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Introduce a supported way to slice children
Introduces a counterpart to mapChildren. It excludes empty children just as mapChildren for compatibility. With might introduce something like sliceChildrenIncludingEmptyValues at some point.
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/** | ||
* Copyright 2013 Facebook, Inc. | ||
* | ||
* Licensed under the Apache License, Version 2.0 (the "License"); | ||
* you may not use this file except in compliance with the License. | ||
* You may obtain a copy of the License at | ||
* | ||
* http://www.apache.org/licenses/LICENSE-2.0 | ||
* | ||
* Unless required by applicable law or agreed to in writing, software | ||
* distributed under the License is distributed on an "AS IS" BASIS, | ||
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
* See the License for the specific language governing permissions and | ||
* limitations under the License. | ||
* | ||
* @emails react-core | ||
* @jsx React.DOM | ||
*/ | ||
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"use strict"; | ||
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describe('sliceChildren', function() { | ||
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var React; | ||
var ReactTestUtils; | ||
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var sliceChildren; | ||
var reactComponentExpect; | ||
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var Partial; | ||
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beforeEach(function() { | ||
React = require('React'); | ||
ReactTestUtils = require('ReactTestUtils'); | ||
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sliceChildren = require('sliceChildren'); | ||
reactComponentExpect = require('reactComponentExpect'); | ||
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Partial = React.createClass({ | ||
render: function() { | ||
return ( | ||
<div> | ||
{sliceChildren( | ||
this.props.children, | ||
this.props.start, | ||
this.props.end | ||
)} | ||
</div> | ||
); | ||
} | ||
}); | ||
}); | ||
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function renderAndSlice(set, start, end) { | ||
var instance = <Partial start={start} end={end}>{set}</Partial>; | ||
ReactTestUtils.renderIntoDocument(instance); | ||
var rendered = reactComponentExpect(instance) | ||
.expectRenderedChild() | ||
.instance(); | ||
return rendered.props.children; | ||
} | ||
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it('should render the whole set if start zero is supplied', function() { | ||
var fullSet = [ | ||
<div key="A" />, | ||
<div key="B" />, | ||
<div key="C" /> | ||
]; | ||
var children = renderAndSlice(fullSet, 0); | ||
expect(children).toEqual({ | ||
'[A]': fullSet[0], | ||
'[B]': fullSet[1], | ||
'[C]': fullSet[2] | ||
}); | ||
}); | ||
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it('should render the remaining set if no end index is supplied', function() { | ||
var fullSet = [ | ||
<div key="A" />, | ||
<div key="B" />, | ||
<div key="C" /> | ||
]; | ||
var children = renderAndSlice(fullSet, 1); | ||
expect(children).toEqual({ | ||
'[B]': fullSet[1], | ||
'[C]': fullSet[2] | ||
}); | ||
}); | ||
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it('should exclude everything at or after the end index', function() { | ||
var fullSet = [ | ||
<div key="A" />, | ||
<div key="B" />, | ||
<div key="C" />, | ||
<div key="D" /> | ||
]; | ||
var children = renderAndSlice(fullSet, 1, 2); | ||
expect(children).toEqual({ | ||
'[B]': fullSet[1] | ||
}); | ||
}); | ||
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it('should allow static children to be sliced', function() { | ||
var a = <div />; | ||
var b = <div />; | ||
var c = <div />; | ||
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var instance = <Partial start={1} end={2}>{a}{b}{c}</Partial>; | ||
ReactTestUtils.renderIntoDocument(instance); | ||
var rendered = reactComponentExpect(instance) | ||
.expectRenderedChild() | ||
.instance(); | ||
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expect(rendered.props.children).toEqual({ | ||
'[1]': b | ||
}); | ||
}); | ||
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}); |
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,59 @@ | ||
/** | ||
* Copyright 2013 Facebook, Inc. | ||
* | ||
* Licensed under the Apache License, Version 2.0 (the "License"); | ||
* you may not use this file except in compliance with the License. | ||
* You may obtain a copy of the License at | ||
* | ||
* http://www.apache.org/licenses/LICENSE-2.0 | ||
* | ||
* Unless required by applicable law or agreed to in writing, software | ||
* distributed under the License is distributed on an "AS IS" BASIS, | ||
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
* See the License for the specific language governing permissions and | ||
* limitations under the License. | ||
* | ||
* @providesModule sliceChildren | ||
*/ | ||
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"use strict"; | ||
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var flattenChildren = require('flattenChildren'); | ||
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/** | ||
* Slice children that are typically specified as `props.children`. This version | ||
* of slice children ignores empty child components. | ||
* | ||
* @param {*} children The children set to filter. | ||
* @param {number} start The first zero-based index to include in the subset. | ||
* @param {?number} end The non-inclusive last index of the subset. | ||
* @return {object} mirrored array with mapped children | ||
*/ | ||
function sliceChildren(children, start, end) { | ||
if (children == null) { | ||
return children; | ||
} | ||
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var slicedChildren = {}; | ||
var flattenedMap = flattenChildren(children); | ||
var ii = 0; | ||
for (var key in flattenedMap) { | ||
if (!flattenedMap.hasOwnProperty(key)) { | ||
continue; | ||
} | ||
var child = flattenedMap[key]; | ||
// In this version of slice children we ignore empty children. | ||
if (child !== null) { | ||
if (ii >= start) { | ||
slicedChildren[key] = child; | ||
} | ||
ii++; | ||
if (end != null && ii >= end) { | ||
break; | ||
} | ||
} | ||
} | ||
return slicedChildren; | ||
} | ||
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module.exports = sliceChildren; |