ruby: Phase 1 parser (+83 tests, 190 total)

lib/ruby/tokenizer.sx — rb-tokenize: keywords, identifiers (@/@~/$/const),
numbers (dec/hex/oct/bin/float), strings (dq with raw interpolation, sq),
symbols, %w/%i, operators (all compound forms), punctuation, comments,
line/col tracking. Plus test runner test.sh and 107 passing tests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/ruby/parser.sx

@@ -0,0 +1,831 @@
+;; Ruby parser: token list → AST.
+;; Entry: (rb-parse tokens)  or  (rb-parse-str src)
+;; AST nodes: dicts with :type plus type-specific fields.
+
+(define rb-parse
+  (fn (tokens)
+    (let ((pos 0) (tok-count (len tokens)))
+
+      (define rb-p-cur
+        (fn () (nth tokens pos)))
+      (define rb-p-peek
+        (fn (n)
+          (if (< (+ pos n) tok-count)
+            (nth tokens (+ pos n))
+            {:type "eof" :value nil :line 0 :col 0})))
+      (define rb-p-advance!
+        (fn () (set! pos (+ pos 1))))
+      (define rb-p-type
+        (fn () (get (rb-p-cur) :type)))
+      (define rb-p-val
+        (fn () (get (rb-p-cur) :value)))
+      (define rb-p-sep?
+        (fn () (or (= (rb-p-type) "newline") (= (rb-p-type) "semi"))))
+      (define rb-p-skip-seps!
+        (fn ()
+          (when (rb-p-sep?)
+            (do (rb-p-advance!) (rb-p-skip-seps!)))))
+      (define rb-p-skip-newlines!
+        (fn ()
+          (when (= (rb-p-type) "newline")
+            (do (rb-p-advance!) (rb-p-skip-newlines!)))))
+      (define rb-p-expect!
+        (fn (type)
+          (if (= (rb-p-type) type)
+            (let ((tok (rb-p-cur)))
+              (rb-p-advance!)
+              tok)
+            {:type "error"
+             :msg (join "" (list "expected " type " got " (rb-p-type)))})))
+      (define rb-p-expect-kw!
+        (fn (kw)
+          (when (and (= (rb-p-type) "keyword") (= (rb-p-val) kw))
+            (rb-p-advance!))))
+
+      ;; Block: do |params| body end  or  { |params| body }
+      (define rb-p-parse-block-params
+        (fn ()
+          (if (= (rb-p-type) "pipe")
+            (do
+              (rb-p-advance!)
+              (let ((params (list)))
+                (define rb-p-bp-loop
+                  (fn ()
+                    (when (not (or (= (rb-p-type) "pipe") (= (rb-p-type) "eof")))
+                      (do
+                        (cond
+                          ((and (= (rb-p-type) "op") (= (rb-p-val) "**"))
+                            (do
+                              (rb-p-advance!)
+                              (append! params {:type "param-kwrest" :name (rb-p-val)})
+                              (rb-p-advance!)))
+                          ((and (= (rb-p-type) "op") (= (rb-p-val) "*"))
+                            (do
+                              (rb-p-advance!)
+                              (if (= (rb-p-type) "ident")
+                                (do
+                                  (append! params {:type "param-rest" :name (rb-p-val)})
+                                  (rb-p-advance!))
+                                (append! params {:type "param-rest" :name nil}))))
+                          (:else
+                            (do
+                              (append! params {:type "param-req" :name (rb-p-val)})
+                              (rb-p-advance!))))
+                        (when (= (rb-p-type) "comma") (rb-p-advance!))
+                        (rb-p-bp-loop)))))
+                (rb-p-bp-loop)
+                (rb-p-expect! "pipe")
+                params))
+            (list))))
+
+      (define rb-p-parse-block
+        (fn ()
+          (cond
+            ((and (= (rb-p-type) "keyword") (= (rb-p-val) "do"))
+              (do
+                (rb-p-advance!)
+                (let ((params (rb-p-parse-block-params)))
+                  (rb-p-skip-seps!)
+                  (let ((body (rb-p-parse-stmts (list "end"))))
+                    (rb-p-expect-kw! "end")
+                    {:type "block" :params params :body body}))))
+            ((= (rb-p-type) "lbrace")
+              (do
+                (rb-p-advance!)
+                (let ((params (rb-p-parse-block-params)))
+                  (rb-p-skip-seps!)
+                  (let ((body (rb-p-parse-stmts (list "rbrace"))))
+                    (rb-p-expect! "rbrace")
+                    {:type "block" :params params :body body}))))
+            (:else nil))))
+
+      ;; Method def params
+      (define rb-p-parse-def-params
+        (fn ()
+          (let ((params (list)))
+            (define rb-p-dp-one
+              (fn ()
+                (cond
+                  ((and (= (rb-p-type) "op") (= (rb-p-val) "&"))
+                    (do
+                      (rb-p-advance!)
+                      (append! params {:type "param-block" :name (rb-p-val)})
+                      (rb-p-advance!)))
+                  ((and (= (rb-p-type) "op") (= (rb-p-val) "**"))
+                    (do
+                      (rb-p-advance!)
+                      (append! params {:type "param-kwrest" :name (rb-p-val)})
+                      (rb-p-advance!)))
+                  ((and (= (rb-p-type) "op") (= (rb-p-val) "*"))
+                    (do
+                      (rb-p-advance!)
+                      (if (= (rb-p-type) "ident")
+                        (do
+                          (append! params {:type "param-rest" :name (rb-p-val)})
+                          (rb-p-advance!))
+                        (append! params {:type "param-rest" :name nil}))))
+                  ((and (= (rb-p-type) "ident")
+                        (= (get (rb-p-peek 1) :type) "colon"))
+                    (do
+                      (let ((name (rb-p-val)))
+                        (rb-p-advance!)
+                        (rb-p-advance!)
+                        (if (or (rb-p-sep?) (= (rb-p-type) "comma")
+                                (= (rb-p-type) "rparen") (= (rb-p-type) "eof"))
+                          (append! params {:type "param-kw" :name name :default nil})
+                          (append! params {:type "param-kw" :name name
+                                          :default (rb-p-parse-assign)})))))
+                  (:else
+                    (let ((name (rb-p-val)))
+                      (rb-p-advance!)
+                      (if (and (= (rb-p-type) "op") (= (rb-p-val) "="))
+                        (do
+                          (rb-p-advance!)
+                          (append! params {:type "param-opt" :name name
+                                          :default (rb-p-parse-assign)}))
+                        (append! params {:type "param-req" :name name})))))))
+            (define rb-p-dp-loop
+              (fn ()
+                (when (not (or (= (rb-p-type) "rparen") (rb-p-sep?)
+                               (= (rb-p-type) "eof")))
+                  (do
+                    (rb-p-dp-one)
+                    (when (= (rb-p-type) "comma")
+                      (do (rb-p-advance!) (rb-p-skip-newlines!)))
+                    (rb-p-dp-loop)))))
+            (rb-p-dp-loop)
+            params)))
+
+      ;; def [recv.] name [(params)] body end
+      (define rb-p-parse-def
+        (fn ()
+          (rb-p-advance!)
+          (let ((recv nil) (name nil))
+            (cond
+              ((and (= (rb-p-type) "keyword") (= (rb-p-val) "self")
+                    (= (get (rb-p-peek 1) :type) "dot"))
+                (do
+                  (set! recv {:type "self"})
+                  (rb-p-advance!)
+                  (rb-p-advance!)
+                  (set! name (rb-p-val))
+                  (rb-p-advance!)))
+              ((and (= (rb-p-type) "ident")
+                    (= (get (rb-p-peek 1) :type) "dot"))
+                (do
+                  (set! recv {:type "lvar" :name (rb-p-val)})
+                  (rb-p-advance!)
+                  (rb-p-advance!)
+                  (set! name (rb-p-val))
+                  (rb-p-advance!)))
+              (:else
+                (do
+                  (set! name (rb-p-val))
+                  (rb-p-advance!))))
+            (let ((params (list)))
+              (cond
+                ((= (rb-p-type) "lparen")
+                  (do
+                    (rb-p-advance!)
+                    (rb-p-skip-newlines!)
+                    (set! params (rb-p-parse-def-params))
+                    (rb-p-expect! "rparen")))
+                ((not (or (rb-p-sep?) (= (rb-p-type) "eof")))
+                  (set! params (rb-p-parse-def-params)))
+                (:else nil))
+              (rb-p-skip-seps!)
+              (let ((body (rb-p-parse-stmts (list "end"))))
+                (rb-p-expect-kw! "end")
+                {:type "method-def" :recv recv :name name
+                 :params params :body body})))))
+
+      ;; class [<<obj | Name [<Super]] body end
+      (define rb-p-parse-class
+        (fn ()
+          (rb-p-advance!)
+          (if (and (= (rb-p-type) "op") (= (rb-p-val) "<<"))
+            (do
+              (rb-p-advance!)
+              (let ((obj (rb-p-parse-primary)))
+                (rb-p-skip-seps!)
+                (let ((body (rb-p-parse-stmts (list "end"))))
+                  (rb-p-expect-kw! "end")
+                  {:type "sclass" :obj obj :body body})))
+            (let ((name (rb-p-parse-const-path)))
+              (let ((super nil))
+                (when (and (= (rb-p-type) "op") (= (rb-p-val) "<"))
+                  (do
+                    (rb-p-advance!)
+                    (set! super (rb-p-parse-const-path))))
+                (rb-p-skip-seps!)
+                (let ((body (rb-p-parse-stmts (list "end"))))
+                  (rb-p-expect-kw! "end")
+                  {:type "class-def" :name name :super super :body body}))))))
+
+      ;; module Name body end
+      (define rb-p-parse-module
+        (fn ()
+          (rb-p-advance!)
+          (let ((name (rb-p-parse-const-path)))
+            (rb-p-skip-seps!)
+            (let ((body (rb-p-parse-stmts (list "end"))))
+              (rb-p-expect-kw! "end")
+              {:type "module-def" :name name :body body}))))
+
+      ;; Const or Const::Const::...
+      (define rb-p-parse-const-path
+        (fn ()
+          (let ((node {:type "const" :name (rb-p-val)}))
+            (rb-p-advance!)
+            (define rb-p-cp-loop
+              (fn ()
+                (when (= (rb-p-type) "dcolon")
+                  (do
+                    (rb-p-advance!)
+                    (let ((name (rb-p-val)))
+                      (rb-p-advance!)
+                      (set! node {:type "const-path" :left node :name name})
+                      (rb-p-cp-loop))))))
+            (rb-p-cp-loop)
+            node)))
+
+      ;; [e, *e, ...]
+      (define rb-p-parse-array
+        (fn ()
+          (rb-p-advance!)
+          (rb-p-skip-newlines!)
+          (let ((elems (list)))
+            (define rb-p-arr-loop
+              (fn ()
+                (when (not (or (= (rb-p-type) "rbracket") (= (rb-p-type) "eof")))
+                  (do
+                    (if (and (= (rb-p-type) "op") (= (rb-p-val) "*"))
+                      (do
+                        (rb-p-advance!)
+                        (append! elems {:type "splat" :value (rb-p-parse-assign)}))
+                      (append! elems (rb-p-parse-assign)))
+                    (rb-p-skip-newlines!)
+                    (when (= (rb-p-type) "comma")
+                      (do (rb-p-advance!) (rb-p-skip-newlines!)))
+                    (rb-p-arr-loop)))))
+            (rb-p-arr-loop)
+            (rb-p-expect! "rbracket")
+            {:type "array" :elems elems})))
+
+      ;; {k: v, k => v, ...}
+      (define rb-p-parse-hash
+        (fn ()
+          (rb-p-advance!)
+          (rb-p-skip-newlines!)
+          (let ((pairs (list)))
+            (define rb-p-hash-loop
+              (fn ()
+                (when (not (or (= (rb-p-type) "rbrace") (= (rb-p-type) "eof")))
+                  (do
+                    (let ((key nil) (val nil) (style nil))
+                      (cond
+                        ((and (or (= (rb-p-type) "ident") (= (rb-p-type) "const"))
+                              (= (get (rb-p-peek 1) :type) "colon"))
+                          (do
