增加 NFA 算法

zhengwei.hzw · zhengwei.hzw · commit 9655ce942f92 · 2016-11-15T01:11:28.000+08:00
diff --git a/src/Digraph/directedDFS.js b/src/Digraph/directedDFS.js
@@ -16,9 +16,6 @@ class DirectedDFS {
     }
 
     _dfs(G, v) {
-        if(!G.isV(v))
-            throw new Error('别犯傻, 这个顶点都不存在')
-
         this._marked.push(v)
 
         ~~(G.adj(v) || []).forEach(w => {
diff --git a/src/Digraph/index.js b/src/Digraph/index.js
@@ -5,6 +5,7 @@ class Digraph {
         this._E = 0
         this._V = []
         // 如果用对象的形式没法区分以 '1' 和 1 做 key
+        // ES6  new Set
         this._adjK = []
         this._adjV = []
     }
diff --git a/src/NFA/index.js b/src/NFA/index.js
@@ -0,0 +1,91 @@
+'use strict'
+
+const Digraph = require('../Digraph/index')
+const DirectedDFS = require('../Digraph/directedDFS')
+
+class NFA {
+
+    constructor(regexp) {
+
+        let ops = []
+        const M = this.__M = regexp.length
+            , G = this.__G = new Digraph()  // epsilon 转换
+
+
+        this.__G.addEdge(M, M + 1)
+
+        this.__re = regexp
+
+        for (let i = 0; i < M; i++) {
+            let lp = i
+
+            if (regexp[i] === '(' || regexp[i] === '|') {
+                ops.push(i)
+            } else if (regexp[i] === ')') {
+                let or = ops.pop()
+                if (regexp[or] === '|') {
+                    lp = ops.pop()
+                    G.addEdge(lp, or + 1)
+                    G.addEdge(or, i)
+                } else {
+                    lp = or
+                }
+            }
+
+            // 查看 '*' 字符
+            if (i < M - 1 && regexp[i + 1] === '*') {
+                G.addEdge(lp, i + 1)
+                G.addEdge(i + 1, lp)
+            }
+
+            if (regexp[i] === '(' || regexp[i] === '*' || regexp[i] === ')') {
+                G.addEdge(i, i + 1)
+            }
+
+        }
+
+    }
+
+    recognizes(txt) {
+
+        let pc = [],
+            G = this.__G,
+            M = this.__M,
+            re = this.__re,
+            dfs = new DirectedDFS(G, 0)
+
+
+        for (let v = 0; v < G.V(); v++) {
+            if (dfs.marked(v)) pc.push(v)
+        }
+
+        for (let i = 0; i < txt.length; i++) {
+            let match = []
+            for (let j = 0; j < pc.length; j++) {
+                if (pc[j] < M) {
+                    if (re[pc[j]] === txt[i] || re[pc[j]] === '.') {
+                        match.push(pc[j] + 1)
+                    }
+                }
+            }
+
+            pc = []
+            dfs = new DirectedDFS(G, match)
+
+            for (let v = 0; v < G.V(); v++) {
+                if (dfs.marked(v)) {
+                    pc.push(v)
+                }
+            }
+
+        }
+
+        return pc.includes(M)
+    }
+
+
+}
+
+
+module.exports = NFA
+
diff --git a/src/NFA/test-case.js b/src/NFA/test-case.js
@@ -0,0 +1,13 @@
+'use strict'
+
+const NFA = require('./index')
+
+
+let data = ['AC', 'AD', 'AAA', 'ABD', 'ACD', 'BCD', 'AAABD','ABCCBD', 'BABAAA', 'BABBAAA']
+    , nfa = new NFA('(A*B|AC)D')
+
+
+data.forEach(v => {
+    console.log(v + ':    ' + nfa.recognizes(v))
+})
+

Original file line number	Diff line number	Diff line change
`@@ -16,9 +16,6 @@ class DirectedDFS {`
`16`	`16`	`}`
`17`	`17`
`18`	`18`	`_dfs(G, v) {`
`19`		`- if(!G.isV(v))`
`20`		`- throw new Error('别犯傻, 这个顶点都不存在')`
`21`		`-`
`22`	`19`	`this._marked.push(v)`
`23`	`20`
`24`	`21`	`~~(G.adj(v) \|\| []).forEach(w => {`
Original file line number	Diff line number	Diff line change
`@@ -5,6 +5,7 @@ class Digraph {`
`5`	`5`	`this._E = 0`
`6`	`6`	`this._V = []`
`7`	`7`	`// 如果用对象的形式没法区分以 '1' 和 1 做 key`
	`8`	`+ // ES6 new Set`
`8`	`9`	`this._adjK = []`
`9`	`10`	`this._adjV = []`
`10`	`11`	`}`