From d363700a39c3c494faaeca02750cff4f4059ca4a Mon Sep 17 00:00:00 2001
From: Pekka Laiho <pekka.i.laiho@gmail.com>
Date: Wed, 16 Dec 2020 22:01:50 +0700
Subject: [PATCH] add shortcut ~@ for unquote-splice

---
 src/Reader.php         | 2 ++
 src/Tokenizer.php      | 8 ++++++++
 test/ReaderTest.php    | 1 +
 test/TokenizerTest.php | 3 +++
 4 files changed, 14 insertions(+)

diff --git a/src/Reader.php b/src/Reader.php
index 1471d3c..3ef2bd1 100644
--- a/src/Reader.php
+++ b/src/Reader.php
@@ -27,6 +27,8 @@ class Reader
             return $this->readSpecialForm($tokens, $index, 'quasiquote');
         } elseif ($tokens[$index] == "~") {
             return $this->readSpecialForm($tokens, $index, 'unquote');
+        } elseif ($tokens[$index] == "~@") {
+            return $this->readSpecialForm($tokens, $index, 'unquote-splice');
         } elseif ($tokens[$index] == '(') {
             return $this->readList($tokens, $index);
         } elseif ($tokens[$index] == '[') {
diff --git a/src/Tokenizer.php b/src/Tokenizer.php
index 98d0d36..020ba59 100644
--- a/src/Tokenizer.php
+++ b/src/Tokenizer.php
@@ -101,6 +101,14 @@ class Tokenizer
                     // Other special characters
                     $addCurrent();
                     $tokens[] = $c;
+                } elseif ($c == '@') {
+                    // If the last token was ~ then add @ to it
+                    if (count($tokens) > 0 && $tokens[count($tokens) - 1] == '~') {
+                        $tokens[count($tokens) - 1] .= $c;
+                    } else {
+                        // Otherwise treat it like normal character
+                        $current .= $c;
+                    }
                 } else {
                     // All other characters
                     $current .= $c;
diff --git a/test/ReaderTest.php b/test/ReaderTest.php
index c62ddfc..160770d 100644
--- a/test/ReaderTest.php
+++ b/test/ReaderTest.php
@@ -28,6 +28,7 @@ class ReaderTest extends TestCase
             ["'", 'quote'],
             ['`', 'quasiquote'],
             ['~', 'unquote'],
+            ['~@', 'unquote-splice'],
         ];
     }
 
diff --git a/test/TokenizerTest.php b/test/TokenizerTest.php
index 583a675..b71e2aa 100644
--- a/test/TokenizerTest.php
+++ b/test/TokenizerTest.php
@@ -76,6 +76,9 @@ class TokenizerTest extends TestCase
             // Other non-alphabet characters are symbols
             ["(aa!@#$%^&*-_=+bb<>,./?\\|cc)", ['(', "aa!@#$%^&*-_=+bb<>,./?\\|cc", ')']],
 
+            // @ after ~ is single token, @ anywhere else is normal character
+            ['aa@~@@bb', ['aa@', '~@', '@bb']],
+
             // Strings
             ['"abc"', ['"abc"']],
             ['aa"bb"cc', ['aa', '"bb"', 'cc']],