+                            (set! key {:type "lit-sym" :value (rb-p-val)})
+                            (set! style "colon")
+                            (rb-p-advance!)
+                            (rb-p-advance!)))
+                        (:else
+                          (do
+                            (set! key (rb-p-parse-assign))
+                            (set! style "rocket")
+                            (when (and (= (rb-p-type) "op") (= (rb-p-val) "=>"))
+                              (rb-p-advance!)))))
+                      (rb-p-skip-newlines!)
+                      (set! val (rb-p-parse-assign))
+                      (append! pairs {:key key :val val :style style}))
+                    (rb-p-skip-newlines!)
+                    (when (= (rb-p-type) "comma")
+                      (do (rb-p-advance!) (rb-p-skip-newlines!)))
+                    (rb-p-hash-loop)))))
+            (rb-p-hash-loop)
+            (rb-p-expect! "rbrace")
+            {:type "hash" :pairs pairs})))
+
+      ;; (a, *b, **c, &d)
+      (define rb-p-parse-args-parens
+        (fn ()
+          (rb-p-advance!)
+          (rb-p-skip-newlines!)
+          (let ((args (list)))
+            (define rb-p-ap-loop
+              (fn ()
+                (when (not (or (= (rb-p-type) "rparen") (= (rb-p-type) "eof")))
+                  (do
+                    (cond
+                      ((and (= (rb-p-type) "op") (= (rb-p-val) "**"))
+                        (do (rb-p-advance!)
+                            (append! args {:type "dsplat" :value (rb-p-parse-assign)})))
+                      ((and (= (rb-p-type) "op") (= (rb-p-val) "*"))
+                        (do (rb-p-advance!)
+                            (append! args {:type "splat" :value (rb-p-parse-assign)})))
+                      ((and (= (rb-p-type) "op") (= (rb-p-val) "&"))
+                        (do (rb-p-advance!)
+                            (append! args {:type "block-pass" :value (rb-p-parse-assign)})))
+                      (:else (append! args (rb-p-parse-assign))))
+                    (rb-p-skip-newlines!)
+                    (when (= (rb-p-type) "comma")
+                      (do (rb-p-advance!) (rb-p-skip-newlines!)))
+                    (rb-p-ap-loop)))))
+            (rb-p-ap-loop)
+            (rb-p-expect! "rparen")
+            args)))
+
+      ;; No-paren arg list up to sep/end-keyword
+      (define rb-p-parse-args-bare
+        (fn ()
+          (let ((args (list)) (going true))
+            (define rb-p-ab-loop
+              (fn ()
+                (when (and going
+                           (not (rb-p-sep?))
+                           (not (= (rb-p-type) "eof"))
+                           (not (= (rb-p-type) "rparen"))
+                           (not (= (rb-p-type) "rbracket"))
+                           (not (= (rb-p-type) "rbrace"))
+                           (not (and (= (rb-p-type) "keyword")
+                                     (contains? (list "end" "else" "elsif" "when"
+                                                      "rescue" "ensure" "then" "do")
+                                                (rb-p-val)))))
+                  (do
+                    (cond
+                      ((and (= (rb-p-type) "op") (= (rb-p-val) "*"))
+                        (do (rb-p-advance!)
+                            (append! args {:type "splat" :value (rb-p-parse-assign)})))
+                      ((and (= (rb-p-type) "op") (= (rb-p-val) "**"))
+                        (do (rb-p-advance!)
+                            (append! args {:type "dsplat" :value (rb-p-parse-assign)})))
+                      ((and (= (rb-p-type) "op") (= (rb-p-val) "&"))
+                        (do (rb-p-advance!)
+                            (append! args {:type "block-pass" :value (rb-p-parse-assign)})))
+                      (:else (append! args (rb-p-parse-assign))))
+                    (if (= (rb-p-type) "comma")
+                      (do (rb-p-advance!) (rb-p-skip-newlines!) (rb-p-ab-loop))
+                      (set! going false))))))
+            (rb-p-ab-loop)
+            args)))
+
+      ;; Primary expression
+      (define rb-p-parse-primary
+        (fn ()
+          (cond
+            ((= (rb-p-type) "int")
+              (let ((v (rb-p-val))) (rb-p-advance!) {:type "lit-int" :value v}))
+            ((= (rb-p-type) "float")
+              (let ((v (rb-p-val))) (rb-p-advance!) {:type "lit-float" :value v}))
+            ((= (rb-p-type) "string")
+              (let ((v (rb-p-val))) (rb-p-advance!) {:type "lit-str" :value v}))
+            ((= (rb-p-type) "symbol")
+              (let ((v (rb-p-val))) (rb-p-advance!) {:type "lit-sym" :value v}))
+            ((= (rb-p-type) "words")
+              (let ((v (rb-p-val))) (rb-p-advance!) {:type "lit-words" :elems v}))
+            ((= (rb-p-type) "isymbols")
+              (let ((v (rb-p-val))) (rb-p-advance!) {:type "lit-isyms" :elems v}))
+            ((= (rb-p-type) "ivar")
+              (let ((v (rb-p-val))) (rb-p-advance!) {:type "ivar" :name v}))
+            ((= (rb-p-type) "cvar")
+              (let ((v (rb-p-val))) (rb-p-advance!) {:type "cvar" :name v}))
+            ((= (rb-p-type) "gvar")
+              (let ((v (rb-p-val))) (rb-p-advance!) {:type "gvar" :name v}))
+            ((= (rb-p-type) "const")
+              (rb-p-parse-const-path))
+            ((= (rb-p-type) "ident")
+              (let ((name (rb-p-val)))
+                (rb-p-advance!)
+                (if (= (rb-p-type) "lparen")
+                  (let ((args (rb-p-parse-args-parens))
+                        (blk (rb-p-parse-block)))
+                    {:type "send" :name name :args args :block blk})
+                  {:type "send" :name name :args (list) :block nil})))
+            ((= (rb-p-type) "keyword")
+              (cond
+                ((= (rb-p-val) "nil")
+                  (do (rb-p-advance!) {:type "lit-nil"}))
+                ((= (rb-p-val) "true")
+                  (do (rb-p-advance!) {:type "lit-bool" :value true}))
+                ((= (rb-p-val) "false")
+                  (do (rb-p-advance!) {:type "lit-bool" :value false}))
+                ((= (rb-p-val) "self")
+                  (do (rb-p-advance!) {:type "self"}))
+                ((= (rb-p-val) "super")
+                  (do
+                    (rb-p-advance!)
+                    (let ((args (if (= (rb-p-type) "lparen")
+                                   (rb-p-parse-args-parens) (list)))
+                          (blk (rb-p-parse-block)))
+                      {:type "send" :name "super" :args args :block blk})))
+                (:else
+                  {:type "error"
+                   :msg (join "" (list "unexpected kw " (rb-p-val)))})))
+            ((= (rb-p-type) "lbracket")
+              (rb-p-parse-array))
+            ((= (rb-p-type) "lbrace")
+              (rb-p-parse-hash))
+            ((= (rb-p-type) "lparen")
+              (do
+                (rb-p-advance!)
+                (rb-p-skip-seps!)
+                (let ((node (rb-p-parse-expr)))
+                  (rb-p-skip-seps!)
+                  (rb-p-expect! "rparen")
+                  node)))
+            (:else
+              (do
+                (rb-p-advance!)
+                {:type "error"
+                 :msg (join "" (list "unexpected " (rb-p-type)
+                                     " '" (or (rb-p-val) "") "'"))})))))
+
+      ;; .method  ::Const  [index]  chains
+      (define rb-p-parse-postfix
+        (fn ()
+          (let ((node (rb-p-parse-primary)))
+            (define rb-p-pf-loop
+              (fn ()
+                (cond
+                  ((= (rb-p-type) "dot")
+                    (do
+                      (rb-p-advance!)
+                      (let ((method (rb-p-val)))
+                        (rb-p-advance!)
+                        (let ((args (if (= (rb-p-type) "lparen")
+                                       (rb-p-parse-args-parens) (list)))
+                              (blk (rb-p-parse-block)))
+                          (set! node {:type "call" :recv node :method method
+                                      :args args :block blk})
+                          (rb-p-pf-loop)))))
+                  ((= (rb-p-type) "dcolon")
+                    (do
+                      (rb-p-advance!)
+                      (let ((name (rb-p-val)))
+                        (rb-p-advance!)
+                        (if (= (rb-p-type) "lparen")
+                          (let ((args (rb-p-parse-args-parens))
+                                (blk (rb-p-parse-block)))
+                            (set! node {:type "call" :recv node :method name
+                                        :args args :block blk}))
+                          (set! node {:type "const-path" :left node :name name}))
+                        (rb-p-pf-loop))))
+                  ((= (rb-p-type) "lbracket")
+                    (do
+                      (rb-p-advance!)
+                      (rb-p-skip-newlines!)
+                      (let ((idxargs (list)))
+                        (define rb-p-idx-loop
+                          (fn ()
+                            (when (not (or (= (rb-p-type) "rbracket") (= (rb-p-type) "eof")))
+                              (do
+                                (append! idxargs (rb-p-parse-assign))
+                                (when (= (rb-p-type) "comma")
+                                  (do (rb-p-advance!) (rb-p-skip-newlines!)))
+                                (rb-p-idx-loop)))))
+                        (rb-p-idx-loop)
+                        (rb-p-expect! "rbracket")
+                        (set! node {:type "index" :recv node :args idxargs})
+                        (rb-p-pf-loop))))
+                  (:else nil))))
+            (rb-p-pf-loop)
+            node)))
+
+      (define rb-p-parse-unary
+        (fn ()
+          (cond
+            ((and (= (rb-p-type) "op") (= (rb-p-val) "!"))
+              (do (rb-p-advance!)
+                  {:type "unop" :op "!" :value (rb-p-parse-unary)}))
+            ((and (= (rb-p-type) "op") (= (rb-p-val) "~"))
+              (do (rb-p-advance!)
+                  {:type "unop" :op "~" :value (rb-p-parse-unary)}))
+            ((and (= (rb-p-type) "op") (= (rb-p-val) "-"))
+              (do (rb-p-advance!)
+                  {:type "unop" :op "-" :value (rb-p-parse-unary)}))
+            ((and (= (rb-p-type) "op") (= (rb-p-val) "+"))
+              (do (rb-p-advance!) (rb-p-parse-unary)))
+            (:else (rb-p-parse-postfix)))))
+
+      (define rb-p-parse-power
+        (fn ()
+          (let ((node (rb-p-parse-unary)))
+            (if (and (= (rb-p-type) "op") (= (rb-p-val) "**"))
+              (do (rb-p-advance!)
+                  {:type "binop" :op "**" :left node :right (rb-p-parse-power)})
+              node))))
+
+      (define rb-p-parse-mul
+        (fn ()
+          (let ((node (rb-p-parse-power)))
+            (define rb-p-mul-loop
+              (fn ()
+                (if (and (= (rb-p-type) "op")
+                         (or (= (rb-p-val) "*") (= (rb-p-val) "/") (= (rb-p-val) "%")))
+                  (let ((op (rb-p-val)))
+                    (rb-p-advance!)
+                    (set! node {:type "binop" :op op :left node :right (rb-p-parse-power)})
+                    (rb-p-mul-loop))
+                  node)))
+            (rb-p-mul-loop))))
+
+      (define rb-p-parse-add
+        (fn ()
+          (let ((node (rb-p-parse-mul)))
+            (define rb-p-add-loop
+              (fn ()
+                (if (and (= (rb-p-type) "op")
+                         (or (= (rb-p-val) "+") (= (rb-p-val) "-")))
+                  (let ((op (rb-p-val)))
+                    (rb-p-advance!)
+                    (set! node {:type "binop" :op op :left node :right (rb-p-parse-mul)})
+                    (rb-p-add-loop))
+                  node)))
+            (rb-p-add-loop))))
+
+      (define rb-p-parse-shift
+        (fn ()
+          (let ((node (rb-p-parse-add)))
+            (define rb-p-sh-loop
+              (fn ()
+                (if (and (= (rb-p-type) "op")
+                         (or (= (rb-p-val) "<<") (= (rb-p-val) ">>")))
+                  (let ((op (rb-p-val)))
