fix README.mkd

Author: mattn

README.mkd

@@ -19,7 +19,9 @@ This parser provide same feature for following languages.
 
 ## Example
 
-All of interfaces are provided from vimlparser module. make StringReader to break a string into tokens, and VimLParser to parse into AST, Compiler to compile nodes.
+### Parse VimL into AST, and print S-expression
+
+All of interfaces are provided from vimlparser module. VimLParser parse into AST using StringReader, and Compiler to compile nodes.
 
 ```vim
 let s:vimlparser = vimlparser#import()
@@ -37,3 +39,34 @@ This above code output following.
 ```
 (let = s:message (printf "hello %d" (+ 1 (* 2 3))))
 ```
+
+### Parse VimL into AST, and print S-expression
+
+ExprTokenizer break a string buffer into tokens for expression.
+
+```vim
+let code = [
+\ 'echo 1+(2*3)'
+\]
+let s:vimlparser = vimlparser#import()
+let r = s:vimlparser.StringReader.new(code)
+let t = s:vimlparser.ExprTokenizer.new(r)
+while !r.eof()
+  let token = t.get()
+  echo token.value
+endwhile
+```
+
+This above code output following.
+
+```
+echo
+1
++
+(
+2
+*
+3
+)
+<EOL>
+```