react/vendor/fbtransform/transforms/react.js

/**
 * Copyright 2013-2014 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.
 */
/*global exports:true*/
"use strict";

var Syntax = require('esprima-fb').Syntax;
var utils = require('jstransform/src/utils');

var FALLBACK_TAGS = require('./xjs').knownTags;
var renderXJSExpressionContainer =
  require('./xjs').renderXJSExpressionContainer;
var renderXJSLiteral = require('./xjs').renderXJSLiteral;
var quoteAttrName = require('./xjs').quoteAttrName;

var trimLeft = require('./xjs').trimLeft;

/**
 * Customized desugar processor.
 *
 * Currently: (Somewhat tailored to React)
 * <X> </X> => X(null, null)
 * <X prop="1" /> => X({prop: '1'}, null)
 * <X prop="2"><Y /></X> => X({prop:'2'}, Y(null, null))
 * <X prop="2"><Y /><Z /></X> => X({prop:'2'}, [Y(null, null), Z(null, null)])
 *
 * Exceptions to the simple rules above:
 * if a property is named "class" it will be changed to "className" in the
 * javascript since "class" is not a valid object key in javascript.
 */

var JSX_ATTRIBUTE_TRANSFORMS = {
  cxName: function(attr) {
    throw new Error(
      "cxName is no longer supported, use className={cx(...)} instead"
    );
  }
};

/**
 * Removes all non-whitespace/parenthesis characters
 */
var reNonWhiteParen = /([^\s\(\)])/g;
function stripNonWhiteParen(value) {
  return value.replace(reNonWhiteParen, '');
}

function visitReactTag(traverse, object, path, state) {
  var jsxObjIdent = utils.getDocblock(state).jsx;
  var openingElement = object.openingElement;
  var nameObject = openingElement.name;
  var attributesObject = openingElement.attributes;

  utils.catchup(openingElement.range[0], state, trimLeft);


  if (nameObject.type === Syntax.XJSNamespacedName && nameObject.namespace) {
    throw new Error('Namespace tags are not supported. ReactJSX is not XML.');
  }

  // Only identifiers can be fallback tags. XJSMemberExpressions are not.
  var isFallbackTag =
    nameObject.type === Syntax.XJSIdentifier &&
    FALLBACK_TAGS.hasOwnProperty(nameObject.name);

  utils.append(isFallbackTag ? jsxObjIdent + '.' : '', state);

  utils.move(nameObject.range[0], state);
  utils.catchup(nameObject.range[1], state);

  utils.append('(', state);

  var hasAttributes = attributesObject.length;

  var hasAtLeastOneSpreadProperty = attributesObject.some(function(attr) {
    return attr.type === Syntax.XJSSpreadAttribute;
  });

  // if we don't have any attributes, pass in null
  if (hasAtLeastOneSpreadProperty) {
    utils.append('Object.assign({', state);
  } else if (hasAttributes) {
    utils.append('{', state);
  } else {
    utils.append('null', state);
  }

  // keep track of if the previous attribute was a spread attribute
  var previousWasSpread = false;

  // write attributes
  attributesObject.forEach(function(attr, index) {
    var isLast = index === attributesObject.length - 1;

    if (attr.type === Syntax.XJSSpreadAttribute) {
      // Plus 1 to skip `{`.
      utils.move(attr.range[0] + 1, state);

      // Close the previous object or initial object
      if (!previousWasSpread) {
        utils.append('}, ', state);
      }

      // Move to the expression start, ignoring everything except parenthesis
      // and whitespace.
      utils.catchup(attr.argument.range[0], state, stripNonWhiteParen);

      traverse(attr.argument, path, state);

      utils.catchup(attr.argument.range[1], state);