+                    (rb-p-advance!)
+                    (set! node {:type "binop" :op op :left node :right (rb-p-parse-add)})
+                    (rb-p-sh-loop))
+                  node)))
+            (rb-p-sh-loop))))
+
+      (define rb-p-parse-bitand
+        (fn ()
+          (let ((node (rb-p-parse-shift)))
+            (define rb-p-ba-loop
+              (fn ()
+                (if (and (= (rb-p-type) "op") (= (rb-p-val) "&"))
+                  (do
+                    (rb-p-advance!)
+                    (set! node {:type "binop" :op "&" :left node :right (rb-p-parse-shift)})
+                    (rb-p-ba-loop))
+                  node)))
+            (rb-p-ba-loop))))
+
+      ;; | is "pipe" token (not "op")
+      (define rb-p-parse-bitor
+        (fn ()
+          (let ((node (rb-p-parse-bitand)))
+            (define rb-p-bo-loop
+              (fn ()
+                (cond
+                  ((= (rb-p-type) "pipe")
+                    (do
+                      (rb-p-advance!)
+                      (set! node {:type "binop" :op "|" :left node :right (rb-p-parse-bitand)})
+                      (rb-p-bo-loop)))
+                  ((and (= (rb-p-type) "op") (= (rb-p-val) "^"))
+                    (do
+                      (rb-p-advance!)
+                      (set! node {:type "binop" :op "^" :left node :right (rb-p-parse-bitand)})
+                      (rb-p-bo-loop)))
+                  (:else node))))
+            (rb-p-bo-loop))))
+
+      (define rb-p-parse-comparison
+        (fn ()
+          (let ((node (rb-p-parse-bitor)))
+            (if (and (= (rb-p-type) "op")
+                     (contains? (list "==" "!=" "<" ">" "<=" ">="
+                                      "<=>" "===" "=~" "!~") (rb-p-val)))
+              (let ((op (rb-p-val)))
+                (rb-p-advance!)
+                {:type "binop" :op op :left node :right (rb-p-parse-bitor)})
+              node))))
+
+      (define rb-p-parse-not
+        (fn ()
+          (if (and (= (rb-p-type) "keyword") (= (rb-p-val) "not"))
+            (do (rb-p-advance!)
+                {:type "not" :value (rb-p-parse-not)})
+            (rb-p-parse-comparison))))
+
+      (define rb-p-parse-and
+        (fn ()
+          (let ((node (rb-p-parse-not)))
+            (define rb-p-and-loop
+              (fn ()
+                (cond
+                  ((and (= (rb-p-type) "op") (= (rb-p-val) "&&"))
+                    (do
+                      (rb-p-advance!)
+                      (set! node {:type "binop" :op "&&" :left node :right (rb-p-parse-not)})
+                      (rb-p-and-loop)))
+                  ((and (= (rb-p-type) "keyword") (= (rb-p-val) "and"))
+                    (do
+                      (rb-p-advance!)
+                      (set! node {:type "binop" :op "and" :left node :right (rb-p-parse-not)})
+                      (rb-p-and-loop)))
+                  (:else node))))
+            (rb-p-and-loop))))
+
+      (define rb-p-parse-or
+        (fn ()
+          (let ((node (rb-p-parse-and)))
+            (define rb-p-or-loop
+              (fn ()
+                (cond
+                  ((and (= (rb-p-type) "op") (= (rb-p-val) "||"))
+                    (do
+                      (rb-p-advance!)
+                      (set! node {:type "binop" :op "||" :left node :right (rb-p-parse-and)})
+                      (rb-p-or-loop)))
+                  ((and (= (rb-p-type) "keyword") (= (rb-p-val) "or"))
+                    (do
+                      (rb-p-advance!)
+                      (set! node {:type "binop" :op "or" :left node :right (rb-p-parse-and)})
+                      (rb-p-or-loop)))
+                  (:else node))))
+            (rb-p-or-loop))))
+
+      (define rb-p-parse-range
+        (fn ()
+          (let ((node (rb-p-parse-or)))
+            (cond
+              ((= (rb-p-type) "dotdot")
+                (do (rb-p-advance!)
+                    {:type "range" :from node :to (rb-p-parse-or) :exclusive false}))
+              ((= (rb-p-type) "dotdotdot")
+                (do (rb-p-advance!)
+                    {:type "range" :from node :to (rb-p-parse-or) :exclusive true}))
+              (:else node)))))
+
+      (define rb-p-parse-assign
+        (fn ()
+          (let ((node (rb-p-parse-range)))
+            (cond
+              ((and (= (rb-p-type) "op") (= (rb-p-val) "="))
+                (do (rb-p-advance!)
+                    {:type "assign" :target node :value (rb-p-parse-assign)}))
+              ((and (= (rb-p-type) "op")
+                    (contains? (list "+=" "-=" "*=" "/=" "%=" "**="
+                                     "<<=" ">>=" "&=" "|=" "^=" "&&=" "||=")
+                               (rb-p-val)))
+                (let ((op (substring (rb-p-val) 0 (- (len (rb-p-val)) 1))))
+                  (rb-p-advance!)
+                  {:type "op-assign" :target node :op op :value (rb-p-parse-assign)}))
+              (:else node)))))
+
+      (define rb-p-parse-expr
+        (fn () (rb-p-parse-assign)))
+
+      ;; e, e, ... → single node or array
+      (define rb-p-parse-multi-val
+        (fn ()
+          (let ((vals (list)))
+            (define rb-p-mv-loop
+              (fn ()
+                (append! vals (rb-p-parse-assign))
+                (when (= (rb-p-type) "comma")
+                  (do (rb-p-advance!) (rb-p-skip-newlines!) (rb-p-mv-loop)))))
+            (rb-p-mv-loop)
+            (if (= (len vals) 1)
+              (nth vals 0)
+              {:type "array" :elems vals}))))
+
+      ;; a, b, *c = rhs
+      (define rb-p-parse-massign
+        (fn ()
+          (let ((targets (list)))
+            (define rb-p-ma-loop
+              (fn ()
+                (cond
+                  ((and (= (rb-p-type) "op") (= (rb-p-val) "*"))
+                    (do
+                      (rb-p-advance!)
+                      (if (= (rb-p-type) "ident")
+                        (do
+                          (append! targets {:type "splat-target" :name (rb-p-val)})
+                          (rb-p-advance!))
+                        (append! targets {:type "splat-target" :name nil}))))
+                  ((= (rb-p-type) "ident")
+                    (do (append! targets {:type "lvar" :name (rb-p-val)}) (rb-p-advance!)))
+                  ((= (rb-p-type) "ivar")
+                    (do (append! targets {:type "ivar" :name (rb-p-val)}) (rb-p-advance!)))
+                  ((= (rb-p-type) "cvar")
+                    (do (append! targets {:type "cvar" :name (rb-p-val)}) (rb-p-advance!)))
+                  ((= (rb-p-type) "gvar")
+                    (do (append! targets {:type "gvar" :name (rb-p-val)}) (rb-p-advance!)))
+                  ((= (rb-p-type) "const")
+                    (do (append! targets {:type "const" :name (rb-p-val)}) (rb-p-advance!)))
+                  (:else nil))
+                (when (= (rb-p-type) "comma")
+                  (do (rb-p-advance!) (rb-p-skip-newlines!) (rb-p-ma-loop)))))
+            (rb-p-ma-loop)
+            (rb-p-advance!)
+            {:type "massign" :targets targets :value (rb-p-parse-multi-val)})))
+
+      (define rb-p-parse-stmt
+        (fn ()
+          (cond
+            ((and (= (rb-p-type) "keyword") (= (rb-p-val) "def"))
+              (rb-p-parse-def))
+            ((and (= (rb-p-type) "keyword") (= (rb-p-val) "class"))
+              (rb-p-parse-class))
+            ((and (= (rb-p-type) "keyword") (= (rb-p-val) "module"))
+              (rb-p-parse-module))
+            ((and (= (rb-p-type) "keyword") (= (rb-p-val) "return"))
+              (do (rb-p-advance!)
+                  {:type "return"
+                   :value (if (or (rb-p-sep?) (= (rb-p-type) "eof"))
+                             nil (rb-p-parse-multi-val))}))
+            ((and (= (rb-p-type) "keyword") (= (rb-p-val) "yield"))
+              (do (rb-p-advance!)
+                  {:type "yield"
+                   :args (cond
+                           ((= (rb-p-type) "lparen") (rb-p-parse-args-parens))
+                           ((or (rb-p-sep?) (= (rb-p-type) "eof")) (list))
+                           (:else (rb-p-parse-args-bare)))}))
+            ((and (= (rb-p-type) "keyword") (= (rb-p-val) "break"))
+              (do (rb-p-advance!)
+                  {:type "break"
+                   :value (if (or (rb-p-sep?) (= (rb-p-type) "eof"))
+                             nil (rb-p-parse-expr))}))
+            ((and (= (rb-p-type) "keyword") (= (rb-p-val) "next"))
+              (do (rb-p-advance!)
+                  {:type "next"
+                   :value (if (or (rb-p-sep?) (= (rb-p-type) "eof"))
+                             nil (rb-p-parse-expr))}))
+            ((and (= (rb-p-type) "keyword") (= (rb-p-val) "redo"))
+              (do (rb-p-advance!) {:type "redo"}))
+            ((and (= (rb-p-type) "keyword") (= (rb-p-val) "raise"))
+              (do (rb-p-advance!)
+                  {:type "raise"
+                   :value (if (or (rb-p-sep?) (= (rb-p-type) "eof"))
+                             nil (rb-p-parse-expr))}))
+            ;; Massign: token followed by comma
+            ((and (or (= (rb-p-type) "ident") (= (rb-p-type) "ivar")
+                      (= (rb-p-type) "cvar") (= (rb-p-type) "gvar")
+                      (= (rb-p-type) "const"))
+                  (= (get (rb-p-peek 1) :type) "comma"))
+              (rb-p-parse-massign))
+            (:else
+              (let ((node (rb-p-parse-assign)))
+                (if (and (= (get node :type) "send")
+                         (= (len (get node :args)) 0)
+                         (nil? (get node :block)))
+                  ;; Bare send: check for block or no-paren args
+                  (cond
+                    ;; Block immediately follows (do or {)
+                    ((or (and (= (rb-p-type) "keyword") (= (rb-p-val) "do"))
+                         (= (rb-p-type) "lbrace"))
+                      (let ((blk (rb-p-parse-block)))
+                        {:type "send" :name (get node :name) :args (list) :block blk}))
+                    ;; No-paren args (stop before block/sep/end keywords)
+                    ((and (not (rb-p-sep?))
+                          (not (= (rb-p-type) "eof"))
+                          (not (= (rb-p-type) "op"))
+                          (not (= (rb-p-type) "dot"))
+                          (not (= (rb-p-type) "dcolon"))
+                          (not (= (rb-p-type) "rparen"))
+                          (not (= (rb-p-type) "rbracket"))
+                          (not (= (rb-p-type) "rbrace"))
+                          (not (= (rb-p-type) "lbrace"))
+                          (not (and (= (rb-p-type) "keyword")
+                                    (contains? (list "end" "else" "elsif" "when"
+                                                     "rescue" "ensure" "then" "do"
+                                                     "and" "or" "not")
+                                               (rb-p-val)))))
+                      (let ((args (rb-p-parse-args-bare))
+                            (blk (rb-p-parse-block)))
+                        (if (> (len args) 0)
+                          {:type "send" :name (get node :name) :args args :block blk}
+                          node)))
+                    (:else node))
+                  node))))))
+
+      (define rb-p-parse-stmts
+        (fn (terminators)
+          (let ((stmts (list)))
+            (define rb-p-at-term?
+              (fn ()
+                (or (= (rb-p-type) "eof")
+                    (and (= (rb-p-type) "keyword")
+                         (contains? terminators (rb-p-val)))
+                    (and (= (rb-p-type) "rbrace")
+                         (contains? terminators "rbrace")))))
+            (define rb-p-ps-loop
+              (fn ()
+                (rb-p-skip-seps!)
+                (when (not (rb-p-at-term?))
+                  (do
+                    (append! stmts (rb-p-parse-stmt))
+                    (rb-p-skip-seps!)
+                    (rb-p-ps-loop)))))
+            (rb-p-ps-loop)
+            stmts)))
+
+      {:type "program" :stmts (rb-p-parse-stmts (list))})))
+
+(define rb-parse-str
+  (fn (src) (rb-parse (rb-tokenize src))))

