some advancement

1 files changed, 108 insertions, 0 deletions

diff --git a/javascripts/RegexParser.js b/javascripts/RegexParser.js
new file mode 100644
index 0000000..f2dd168
--- /dev/null
+++ b/javascripts/RegexParser.js
@@ -0,0 +1,108 @@
+/*
+ * RegexParser
+ *
+ */
+function RegexParser() {
+    this.alphabet         = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUWXYZ';
+    this.str = this.regex = '';
+    this.errorMessage     = 'Ok'
+    this.errorPosition    = -1;
+}
+
+
+RegexParser.prototype.lookahead = function() {
+    if (this.str.length > 0) {
+        return this.str.substring(0,1);
+    }
+    return '';
+}
+
+RegexParser.prototype.consume = function(symbol) {
+    this.str = this.str.substring(1);
+}
+
+RegexParser.prototype.trymatch = function(symbol) {
+    if (this.str.substring(0, 1) == symbol) {
+        this.consume(symbol);
+        return true;
+    }
+    return false;
+}
+
+RegexParser.prototype.match = function(symbol) {
+    if (!this.trymatch(symbol)) {
+        throw('Expected symbol '+symbol);
+    }
+}
+
+RegexParser.prototype.isLetter = function(symbol) {
+    return this.alphabet.indexOf(symbol) >= 0;
+}
+
+RegexParser.prototype.literal = function() {
+    var symbol = this.lookahead();
+    if(this.isLetter(symbol)) {
+        this.consume(symbol);
+        return new Nfa(symbol);
+    }
+    throw('Expected symbol or %.'); 
+}
+
+RegexParser.prototype.atom = function() {
+    if(this.trymatch('(')) {
+        var nfa = this.expr();
+        this.match(')');
+        return nfa;
+    }
+    return this.literal();
+}
+
+RegexParser.prototype.factor = function() {
+    return this.stars(this.atom());
+}
+
+RegexParser.prototype.stars = function(nfa) {
+    if (this.trymatch('*')) {
+        return this.stars(nfa.star());
+    }
+    return nfa;
+}
+
+RegexParser.prototype.term = function() {
+    var nfa = this.factor();
+    var symbol = this.lookahead();
+    if (this.isLetter(symbol) || (symbol == '(')) {
+        return nfa.concatenation(this.term());
+    }
+    return nfa;
+}
+
+RegexParser.prototype.expr = function() {
+    var nfa = this.term();
+    if (this.trymatch('|')) {
+        return nfa.union(this.expr());
+    }
+    return nfa;
+}
+
+RegexParser.prototype.parse = function(str) {
+    var nfa;
+    this.str = this.regex = str;
+
+    //try {
+        nfa = this.expr();
+        if(this.str.length>0) {
+            throw('Supernumerous symbols');
+        }
+    //} catch(e) {
+    //    this.errorMessage = e;
+    //    this.errorPosition = str.length - this.str.length;        
+    //    nfa = null;
+    //}
+    return nfa;
+}
+
+RegexParser.prototype.getRegex = function() { return this.regex }
+RegexParser.prototype.getErrorMessage = function() { return this.errorMessage }
+RegexParser.prototype.getErrorPosition = function() { return this.errorPosition }
+