feat(b-row): add Bootstrap v4.4 row columns support

src/components/layout/README.md

@@ -70,11 +70,10 @@ like the
 
 ## Containers `<b-container>`
 
-Containers (`<b-container>`) are the most basic layout element in Bootstrap and is **required when
-using the grid system**. Choose from a responsive, fixed-width container (meaning its max-width
-changes at each breakpoint) by default, or fluid-width (meaning it's 100% wide all the time) by
-setting 'fluid' prop, or responsive containers where the container is fluid up until a specific
-breakpoint.
+Containers (`<b-container>`) are the most basic layout element in Bootstrap. Choose from a
+responsive, fixed-width container (meaning its max-width changes at each breakpoint) by default, or
+fluid-width (meaning it's 100% wide all the time) by setting 'fluid' prop, or responsive containers
+where the container is fluid up until a specific breakpoint (requires Bootstrap CSS `v4.4+`).
 
 While containers can be nested, most layouts do not require a nested container.
 
@@ -85,7 +84,7 @@ The default breakpoint widths can be configured using Bootstrap V4.x SCSS variab
 ### Default container
 
 The default `<b-container>` is a responsive, fixed-width container, meaning its `max-width` changes
-at each breakpoint.
+at each viewport width breakpoint.
 
 ```html
 <b-container>
@@ -109,7 +108,7 @@ Setting the `fluid` prop to true (or an empty string) is equivalent to the Boots
 
 ### Responsive fluid containers
 
-<span class="badge badge-warning small">Requires Bootstrap v4.4+ CSS</span>
+<span class="badge badge-info small">Requires Bootstrap v4.4+ CSS</span>
 
 Responsive containers are new in Bootstrap v4.4. They allow you to specify a container that is 100%
 wide (fluid) until particular breakpoint is reached at which point a `max-width` is applied. For
@@ -137,8 +136,9 @@ Setting the fluid prop to a breakpoint name translates to the Bootstrap class
 
 ## Rows `<b-row>` and `<b-form-row>`
 
-`<b-row>` components should be placed inside a `<b-container>` component, or an element (such as a
-`<div>`) that has the class `container` or `container-fluid` applied to it.
+Rows are wrappers for [columns](#columns-b-col). Each column has horizontal padding (called a
+gutter) for controlling the space between them. This padding is then counteracted on the rows with
+negative margins. This way, all the content in your columns is visually aligned down the left side.
 
 You can remove the margin from `<b-row>` and padding from `<b-col>` by setting the `no-gutters` prop
 on `<b-row>`.
@@ -622,4 +622,85 @@ within an existing `<b-col>` component. Nested rows should include a set of colu
 <!-- b-grid-nesting.vue -->
 ```
 
+## Row columns
+
+<span class="badge badge-info small">Requires Bootstrap v4.4+ CSS</span>
+
+Use the responsive `cols-*` props in `<b-row>` to quickly set the number of columns that best render
+your content and layout. Whereas normal column widths are apply to the individual `<b-col>` columns
+(e.g., `<b-col md="4">`), the row columns `col-*` props are set on the parent `<b-row>` as a
+shortcut.
+
+Use these row columns to quickly create basic grid layouts or to control your card layouts. The
+default maximum number of row columns in Bootstrap v4.4 is `6` (unlike the regular columns which
+have a default maximum of `12` columns)
+
+The value specified in the `<b-row>` prop(s) is the number of columns to create per row (whereas the
+props on `<b-col>` refer to the number of columns to occupy).
+
+```html
+<b-container class="bv-example-row">
+  <b-row cols="2">
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+  </b-row>
+</b-container>
+
+<b-container class="bv-example-row">
+  <b-row cols="3">
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+  </b-row>
+</b-container>
+
+<b-container class="bv-example-row">
+  <b-row cols="4">
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+  </b-row>
+</b-container>
+
+<b-container class="bv-example-row">
+  <b-row cols="4">
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col cols="6">Column</b-col>
+    <b-col>Column</b-col>
+  </b-row>
+</b-container>
+
+<!-- b-grid-row-cols-introduction.vue -->
+```
+
+You can control the number of columns at each breakpoint level via the following `<b-row>` props:
+
+- `cols` for `xs` and up screens
+- `cols-sm` for `sm` and up screens
+- `cols-md` for `md` and up screens
+- `cols-lg` for `lg` and up screens
+- `cols-xl` for `xl` and up screens
+
+```html
+<b-container class="bv-example-row">
+  <b-row cols="1" cols-sm="2" cols-md="4" cols-lg="6" cols-xl="8">
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+    <b-col>Column</b-col>
+  </b-row>
+</b-container>
+
+<!-- b-grid-row-cols-breakpoints.vue -->
+```
+
 <!-- Component reference added automatically from component package.json -->

