Class: Coradoc::Input::HTML::Converters::Table

Inherits:
Base
  • Object
show all
Defined in:
lib/coradoc/input/html/converters/table.rb

Instance Method Summary collapse

Methods inherited from Base

#convert, #extract_leading_trailing_whitespace, #node_has_ancestor?, #textnode_after_start_with?, #textnode_before_end_with?, #treat, #treat_children, #treat_children_coradoc, #treat_coradoc, #unconstrained_after?, #unconstrained_before?

Instance Method Details

#empty?(node) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/coradoc/input/html/converters/table.rb', line 75

def empty?(node)
  !node.at_xpath(".//td | .//th")
end

#ensure_row_column_integrity_and_get_column_sizes(node) ⇒ Object 



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# File 'lib/coradoc/input/html/converters/table.rb', line 79

def ensure_row_column_integrity_and_get_column_sizes(node)
  rows = node.xpath(".//tr")
  num_rows = rows.length
  computed_columns_per_row = [0] * num_rows
  # Both those variables may seem the same, but they have a crucial
  # difference.
  #
  # cell_references don't necessarily contain an image of created
  # table. New cells are pushed to it as needed, so if we have a
  # one cell with colspan and rowspan of 2 on the previous row,
  # those will always be first in the row, regardless of their
  # position. This array is only used to warrant the table
  # integrity.
  #
  # cell_matrix, on the other hand, can't be constructed outright.
  # It will be incorrect as long as the table isn't fixed. So we
  # can't use it to correct colspans/rowspans/missing rows. Once
  # we have it constructed, only then we can calculate the correct
  # column widths.
  cell_references = [nil] * num_rows
  cell_matrix = [nil] * num_rows

  recompute = proc do
    return ensure_row_column_integrity_and_get_column_sizes(node)
  end

  fits_in_cell_matrix = proc do |y,x,rowspan,colspan|
    rowspan.times.all? do |yy|
      colspan.times.all? do |xx|
        !cell_matrix.dig(y+yy, x+xx)
      end
    end
  end

  rows.each_with_index do |row, i|
    columns = row.xpath("./td | ./th")
    column_id = 0

    columns.each do |cell|
      colspan = cell["colspan"]&.to_i || 1
      rowspan = cell["rowspan"]&.to_i || 1

      column_id += 1 until fits_in_cell_matrix.(i,column_id,rowspan,colspan)

      rowspan.times do |j|
        # Let's increase the table for particularly bad documents
        computed_columns_per_row[i + j] ||= 0
        computed_columns_per_row[i + j] += colspan

        cell_references[i + j] ||= []
        cell_matrix[i + j] ||= []
        colspan.times do |k|
          cell_references[i + j] << [cell, k > 0]
          cell_matrix[i + j][column_id] = cell
          column_id += 1
        end
        column_id -= colspan
      end
      column_id += colspan
    end
  end

  ##### Fixups
  cpr = computed_columns_per_row

  # Some cell has too high colspan
  if cpr.length > num_rows
    cell_references[num_rows].each do |cell,|
      next unless cell

      cell["rowspan"] = cell["rowspan"].to_i - 1
    end

    # Let's recompute the numbers
    recompute.()
  end

  if [cpr.first] * num_rows != cpr
    # Colspan inconsistencies
    modified = false
    cpr_max = cpr.max
    max_rows = cell_references.sort_by(&:length).reverse
    max_rows.each do |row|
      break if row.length != cpr_max

      cell, spanning = row.last

      if spanning
        modified = true
        cell["colspan"] = cell["colspan"].to_i - 1
      end
    end

    recompute.() if modified

    # We are out of colspans to fix. If we are at this point, this
    # means there is an inconsistent number of TH/TDs simply.
    # Here, the solution is to add empty TDs.
    min_rows = cell_references.sort_by(&:length)
    cpr_min = cpr.min
    min_rows.each do |row|
      break if row.length != cpr_min

      row_obj = row.last.first.parent
      doc = row_obj.document
      added_node = Nokogiri::XML::Node.new("td", doc)
      added_node["x-added"] = "x-added"
      row_obj.add_child(added_node)

      modified = true
    end

    recompute.() if modified

    ### We should have a correct document now and we should never
    ### end up here.
    warn "**** Couldn't fix table sizes for table on line #{node.line}"
  end