lib/ruby/test.sh

@@ -0,0 +1,92 @@
+#!/usr/bin/env bash
+# Ruby-on-SX test runner.
+# Usage:
+#   bash lib/ruby/test.sh              # run all tests
+#   bash lib/ruby/test.sh -v           # verbose
+#   bash lib/ruby/test.sh tests/parse.sx   # single file
+
+set -euo pipefail
+cd "$(git rev-parse --show-toplevel)"
+
+SX_SERVER="hosts/ocaml/_build/default/bin/sx_server.exe"
+if [ ! -x "$SX_SERVER" ]; then
+  MAIN_ROOT=$(git worktree list | head -1 | awk '{print $1}')
+  if [ -x "$MAIN_ROOT/$SX_SERVER" ]; then
+    SX_SERVER="$MAIN_ROOT/$SX_SERVER"
+  else
+    echo "ERROR: sx_server.exe not found."
+    exit 1
+  fi
+fi
+
+VERBOSE=""
+FILES=()
+for arg in "$@"; do
+  case "$arg" in
+    -v|--verbose) VERBOSE=1 ;;
+    *) FILES+=("$arg") ;;
+  esac
+done
+
+if [ ${#FILES[@]} -eq 0 ]; then
+  mapfile -t FILES < <(find lib/ruby/tests -maxdepth 2 -name '*.sx' | sort)
+fi
+
+TOTAL_PASS=0
+TOTAL_FAIL=0
+FAILED_FILES=()
+
+for FILE in "${FILES[@]}"; do
+  [ -f "$FILE" ] || { echo "skip $FILE (not found)"; continue; }
+  TMPFILE=$(mktemp)
+  # Build epoch sequence: load runtime files, then test file, then eval summary.
+  {
+    echo "(epoch 1)"
+    echo "(load \"lib/ruby/tokenizer.sx\")"
+    if [ -f "lib/ruby/parser.sx" ]; then
+      echo "(epoch 2)"
+      echo "(load \"lib/ruby/parser.sx\")"
+    fi
+    echo "(epoch 3)"
+    echo "(load \"$FILE\")"
+    echo "(epoch 4)"
+    echo "(eval \"(list rb-test-pass rb-test-fail)\")"
+  } > "$TMPFILE"
+
+  OUTPUT=$(timeout 60 "$SX_SERVER" < "$TMPFILE" 2>&1 || true)
+  rm -f "$TMPFILE"
+
+  # Extract epoch 4 result: (ok-len 4 N)\n<val>  or  (ok 4 <val>)
+  LINE=$(printf '%s\n' "$OUTPUT" | awk '/^\(ok-len 4 / {getline; print; exit}')
+  if [ -z "$LINE" ]; then
+    LINE=$(printf '%s\n' "$OUTPUT" \
+           | grep -E '^\(ok 4 \([0-9]+ [0-9]+\)\)' | tail -1 \
+           | sed -E 's/^\(ok 4 //; s/\)$//')
+  fi
+  if [ -z "$LINE" ]; then
+    echo "✗ $FILE: could not extract summary"
+    printf '%s\n' "$OUTPUT" | grep -v '^(ok ' | tail -10
+    TOTAL_FAIL=$((TOTAL_FAIL + 1))
+    FAILED_FILES+=("$FILE")
+    continue
+  fi
+  P=$(printf '%s\n' "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\1/')
+  F=$(printf '%s\n' "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\2/')
+  TOTAL_PASS=$((TOTAL_PASS + P))
+  TOTAL_FAIL=$((TOTAL_FAIL + F))
+  if [ "$F" -gt 0 ]; then
+    FAILED_FILES+=("$FILE")
+    printf '✗ %-40s %d/%d\n' "$FILE" "$P" "$((P+F))"
+  elif [ "$VERBOSE" = "1" ]; then
+    printf '✓ %-40s %d passed\n' "$FILE" "$P"
+  fi
+done
+
+TOTAL=$((TOTAL_PASS + TOTAL_FAIL))
+if [ $TOTAL_FAIL -eq 0 ]; then
+  echo "✓ $TOTAL_PASS/$TOTAL ruby-on-sx tests passed"
+else
+  echo "✗ $TOTAL_PASS/$TOTAL passed, $TOTAL_FAIL failed in: ${FAILED_FILES[*]}"
+fi
+
+[ $TOTAL_FAIL -eq 0 ]

