[improvement] rename packages dir to src (#3659)

src/collapse/index.js

@@ -0,0 +1,37 @@
+import { createNamespace } from '../utils';
+import { ParentMixin } from '../mixins/relation';
+
+const [createComponent, bem] = createNamespace('collapse');
+
+export default createComponent({
+  mixins: [ParentMixin('vanCollapse')],
+
+  props: {
+    accordion: Boolean,
+    value: [String, Number, Array],
+    border: {
+      type: Boolean,
+      default: true
+    }
+  },
+
+  methods: {
+    switch(name, expanded) {
+      if (!this.accordion) {
+        name = expanded
+          ? this.value.concat(name)
+          : this.value.filter(activeName => activeName !== name);
+      }
+      this.$emit('change', name);
+      this.$emit('input', name);
+    }
+  },
+
+  render(h) {
+    return (
+      <div class={[bem(), { 'van-hairline--top-bottom': this.border }]}>
+        {this.slots()}
+      </div>
+    );
+  }
+});