DSL语法解析器生成器：dropincc.java

dropincc.java 是

• 一个简单、好用的语法解析器生成器；
• 专为java语言环境下，实施DSL方案而设计；
• 特点：使用纯java语法(Fluent Interface)制定用户的词法、语法规则；jdk1.6 compiler API动态编译为字节码；自动管理字节码、用户无需关心具体生成的解析器源码；专为DSL打造，相对与使用其它常见工具(javacc, antlr等)做DSL解析，代码量急剧下降；上手较为容易，让用户更加关注自身业务内容
• 需要jdk1.6或以上版本运行,无任何其它依赖
• 识别LL(*)语法

/**
 * EBNF of Calculator:
 * <pre>
 * calc ::= expr $
 * expr ::= addend (('+'|'-') addend)*
 * addend ::= factor (('*'|'/') factor)*
 * factor ::= '(' expr ')'
 *          | '\\d+(\\.\\d+)?'
 * </pre>
 */
public static void main(String... args) throws Throwable {
    Lang c = new Lang("Calculator");
    Grule expr = c.newGrule();
    c.defineGrule(expr, CC.EOF).action(new Action() {
        public Double act(Object matched) {
            return (Double) ((Object[]) matched)[0];
        }
    });
    TokenDef a = c.newToken("\\+");
    Grule addend = c.newGrule();
    expr.define(addend, CC.ks(a.or("\\-"), addend)).action(new Action() {
        public Double act(Object matched) {
            Object[] ms = (Object[]) matched;
            Double a0 = (Double) ms[0];
            Object[] aPairs = (Object[]) ms[1];
            for (Object p : aPairs) {
                String op = (String) ((Object[]) p)[0];
                Double a = (Double) ((Object[]) p)[1];
                if ("+".equals(op)) {
                    a0 += a;
                } else {
                    a0 -= a;
                }
            }
            return a0;
        }
    });
    TokenDef m = c.newToken("\\*");
    Grule factor = c.newGrule();
    addend.define(factor, CC.ks(m.or("/"), factor)).action(new Action() {
        public Double act(Object matched) {
            Object[] ms = (Object[]) matched;
            Double f0 = (Double) ms[0];
            Object[] fPairs = (Object[]) ms[1];
            for (Object p : fPairs) {
                String op = (String) ((Object[]) p)[0];
                Double f = (Double) ((Object[]) p)[1];
                if ("*".equals(op)) {
                    f0 *= f;
                } else {
                    f0 /= f;
                }
            }
            return f0;
        }
    });
    factor.define("\\(", expr, "\\)").action(new Action() {
        public Double act(Object matched) {
            return (Double) ((Object[]) matched)[1];
        }
    }).alt("\\d+(\\.\\d+)?").action(new Action() {
        public Double act(Object matched) {
            return Double.parseDouble((String) matched);
        }
    });
    Exe exe = c.compile();
    System.out.println(exe.eval("1 +2+3+(4 +5*6*7*(64/8/2/(2/1 )/1)*8  +9  )+   10"));
}

项目主页：http://www.open-open.com/lib/view/home/1377095164319