lib/ruby/tests/parse.sx

@@ -0,0 +1,439 @@
+;; Parser tests for Ruby 2.7 subset.
+
+(define rb-deep=?
+  (fn (a b)
+    (cond
+      ((= a b) true)
+      ((and (dict? a) (dict? b))
+        (let ((ak (keys a)) (bk (keys b)))
+          (if (not (= (len ak) (len bk)))
+            false
+            (every?
+              (fn (k)
+                (and (has-key? b k) (rb-deep=? (get a k) (get b k))))
+              ak))))
+      ((and (list? a) (list? b))
+        (if (not (= (len a) (len b)))
+          false
+          (let ((i 0) (ok true))
+            (define rb-de-loop
+              (fn ()
+                (when (and ok (< i (len a)))
+                  (do
+                    (when (not (rb-deep=? (nth a i) (nth b i)))
+                      (set! ok false))
+                    (set! i (+ i 1))
+                    (rb-de-loop)))))
+            (rb-de-loop)
+            ok)))
+      (:else false))))
+
+(define rb-test-pass 0)
+(define rb-test-fail 0)
+(define rb-test-fails (list))
+
+(define rb-test
+  (fn (name actual expected)
+    (if (rb-deep=? actual expected)
+      (set! rb-test-pass (+ rb-test-pass 1))
+      (do
+        (set! rb-test-fail (+ rb-test-fail 1))
+        (append! rb-test-fails {:name name :actual actual :expected expected})))))
+
+;; Shorthand: parse src and extract :stmts list
+(define rb-p-stmts
+  (fn (src)
+    (get (rb-parse-str src) :stmts)))
+
+;; Shorthand: parse and get first statement
+(define rb-p-first
+  (fn (src)
+    (nth (rb-p-stmts src) 0)))
+
+;; ── Literals ─────────────────────────────────────────────────────────────────
+
+(rb-test "int literal"
+  (rb-p-first "42")
+  {:type "lit-int" :value 42})
+
+(rb-test "negative int"
+  (rb-p-first "-7")
+  {:type "unop" :op "-" :value {:type "lit-int" :value 7}})
+
+(rb-test "float literal"
+  (rb-p-first "3.14")
+  {:type "lit-float" :value "3.14"})
+
+(rb-test "string literal"
+  (rb-p-first "\"hello\"")
+  {:type "lit-str" :value "hello"})
+
+(rb-test "symbol literal"
+  (rb-p-first ":foo")
+  {:type "lit-sym" :value "foo"})
+
+(rb-test "nil literal"
+  (rb-p-first "nil")
+  {:type "lit-nil"})
+
+(rb-test "true literal"
+  (rb-p-first "true")
+  {:type "lit-bool" :value true})
+
+(rb-test "false literal"
+  (rb-p-first "false")
+  {:type "lit-bool" :value false})
+
+(rb-test "self"
+  (rb-p-first "self")
+  {:type "self"})
+
+(rb-test "%w[] words"
+  (rb-p-first "%w[a b c]")
+  {:type "lit-words" :elems (list "a" "b" "c")})
+
+(rb-test "%i[] isymbols"
+  (rb-p-first "%i[x y]")
+  {:type "lit-isyms" :elems (list "x" "y")})
+
+;; ── Variables ─────────────────────────────────────────────────────────────────
+
+(rb-test "local var / send"
+  (rb-p-first "x")
+  {:type "send" :name "x" :args (list) :block nil})
+
+(rb-test "ivar"
+  (rb-p-first "@foo")
+  {:type "ivar" :name "@foo"})
+
+(rb-test "cvar"
+  (rb-p-first "@@count")
+  {:type "cvar" :name "@@count"})
+
+(rb-test "gvar"
+  (rb-p-first "$stdout")
+  {:type "gvar" :name "$stdout"})
+
+(rb-test "constant"
+  (rb-p-first "Foo")
+  {:type "const" :name "Foo"})
+
+(rb-test "const path"
+  (rb-p-first "Foo::Bar")
+  {:type "const-path"
+   :left {:type "const" :name "Foo"}
+   :name "Bar"})
+
+(rb-test "triple const path"
+  (rb-p-first "A::B::C")
+  {:type "const-path"
+   :left {:type "const-path"
+          :left {:type "const" :name "A"}
+          :name "B"}
+   :name "C"})
+
+;; ── Arrays and Hashes ─────────────────────────────────────────────────────────
+
+(rb-test "empty array"
+  (rb-p-first "[]")
+  {:type "array" :elems (list)})
+
+(rb-test "array literal"
+  (rb-p-first "[1, 2, 3]")
+  {:type "array" :elems (list {:type "lit-int" :value 1}
+                               {:type "lit-int" :value 2}
+                               {:type "lit-int" :value 3})})
+
+(rb-test "hash colon style"
+  (get (rb-p-first "{a: 1}") :type)
+  "hash")
+
+(rb-test "hash pair style"
+  (get (nth (get (rb-p-first "{a: 1}") :pairs) 0) :style)
+  "colon")
+
+(rb-test "hash symbol key"
+  (get (get (nth (get (rb-p-first "{a: 1}") :pairs) 0) :key) :value)
+  "a")
+
+;; ── Binary operators ──────────────────────────────────────────────────────────
+
+(rb-test "addition"
+  (rb-p-first "1 + 2")
+  {:type "binop" :op "+"
+   :left {:type "lit-int" :value 1}
+   :right {:type "lit-int" :value 2}})
+
+(rb-test "subtraction"
+  (get (rb-p-first "a - b") :op)
+  "-")
+
+(rb-test "multiplication"
+  (get (rb-p-first "x * y") :op)
+  "*")
+
+(rb-test "precedence: * before +"
+  (rb-p-first "1 + 2 * 3")
+  {:type "binop" :op "+"
+   :left {:type "lit-int" :value 1}
+   :right {:type "binop" :op "*"
+           :left {:type "lit-int" :value 2}
+           :right {:type "lit-int" :value 3}}})
+
+(rb-test "power right-assoc"
+  (rb-p-first "2 ** 3 ** 4")
+  {:type "binop" :op "**"
+   :left {:type "lit-int" :value 2}
+   :right {:type "binop" :op "**"
+           :left {:type "lit-int" :value 3}
+           :right {:type "lit-int" :value 4}}})
+
+(rb-test "equality"
+  (get (rb-p-first "a == b") :op)
+  "==")
+
+(rb-test "logical and"
+  (get (rb-p-first "a && b") :op)
+  "&&")
+
+(rb-test "logical or"
+  (get (rb-p-first "a || b") :op)
+  "||")
+
+(rb-test "range inclusive"
+  (rb-p-first "1..5")
+  {:type "range"
+   :from {:type "lit-int" :value 1}
+   :to {:type "lit-int" :value 5}
+   :exclusive false})
+
+(rb-test "range exclusive"
+  (get (rb-p-first "1...5") :exclusive)
+  true)
+
+;; ── Assignment ────────────────────────────────────────────────────────────────
+
+(rb-test "assign"
+  (rb-p-first "x = 1")
+  {:type "assign"
+   :target {:type "send" :name "x" :args (list) :block nil}
+   :value {:type "lit-int" :value 1}})
+
+(rb-test "op-assign +="
+  (get (rb-p-first "x += 1") :type)
+  "op-assign")
+
+(rb-test "op-assign op"
+  (get (rb-p-first "x += 1") :op)
+  "+")
+
+(rb-test "massign"
+  (get (rb-p-first "a, b = 1, 2") :type)
+  "massign")
+
+(rb-test "massign targets"
+  (len (get (rb-p-first "a, b = 1, 2") :targets))
+  2)
+
+(rb-test "massign value array"
+  (get (get (rb-p-first "a, b = 1, 2") :value) :type)
+  "array")
+
+;; ── Method calls ──────────────────────────────────────────────────────────────
+
+(rb-test "call with parens"
+  (rb-p-first "foo(1, 2)")
+  {:type "send" :name "foo"
+   :args (list {:type "lit-int" :value 1}
+               {:type "lit-int" :value 2})
+   :block nil})
+
+(rb-test "chained call"
+  (get (rb-p-first "obj.foo") :type)
+  "call")
+
+(rb-test "chained call method"
+  (get (rb-p-first "obj.foo") :method)
+  "foo")
+
+(rb-test "chained call with args"
+  (len (get (rb-p-first "obj.foo(1, 2)") :args))
+  2)
+
+(rb-test "no-paren call"
+  (get (rb-p-first "puts \"hello\"") :type)
+  "send")
+
+(rb-test "no-paren call name"
+  (get (rb-p-first "puts \"hello\"") :name)
+  "puts")
+
+(rb-test "no-paren call args"
+  (len (get (rb-p-first "puts \"hello\"") :args))
+  1)
+
+(rb-test "indexing"
+  (get (rb-p-first "a[0]") :type)
+  "index")
+
+;; ── Unary operators ───────────────────────────────────────────────────────────
+
+(rb-test "unary not"
+  (rb-p-first "!x")
+  {:type "unop" :op "!"
+   :value {:type "send" :name "x" :args (list) :block nil}})
+
+(rb-test "unary minus"
+  (get (rb-p-first "-x") :op)
+  "-")
+
+;; ── Method def ────────────────────────────────────────────────────────────────
+
+(rb-test "empty method def"
+  (get (rb-p-first "def foo; end") :type)
+  "method-def")
+
+(rb-test "method def name"
+  (get (rb-p-first "def foo; end") :name)
+  "foo")
+
+(rb-test "method def no params"
+  (len (get (rb-p-first "def foo; end") :params))
+  0)
+
+(rb-test "method def with params"
+  (len (get (rb-p-first "def foo(a, b); end") :params))
+  2)
+
+(rb-test "method def param-req"
+  (get (nth (get (rb-p-first "def foo(a); end") :params) 0) :type)
+  "param-req")
+
+(rb-test "method def param name"
+  (get (nth (get (rb-p-first "def foo(a); end") :params) 0) :name)
+  "a")
+
+(rb-test "method def optional param"
+  (get (nth (get (rb-p-first "def foo(a, b=1); end") :params) 1) :type)
+  "param-opt")
+
+(rb-test "method def splat"
+  (get (nth (get (rb-p-first "def foo(*args); end") :params) 0) :type)
+  "param-rest")
+
+(rb-test "method def double splat"
+  (get (nth (get (rb-p-first "def foo(**opts); end") :params) 0) :type)
+  "param-kwrest")
+
+(rb-test "method def block param"
+  (get (nth (get (rb-p-first "def foo(&blk); end") :params) 0) :type)
+  "param-block")
+
+(rb-test "method def all param types"
+  (len (get (rb-p-first "def foo(a, b=1, *c, **d, &e); end") :params))
+  5)
+
+(rb-test "method def singleton recv"
+  (get (get (rb-p-first "def self.bar; end") :recv) :type)
+  "self")
+
+(rb-test "method def body"
+  (len (get (rb-p-first "def foo; 1; 2; end") :body))
+  2)
+
+;; ── Class def ────────────────────────────────────────────────────────────────
+
+(rb-test "class def type"
+  (get (rb-p-first "class Foo; end") :type)
+  "class-def")
+
+(rb-test "class def name"
+  (get (get (rb-p-first "class Foo; end") :name) :name)
+  "Foo")
+
+(rb-test "class def no super"
+  (nil? (get (rb-p-first "class Foo; end") :super))
+  true)
+
+(rb-test "class def with super"
+  (get (get (rb-p-first "class Foo < Bar; end") :super) :name)
+  "Bar")
+
+(rb-test "singleton class"
+  (get (rb-p-first "class << self; end") :type)
+  "sclass")
+
+;; ── Module def ────────────────────────────────────────────────────────────────
+
+(rb-test "module def type"
+  (get (rb-p-first "module M; end") :type)
+  "module-def")
+
+(rb-test "module def name"
+  (get (get (rb-p-first "module M; end") :name) :name)
+  "M")
+
+;; ── Blocks ────────────────────────────────────────────────────────────────────
+
+(rb-test "block do...end"
+  (get (get (rb-p-first "foo do |x| x end") :block) :type)
+  "block")
+
+(rb-test "block brace"
+  (get (get (rb-p-first "foo { |x| x }") :block) :type)
+  "block")
+
+(rb-test "block params"
+  (len (get (get (rb-p-first "foo { |a, b| a }") :block) :params))
+  2)
+
+(rb-test "block no params"
+  (len (get (get (rb-p-first "foo { 42 }") :block) :params))
+  0)
+
+;; ── Control flow ──────────────────────────────────────────────────────────────
+
+(rb-test "return type"
+  (get (rb-p-first "return 1") :type)
+  "return")
+
+(rb-test "return value"
+  (get (get (rb-p-first "return 1") :value) :value)
+  1)
+
+(rb-test "return nil"
+  (nil? (get (rb-p-first "return") :value))
+  true)
+
+(rb-test "yield type"
+  (get (rb-p-first "yield 1") :type)
+  "yield")
+
+(rb-test "break type"
+  (get (rb-p-first "break") :type)
+  "break")
+
+(rb-test "next type"
+  (get (rb-p-first "next") :type)
+  "next")
+
+(rb-test "redo type"
+  (get (rb-p-first "redo") :type)
+  "redo")
+
+;; ── Multi-statement program ───────────────────────────────────────────────────
+
+(rb-test "two statements"
+  (len (rb-p-stmts "1\n2"))
+  2)
+
+(rb-test "semi-separated"
+  (len (rb-p-stmts "1; 2; 3"))
+  3)
+
+(rb-test "class with method"
+  (let ((cls (rb-p-first "class Foo\n  def bar\n    1\n  end\nend")))
+    (len (get cls :body)))
+  1)
+
+(list rb-test-pass rb-test-fail)

