planning

node_modules/react-router/modules/Switch.js

@@ -0,0 +1,67 @@
+import React from "react";
+import PropTypes from "prop-types";
+import invariant from "tiny-invariant";
+import warning from "tiny-warning";
+
+import RouterContext from "./RouterContext.js";
+import matchPath from "./matchPath.js";
+
+/**
+ * The public API for rendering the first <Route> that matches.
+ */
+class Switch extends React.Component {
+  render() {
+    return (
+      <RouterContext.Consumer>
+        {context => {
+          invariant(context, "You should not use <Switch> outside a <Router>");
+
+          const location = this.props.location || context.location;
+
+          let element, match;
+
+          // We use React.Children.forEach instead of React.Children.toArray().find()
+          // here because toArray adds keys to all child elements and we do not want
+          // to trigger an unmount/remount for two <Route>s that render the same
+          // component at different URLs.
+          React.Children.forEach(this.props.children, child => {
+            if (match == null && React.isValidElement(child)) {
+              element = child;
+
+              const path = child.props.path || child.props.from;
+
+              match = path
+                ? matchPath(location.pathname, { ...child.props, path })
+                : context.match;
+            }
+          });
+
+          return match
+            ? React.cloneElement(element, { location, computedMatch: match })
+            : null;
+        }}
+      </RouterContext.Consumer>
+    );
+  }
+}
+
+if (__DEV__) {
+  Switch.propTypes = {
+    children: PropTypes.node,
+    location: PropTypes.object
+  };
+
+  Switch.prototype.componentDidUpdate = function(prevProps) {
+    warning(
+      !(this.props.location && !prevProps.location),
+      '<Switch> elements should not change from uncontrolled to controlled (or vice versa). You initially used no "location" prop and then provided one on a subsequent render.'
+    );
+
+    warning(
+      !(!this.props.location && prevProps.location),
+      '<Switch> elements should not change from controlled to uncontrolled (or vice versa). You provided a "location" prop initially but omitted it on a subsequent render.'
+    );
+  };
+}
+
+export default Switch;