Implement support for \' as the CSV separator.

The option "fields optionally enclosed by" was missing a way to easily
specify a single quote as the quoting character. Add '\'' to the existing
solution '0x27' which isn't as friendly.

See #705.

docs/_build/html/_sources/ref/csv.rst.txt

@@ -184,10 +184,16 @@ When loading from a `CSV` file, the following options are supported:
 
   - *fields optionally enclosed by*
 
-    Takes a single character as argument, which must be found inside
-    single quotes, and might be given as the printable character itself,
-    the special value \t to denote a tabulation character, or `0x` then
-    an hexadecimal value read as the ASCII code for the character.
+    Takes a single character as argument, which must be found inside single
+    quotes, and might be given as the printable character itself, the
+    special value \t to denote a tabulation character, the special value \'
+    to denote a single-quote, or `0x` then an hexadecimal value read as the
+    ASCII code for the character.
+
+    The following options specify the same enclosing character, a single quote::
+
+      fields optionally enclosed by '\''
+      fields optionally enclosed by '0x27'
 
     This character is used as the quoting character in the `CSV` file,
     and defaults to double-quote.

docs/_build/html/ref/csv.html

@@ -215,10 +215,16 @@ default.</p>
 between the separator and the value.</p>
 </li>
 <li><p class="first"><em>fields optionally enclosed by</em></p>
-<p>Takes a single character as argument, which must be found inside
-single quotes, and might be given as the printable character itself,
-the special value t to denote a tabulation character, or <cite>0x</cite> then
-an hexadecimal value read as the ASCII code for the character.</p>
+<p>Takes a single character as argument, which must be found inside single
+quotes, and might be given as the printable character itself, the
+special value t to denote a tabulation character, the special value ‘
+to denote a single-quote, or <cite>0x</cite> then an hexadecimal value read as the
+ASCII code for the character.</p>
+<p>The following options specify the same enclosing character, a single quote:</p>
+<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">fields</span> <span class="n">optionally</span> <span class="n">enclosed</span> <span class="n">by</span> <span class="s1">&#39;</span><span class="se">\&#39;</span><span class="s1">&#39;</span>
+<span class="n">fields</span> <span class="n">optionally</span> <span class="n">enclosed</span> <span class="n">by</span> <span class="s1">&#39;0x27&#39;</span>
+</pre></div>
+</div>
 <p>This character is used as the quoting character in the <cite>CSV</cite> file,
 and defaults to double-quote.</p>
 </li>

docs/ref/csv.rst

@@ -184,10 +184,16 @@ When loading from a `CSV` file, the following options are supported:
 
   - *fields optionally enclosed by*
 
-    Takes a single character as argument, which must be found inside
-    single quotes, and might be given as the printable character itself,
-    the special value \t to denote a tabulation character, or `0x` then
-    an hexadecimal value read as the ASCII code for the character.
+    Takes a single character as argument, which must be found inside single
+    quotes, and might be given as the printable character itself, the
+    special value \t to denote a tabulation character, the special value \'
+    to denote a single-quote, or `0x` then an hexadecimal value read as the
+    ASCII code for the character.
+
+    The following options specify the same enclosing character, a single quote::
+
+      fields optionally enclosed by '\''
+      fields optionally enclosed by '0x27'
 
     This character is used as the quoting character in the `CSV` file,
     and defaults to double-quote.

src/parsers/command-csv.lisp

@@ -36,7 +36,9 @@
 
 (defrule tab (and #\\ #\t) (:constant #\Tab))
 
-(defrule separator (and #\' (or hex-char-code tab character ) #\')
+(defrule single-quote (and #\\ #\') (:constant #\'))
+
+(defrule separator (and #\' (or hex-char-code tab single-quote character) #\')
   (:lambda (sep)
     (bind (((_ char _) sep)) char)))