add Collapse component

add Collapse component

components/collapse/collapse.vue

@@ -0,0 +1,98 @@
+<template>
+    <div :class="classes">
+        <slot></slot>
+    </div>
+</template>
+<script>
+    const prefixCls = 'ivu-collapse';
+
+    export default {
+        props: {
+            accordion: {
+                type: Boolean,
+                default: false
+            },
+            activeKey: {
+                type: [Array, String]
+            }
+        },
+        computed: {
+            classes () {
+                return `${prefixCls}`;
+            }
+        },
+        compiled () {
+            this.setActive();
+        },
+        methods: {
+            setActive () {
+                const activeKey = this.getActiveKey();
+
+                this.$children.forEach((child, index) => {
+                    const key = child.key || index.toString();
+                    let isActive = false;
+
+                    if (self.accordion) {
+                        isActive = activeKey === key;
+                    } else {
+                        isActive = activeKey.indexOf(key) > -1;
+                    }
+
+                    child.isActive = isActive;
+                    child.index = index;
+                })
+            },
+            getActiveKey () {
+                let activeKey = this.activeKey || [];
+                const accordion = this.accordion;
+
+                if (!Array.isArray(activeKey)) {
+                    activeKey = [activeKey];
+                }
+
+                if (accordion && activeKey.length > 1) {
+                    activeKey = [activeKey[0]];
+                }
+
+                for (let i = 0; i < activeKey.length; i++) {
+                    activeKey[i] = activeKey[i].toString();
+                }
+
+                return activeKey;
+            },
+            toggle (data) {
+                const key = data.key.toString();
+                let newActiveKey = [];
+
+                if (this.accordion) {
+                    if (!data.isActive) {
+                        newActiveKey.push(key);
+                    }
+                } else {
+                    let activeKey = this.getActiveKey();
+                    const keyIndex = activeKey.indexOf(key);
+
+                    if (data.isActive) {
+                        if (keyIndex > -1) {
+                            activeKey.splice(keyIndex, 1);
+                        }
+                    } else {
+                        if (keyIndex < 0) {
+                            activeKey.push(key);
+                        }
+                    }
+
+                    newActiveKey = activeKey;
+                }
+
+                this.activeKey = newActiveKey;
+                this.$emit('on-change', newActiveKey);
+            }
+        },
+        watch: {
+            activeKey () {
+                this.setActive();
+            }
+        }
+    }
+</script>