Don't chain
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# destructive methods (like []=()) this way though, since you are working
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# with a duplicate.
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#
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def by_col
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self.class.new(@table.dup).by_col!
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end
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#
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# Switches the mode of this table to column mode. All calls to indexing and
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# iteration methods will work with columns until the mode is changed again.
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#
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# This method returns the table and is safe to chain.
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#
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def by_col!
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@mode = :col
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self
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end
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#
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# Returns a duplicate table object, in mixed mode. This is handy for
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# chaining in a single call without changing the table mode, but be aware
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# that this method can consume a fair amount of memory for bigger data sets.
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#
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# This method returns the duplicate table for chaining. Don't chain
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# destructive methods (like []=()) this way though, since you are working
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# with a duplicate.
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#
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def by_col_or_row
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self.class.new(@table.dup).by_col_or_row!
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end
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#
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# Switches the mode of this table to mixed mode. All calls to indexing and
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# iteration methods will use the default intelligent indexing system until
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# the mode is changed again. In mixed mode an index is assumed to be a row
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# reference while anything else is assumed to be column access by headers.
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#
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# This method returns the table and is safe to chain.
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#
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def by_col_or_row!
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@mode = :col_or_row
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self
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end
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#
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# Returns a duplicate table object, in row mode. This is handy for chaining
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# in a single call without changing the table mode, but be aware that this
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# method can consume a fair amount of memory for bigger data sets.
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#
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# This method returns the duplicate table for chaining. Don't chain
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# destructive methods (like []=()) this way though, since you are working
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# with a duplicate.
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#
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def by_row
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self.class.new(@table.dup).by_row!
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end
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#
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# Switches the mode of this table to row mode. All calls to indexing and
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# iteration methods will work with rows until the mode is changed again.
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#
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# This method returns the table and is safe to chain.
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#
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def by_row!
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@mode = :row
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self
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end
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#
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# Returns the headers for the first row of this table (assumed to match all
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# other rows). The headers Array passed to CSV::Table.new is returned for
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# empty tables.
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#
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def headers
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if @table.empty?
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@headers.dup
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else
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@table.first.headers
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end
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end
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#
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# In the default mixed mode, this method returns rows for index access and
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# columns for header access. You can force the index association by first
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# calling by_col!() or by_row!().
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#
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# Columns are returned as an Array of values. Altering that Array has no
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# effect on the table.
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#
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def [](index_or_header)
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if @mode == :row or # by index
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(@mode == :col_or_row and (index_or_header.is_a?(Integer) or index_or_header.is_a?(Range)))
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@table[index_or_header]
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else # by header
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@table.map { |row| row[index_or_header] }
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end
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end
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#
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# In the default mixed mode, this method assigns rows for index access and
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# columns for header access. You can force the index association by first
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# calling by_col!() or by_row!().
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#
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# Rows may be set to an Array of values (which will inherit the table's
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# headers()) or a CSV::Row.
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#
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# Columns may be set to a single value, which is copied to each row of the
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# column, or an Array of values. Arrays of values are assigned to rows top
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# to bottom in row major order. Excess values are ignored and if the Array
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# does not have a value for each row the extra rows will receive a +nil+.
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#
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# Assigning to an existing column or row clobbers the data. Assigning to
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# new columns creates them at the right end of the table.
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#
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def []=(index_or_header, value)
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if @mode == :row or # by index
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(@mode == :col_or_row and index_or_header.is_a? Integer)
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if value.is_a? Array
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@table[index_or_header] = Row.new(headers, value)
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else
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@table[index_or_header] = value
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end
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else # set column
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unless index_or_header.is_a? Integer
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index = @headers.index(index_or_header) || @headers.size
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@headers[index] = index_or_header
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end
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if value.is_a? Array # multiple values
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@table.each_with_index do |row, i|
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if row.header_row?
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row[index_or_header] = index_or_header
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else
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row[index_or_header] = value[i]
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end
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end
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else # repeated value
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@table.each do |row|
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if row.header_row?
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row[index_or_header] = index_or_header
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else
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row[index_or_header] = value
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end
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end
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end
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end
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end
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#
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# The mixed mode default is to treat a list of indices as row access,
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# returning the rows indicated. Anything else is considered columnar
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# access. For columnar access, the return set has an Array for each row
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# with the values indicated by the headers in each Array. You can force
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# column or row mode using by_col!() or by_row!().
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#
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# You cannot mix column and row access.
