rename expression.js -> syntax.js

src/syntax.js

@@ -1,13 +1,55 @@
-var operators = {
-    '==': (l, r) => l == r,
-    '!=': (l, r) => l != r,
-    '>': (l, r) => l > r,
-    '<': (l, r) => l < r,
-    '>=': (l, r) => l >= r,
-    '<=': (l, r) => l <= r,
-    'contains': (l, r) => l.indexOf(r) > -1,
-    'and': (l, r) => l && r,
-    'or': (l, r) => l || r
-};
+const operators = require('./operators.js');
+const lexical = require('./lexical.js');
 
-exports.operators = operators;
+function evalExp(exp, scope) {
+    if (!scope) throw new Error('unable to evalExp: scope undefined');
+    var operatorREs = lexical.operators,
+        match;
+    for (var i = 0; i < operatorREs.length; i++) {
+        var operatorRE = operatorREs[i];
+        var expRE = new RegExp(`^(${lexical.quoteBalanced.source})(${operatorRE.source})(${lexical.quoteBalanced.source})$`);
+        if (match = exp.match(expRE)) {
+            var l = evalExp(match[1], scope);
+            var op = operators[match[2].trim()];
+            var r = evalExp(match[3], scope);
+            return op(l, r);
+        }
+    }
+
+    if (match = exp.match(lexical.rangeLine)) {
+        var low = evalValue(match[1], scope),
+            high = evalValue(match[2], scope);
+        var range = [];
+        for (var j = low; j <= high; j++) {
+            range.push(j);
+        }
+        return range;
+    }
+
+    return evalValue(exp, scope);
+}
+
+function evalValue(str, scope) {
+    str = str && str.trim();
+    if (!str) return undefined;
+
+    if (lexical.isLiteral(str)) {
+        return lexical.parseLiteral(str);
+    }
+    if (lexical.isVariable(str)) {
+        return scope.get(str);
+    }
+}
+
+function isTruthy(val) {
+    if (val instanceof Array) return !!val.length;
+    return !!val;
+}
+
+function isFalsy(val) {
+    return !isTruthy(val);
+}
+
+module.exports = {
+    evalExp, evalValue, isTruthy, isFalsy
+};