Create lexer for lox (#1100)

Close #1073 

The Lox language is from the book "Crafting Interpreters"
https://craftinginterpreters.com/

Author: sebastianertz

lexers/embedded/lox.xml

@@ -0,0 +1,83 @@
+<lexer>
+  <config>
+    <name>lox</name>
+    <filename>*.lox</filename>
+    <dot_all>true</dot_all>
+    <ensure_nl>true</ensure_nl>
+  </config>
+  <rules>
+    <state name="classname">
+      <rule pattern="[a-zA-Z_]\w*">
+        <token type="NameClass"/>
+        <pop depth="1"/>
+      </rule>
+    </state>
+    <state name="funname">
+      <rule pattern="[a-zA-Z_]\w*">
+        <token type="NameFunction"/>
+        <pop depth="1"/>
+      </rule>
+    </state>
+    <state name="varname">
+      <rule pattern="[a-zA-Z_]\w*">
+        <token type="NameVariable"/>
+        <pop depth="1"/>
+      </rule>
+    </state>
+    <state name="whitespace">
+      <rule pattern="\n">
+        <token type="Text"/>
+      </rule>
+      <rule pattern="\s+">
+        <token type="Text"/>
+      </rule>
+    </state>
+    <state name="root">
+      <rule>
+        <include state="whitespace"/>
+      </rule>
+      <rule pattern="//.*?\n">
+        <token type="CommentSingle"/>
+      </rule>
+      <rule pattern="(and|else|for|if|or|print|return|super|this|while)\b">
+        <token type="Keyword"/>
+      </rule>
+      <rule pattern="(false|nil|true)\b">
+        <token type="KeywordConstant"/>
+      </rule>
+      <rule pattern="(class)(\s*)">
+        <token type="KeywordDeclaration"/>
+        <push state="classname"/>
+      </rule>
+      <rule pattern="(fun)(\s*)">
+        <token type="KeywordDeclaration"/>
+        <push state="funname"/>
+      </rule>
+      <rule pattern="(var)(\s*)">
+        <token type="KeywordDeclaration"/>
+        <push state="varname"/>
+      </rule>
+      <rule pattern="\d+(\.\d*|[eE][+\-]?\d+)">
+        <token type="LiteralNumberFloat"/>
+      </rule>
+      <rule pattern="[0-9][0-9]*">
+        <token type="LiteralNumberInteger"/>
+      </rule>
+      <rule pattern="&#34;(\\\\|\\&#34;|[^&#34;])*&#34;">
+        <token type="LiteralStringDouble"/>
+      </rule>
+      <rule pattern="!|\+|-|\*|/|&lt;|&gt;|=">
+        <token type="Operator"/>
+      </rule>
+      <rule pattern="[{(;,]">
+        <token type="Punctuation"/>
+      </rule>
+      <rule pattern="[}).]">
+        <token type="Punctuation"/>
+      </rule>
+      <rule pattern="[a-zA-Z_]\w*">
+        <token type="NameVariable"/>
+      </rule>
+    </state>
+  </rules>
+</lexer>

lexers/testdata/lox.actual

@@ -0,0 +1,132 @@
+// Your first Lox program!
+print "Hello, world!";
+
+true;  // Not false.
+false; // Not *not* false.
+
+1234;  // An integer.
+12.34; // A decimal number.
+
+"I am a string";
+"";    // The empty string.
+"123"; // This is a string, not a number.
+
+nil;
+
+add + me;
+subtract - me;
+multiply * me;
+divide / me;
+
+-negateMe;
+
+less < than;
+lessThan <= orEqual;
+greater > than;
+greaterThan >= orEqual;
+
+1 == 2;         // false.
+"cat" != "dog"; // true.
+
+314 == "pi"; // false.
+
+123 == "123"; // false.
+
+!true;  // false.
+!false; // true.
+
+true and false; // false.
+true and true;  // true.
+
+false or false; // false.
+true or false;  // true.
+
+{
+  print "One statement.";
+  print "Two statements.";
+}
+
+var imAVariable = "here is my value";
+var iAmNil;
+
+var breakfast = "bagels";
+print breakfast; // "bagels".
+breakfast = "beignets";
+print breakfast; // "beignets".
+
+if (condition) {
+  print "yes";
+} else {
+  print "no";
+}
+
+var a = 1;
+while (a < 10) {
+  print a;
+  a = a + 1;
+}
+
+for (var a = 1; a < 10; a = a + 1) {
+  print a;
+}
+
+makeBreakfast(bacon, eggs, toast);
+
+makeBreakfast();
+
+fun addPair(a, b) {
+  return a + b;
+}
+fun identity(a) {
+  return a;
+}
+print identity(addPair)(1, 2); // Prints "3".
+
+fun returnFunction() {
+  var outside = "outside";
+  fun inner() {
+    print outside;
+  }
+  return inner;
+}
+var fn = returnFunction();
+fn();
+
+class Breakfast {
+  cook() {
+    print "Eggs a-fryin'!";
+  }
+  serve(who) {
+    print "Enjoy your breakfast, " + who + ".";
+  }
+}
+
+// Store it in variables.
+var someVariable = Breakfast;
+
+// Pass it to functions.
+someFunction(Breakfast);
+
+breakfast.meat = "sausage";
+breakfast.bread = "sourdough";
+
+class Breakfast {
+  init(meat, bread) {
+    this.meat = meat;
+    this.bread = bread;
+  }
+  // ...
+}
+var baconAndToast = Breakfast("bacon", "toast");
+baconAndToast.serve("Dear Reader");
+// "Enjoy your bacon and toast, Dear Reader."
+
+class Brunch < Breakfast {
+  init(meat, bread, drink) {
+    super.init(meat, bread);
+    this.drink = drink;
+  }
+  drink() {
+    print "How about a Bloody Mary?";
+  }
+}