context and identifier

identifier.js

@@ -0,0 +1,41 @@
+const _ = require('lodash');
+
+var singleQuoted = /^'[^']*'$/;
+var doubleQuoted = /^"[^"]*"$/;
+
+var number = /^(?:\d+\.?\d*|\.?\d+)$/;
+var bool = /^(?:true|false)$/i;
+var range = /^\((\d+)\.\.(\d+)\)$/;
+
+var quoted = new RegExp(`${singleQuoted.source}|${doubleQuoted.source}`);
+var literal = new RegExp(`${quoted.source}|${range.source}|${bool.source}|${number.source}`, 'i');
+var variable = /^[a-zA-Z_]\w*(?:\.[a-zA-Z_]\w*|\[\d+\])*$/;
+var identifier = new RegExp(`${literal.source}|${variable.source}`, 'i');
+
+exports.patterns = {
+    quoted, number, bool, range, literal
+};
+
+exports.isLiteral = function(str) {
+    return literal.test(str);
+};
+
+exports.isVariable = function(str) {
+    return variable.test(str);
+};
+
+exports.parseLiteral = function(str) {
+    var res;
+    if(res = str.match(number)){
+        return Number(str);
+    }
+    if(res = str.match(bool)){
+        return str.toLowerCase() === 'true';
+    }
+    if(res = str.match(quoted)){
+        return str.slice(1, -1);
+    }
+    if(res = str.match(range)){
+        return _.range(res[1], res[2]);
+    }
+};