Current state of mal for Clojure West lighting talk.

1 files changed, 115 insertions, 0 deletions

diff --git a/php/reader.php b/php/reader.php
new file mode 100644
index 0000000..0524b31
--- /dev/null
+++ b/php/reader.php
@@ -0,0 +1,115 @@
+<?php
+
+require_once 'types.php';
+
+class Reader {
+    protected $tokens = array();
+    protected $position = 0;
+    public function __construct($tokens) {
+        $this->tokens = $tokens;
+        $this->position = 0;
+    }
+    public function next() {
+        return $this->tokens[$this->position++];
+    }
+    public function peek() {
+        return $this->tokens[$this->position];
+    }
+}
+
+class BlankException extends Exception {
+}
+
+function _real_token($s) {
+    return $s !== '' && $s[0] !== ';';
+}
+
+function tokenize($str) {
+    $pat = "/[\s,]*(~@|[\[\]{}()'`~^@]|\"(?:\\\\.|[^\\\\\"])*\"|;.*|[^\s\[\]{}('\"`,;)]*)/";
+    preg_match_all($pat, $str, $matches);
+    return array_values(array_filter($matches[1], '_real_token'));
+}
+
+function read_atom($reader) {
+    $token = $reader->next();
+    if (preg_match("/^-?[0-9]+$/", $token)) {
+        return intval($token, 10);
+    } elseif ($token[0] === "\"") {
+        $str = substr($token, 1, -1);
+        $str = preg_replace('/\\\\"/', '"', $str);
+        return $str;
+    } elseif ($token === "nil") {
+        return NULL;
+    } elseif ($token === "true") {
+        return true;
+    } elseif ($token === "false") {
+        return false;
+    } else {
+        return new_symbol($token);
+    }
+}
+
+function read_list($reader, $constr='new_list', $start='(', $end=')') {
+    $ast = $constr();
+    $token = $reader->next();
+    if ($token !== $start) {
+        throw new Exception("expected '" . $start . "'");
+    }
+    while (($token = $reader->peek()) !== $end) {
+        if ($token === "") {
+            throw new Exception("expected '" . $end . "', got EOF");
+        }
+        $ast[] = read_form($reader);
+    }
+    $reader->next();
+    return $ast;
+}
+
+function read_hash_map($reader) {
+    $lst = read_list($reader, 'new_list', '{', '}');
+    return call_user_func_array('new_hash_map', $lst->getArrayCopy());
+}
+
+function read_form($reader) {
+    $token = $reader->peek();
+    switch ($token) {
+    case '\'': $reader->next();
+               return new_list(new_symbol('quote'),
+                               read_form($reader));
+    case '`':  $reader->next();
+               return new_list(new_symbol('quasiquote'),
+                               read_form($reader));
+    case '~':  $reader->next();
+               return new_list(new_symbol('unquote'),
+                               read_form($reader));
+    case '~@': $reader->next();
+               return new_list(new_symbol('splice-unquote'),
+                               read_form($reader));
+    case '^':  $reader->next();
+               $meta = read_form($reader);
+               return new_list(new_symbol('with-meta'),
+                               read_form($reader),
+                               $meta);
+
+    case '@':  $reader->next();
+               return new_list(new_symbol('deref'),
+                               read_form($reader));
+
+    case ')': throw new Exception("unexpected ')'");
+    case '(': return read_list($reader);
+    case ']': throw new Exception("unexpected ']'");
+    case '[': return read_list($reader, 'new_vector', '[', ']');
+    case '}': throw new Exception("unexpected '}'");
+    case '{': return read_hash_map($reader);
+
+    default:  return read_atom($reader);
+    }
+}
+
+function read_str($str) {
+    $tokens = tokenize($str);
+    if (count($tokens) === 0) { throw new BlankException(); }
+    return read_form(new Reader($tokens));
+}
+
+?>