src/components/layout/col.js

@@ -3,9 +3,10 @@ import identity from '../../utils/identity'
 import memoize from '../../utils/memoize'
 import suffixPropName from '../../utils/suffix-prop-name'
 import { arrayIncludes } from '../../utils/array'
-import { isUndefinedOrNull } from '../../utils/inspect'
-import { keys, assign, create } from '../../utils/object'
 import { getBreakpointsUpCached } from '../../utils/config'
+import { isUndefinedOrNull } from '../../utils/inspect'
+import { assign, create, keys } from '../../utils/object'
+import { lowerCase } from '../../utils/string'
 
 const RX_COL_CLASS = /^col-/
 
@@ -35,11 +36,11 @@ const computeBreakpoint = (type, breakpoint, val) => {
   // Since the default is false, an empty string indicates the prop's presence.
   if (type === 'col' && (val === '' || val === true)) {
     // .col-md
-    return className.toLowerCase()
+    return lowerCase(className)
   }
   // .order-md-6
   className += `-${val}`
-  return className.toLowerCase()
+  return lowerCase(className)
 }
 
 // Memoized function for better performance on generating class names

src/components/layout/package.json

@@ -11,7 +11,7 @@
         "props": [
           {
             "prop": "fluid",
-            "description": "When set to true, makes the row 100% wide all the time, or set to one of the Bootstrap breakpoint names for 100% width up to the breakpoint"
+            "description": "When set to true, makes the row 100% wide all the time, or set to one of the Bootstrap breakpoint names for 100% width up to the breakpoint (requires Bootstrap v4.4+ CSS for breakpoint specific value)"
           }
         ]
       },
@@ -33,6 +33,31 @@
           {
             "prop": "alignContent",
             "description": "Align columns items together on the cross axis: 'start', 'center', 'end', 'around', 'between' or 'stretch'. Has no effect on single rows of items"
+          },
+          {
+            "prop": "cols",
+            "version": "2.2.0",
+            "description": "The number row columns to create at the 'xs' breakpoint. Requires Bootstrap v4.4 CSS"
+          },
+          {
+            "prop": "cols-sm",
+            "version": "2.2.0",
+            "description": "The number row columns to create at the 'sm' breakpoint. Requires Bootstrap v4.4 CSS"
+          },
+          {
+            "prop": "cols-md",
+            "version": "2.2.0",
+            "description": "The number row columns to create at the 'md' breakpoint. Requires Bootstrap v4.4 CSS"
+          },
+          {
+            "prop": "cols-lg",
+            "version": "2.2.0",
+            "description": "The number row columns to create at the 'lg' breakpoint. Requires Bootstrap v4.4 CSS"
+          },
+          {
+            "prop": "cols-xl",
+            "version": "2.2.0",
+            "description": "The number row columns to create at the 'xl' breakpoint. Requires Bootstrap v4.4 CSS"
           }
         ]
       },

src/components/layout/row.js

@@ -1,53 +1,110 @@
-import Vue from '../../utils/vue'
 import { mergeData } from 'vue-functional-data-merge'
+import identity from '../../utils/identity'
+import memoize from '../../utils/memoize'
+import suffixPropName from '../../utils/suffix-prop-name'
 import { arrayIncludes } from '../../utils/array'
+import { getBreakpointsUpCached } from '../../utils/config'
+import { create, keys } from '../../utils/object'
+import { lowerCase, toString, trim } from '../../utils/string'
 
 const COMMON_ALIGNMENT = ['start', 'end', 'center']
 