  # For column size computation, we must have an integral cell_matrix.
  # Let's verify that all columns and rows are populated.
  cell_matrix_correct = cell_matrix.length.times.all? do |y|
    cell_matrix[y].length.times.all? do |x|
      cell_matrix[y][x]
    end
  end

  unless cell_matrix_correct
    # It may be a special case that we need to add virtual cells at the
    # beginning not the end of a row.
    needs_recompute = false
    cell_matrix.each do |row|
      if row.compact.length != row.length
        last_cell = row.last
        if last_cell["x-added"]
          last_cell.parent.prepend_child(last_cell)
          needs_recompute = true
        end
      end
    end
    recompute.() if needs_recompute

    # But otherwise... we've got a really nasty table.
    warn <<~WARNING.gsub("\n", " ")
      **** Couldn't construct a valid image of a table on line
      #{node.line}. We need that to reliably compute column
      widths of that table. Please report a bug to metanorma/coradoc
      repository.
    WARNING
  end

  # Compute column sizes
  column_sizes = []
  cell_matrix.each do |row|
    row.each_with_index do |(cell,_), i|
      next unless !cell || [nil, "", "1"].include?(cell["colspan"])

      column_sizes[i] ||= []
      column_sizes[i] << cell["width"]
    end
  end

  document_width = Coradoc::Input::HTML.config.doc_width.to_r

  column_sizes += [nil] * (cpr.first - column_sizes.length)

  sizes = column_sizes.map do |col|
    col = [] if col.nil?

    max = col.map do |i|
      if i.nil?
        0r
      elsif i.end_with?("%")
        document_width * i.to_i / 100
      else
        i.to_r
      end
    end.max

    if max.nil? || max.negative?
      0r
    else
      max
    end
  end

  # The table seems bigger than the document... let's scale all
  # values.
  while sizes.map { |i|
                    i.zero? ? document_width / 3 / sizes.length : i
                  }.sum > document_width

    sizes = sizes.map { |i| i * 4 / 5 }
  end

  rest = document_width - sizes.sum
  unset = sizes.count(&:zero?)

  # Fill in zeros with remainder space
  sizes = sizes.map do |i|
    if i.zero?
      rest / unset
    else
      i
    end
  end

  # Scale to integers
  lcm = sizes.map(&:denominator).inject(1) { |i,j| i.lcm(j) }
  sizes = sizes.map { |i| i * lcm }.map(&:to_i)

  # Scale down by gcd
  gcd = sizes.inject(sizes.first) { |i,j| i.gcd(j) }
  sizes = sizes.map { |i| i / gcd }

  # Try to generate a shorter definition
  if [sizes.first] * sizes.length == sizes
    sizes.length
  else
    sizes.join(",")
  end
end

#extract_title(node) ⇒ Object 



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# File 'lib/coradoc/input/html/converters/table.rb', line 12

def extract_title(node)
  title = node.at("./caption")
  return "" if title.nil?

  treat_children(title, {})
end

#frame(node) ⇒ Object 



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# File 'lib/coradoc/input/html/converters/table.rb', line 19

def frame(node)
  case node["frame"]
  when "void"
    "none"
  when "hsides"
    "topbot"
  when "vsides"
    "sides"
  when "box", "border"
    "all"
  end
end

#rules(node) ⇒ Object 



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# File 'lib/coradoc/input/html/converters/table.rb', line 32

def rules(node)
  case node["rules"]
  when "all"
    "all"
  when "rows"
    "rows"
  when "cols"
    "cols"
  when "none"
    "none"
  end
end

#style(node) ⇒ Object 



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# File 'lib/coradoc/input/html/converters/table.rb', line 45

def style(node)
  attrs = Coradoc::Element::AttributeList.new
  # Width is disabled on tables for now. (From #88)
  # attrs.add_named("width", node["width"]) if node["width"]

  frame_attr = frame(node)
  attrs.add_named("frame", frame_attr) if frame_attr

  rules_attr = rules(node)
  attrs.add_named("rules", rules_attr) if rules_attr

  # We can't, and shouldn't do those calculation if the table we are
  # processing is empty.
  unless empty?(node)
    cols = ensure_row_column_integrity_and_get_column_sizes(node)
    attrs.add_named("cols", cols)

    # Header first rows can't span multiple riws - drop header if they do.
    header = node.at_xpath(".//tr")
    unless header.xpath("./td | ./th").all? { |i| [nil, "1", ""].include? i["rowspan"] }
      attrs.add_named("options", ["noheader"])
    end
  end

  # This line should be removed.
  return "" if attrs.empty?

  attrs
end

#to_coradoc(node, state = {}) ⇒ Object 



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# File 'lib/coradoc/input/html/converters/table.rb', line 4

def to_coradoc(node, state = {})
  id = node["id"]
  title = extract_title(node)
  attributes = style(node)
  content = treat_children_coradoc(node, state)
  Coradoc::Element::Table.new(title, content, { id: id, attributes: attributes })
end