lib/ruby/tests/tokenizer.sx

@@ -0,0 +1,210 @@
+;; Ruby tokenizer tests.
+;; Final value: {:pass N :fail N :fails (list)}
+
+(define rb-deep=?
+  (fn (a b)
+    (cond
+      ((= a b) true)
+      ((and (dict? a) (dict? b))
+        (let ((ak (keys a)) (bk (keys b)))
+          (if (not (= (len ak) (len bk)))
+            false
+            (every?
+              (fn (k) (and (has-key? b k) (rb-deep=? (get a k) (get b k))))
+              ak))))
+      ((and (list? a) (list? b))
+        (if (not (= (len a) (len b)))
+          false
+          (let ((i 0) (ok true))
+            (define rb-de-loop
+              (fn ()
+                (when (and ok (< i (len a)))
+                  (do
+                    (when (not (rb-deep=? (nth a i) (nth b i)))
+                      (set! ok false))
+                    (set! i (+ i 1))
+                    (rb-de-loop)))))
+            (rb-de-loop)
+            ok)))
+      (:else false))))
+
+(define rb-test-pass 0)
+(define rb-test-fail 0)
+(define rb-test-fails (list))
+
+(define rb-test
+  (fn (name actual expected)
+    (if (rb-deep=? actual expected)
+      (set! rb-test-pass (+ rb-test-pass 1))
+      (do
+        (set! rb-test-fail (+ rb-test-fail 1))
+        (append! rb-test-fails {:name name :actual actual :expected expected})))))
+
+;; Helper: tokenize, drop newline+eof, return {:type :value} pairs
+(define rb-toks
+  (fn (src)
+    (map
+      (fn (tok) {:value (get tok "value") :type (get tok "type")})
+      (filter
+        (fn (tok)
+          (let ((ty (get tok "type")))
+            (not (or (= ty "newline") (= ty "eof")))))
+        (rb-tokenize src)))))
+
+;; Helper: get just types
+(define rb-types
+  (fn (src) (map (fn (t) (get t "type")) (rb-toks src))))
+
+;; Helper: get first token type
+(define rb-first-type
+  (fn (src) (get (get (rb-tokenize src) 0) "type")))
+
+(define rb-first-value
+  (fn (src) (get (get (rb-tokenize src) 0) "value")))
+
+;; ── 1. Keywords ────────────────────────<E29480><E29480><EFBFBD>─────────────────────────
+(rb-test "keyword def" (rb-toks "def") (list {:value "def" :type "keyword"}))
+(rb-test "keyword end" (rb-toks "end") (list {:value "end" :type "keyword"}))
+(rb-test "keyword class" (rb-toks "class") (list {:value "class" :type "keyword"}))
+(rb-test "keyword if" (rb-toks "if") (list {:value "if" :type "keyword"}))
+(rb-test "keyword while" (rb-toks "while") (list {:value "while" :type "keyword"}))
+(rb-test "keyword nil" (rb-toks "nil") (list {:value "nil" :type "keyword"}))
+(rb-test "keyword true" (rb-toks "true") (list {:value "true" :type "keyword"}))
+(rb-test "keyword false" (rb-toks "false") (list {:value "false" :type "keyword"}))
+(rb-test "keyword return" (rb-toks "return") (list {:value "return" :type "keyword"}))
+(rb-test "keyword yield" (rb-toks "yield") (list {:value "yield" :type "keyword"}))
+(rb-test "keyword begin" (rb-toks "begin") (list {:value "begin" :type "keyword"}))
+(rb-test "keyword rescue" (rb-toks "rescue") (list {:value "rescue" :type "keyword"}))
+(rb-test "keyword self" (rb-toks "self") (list {:value "self" :type "keyword"}))
+(rb-test "keyword super" (rb-toks "super") (list {:value "super" :type "keyword"}))
+
+;; ── 2. Identifiers ────────────────────────────────────────────────
+(rb-test "ident simple" (rb-toks "foo") (list {:value "foo" :type "ident"}))
+(rb-test "ident underscore" (rb-toks "_foo") (list {:value "_foo" :type "ident"}))
+(rb-test "ident with digit" (rb-toks "foo2") (list {:value "foo2" :type "ident"}))
+(rb-test "ident predicate" (rb-toks "empty?") (list {:value "empty?" :type "ident"}))
+(rb-test "ident bang" (rb-toks "save!") (list {:value "save!" :type "ident"}))
+(rb-test "defined?" (rb-toks "defined?") (list {:value "defined?" :type "keyword"}))
+
+;; ── 3. Constants ──────────────────────────────────────────────────
+(rb-test "const simple" (rb-toks "Foo") (list {:value "Foo" :type "const"}))
+(rb-test "const upcase" (rb-toks "MY_CONST") (list {:value "MY_CONST" :type "const"}))
+(rb-test "const class" (rb-toks "String") (list {:value "String" :type "const"}))
+
+;; ── 4. Sigil variables ───────────────────────────────────────────
+(rb-test "ivar" (rb-toks "@name") (list {:value "@name" :type "ivar"}))
+(rb-test "cvar" (rb-toks "@@count") (list {:value "@@count" :type "cvar"}))
+(rb-test "gvar" (rb-toks "$global") (list {:value "$global" :type "gvar"}))
+
+;; ── 5. Integers ───────────────────────────────────────────────────
+(rb-test "int decimal" (rb-first-value "42") 42)
+(rb-test "int zero" (rb-first-value "0") 0)
+(rb-test "int underscore" (rb-first-value "1_000") 1000)
+(rb-test "int hex" (rb-first-value "0xFF") 255)
+(rb-test "int hex lower" (rb-first-value "0xff") 255)
+(rb-test "int octal" (rb-first-value "0o17") 15)
+(rb-test "int binary" (rb-first-value "0b1010") 10)
+(rb-test "int type" (rb-first-type "42") "int")
+
+;; ── 6. Floats ─────────────────────────────────────────────────────
+(rb-test "float simple" (rb-first-type "3.14") "float")
+(rb-test "float value" (rb-first-value "3.14") "3.14")
+(rb-test "float exp" (rb-first-type "1.5e10") "float")
+(rb-test "float exp value" (rb-first-value "1.5e10") "1.5e10")
+
+;; ── 7. Strings ────────────────────────────────────────────────────
+(rb-test "dq string" (rb-first-value "\"hello\"") "hello")
+(rb-test "dq string type" (rb-first-type "\"hello\"") "string")
+(rb-test "sq string" (rb-first-value "'world'") "world")
+(rb-test "dq escape nl" (rb-first-value "\"a\\nb\"") "a\nb")
+(rb-test "dq escape tab" (rb-first-value "\"a\\tb\"") "a\tb")
+(rb-test "dq escape quote" (rb-first-value "\"a\\\"b\"") "a\"b")
+(rb-test "sq no escape" (rb-first-value "'a\\nb'") "a\\nb")
+(rb-test "sq escape backslash" (rb-first-value "'a\\\\'") "a\\")
+(rb-test "dq interp kept" (rb-first-value "\"#{x}\"") "#{x}")
+
+;; ── 8. Symbols ────────────────────────────────────────────────────
+(rb-test "symbol simple" (rb-first-type ":foo") "symbol")
+(rb-test "symbol value" (rb-first-value ":foo") "foo")
+(rb-test "symbol predicate" (rb-first-value ":empty?") "empty?")
+(rb-test "symbol dq" (rb-first-value ":\"hello world\"") "hello world")
+(rb-test "symbol sq" (rb-first-value ":'hello'") "hello")
+
+;; ── 9. %w and %i literals ────────────────────────────────────────
+(rb-test "%w bracket" (rb-first-type "%w[a b c]") "words")
+(rb-test "%w value" (rb-first-value "%w[a b c]") (list "a" "b" "c"))
+(rb-test "%w paren" (rb-first-value "%w(x y)") (list "x" "y"))
+(rb-test "%i bracket" (rb-first-type "%i[a b]") "isymbols")
+(rb-test "%i value" (rb-first-value "%i[foo bar]") (list "foo" "bar"))
+
+;; ── 10. Punctuation ───────────────────────────────────────────────
+(rb-test "dot" (rb-first-type ".") "dot")
+(rb-test "dotdot" (rb-first-type "..") "dotdot")
+(rb-test "dotdotdot" (rb-first-type "...") "dotdotdot")
+(rb-test "dcolon" (rb-first-type "::") "dcolon")
+(rb-test "comma" (rb-first-type ",") "comma")
+(rb-test "semi" (rb-first-type ";") "semi")
+(rb-test "lparen" (rb-first-type "(") "lparen")
+(rb-test "rparen" (rb-first-type ")") "rparen")
+(rb-test "lbracket" (rb-first-type "[") "lbracket")
+(rb-test "rbracket" (rb-first-type "]") "rbracket")
+(rb-test "lbrace" (rb-first-type "{") "lbrace")
+(rb-test "rbrace" (rb-first-type "}") "rbrace")
+(rb-test "pipe" (rb-first-type "|") "pipe")
+
+;; ── 11. Operators ─────────────────────────────────────────────────
+(rb-test "op plus" (rb-first-value "+") "+")
+(rb-test "op minus" (rb-first-value "-") "-")
+(rb-test "op star" (rb-first-value "*") "*")
+(rb-test "op slash" (rb-first-value "/") "/")
+(rb-test "op eq" (rb-first-value "=") "=")
+(rb-test "op eqeq" (rb-first-value "==") "==")
+(rb-test "op neq" (rb-first-value "!=") "!=")
+(rb-test "op lt" (rb-first-value "<") "<")
+(rb-test "op gt" (rb-first-value ">") ">")
+(rb-test "op lte" (rb-first-value "<=") "<=")
+(rb-test "op gte" (rb-first-value ">=") ">=")
+(rb-test "op spaceship" (rb-first-value "<=>") "<=>")
+(rb-test "op tripleq" (rb-first-value "===") "===")
+(rb-test "op match" (rb-first-value "=~") "=~")
+(rb-test "op nomatch" (rb-first-value "!~") "!~")
+(rb-test "op lshift" (rb-first-value "<<") "<<")
+(rb-test "op rshift" (rb-first-value ">>") ">>")
+(rb-test "op and" (rb-first-value "&&") "&&")
+(rb-test "op or" (rb-first-value "||") "||")
+(rb-test "op power" (rb-first-value "**") "**")
+(rb-test "op plus-eq" (rb-first-value "+=") "+=")
+(rb-test "op minus-eq" (rb-first-value "-=") "-=")
+(rb-test "op arrow" (rb-first-value "->") "->")
+(rb-test "op hash-rocket" (rb-first-value "=>") "=>")
+
+;; ── 12. Comments ──────────────────────────────────────────────────
+(rb-test "comment skipped" (len (rb-toks "# this is a comment")) 0)
+(rb-test "comment mid-line" (rb-types "x = 1 # comment") (list "ident" "op" "int"))
+
+;; ── 13. Multi-token sequences ─────────────────────────────────────
+(rb-test "method call" (rb-types "foo.bar")
+  (list "ident" "dot" "ident"))
+(rb-test "class def" (rb-types "class Foo")
+  (list "keyword" "const"))
+(rb-test "method def" (rb-types "def greet(name)")
+  (list "keyword" "ident" "lparen" "ident" "rparen"))
+(rb-test "assignment" (rb-types "x = 42")
+  (list "ident" "op" "int"))
+(rb-test "block params" (rb-types "|x, y|")
+  (list "pipe" "ident" "comma" "ident" "pipe"))
+(rb-test "scope resolution" (rb-types "Foo::Bar")
+  (list "const" "dcolon" "const"))
+(rb-test "range" (rb-types "1..10")
+  (list "int" "dotdot" "int"))
+(rb-test "exclusive range" (rb-types "1...10")
+  (list "int" "dotdotdot" "int"))
+
+;; ── 14. Line/col tracking ────────────────────────────────────────
+(define rb-tok1 (get (rb-tokenize "hello\nworld") 0))
+(define rb-tok2 (get (rb-tokenize "hello\nworld") 2))
+(rb-test "line track start" (get rb-tok1 "line") 1)
+(rb-test "line track second" (get rb-tok2 "line") 2)
+(rb-test "col track start" (get rb-tok1 "col") 1)
+
+(list rb-test-pass rb-test-fail)

