doc

Author: yufengzjj

README.md

@@ -1,2 +1,34 @@
 # ERE
-Educational Regular expression Engine 
+**Educational Regular expression Engine--purpose for education of automata theory.**
+
+all base on C++11 standard library and a tiny C++11 template library [ATMPL](https://github.com/yufengzjj/ATMPL) .
+
+this regular expression engine only support core operations:alternate,concat and closure.
+
+it uses recursive descent parsing to parse regular expression and then generate finite state automata.it can generate DOT(Graphviz) file of NFA/DFA/miniDFA of the regular expression automata.
+
+examples:
+
+> ERE.exe --help
+>
+> -h [ --help ] produce help message
+>
+> -e [ --expr ] arg set regular expression
+>
+> -s [ --string ] arg string to check by regular expression
+>
+> -a [ --alphabet ] arg set regular expression alphabet
+
+ERE.exe -e "a(b|cd)*e" -s abbbcdcde
+
+![](doc/1.png)
+
+dot -T png -O NFA.dot DFA.dot min_DFA.dot
+
+
+
+![](doc/NFA.dot.png)
+
+![](doc/DFA.dot.png)
+
+![](doc/min_DFA.dot.png)