From 3a3bee771a42cff3836273a98b5d2dcd2e2e37f3 Mon Sep 17 00:00:00 2001
From: Alex Kotov <kotovalexarian@gmail.com>
Date: Wed, 6 Mar 2024 21:59:25 +0400
Subject: [PATCH] Add Repubmark::Elems::Power

---
 lib/repubmark.rb                | 45 +++++++++++++++++++++++++++++++++
 lib/repubmark/elems/fraction.rb |  4 +--
 lib/repubmark/elems/joint.rb    |  4 +++
 lib/repubmark/elems/note.rb     | 16 +-----------
 lib/repubmark/elems/power.rb    | 34 +++++++++++++++++++++++++
 5 files changed, 85 insertions(+), 18 deletions(-)
 create mode 100644 lib/repubmark/elems/power.rb

diff --git a/lib/repubmark.rb b/lib/repubmark.rb
index ff58ca7..dd6ce0a 100644
--- a/lib/repubmark.rb
+++ b/lib/repubmark.rb
@@ -55,7 +55,52 @@ require_relative 'repubmark/elems/section'
 require_relative 'repubmark/elems/special'
 require_relative 'repubmark/elems/text'
 require_relative 'repubmark/elems/link'
+require_relative 'repubmark/elems/power'
 
 module Repubmark
   FORMATS = %i[gemtext html summary_plain word_count].freeze
+
+  UNICODE_SUPS = {
+    '0' => '⁰',
+    '1' => '¹',
+    '2' => '²',
+    '3' => '³',
+    '4' => '⁴',
+    '5' => '⁵',
+    '6' => '⁶',
+    '7' => '⁷',
+    '8' => '⁸',
+    '9' => '⁹',
+    '+' => '⁺',
+    '-' => '⁻',
+    '=' => '⁼',
+    '(' => '⁽',
+    ')' => '⁾',
+  }.freeze
+
+  UNICODE_SUBS = {
+    '0' => '₀',
+    '1' => '₁',
+    '2' => '₂',
+    '3' => '₃',
+    '4' => '₄',
+    '5' => '₅',
+    '6' => '₆',
+    '7' => '₇',
+    '8' => '₈',
+    '9' => '₉',
+    '+' => '₊',
+    '-' => '₋',
+    '=' => '₌',
+    '(' => '₍',
+    ')' => '₎',
+  }.freeze
+
+  def self.unicode_sup(val)
+    String(val).each_char.map { |chr| UNICODE_SUPS.fetch chr }.join.freeze
+  end
+
+  def self.unicode_sub(val)
+    String(val).each_char.map { |chr| UNICODE_SUBS.fetch chr }.join.freeze
+  end
 end
diff --git a/lib/repubmark/elems/fraction.rb b/lib/repubmark/elems/fraction.rb
index f78d1f1..13e98d3 100644
--- a/lib/repubmark/elems/fraction.rb
+++ b/lib/repubmark/elems/fraction.rb
@@ -23,9 +23,7 @@ module Repubmark
 
       def to_summary_plain = "#@top/#@bottom".freeze
 
-      def to_html
-        "<sup>#@top</sup>&frasl;<sub>#@bottom</sub>".freeze
-      end
+      def to_html = "<sup>#@top</sup>&frasl;<sub>#@bottom</sub>".freeze
 
       def to_gemtext = "#@top/#@bottom".freeze
     end
diff --git a/lib/repubmark/elems/joint.rb b/lib/repubmark/elems/joint.rb
index ea21bad..5b11672 100644
--- a/lib/repubmark/elems/joint.rb
+++ b/lib/repubmark/elems/joint.rb
@@ -73,6 +73,8 @@ module Repubmark
 
       def mdash = base Special.new self, :mdash
 
+      def power(base, exponent) = base Power.new self, base, exponent
+
       def quote(str = nil)
         quote = Quote.new self
         case [!!str, block_given?]
@@ -161,6 +163,8 @@ module Repubmark
 
         def mdash(*args) = joint { |joint| joint.mdash(*args) }
 
+        def power(*args) = joint { |joint| joint.power(*args) }
+
         def quote_italic(*args) = joint { |joint| joint.quote_italic(*args) }
 
         def section(*args) = joint { |joint| joint.section(*args) }
diff --git a/lib/repubmark/elems/note.rb b/lib/repubmark/elems/note.rb
index 9d268db..1f4ef45 100644
--- a/lib/repubmark/elems/note.rb
+++ b/lib/repubmark/elems/note.rb
@@ -5,19 +5,6 @@ module Repubmark
     class Note < Base
       parents :Joint
 
-      UNICODE_SUPS = {
-        '1' => '¹',
-        '2' => '²',
-        '3' => '³',
-        '4' => '⁴',
-        '5' => '⁵',
-        '6' => '⁶',
-        '7' => '⁷',
-        '8' => '⁸',
-        '9' => '⁹',
-        '0' => '⁰',
-      }.freeze
-
       def initialize(parent, index, anchor)
         super parent
         @index = index
@@ -43,8 +30,7 @@ module Repubmark
     private
 
       def index_unicode_sup
-        @index_unicode_sup ||=
-          @index.to_s.each_char.map { |chr| UNICODE_SUPS.fetch chr }.join.freeze
+        @index_unicode_sup ||= Repubmark.unicode_sup @index
       end
     end
   end
diff --git a/lib/repubmark/elems/power.rb b/lib/repubmark/elems/power.rb
new file mode 100644
index 0000000..2d4f857
--- /dev/null
+++ b/lib/repubmark/elems/power.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module Repubmark
+  module Elems
+    class Power < Base
+      parents :Joint
+
+      def initialize(parent, base, exponent)
+        super parent
+
+        @base     = Integer base
+        @exponent = Integer exponent
+      end
+
+      #################
+      # Basic methods #
+      #################
+
+      def word_count = 1
+
+      def to_summary_plain = "#@base#{unicode_exponent}".freeze
+
+      def to_html = "#@base<sup>#@exponent</sup>".freeze
+
+      def to_gemtext = "#@base#{unicode_exponent}".freeze
+
+    private
+
+      def unicode_exponent
+        @unicode_exponent ||= Repubmark.unicode_sup @exponent
+      end
+    end
+  end
+end