lib/ruby/tokenizer.sx

@@ -0,0 +1,549 @@
+;; Ruby tokenizer for Ruby 2.7 subset.
+;; Token: {:type T :value V :line L :col C}
+;;
+;; Types: keyword ident ivar cvar gvar const
+;;        int float string symbol
+;;        op dot dotdot dotdotdot dcolon colon
+;;        lparen rparen lbracket rbracket lbrace rbrace
+;;        comma semi pipe newline words isymbols eof
+
+;; ── Character code table ──────────────────────────────────────────
+(define rb-ord-table
+  (let ((t (dict)) (i 0))
+    (define rb-build-table
+      (fn ()
+        (when (< i 128)
+          (do
+            (dict-set! t (char-from-code i) i)
+            (set! i (+ i 1))
+            (rb-build-table)))))
+    (rb-build-table)
+    t))
+
+(define rb-ord (fn (c) (or (get rb-ord-table c) 0)))
+
+;; ── Character predicates ──────────────────────────────────────────
+(define rb-digit?
+  (fn (c) (and (string? c) (>= (rb-ord c) 48) (<= (rb-ord c) 57))))
+
+(define rb-hex-digit?
+  (fn (c)
+    (and (string? c)
+         (or (and (>= (rb-ord c) 48) (<= (rb-ord c) 57))
+             (and (>= (rb-ord c) 97) (<= (rb-ord c) 102))
+             (and (>= (rb-ord c) 65) (<= (rb-ord c) 70))))))
+
+(define rb-octal-digit?
+  (fn (c) (and (string? c) (>= (rb-ord c) 48) (<= (rb-ord c) 55))))
+
+(define rb-binary-digit? (fn (c) (or (= c "0") (= c "1"))))
+
+(define rb-lower?
+  (fn (c) (and (string? c) (>= (rb-ord c) 97) (<= (rb-ord c) 122))))
+
+(define rb-upper?
+  (fn (c) (and (string? c) (>= (rb-ord c) 65) (<= (rb-ord c) 90))))
+
+(define rb-ident-start?
+  (fn (c) (or (rb-lower? c) (rb-upper? c) (= c "_"))))
+
+(define rb-ident-cont?
+  (fn (c) (or (rb-lower? c) (rb-upper? c) (rb-digit? c) (= c "_"))))
+
+(define rb-space? (fn (c) (or (= c " ") (= c "\t") (= c "\r"))))
+
+;; ── Reserved words ────────────────────────────────────────────────
+(define rb-keywords
+  (list "__ENCODING__" "__LINE__" "__FILE__"
+        "BEGIN" "END"
+        "alias" "and"
+        "begin" "break"
+        "case" "class"
+        "def" "defined?" "do"
+        "else" "elsif" "end" "ensure"
+        "false" "for"
+        "if" "in"
+        "module"
+        "next" "nil" "not"
+        "or"
+        "redo" "rescue" "retry" "return"
+        "self" "super"
+        "then" "true"
+        "undef" "unless" "until"
+        "when" "while"
+        "yield"))
+
+(define rb-keyword? (fn (w) (contains? rb-keywords w)))
+
+;; ── Token constructor ─────────────────────────────────────────────
+(define rb-make-token
+  (fn (type value line col) {:type type :value value :line line :col col}))
+
+;; ── Radix number parser ───────────────────────────────────────────
+(define rb-parse-radix
+  (fn (s radix)
+    (let ((n (len s)) (i 0) (acc 0))
+      (define rb-rad-loop
+        (fn ()
+          (when (< i n)
+            (do
+              (let ((c (substring s i (+ i 1))))
+                (cond
+                  ((and (>= (rb-ord c) 48) (<= (rb-ord c) 57))
+                    (set! acc (+ (* acc radix) (- (rb-ord c) 48))))
+                  ((and (>= (rb-ord c) 97) (<= (rb-ord c) 102))
+                    (set! acc (+ (* acc radix) (+ 10 (- (rb-ord c) 97)))))
+                  ((and (>= (rb-ord c) 65) (<= (rb-ord c) 70))
+                    (set! acc (+ (* acc radix) (+ 10 (- (rb-ord c) 65)))))))
+              (set! i (+ i 1))
+              (rb-rad-loop)))))
+      (rb-rad-loop)
+      acc)))
+
+;; ── Strip underscores from numeric literals ───────────────────────
+(define rb-strip-underscores
+  (fn (s)
+    (let ((n (len s)) (i 0) (parts (list)))
+      (define rb-su-loop
+        (fn ()
+          (when (< i n)
+            (do
+              (let ((c (substring s i (+ i 1))))
+                (when (not (= c "_"))
+                  (append! parts c)))
+              (set! i (+ i 1))
+              (rb-su-loop)))))
+      (rb-su-loop)
+      (join "" parts))))
+
+;; ── Main tokenizer ────────────────────────────────────────────────
+(define rb-tokenize
+  (fn (src)
+    (let ((tokens (list))
+          (pos 0)
+          (line 1)
+          (col 1)
+          (src-len (len src)))
+      (define rb-peek
+        (fn (offset)
+          (if (< (+ pos offset) src-len)
+            (substring src (+ pos offset) (+ pos offset 1))
+            nil)))
+      (define rb-cur (fn () (rb-peek 0)))
+      (define rb-advance!
+        (fn ()
+          (let ((c (rb-cur)))
+            (set! pos (+ pos 1))
+            (if (= c "\n")
+              (do (set! line (+ line 1)) (set! col 1))
+              (set! col (+ col 1))))))
+      (define rb-advance-n!
+        (fn (n)
+          (when (> n 0)
+            (do (rb-advance!) (rb-advance-n! (- n 1))))))
+      (define rb-push!
+        (fn (type value tok-line tok-col)
+          (append! tokens (rb-make-token type value tok-line tok-col))))
+      (define rb-read-while
+        (fn (pred)
+          (let ((start pos))
+            (define rb-rw-loop
+              (fn ()
+                (when (and (< pos src-len) (pred (rb-cur)))
+                  (do (rb-advance!) (rb-rw-loop)))))
+            (rb-rw-loop)
+            (substring src start pos))))
+      (define rb-skip-line-comment!
+        (fn ()
+          (define rb-slc-loop
+            (fn ()
+              (when (and (< pos src-len) (not (= (rb-cur) "\n")))
+                (do (rb-advance!) (rb-slc-loop)))))
+          (rb-slc-loop)))
+      (define rb-read-escape
+        (fn ()
+          (rb-advance!)
+          (let ((c (rb-cur)))
+            (cond
+              ((= c "n") (do (rb-advance!) "\n"))
+              ((= c "t") (do (rb-advance!) "\t"))
+              ((= c "r") (do (rb-advance!) "\r"))
+              ((= c "\\") (do (rb-advance!) "\\"))
+              ((= c "'") (do (rb-advance!) "'"))
+              ((= c "\"") (do (rb-advance!) "\""))
+              ((= c "a") (do (rb-advance!) (char-from-code 7)))
+              ((= c "b") (do (rb-advance!) (char-from-code 8)))
+              ((= c "f") (do (rb-advance!) (char-from-code 12)))
+              ((= c "v") (do (rb-advance!) (char-from-code 11)))
+              ((= c "e") (do (rb-advance!) (char-from-code 27)))
+              ((= c "s") (do (rb-advance!) " "))
+              ((= c "0") (do (rb-advance!) (char-from-code 0)))
+              (:else (do (rb-advance!) (str "\\" c)))))))
+      (define rb-read-sq-string
+        (fn ()
+          (let ((parts (list)))
+            (rb-advance!)
+            (define rb-sq-loop
+              (fn ()
+                (cond
+                  ((>= pos src-len) nil)
+                  ((= (rb-cur) "'") (rb-advance!))
+                  ((and (= (rb-cur) "\\")
+                        (let ((n (rb-peek 1)))
+                          (or (= n "\\") (= n "'"))))
+                    (do
+                      (rb-advance!)
+                      (append! parts (rb-cur))
+                      (rb-advance!)
+                      (rb-sq-loop)))
+                  (:else
+                    (do
+                      (append! parts (rb-cur))
+                      (rb-advance!)
+                      (rb-sq-loop))))))
+            (rb-sq-loop)
+            (join "" parts))))
+      (define rb-read-dq-string
+        (fn ()
+          (let ((parts (list)))
+            (rb-advance!)
+            (define rb-dq-loop
+              (fn ()
+                (cond
+                  ((>= pos src-len) nil)
+                  ((= (rb-cur) "\"") (rb-advance!))
+                  ((= (rb-cur) "\\")
+                    (do
+                      (append! parts (rb-read-escape))
+                      (rb-dq-loop)))
+                  ((and (= (rb-cur) "#") (= (rb-peek 1) "{"))
+                    (do
+                      (append! parts "#{")
+                      (rb-advance-n! 2)
+                      (let ((depth 1))
+                        (define rb-interp-inner
+                          (fn ()
+                            (when (and (< pos src-len) (> depth 0))
+                              (do
+                                (let ((c (rb-cur)))
+                                  (cond
+                                    ((= c "{")
+                                      (do
+                                        (set! depth (+ depth 1))
+                                        (append! parts c)
+                                        (rb-advance!)))
+                                    ((= c "}")
+                                      (do
+                                        (set! depth (- depth 1))
+                                        (when (> depth 0)
+                                          (do (append! parts c) (rb-advance!)))))
+                                    (:else
+                                      (do (append! parts c) (rb-advance!)))))
+                                (rb-interp-inner)))))
+                        (rb-interp-inner))
+                      (when (= (rb-cur) "}")
+                        (do (append! parts "}") (rb-advance!)))
+                      (rb-dq-loop)))
+                  (:else
+                    (do
+                      (append! parts (rb-cur))
+                      (rb-advance!)
+                      (rb-dq-loop))))))
+            (rb-dq-loop)
+            (join "" parts))))
+      (define rb-read-percent-words
+        (fn ()
+          (rb-advance-n! 2)
+          (let ((open-ch (rb-cur)))
+            (let ((close-ch
+                    (cond
+                      ((= open-ch "[") "]")
+                      ((= open-ch "(") ")")
+                      ((= open-ch "{") "}")
+                      ((= open-ch "<") ">")
+                      (:else open-ch))))
+              (rb-advance!)
+              (let ((items (list)))
+                (define rb-pw-skip
+                  (fn ()
+                    (when (and (< pos src-len) (or (rb-space? (rb-cur)) (= (rb-cur) "\n")))
+                      (do (rb-advance!) (rb-pw-skip)))))
+                (define rb-pw-word
+                  (fn (wparts)
+                    (if (or (>= pos src-len)
+                             (rb-space? (rb-cur))
+                             (= (rb-cur) "\n")
+                             (= (rb-cur) close-ch))
+                      (append! items (join "" wparts))
+                      (do
+                        (append! wparts (rb-cur))
+                        (rb-advance!)
+                        (rb-pw-word wparts)))))
+                (define rb-pw-loop
+                  (fn ()
+                    (rb-pw-skip)
+                    (when (and (< pos src-len) (not (= (rb-cur) close-ch)))
+                      (do
+                        (rb-pw-word (list))
+                        (rb-pw-loop)))))
+                (rb-pw-loop)
+                (when (= (rb-cur) close-ch) (rb-advance!))
+                items)))))
+      (define rb-read-ident-word
+        (fn ()
+          (let ((start pos))
+            (rb-read-while rb-ident-cont?)
+            (when (and (= (rb-cur) "?") (not (= (rb-peek 1) "=")))
+              (rb-advance!))
+            (when (and (= (rb-cur) "!") (not (or (= (rb-peek 1) "=") (= (rb-peek 1) "~"))))
+              (rb-advance!))
+            (substring src start pos))))
+      (define rb-read-number!
+        (fn (tok-line tok-col)
+          (let ((start pos))
+            (cond
+              ((and (= (rb-cur) "0") (let ((p (rb-peek 1))) (or (= p "b") (= p "B"))))
+                (do
+                  (rb-advance-n! 2)
+                  (let ((bin-str (rb-read-while rb-binary-digit?)))
+                    (rb-push! "int" (rb-parse-radix bin-str 2) tok-line tok-col))))
+              ((and (= (rb-cur) "0") (let ((p (rb-peek 1))) (or (= p "o") (= p "O"))))
+                (do
+                  (rb-advance-n! 2)
+                  (let ((oct-str (rb-read-while rb-octal-digit?)))
+                    (rb-push! "int" (rb-parse-radix oct-str 8) tok-line tok-col))))
+              ((and (= (rb-cur) "0") (let ((p (rb-peek 1))) (or (= p "x") (= p "X"))))
+                (do
+                  (rb-advance-n! 2)
+                  (let ((hex-str (rb-read-while rb-hex-digit?)))
+                    (rb-push! "int" (rb-parse-radix hex-str 16) tok-line tok-col))))
+              (:else
+                (do
+                  (rb-read-while (fn (c) (or (rb-digit? c) (= c "_"))))
+                  (let ((is-float false))
+                    (when (and (= (rb-cur) ".") (rb-digit? (rb-peek 1)))
+                      (do
+                        (set! is-float true)
+                        (rb-advance!)
+                        (rb-read-while (fn (c) (or (rb-digit? c) (= c "_"))))))
+                    (when (or (= (rb-cur) "e") (= (rb-cur) "E"))
+                      (do
+                        (set! is-float true)
+                        (rb-advance!)
+                        (when (or (= (rb-cur) "+") (= (rb-cur) "-"))
+                          (rb-advance!))
+                        (rb-read-while rb-digit?)))
+                    (let ((num-str (rb-strip-underscores (substring src start pos))))
+                      (if is-float
+                        (rb-push! "float" num-str tok-line tok-col)
+                        (rb-push! "int" (parse-int num-str) tok-line tok-col))))))))))
+      (define rb-read-op!
+        (fn (tok-line tok-col)
+          (let ((c0 (rb-cur)) (c1 (rb-peek 1)) (c2 (rb-peek 2)))
+            (cond
+              ((and (= c0 "<") (= c1 "=") (= c2 ">"))
+                (do (rb-advance-n! 3) (rb-push! "op" "<=>" tok-line tok-col)))
+              ((and (= c0 "=") (= c1 "=") (= c2 "="))
+                (do (rb-advance-n! 3) (rb-push! "op" "===" tok-line tok-col)))
+              ((and (= c0 "*") (= c1 "*") (= c2 "="))
+                (do (rb-advance-n! 3) (rb-push! "op" "**=" tok-line tok-col)))
+              ((and (= c0 "<") (= c1 "<") (= c2 "="))
+                (do (rb-advance-n! 3) (rb-push! "op" "<<=" tok-line tok-col)))
+              ((and (= c0 ">") (= c1 ">") (= c2 "="))
+                (do (rb-advance-n! 3) (rb-push! "op" ">>=" tok-line tok-col)))
+              ((and (= c0 "&") (= c1 "&") (= c2 "="))
+                (do (rb-advance-n! 3) (rb-push! "op" "&&=" tok-line tok-col)))
+              ((and (= c0 "|") (= c1 "|") (= c2 "="))
+                (do (rb-advance-n! 3) (rb-push! "op" "||=" tok-line tok-col)))
+              ((and (= c0 "*") (= c1 "*"))
+                (do (rb-advance-n! 2) (rb-push! "op" "**" tok-line tok-col)))
+              ((and (= c0 "=") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" "==" tok-line tok-col)))
+              ((and (= c0 "!") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" "!=" tok-line tok-col)))
+              ((and (= c0 "<") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" "<=" tok-line tok-col)))
+              ((and (= c0 ">") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" ">=" tok-line tok-col)))
+              ((and (= c0 "=") (= c1 "~"))
+                (do (rb-advance-n! 2) (rb-push! "op" "=~" tok-line tok-col)))
+              ((and (= c0 "!") (= c1 "~"))
+                (do (rb-advance-n! 2) (rb-push! "op" "!~" tok-line tok-col)))
+              ((and (= c0 "<") (= c1 "<"))
+                (do (rb-advance-n! 2) (rb-push! "op" "<<" tok-line tok-col)))
+              ((and (= c0 ">") (= c1 ">"))
+                (do (rb-advance-n! 2) (rb-push! "op" ">>" tok-line tok-col)))
+              ((and (= c0 "&") (= c1 "&"))
+                (do (rb-advance-n! 2) (rb-push! "op" "&&" tok-line tok-col)))
+              ((and (= c0 "|") (= c1 "|"))
+                (do (rb-advance-n! 2) (rb-push! "op" "||" tok-line tok-col)))
+              ((and (= c0 "+") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" "+=" tok-line tok-col)))
+              ((and (= c0 "-") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" "-=" tok-line tok-col)))
+              ((and (= c0 "*") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" "*=" tok-line tok-col)))
+              ((and (= c0 "/") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" "/=" tok-line tok-col)))
+              ((and (= c0 "%") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" "%=" tok-line tok-col)))
+              ((and (= c0 "&") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" "&=" tok-line tok-col)))
+              ((and (= c0 "|") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" "|=" tok-line tok-col)))
+              ((and (= c0 "^") (= c1 "="))
+                (do (rb-advance-n! 2) (rb-push! "op" "^=" tok-line tok-col)))
+              ((and (= c0 "-") (= c1 ">"))
+                (do (rb-advance-n! 2) (rb-push! "op" "->" tok-line tok-col)))
+              ((and (= c0 "=") (= c1 ">"))
+                (do (rb-advance-n! 2) (rb-push! "op" "=>" tok-line tok-col)))
+              ((and (= c0 "|") (nil? c1))
+                (do (rb-advance!) (rb-push! "pipe" "|" tok-line tok-col)))
+              ((= c0 "|")
+                (do (rb-advance!) (rb-push! "pipe" "|" tok-line tok-col)))
+              (:else
+                (do (rb-advance!) (rb-push! "op" c0 tok-line tok-col)))))))
+      (define rb-scan!
+        (fn ()
+          (cond
+            ((>= pos src-len) nil)
+            ((rb-space? (rb-cur)) (do (rb-advance!) (rb-scan!)))
+            ((= (rb-cur) "#") (do (rb-skip-line-comment!) (rb-scan!)))
+            ((= (rb-cur) "\n")
+              (do
+                (let ((l line) (c col))
+                  (rb-advance!)
+                  (rb-push! "newline" nil l c))
+                (rb-scan!)))
+            ((rb-digit? (rb-cur))
+              (do
+                (let ((l line) (c col))
+                  (rb-read-number! l c))
+                (rb-scan!)))
+            ((rb-ident-start? (rb-cur))
+              (do
+                (let ((l line) (c col))
+                  (let ((w (rb-read-ident-word)))
+                    (if (rb-keyword? w)
+                      (rb-push! "keyword" w l c)
+                      (if (rb-upper? (substring w 0 1))
+                        (rb-push! "const" w l c)
+                        (rb-push! "ident" w l c)))))
+                (rb-scan!)))
+            ((= (rb-cur) "@")
+              (do
+                (let ((l line) (c col))
+                  (if (= (rb-peek 1) "@")
+                    (do
+                      (rb-advance-n! 2)
+                      (let ((name (rb-read-while rb-ident-cont?)))
+                        (rb-push! "cvar" (str "@@" name) l c)))
+                    (do
+                      (rb-advance!)
+                      (let ((name (rb-read-while rb-ident-cont?)))
+                        (rb-push! "ivar" (str "@" name) l c)))))
+                (rb-scan!)))
+            ((= (rb-cur) "$")
+              (do
+                (let ((l line) (c col))
+                  (rb-advance!)
+                  (let ((name (rb-read-while rb-ident-cont?)))
+                    (rb-push! "gvar" (str "$" name) l c)))
+                (rb-scan!)))
+            ((= (rb-cur) "\"")
+              (do
+                (let ((l line) (c col))
+                  (rb-push! "string" (rb-read-dq-string) l c))
+                (rb-scan!)))
+            ((= (rb-cur) "'")
+              (do
+                (let ((l line) (c col))
+                  (rb-push! "string" (rb-read-sq-string) l c))
+                (rb-scan!)))
+            ((and (= (rb-cur) ":") (= (rb-peek 1) ":"))
+              (do
+                (let ((l line) (c col))
+                  (rb-advance-n! 2)
+                  (rb-push! "dcolon" "::" l c))
+                (rb-scan!)))
+            ((= (rb-cur) ":")
+              (do
+                (let ((l line) (c col))
+                  (rb-advance!)
+                  (cond
+                    ((= (rb-cur) "\"")
+                      (rb-push! "symbol" (rb-read-dq-string) l c))
+                    ((= (rb-cur) "'")
+                      (rb-push! "symbol" (rb-read-sq-string) l c))
+                    ((rb-ident-start? (rb-cur))
+                      (let ((name (rb-read-ident-word)))
+                        (rb-push! "symbol" name l c)))
+                    (:else
+                      (rb-push! "colon" ":" l c))))
+                (rb-scan!)))
+            ((and (= (rb-cur) "%")
+                  (let ((p (rb-peek 1)))
+                    (or (= p "w") (= p "W") (= p "i") (= p "I"))))
+              (do
+                (let ((l line) (c col))
+                  (let ((kind (rb-peek 1)))
+                    (let ((items (rb-read-percent-words)))
+                      (if (or (= kind "i") (= kind "I"))
+                        (rb-push! "isymbols" items l c)
+                        (rb-push! "words" items l c)))))
+                (rb-scan!)))
+            ((= (rb-cur) ".")
+              (do
+                (let ((l line) (c col))
+                  (cond
+                    ((and (= (rb-peek 1) ".") (= (rb-peek 2) "."))
+                      (do (rb-advance-n! 3) (rb-push! "dotdotdot" "..." l c)))
+                    ((= (rb-peek 1) ".")
+                      (do (rb-advance-n! 2) (rb-push! "dotdot" ".." l c)))
+                    (:else
+                      (do (rb-advance!) (rb-push! "dot" "." l c)))))
+                (rb-scan!)))
+            ((= (rb-cur) ",")
+              (do
+                (let ((l line) (c col)) (rb-push! "comma" "," l c) (rb-advance!))
+                (rb-scan!)))
+            ((= (rb-cur) ";")
+              (do
+                (let ((l line) (c col)) (rb-push! "semi" ";" l c) (rb-advance!))
+                (rb-scan!)))
+            ((= (rb-cur) "(")
+              (do
+                (let ((l line) (c col)) (rb-push! "lparen" "(" l c) (rb-advance!))
+                (rb-scan!)))
+            ((= (rb-cur) ")")
+              (do
+                (let ((l line) (c col)) (rb-push! "rparen" ")" l c) (rb-advance!))
+                (rb-scan!)))
+            ((= (rb-cur) "[")
+              (do
+                (let ((l line) (c col)) (rb-push! "lbracket" "[" l c) (rb-advance!))
+                (rb-scan!)))
+            ((= (rb-cur) "]")
+              (do
+                (let ((l line) (c col)) (rb-push! "rbracket" "]" l c) (rb-advance!))
+                (rb-scan!)))
+            ((= (rb-cur) "{")
+              (do
+                (let ((l line) (c col)) (rb-push! "lbrace" "{" l c) (rb-advance!))
+                (rb-scan!)))
+            ((= (rb-cur) "}")
+              (do
+                (let ((l line) (c col)) (rb-push! "rbrace" "}" l c) (rb-advance!))
+                (rb-scan!)))
+            ((or (= (rb-cur) "+") (= (rb-cur) "-") (= (rb-cur) "*")
+                 (= (rb-cur) "/") (= (rb-cur) "%") (= (rb-cur) "=")
+                 (= (rb-cur) "!") (= (rb-cur) "<") (= (rb-cur) ">")
+                 (= (rb-cur) "&") (= (rb-cur) "^") (= (rb-cur) "~")
+                 (= (rb-cur) "|"))
+              (do
+                (let ((l line) (c col)) (rb-read-op! l c))
+                (rb-scan!)))
+            (:else (do (rb-advance!) (rb-scan!))))))
+      (rb-scan!)
+      (rb-push! "eof" nil line col)
+      tokens)))

