all: implement macro "footnote:"

Macro footnote grammar,

----
"footnote:" [ REF_ID ] "[" STRING "]"
----

In asciidoctor, footnote can be placed anywhere, even after WORD without
space in between.

The REF_ID, define the unique ID for footnote and can be used to reference
the previous footnote.
The first footnote with REF_ID, should have the STRING defined.
The next footnote with the same REF_ID, should not have the STRING
defined; if its defined, the STRING is ignored.

3 files changed, 113 insertions, 2 deletions

diff --git a/testdata/inline_parser/macro_footnote_externalized_test.txt b/testdata/inline_parser/macro_footnote_externalized_test.txt
new file mode 100644
index 0000000..bd8736c
--- /dev/null
+++ b/testdata/inline_parser/macro_footnote_externalized_test.txt
@@ -0,0 +1,56 @@
+>>> input.adoc
+:fn-hail-and-rainbow: footnote:[The _double_ hail-and-rainbow level makes my toes tingle.]
+:fn-disclaimer: footnote:disclaimer[Opinions are my own.]
+
+The hail-and-rainbow protocol can be initiated at five levels:
+
+. double{fn-hail-and-rainbow}
+. tertiary
+. supernumerary
+. supermassive
+. apocalyptic
+
+A bold statement!{fn-disclaimer}
+
+Another outrageous statement.{fn-disclaimer}
+
+<<< output.html
+
+<div class="paragraph">
+<p>The hail-and-rainbow protocol can be initiated at five levels:</p>
+</div>
+<div class="olist arabic">
+<ol class="arabic">
+<li>
+<p>double<sup class="footnote">[<a id="_footnoteref_1" class="footnote" href="#_footnotedef_1" title="View footnote.">1</a>]</sup>
+</p>
+</li>
+<li>
+<p>tertiary</p>
+</li>
+<li>
+<p>supernumerary</p>
+</li>
+<li>
+<p>supermassive</p>
+</li>
+<li>
+<p>apocalyptic</p>
+</li>
+</ol>
+</div>
+<div class="paragraph">
+<p>A bold statement!<sup class="footnote" id="_footnote_disclaimer">[<a id="_footnoteref_2" class="footnote" href="#_footnotedef_2" title="View footnote.">2</a>]</sup></p>
+</div>
+<div class="paragraph">
+<p>Another outrageous statement.<sup class="footnoteref">[<a class="footnote" href="#_footnotedef_2" title="View footnote.">2</a>]</sup></p>
+</div>
+<div id="footnotes">
+<hr>
+<div class="footnote" id="_footnotedef_1">
+<a href="#_footnoteref_1">1</a>. The <em>double</em> hail-and-rainbow level makes my toes tingle.
+</div>
+<div class="footnote" id="_footnotedef_2">
+<a href="#_footnoteref_2">2</a>. Opinions are my own.
+</div>
+</div>
diff --git a/testdata/inline_parser/macro_footnote_test.txt b/testdata/inline_parser/macro_footnote_test.txt
new file mode 100644
index 0000000..f89c0c1
--- /dev/null
+++ b/testdata/inline_parser/macro_footnote_test.txt
@@ -0,0 +1,55 @@
+
+>>> input.adoc
+
+The hail-and-rainbow protocol can be initiated at five levels:
+
+. doublefootnote:[The _double_ hail-and-rainbow level makes my toes tingle.]
+. tertiary
+. supernumerary
+. supermassive
+. apocalyptic
+
+A bold statement!footnote:disclaimer[Opinions are my own.]
+
+Another outrageous statement.footnote:disclaimer[]
+
+<<< output.html
+
+<div class="paragraph">
+<p>The hail-and-rainbow protocol can be initiated at five levels:</p>
+</div>
+<div class="olist arabic">
+<ol class="arabic">
+<li>
+<p>double<sup class="footnote">[<a id="_footnoteref_1" class="footnote" href="#_footnotedef_1" title="View footnote.">1</a>]</sup>
+</p>
+</li>
+<li>
+<p>tertiary</p>
+</li>
+<li>
+<p>supernumerary</p>
+</li>
+<li>
+<p>supermassive</p>
+</li>
+<li>
+<p>apocalyptic</p>
+</li>
+</ol>
+</div>
+<div class="paragraph">
+<p>A bold statement!<sup class="footnote" id="_footnote_disclaimer">[<a id="_footnoteref_2" class="footnote" href="#_footnotedef_2" title="View footnote.">2</a>]</sup></p>
+</div>
+<div class="paragraph">
+<p>Another outrageous statement.<sup class="footnoteref">[<a class="footnote" href="#_footnotedef_2" title="View footnote.">2</a>]</sup></p>
+</div>
+<div id="footnotes">
+<hr>
+<div class="footnote" id="_footnotedef_1">
+<a href="#_footnoteref_1">1</a>. The <em>double</em> hail-and-rainbow level makes my toes tingle.
+</div>
+<div class="footnote" id="_footnotedef_2">
+<a href="#_footnoteref_2">2</a>. Opinions are my own.
+</div>
+</div>
diff --git a/testdata/test.got.html b/testdata/test.got.html
index 33b917d..d21e7a4 100644
--- a/testdata/test.got.html
+++ b/testdata/test.got.html
@@ -6,7 +6,7 @@
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <meta name="author" content="Author A, Author mid dle B">
 <meta name="description" content="meta description">
-<meta name="generator" content="asciidoctor-go 0.3.1">
+<meta name="generator" content="asciidoctor-go 0.3.2">
 <meta name="keywords" content="key, words">
 <title>Example Document title</title>
 <style>
@@ -3000,7 +3000,7 @@ this sidebar.</p>
 <div id="footer">
 <div id="footer-text">
  1.1.1<br>
-Last updated 2022-09-04 23:41:43 +0700
+Last updated 2022-10-18 00:21:58 +0700
 </div>
 </div>
 </body>