1 files changed, 67 insertions, 0 deletions
diff --git a/src/cljcc/lexer.clj b/src/cljcc/lexer.clj
new file mode 100644
index 0000000..a6319f9
--- /dev/null
+++ b/src/cljcc/lexer.clj
@@ -0,0 +1,67 @@
+(ns cljcc.lexer
+  (:require
+   [cljcc.util :refer [newline? whitespace? read-number digit? letter-digit? letter?]]
+   [cljcc.token :as t]
+   [clojure.pprint :as pp]))
+
+(re-find #"[0-9]+\b" "123213bbb 456")
+
+(defn- lexer-ctx []
+  {:tokens []
+   :line 1
+   :col 1})
+
+(defn lex
+  ([source]
+   (lex source 0 (lexer-ctx)))
+  ([[ch pk & rst :as source] pos {:keys [line col] :as ctx}]
+   (cond
+     (empty? source) (update ctx :tokens #(conj % (t/create :eof line col)))
+     (newline? ch) (recur (next source)
+                          (+ pos 1)
+                          (-> ctx
+                              (update :line inc)
+                              (update :col (fn [_] 1))))
+     (contains?
+      t/chrs-kind-map ch) (recur (next source)
+                                 (+ pos 1)
+                                 (-> ctx
+                                     (update :col inc)
+                                     (update :tokens #(conj % (t/create (get t/chrs-kind-map ch) line col)))))
+     (whitespace? ch) (recur (next source)
+                             (+ pos 1)
+                             (-> ctx
+                                 (update :col inc)))
+     (digit? ch) (let [[chrs rst] (split-with letter-digit? source)
+                       number (read-number (apply str chrs))
+                       cnt (count chrs)
+                       npos (+ pos cnt)
+                       token (t/create :number line col number)]
+                   (recur (apply str rst)
+                          npos
+                          (-> ctx
+                              (update :col #(+ % cnt))
+                              (update :tokens #(conj % token)))))
+     (letter? ch) (let [[chrs rst] (split-with letter-digit? source)
+                        lexeme (apply str chrs)
+                        cnt (count chrs)
+                        kind (t/identifier->kind lexeme)
+                        token (if (= :identifier kind)
+                                (t/create kind line col lexeme)
+                                (t/create kind line col))
+                        npos (+ pos cnt)]
+                    (recur (apply str rst) npos (-> ctx
+                                                    (update :col #(+ % cnt))
+                                                    (update :tokens #(conj % token)))))
+     :else (throw (ex-info "Lexer error. Invalid token." {:line line :col col})))))
+
+(comment
+
+  "int main(void) {
+    return 2;
+  }"
+
+  (pp/pprint
+   (lex "int main(void) {return 2;}"))
+
+  ())