plans/ruby-on-sx.md

@@ -51,11 +51,11 @@ Core mapping:
 ## Roadmap
 
 ### Phase 1 — tokenizer + parser
-- [ ] Tokenizer: keywords (`def end class module if unless while until do return yield begin rescue ensure case when then else elsif`), identifiers (lowercase = local/method, `@` = ivar, `@@` = cvar, `$` = global, uppercase = constant), numbers (int, float, `0x` `0o` `0b`, `_` separators), strings (`"…"` interpolation, `'…'` literal, `%w[a b c]`, `%i[a b c]`), symbols `:foo` `:"…"`, operators (`+ - * / % ** == != < > <= >= <=> === =~ !~ << >> & | ^ ~ ! && || and or not`), `:: . , ; ( ) [ ] { } -> => |`, comments `#`
-- [ ] Parser: program is sequence of statements separated by newlines or `;`; method def `def name(args) … end`; class `class Foo < Bar … end`; module `module M … end`; block `do |a, b| … end` and `{ |a, b| … }`; call sugar (no parens), `obj.method`, `Mod::Const`; arg shapes (positional, default, splat `*args`, double-splat `**opts`, block `&blk`)
+- [x] Tokenizer: keywords (`def end class module if unless while until do return yield begin rescue ensure case when then else elsif`), identifiers (lowercase = local/method, `@` = ivar, `@@` = cvar, `$` = global, uppercase = constant), numbers (int, float, `0x` `0o` `0b`, `_` separators), strings (`"…"` interpolation, `'…'` literal, `%w[a b c]`, `%i[a b c]`), symbols `:foo` `:"…"`, operators (`+ - * / % ** == != < > <= >= <=> === =~ !~ << >> & | ^ ~ ! && || and or not`), `:: . , ; ( ) [ ] { } -> => |`, comments `#`
+- [x] Parser: program is sequence of statements separated by newlines or `;`; method def `def name(args) … end`; class `class Foo < Bar … end`; module `module M … end`; block `do |a, b| … end` and `{ |a, b| … }`; call sugar (no parens), `obj.method`, `Mod::Const`; arg shapes (positional, default, splat `*args`, double-splat `**opts`, block `&blk`)
 - [ ] If/while/case expressions (return values), `unless`/`until`, postfix modifiers
 - [ ] Begin/rescue/ensure/retry, raise, raise with class+message
-- [ ] Unit tests in `lib/ruby/tests/parse.sx`
+- [x] Unit tests in `lib/ruby/tests/parse.sx`
 
 ### Phase 2 — object model + sequential eval
 - [ ] Class table bootstrap: `BasicObject`, `Object`, `Kernel`, `Module`, `Class`, `Numeric`, `Integer`, `Float`, `String`, `Symbol`, `Array`, `Hash`, `Range`, `NilClass`, `TrueClass`, `FalseClass`, `Proc`, `Method`
@@ -117,7 +117,8 @@ Core mapping:
 
 _Newest first._
 
-- _(none yet)_
+- 2026-04-25: Phase 1 parser complete — `lib/ruby/parser.sx` (rb-parse/rb-parse-str) + `lib/ruby/tests/parse.sx` (83/83 tests). Program, method-def (all param shapes), class/module/sclass, blocks (do/brace), method calls (parens + no-parens + chains), const-path, assignment (=, op=, massign), binary/unary ops with precedence, array/hash literals, return/yield/break/next/redo/raise, indexing.
+- 2026-04-25: Phase 1 tokenizer complete — `lib/ruby/tokenizer.sx` + `lib/ruby/tests/tokenizer.sx` (107/107 tests). Keywords, identifiers (@ivar @@cvar $gvar), numbers (dec/hex/octal/binary/float), strings (dq with interpolation kept raw, sq), symbols, %w/%i literals, operators (all compound forms), punctuation, comments, line/col tracking.
 
 ## Blockers