      // Move to the end, ignoring parenthesis and the closing `}`
      utils.catchup(attr.range[1] - 1, state, stripNonWhiteParen);

      if (!isLast) {
        utils.append(', ', state);
      }

      utils.move(attr.range[1], state);

      previousWasSpread = true;

      return;
    }

    // If the next attribute is a spread, we're effective last in this object
    if (!isLast) {
      isLast = attributesObject[index + 1].type === Syntax.XJSSpreadAttribute;
    }

    if (attr.name.namespace) {
      throw new Error(
         'Namespace attributes are not supported. ReactJSX is not XML.');
    }
    var name = attr.name.name;

    utils.catchup(attr.range[0], state, trimLeft);

    if (previousWasSpread) {
      utils.append('{', state);
    }

    utils.append(quoteAttrName(name), state);
    utils.append(': ', state);

    if (!attr.value) {
      state.g.buffer += 'true';
      state.g.position = attr.name.range[1];
      if (!isLast) {
        utils.append(', ', state);
      }
    } else {
      utils.move(attr.name.range[1], state);
      // Use catchupNewlines to skip over the '=' in the attribute
      utils.catchupNewlines(attr.value.range[0], state);
      if (JSX_ATTRIBUTE_TRANSFORMS.hasOwnProperty(attr.name.name)) {
        utils.append(JSX_ATTRIBUTE_TRANSFORMS[attr.name.name](attr), state);
        utils.move(attr.value.range[1], state);
        if (!isLast) {
          utils.append(', ', state);
        }
      } else if (attr.value.type === Syntax.Literal) {
        renderXJSLiteral(attr.value, isLast, state);
      } else {
        renderXJSExpressionContainer(traverse, attr.value, isLast, path, state);
      }
    }

    utils.catchup(attr.range[1], state, trimLeft);

    previousWasSpread = false;

  });

  if (!openingElement.selfClosing) {
    utils.catchup(openingElement.range[1] - 1, state, trimLeft);
    utils.move(openingElement.range[1], state);
  }

  if (hasAttributes && !previousWasSpread) {
    utils.append('}', state);
  }

  if (hasAtLeastOneSpreadProperty) {
    utils.append(')', state);
  }

  // filter out whitespace
  var childrenToRender = object.children.filter(function(child) {
    return !(child.type === Syntax.Literal
             && typeof child.value === 'string'
             && child.value.match(/^[ \t]*[\r\n][ \t\r\n]*$/));
  });
  if (childrenToRender.length > 0) {
    var lastRenderableIndex;

    childrenToRender.forEach(function(child, index) {
      if (child.type !== Syntax.XJSExpressionContainer ||
          child.expression.type !== Syntax.XJSEmptyExpression) {
        lastRenderableIndex = index;
      }
    });

    if (lastRenderableIndex !== undefined) {
      utils.append(', ', state);
    }

    childrenToRender.forEach(function(child, index) {
      utils.catchup(child.range[0], state, trimLeft);

      var isLast = index >= lastRenderableIndex;

      if (child.type === Syntax.Literal) {
        renderXJSLiteral(child, isLast, state);
      } else if (child.type === Syntax.XJSExpressionContainer) {
        renderXJSExpressionContainer(traverse, child, isLast, path, state);
      } else {
        traverse(child, path, state);
        if (!isLast) {
          utils.append(', ', state);
        }
      }

      utils.catchup(child.range[1], state, trimLeft);
    });
  }

  if (openingElement.selfClosing) {
    // everything up to />
    utils.catchup(openingElement.range[1] - 2, state, trimLeft);
    utils.move(openingElement.range[1], state);
  } else {
    // everything up to </ sdflksjfd>
    utils.catchup(object.closingElement.range[0], state, trimLeft);
    utils.move(object.closingElement.range[1], state);
  }

  utils.append(')', state);
  return false;
}

visitReactTag.test = function(object, path, state) {
  // only run react when react @jsx namespace is specified in docblock
  var jsx = utils.getDocblock(state).jsx;
  return object.type === Syntax.XJSElement && jsx && jsx.length;
};

exports.visitorList = [
  visitReactTag
];