struct Tablo::Border

Overview

The Border class enhances the layout of a data table by separating rows and columns with interconnected horizontal and vertical lines.

Various predefined line types are available, but you are free to create your own.

A border can be styled by a user defined proc, of type Styler allowing for colorized output, either by using ANSI sequences or the colorize module from the stdlib (default: no style).

A border is defined by a string of exactly 16 characters, which is then converted into 16 strings of up to 1 character each. The definition string can contain any character, but two of them have a special meaning: during conversion, the uppercase E is replaced by an empty string, and the uppercase S is replaced by a space (a simple space may also be used, of course).

Please note that using the capital E may cause alignment difficulties.

Examples of text or graphic connectors:

| Name                           | 16 chars string  |
| ------------------------------ | ---------------  |
| CONNECTORS_SINGLE_ROUNDED      | ╭┬╮├┼┤╰┴╯│││──── |
| CONNECTORS_SINGLE              | ┌┬┐├┼┤└┴┘│││──── |
| CONNECTORS_DOUBLE              | ╔╦╗╠╬╣╚╩╝║║║════ |
| CONNECTORS_SINGLE_DOUBLE       | ╒╤╕╞╪╡╘╧╛│││════ |
| CONNECTORS_DOUBLE_SINGLE       | ╓╥╖╟╫╢╙╨╜║║║──── |
| CONNECTORS_HEAVY               | ┏┳┓┣╋┫┗┻┛┃┃┃━━━━ |
| CONNECTORS_LIGHT_HEAVY         | ┍┯┑┝┿┥┕┷┙│││━━━━ |
| CONNECTORS_HEAVY_LIGHT         | ┎┰┒┠╂┨┖┸┚┃┃┃──── |
| CONNECTORS_TEXT_CLASSIC        | +++++++++|||---- |

Mixed graphic character sets, such as:

| Name                           | 16 chars string  |
| ------------------------------ | ---------------  |
| CONNECTORS_SINGLE_DOUBLE_MIXED | ╔╤╗╟┼╢╚╧╝║│║═─═- |

may not be correctly rendered.

Below is a detailed representation of each ruletype and meaning:

The first 9 characters define the junction or intersection of horizontal and vertical border lines.

Pos Connector name     Example (using Fancy border preset)
--- --------------     -----------------------------------
 0  top_left           "┌"
 1  top_mid            "┬"
 2  top_right          "┐"

 3  mid_left           "├"
 4  mid_mid            "┼"
 5  mid_right          "┤"

 6  bottom_left        "└"
 7  bottom_mid         "┴"
 8  bottom_right       "┘"

The next three characters define vertical separators in data rows.

 9  vdiv_left          "│"
10  vdiv_mid           ":"
11  vdiv_right         "│"

And finally, the last four characters define the different types of horizontal border, depending on the type of data row or types of adjacent data rows.

12  hdiv_tbs           "─"     (title or top or bottom or summary)
13  hdiv_grp           "−"     (group)
14  hdiv_hdr           "-"     (header)
15  hdiv_bdy           "⋅"     (body)

Eight predefined borders, of type PreSet, can also be used instead of a definition string.

| name          | 16 chars string  |
| ------------- | ---------------- |
| Ascii         | +++++++++|||---- |
| ReducedAscii  | ESEESEESEESE---- |
| ReducedModern | ESEESEESEESE──── |
| Markdown      | EEE|||EEE|||ES-S |
| Modern        | ┌┬┐├┼┤└┴┘│││──── |
| Fancy         | ╭┬╮├┼┤╰┴╯│:│─−-⋅ |
| Blank         | SSSSSSSSSSSSSSSS |
| Empty         | EEEEEEEEEEEEEEEE |

For example, the string "ESEESEESEESE───" is how the PreSet::ReducedModern style is defined.

Defined in:

border.cr

Constant Summary

PREDEFINED_BORDERS = {PreSet::Ascii => "+++++++++|||----", PreSet::ReducedAscii => "ESEESEESEESE----", PreSet::Modern => "┌┬┐├┼┤└┴┘│││────", PreSet::ReducedModern => "ESEESEESEESE────", PreSet::Markdown => "EEE|||EEE|||ES-S", PreSet::Fancy => "╭┬╮├┼┤╰┴╯│:│─−-⋅", PreSet::Blank => "SSSSSSSSSSSSSSSS", PreSet::Empty => "EEEEEEEEEEEEEEEE"}

PreSet border definition hash constant

Constructors

Constructor Detail

def self.new(definition : String | PreSet = Config::Defaults.border_definition, styler : Styler = Config::Defaults.border_styler) #

Creates a Border.

Optional (named) parameters, with default values:

Examples :

border = Tablo::Border.new(Tablo::Border::PreSet::Fancy,
  styler: ->(connectors : String) { connectors.colorize(:yellow).to_s })

or

border = Tablo::Border.new("┌┬┐├┼┤└┴┘│││────",
  styler: ->(connectors : String) { connectors.colorize.fore(:blue).mode(:bold).to_s })

In general, a border is defined directly in table creation, as :

require "tablo"
table = Tablo::Table.new(["abc"],
  border: Tablo::Border.new(:fancy)) do |t|
  t.add_column("itself", &.itself)
end
puts table

[View source]