-export const props = {
-  tag: {
-    type: String,
-    default: 'div'
-  },
-  noGutters: {
-    type: Boolean,
-    default: false
-  },
-  alignV: {
-    type: String,
-    default: null,
-    validator: str => arrayIncludes(COMMON_ALIGNMENT.concat(['baseline', 'stretch']), str)
-  },
-  alignH: {
-    type: String,
-    default: null,
-    validator: str => arrayIncludes(COMMON_ALIGNMENT.concat(['between', 'around']), str)
-  },
-  alignContent: {
-    type: String,
-    default: null,
-    validator: str => arrayIncludes(COMMON_ALIGNMENT.concat(['between', 'around', 'stretch']), str)
+// Generates a prop object with a type of `[String, Number]`
+const strNum = () => ({
+  type: [String, Number],
+  default: null
+})
+
+// Compute a `row-cols-{breakpoint}-{cols}` class name
+// Memoized function for better performance on generating class names
+const computeRowColsClass = memoize((breakpoint, cols) => {
+  cols = trim(toString(cols))
+  return cols ? lowerCase(['row-cols', breakpoint, cols].filter(identity).join('-')) : null
+})
+
+// Get the breakpoint name from the `rowCols` prop name
+// Memoized function for better performance on extracting breakpoint names
+const computeRowColsBreakpoint = memoize(prop => lowerCase(prop.replace('cols', '')))
+
+// Cached copy of the `row-cols` breakpoint prop names
+// Will be populated when the props are generated
+let rowColsPropList = []
+
+// Lazy evaled props factory for <b-row> (called only once,
+// the first time the component is used)
+const generateProps = () => {
+  // Grab the breakpoints from the cached config (including the '' (xs) breakpoint)
+  const breakpoints = getBreakpointsUpCached()
+
+  // Supports classes like: `row-cols-2`, r`ow-cols-md-4`, `row-cols-xl-6`
+  const rowColsProps = breakpoints.reduce((props, breakpoint) => {
+    props[suffixPropName(breakpoint, 'cols')] = strNum()
+    return props
+  }, create(null))
+
+  // Cache the row-cols prop names
+  rowColsPropList = keys(rowColsProps)
+
+  // Return the generated props
+  return {
+    tag: {
+      type: String,
+      default: 'div'
+    },
+    noGutters: {
+      type: Boolean,
+      default: false
+    },
+    alignV: {
+      type: String,
+      default: null,
+      validator: str => arrayIncludes(COMMON_ALIGNMENT.concat(['baseline', 'stretch']), str)
+    },
+    alignH: {
+      type: String,
+      default: null,
+      validator: str => arrayIncludes(COMMON_ALIGNMENT.concat(['between', 'around']), str)
+    },
+    alignContent: {
+      type: String,
+      default: null,
+      validator: str =>
+        arrayIncludes(COMMON_ALIGNMENT.concat(['between', 'around', 'stretch']), str)
+    },
+    ...rowColsProps
   }
 }
 
+// We do not use `Vue.extend()` here as that would evaluate the props
+// immediately, which we do not want to happen
 // @vue/component
-export const BRow = /*#__PURE__*/ Vue.extend({
+export const BRow = {
   name: 'BRow',
   functional: true,
-  props,
+  get props() {
+    // Allow props to be lazy evaled on first access and
+    // then they become a non-getter afterwards
+    // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/get#Smart_self-overwriting_lazy_getters
+    delete this.props
+    this.props = generateProps()
+    return this.props
+  },
   render(h, { props, data, children }) {
-    return h(
-      props.tag,
-      mergeData(data, {
-        staticClass: 'row',
-        class: {
-          'no-gutters': props.noGutters,
-          [`align-items-${props.alignV}`]: props.alignV,
-          [`justify-content-${props.alignH}`]: props.alignH,
-          [`align-content-${props.alignContent}`]: props.alignContent
-        }
-      }),
-      children
-    )
+    const classList = []
+    // Loop through row-cols breakpoint props and generate the classes
+    rowColsPropList.forEach(prop => {
+      const c = computeRowColsClass(computeRowColsBreakpoint(prop), props[prop])
+      // If a class is returned, push it onto the array
+      if (c) {
+        classList.push(c)
+      }
+    })
+    classList.push({
+      'no-gutters': props.noGutters,
+      [`align-items-${props.alignV}`]: props.alignV,
+      [`justify-content-${props.alignH}`]: props.alignH,
+      [`align-content-${props.alignContent}`]: props.alignContent
+    })
+    return h(props.tag, mergeData(data, { staticClass: 'row', class: classList }), children)
   }
-})
+}