update expression parsing

Author: Steffan

src/fields.vue

@@ -18,7 +18,7 @@
     import FieldSelect from './components/Select.vue';
     import FieldRange from './components/Range.vue';
     import FieldNumber from './components/Number.vue';
-    import {assign, each, evaluate, get, isArray, isString, isUndefined, set, warn} from './util';
+    import {assign, each, get, parse, isArray, isString, isUndefined, set, warn} from './util';
 
     export default {
 
@@ -74,16 +74,23 @@
                 }
             },
 
-            evaluate(expr, values = this.values) {
+            evaluate(expression, values = this.values) {
 
-                if (isString(expr)) {
+                try {
 
-                    const context = {$match, $values: values, $get: key => get(values, key)};
+                    if (isString(expression)) {
+                        expression = parse(expression);
+                    }
+
+                    return expression.call(this, values, {
+                        $match, $get: key => get(values, key)
+                    });
 
-                    return evaluate(this, expr, context);
+                } catch (e) {
+                    warn(e);
                 }
 
-                return expr.call(this, values, this);
+                return true;
             },
 
             prepare(config = this.config, prefix = this.prefix) {

src/util.js

@@ -68,24 +68,17 @@ export function set(obj, key, val) {
     _set(obj, parts.shift(), val);
 }
 
-const quotedStringRe = /([^"']+)((.)(?:[^\3\\]|\\.)*?\3|.)?/g;
+const parsedFunc = {};
 const expressionRe = /((?:\d|true|false|null|undefined|(?:this\.|\$)[\S]+|\W)*)([\w][\w+.]*)?/g;
-const expressions = {};
-export function evaluate(self, expr, context) {
-
-    expressions[expr] = expressions[expr] || expr.replace(quotedStringRe, (match, unquoted, quoted = '') =>
-        unquoted.replace(expressionRe, (match, prefix = '', expr) =>
-            match ? `${prefix}${expr ? `$get('${expr}')` : ''}` : ''
-        ) + quoted
-    );
-
-    try {
-        return (Function('c', `with(c){return ${expressions[expr]}}`)).call(self, context);
-    } catch (e) {
-        warn(e);
-    }
+const quotedStringRe = /([^"']+)((.)(?:[^\3\\]|\\.)*?\3|.)?/g;
 
-    return false;
+export function parse(expr) {
+    return parsedFunc[expr] = parsedFunc[expr] ||
+        Function('$values', '$context', `with($context){return ${expr.replace(quotedStringRe,
+            (match, unquoted, quoted = '') => unquoted.replace(expressionRe,
+                (match, prefix = '', expression) => match ? `${prefix}${expression ? `$get('${expression}')` : ''}` : ''
+            ) + quoted
+    )}}`);
 }
 
 export function each(obj, iterator) {

stories/index.js

@@ -2,4 +2,4 @@ import FieldsStory from './components/FieldsStory.vue';
 import {storiesOf} from '@storybook/vue';
 
 storiesOf('Fields', module)
-    .add('Default', () => ({extends: FieldsStory}));
+    .add('Default', () => FieldsStory);