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#
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def values_at(*indices_or_headers)
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if @mode == :row or # by indices
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( @mode == :col_or_row and indices_or_headers.all? do |index|
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index.is_a?(Integer) or
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( index.is_a?(Range) and
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index.first.is_a?(Integer) and
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index.last.is_a?(Integer) )
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end )
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@table.values_at(*indices_or_headers)
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else # by headers
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@table.map { |row| row.values_at(*indices_or_headers) }
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end
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end
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#
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# Adds a new row to the bottom end of this table. You can provide an Array,
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# which will be converted to a CSV::Row (inheriting the table's headers()),
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# or a CSV::Row.
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#
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# This method returns the table for chaining.
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#
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def <<(row_or_array)
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if row_or_array.is_a? Array # append Array
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@table << Row.new(headers, row_or_array)
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else # append Row
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@table << row_or_array
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end
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self # for chaining
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end
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#
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# A shortcut for appending multiple rows. Equivalent to:
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#
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# rows.each { |row| self << row }
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#
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# This method returns the table for chaining.
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#
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def push(*rows)
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rows.each { |row| self << row }
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self # for chaining
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end
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#
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# Removes and returns the indicated columns or rows. In the default mixed
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# mode indices refer to rows and everything else is assumed to be a column
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# headers. Use by_col!() or by_row!() to force the lookup.
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#
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def delete(*indexes_or_headers)
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if indexes_or_headers.empty?
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raise ArgumentError, "wrong number of arguments (given 0, expected 1+)"
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end
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deleted_values = indexes_or_headers.map do |index_or_header|
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if @mode == :row or # by index
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(@mode == :col_or_row and index_or_header.is_a? Integer)
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@table.delete_at(index_or_header)
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else # by header
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if index_or_header.is_a? Integer
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@headers.delete_at(index_or_header)
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else
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@headers.delete(index_or_header)
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end
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@table.map { |row| row.delete(index_or_header).last }
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end
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end
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if indexes_or_headers.size == 1
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deleted_values[0]
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else
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deleted_values
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end
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end
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#
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# Removes any column or row for which the block returns +true+. In the
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# default mixed mode or row mode, iteration is the standard row major
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# walking of rows. In column mode, iteration will +yield+ two element
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# tuples containing the column name and an Array of values for that column.
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#
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# This method returns the table for chaining.
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#
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# If no block is given, an Enumerator is returned.
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#
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def delete_if(&block)
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return enum_for(__method__) { @mode == :row or @mode == :col_or_row ? size : headers.size } unless block_given?
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if @mode == :row or @mode == :col_or_row # by index
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@table.delete_if(&block)
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else # by header
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deleted = []
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headers.each do |header|
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deleted << delete(header) if yield([header, self[header]])
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end
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end
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self # for chaining
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end
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include Enumerable
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#
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# In the default mixed mode or row mode, iteration is the standard row major
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# walking of rows. In column mode, iteration will +yield+ two element
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# tuples containing the column name and an Array of values for that column.
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#
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# This method returns the table for chaining.
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#
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# If no block is given, an Enumerator is returned.
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#
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def each(&block)
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return enum_for(__method__) { @mode == :col ? headers.size : size } unless block_given?
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if @mode == :col
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headers.each { |header| yield([header, self[header]]) }
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else
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@table.each(&block)
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end
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self # for chaining
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end
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# Returns +true+ if all rows of this table ==() +other+'s rows.
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def ==(other)
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return @table == other.table if other.is_a? CSV::Table
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@table == other
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end
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#
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# Returns the table as an Array of Arrays. Headers will be the first row,
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# then all of the field rows will follow.
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#
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def to_a
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array = [headers]
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@table.each do |row|
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array.push(row.fields) unless row.header_row?
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end
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array
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end
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#
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# Returns the table as a complete CSV String. Headers will be listed first,
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# then all of the field rows.
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#
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# This method assumes you want the Table.headers(), unless you explicitly
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# pass <tt>:write_headers => false</tt>.
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#
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def to_csv(write_headers: true, **options)
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array = write_headers ? [headers.to_csv(options)] : []
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@table.each do |row|
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array.push(row.fields.to_csv(options)) unless row.header_row?
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end
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array.join("")
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end
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alias_method :to_s, :to_csv
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#
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# Extracts the nested value specified by the sequence of +index+ or +header+ objects by calling dig at each step,
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# returning nil if any intermediate step is nil.
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#
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def dig(index_or_header, *index_or_headers)
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value = self[index_or_header]
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if value.nil?
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nil
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elsif index_or_headers.empty?
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value
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else
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unless value.respond_to?(:dig)
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raise TypeError, "#{value.class} does not have \#dig method"
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end
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value.dig(*index_or_headers)
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end
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end
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# Shows the mode and size of this table in a US-ASCII String.
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def inspect
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"#<#{self.class} mode:#{@mode} row_count:#{to_a.size}>".encode("US-ASCII")
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end
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end
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end
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