incremental example

README.asciidoc

@@ -115,6 +115,8 @@ A parser is created using the `parser` or `make-parser` functions.
 
 == Creating buffers ==
 
+Creating a buffer, editing it and getting its resulting parse-tree:
+
 ----
     (-> p p/incremental-buffer (p/edit 0 0 "(") (p/edit 1 0 "(x)") p/parse-tree pprint)
 
@@ -126,6 +128,25 @@ A parser is created using the `parser` or `make-parser` functions.
         {:tag :expr, :content ["(" {:tag :expr, :content ["x"]} ")"]}]}]}
 ----
 
+Incremental parsing at work:
+
+----
+=> (def p (p/parser :expr #{"x" "\n" ["(" :expr* ")"]}))
+#'net.cgrand.parsley/p
+=> (let [line (apply str "\n" (repeat 10 "((x))"))
+         input (str "(" (apply str (repeat 1000 line)) ")")
+         buf (p/incremental-buffer p)
+         buf (p/edit buf 0 0 input)]
+     (time (p/parse-tree buf))
+     (time (p/parse-tree (-> buf (p/edit 2 0 "(") (p/edit 51002 0 ")"))))
+     nil)
+"Elapsed time: 508.834 msecs"
+"Elapsed time: 86.038 msecs"
+nil
+----
+
+Hence, *reparsing the buffer only took a fraction of the original time* despite
+the buffer having been modified at the start and at the end.
 
 == Options ==