File: dataschema/js/dataschema-xml.js

            /**
            Provides a DataSchema implementation which can be used to work with XML data.
            
            @module dataschema
            @submodule dataschema-xml
            **/
            
            /**
            Provides a DataSchema implementation which can be used to work with XML data.
            
            See the `apply` method for usage.
            
            @class DataSchema.XML
            @extends DataSchema.Base
            @static
            **/
            var Lang = Y.Lang,
            
                okNodeType = {
                    1 : true,
                    9 : true,
                    11: true
                },
            
                SchemaXML;
            
            SchemaXML = {
            
                ////////////////////////////////////////////////////////////////////////////
                //
                // DataSchema.XML static methods
                //
                ////////////////////////////////////////////////////////////////////////////
                /**
                Applies a schema to an XML data tree, returning a normalized object with
                results in the `results` property. Additional information can be parsed out
                of the XML for inclusion in the `meta` property of the response object.  If
                an error is encountered during processing, an `error` property will be
                added.
            
                Field data in the nodes captured by the XPath in _schema.resultListLocator_
                is extracted with the field identifiers described in _schema.resultFields_.
                Field identifiers are objects with the following properties:
            
                  * `key`    : <strong>(required)</strong> The desired property name to use
                        store the retrieved value in the result object.  If `locator` is
                        not specified, `key` is also used as the XPath locator (String)
                  * `locator`: The XPath locator to the node or attribute within each
                        result node found by _schema.resultListLocator_ containing the
                        desired field data (String)
                  * `parser` : A function or the name of a function on `Y.Parsers` used
                        to convert the input value into a normalized type.  Parser
                        functions are passed the value as input and are expected to
                        return a value.
                  * `schema` : Used to retrieve nested field data into an array for
                        assignment as the result field value.  This object follows the same
                        conventions as _schema_.
            
                If no value parsing or nested parsing is needed, you can use XPath locators
                (strings) instead of field identifiers (objects) -- see example below.
            
                `response.results` will contain an array of objects with key:value pairs.
                The keys are the field identifier `key`s, and the values are the data
                values extracted from the nodes or attributes found by the field `locator`
                (or `key` fallback).
            
                To extract additional information from the XML, include an array of
                XPath locators in _schema.metaFields_.  The collected values will be
                stored in `response.meta` with the XPath locator as keys.
            
                @example
                    var schema = {
                            resultListLocator: '//produce/item',
                            resultFields: [
                                {
                                    locator: 'name',
                                    key: 'name'
                                },
                                {
                                    locator: 'color',
                                    key: 'color',
                                    parser: function (val) { return val.toUpperCase(); }
                                }
                            ]
                        };
            
                    // Assumes data like
                    // <inventory>
                    //   <produce>
                    //     <item><name>Banana</name><color>yellow</color></item>
                    //     <item><name>Orange</name><color>orange</color></item>
                    //     <item><name>Eggplant</name><color>purple</color></item>
                    //   </produce>
                    // </inventory>
            
                    var response = Y.DataSchema.JSON.apply(schema, data);
            
                    // response.results[0] is { name: "Banana", color: "YELLOW" }
            
                @method apply
                @param {Object} schema Schema to apply.  Supported configuration
                    properties are:
                  @param {String} [schema.resultListLocator] XPath locator for the
                      XML nodes that contain the data to flatten into `response.results`
                  @param {Array} [schema.resultFields] Field identifiers to
                      locate/assign values in the response records. See above for
                      details.
                  @param {Array} [schema.metaFields] XPath locators to extract extra
                      non-record related information from the XML data
                @param {XMLDocument} data XML data to parse
                @return {Object} An Object with properties `results` and `meta`
                @static
                **/
                apply: function(schema, data) {
                    var xmldoc = data, // unnecessary variables
                        data_out = { results: [], meta: {} };
            
                    if (xmldoc && okNodeType[xmldoc.nodeType] && schema) {
                        // Parse results data
                        data_out = SchemaXML._parseResults(schema, xmldoc, data_out);
            
                        // Parse meta data
                        data_out = SchemaXML._parseMeta(schema.metaFields, xmldoc, data_out);
                    } else {
                        Y.log("XML data could not be schema-parsed: " + Y.dump(data) + " " + Y.dump(data), "error", "dataschema-xml");
                        data_out.error = new Error("XML schema parse failure");
                    }
            
                    return data_out;
                },
            
                /**
                 * Get an XPath-specified value for a given field from an XML node or document.
                 *
                 * @method _getLocationValue
                 * @param field {String | Object} Field definition.
                 * @param context {Object} XML node or document to search within.
                 * @return {Object} Data value or null.
                 * @static
                 * @protected
                 */
                _getLocationValue: function(field, context) {
                    var locator = field.locator || field.key || field,
                        xmldoc = context.ownerDocument || context,
                        result, res, value = null;
            
                    try {
                        result = SchemaXML._getXPathResult(locator, context, xmldoc);
                        while ((res = result.iterateNext())) {
                            value = res.textContent || res.value || res.text || res.innerHTML || res.innerText || null;
                        }
            
                        // FIXME: Why defer to a method that is mixed into this object?
                        // DSchema.Base is mixed into DSchema.XML (et al), so
                        // DSchema.XML.parse(...) will work.  This supports the use case
                        // where DSchema.Base.parse is changed, and that change is then
                        // seen by all DSchema.* implementations, but does not support the
                        // case where redefining DSchema.XML.parse changes behavior. In
                        // fact, DSchema.XML.parse is never even called.
                        return Y.DataSchema.Base.parse.call(this, value, field);
                    } catch (e) {
                        Y.log('SchemaXML._getLocationValue failed: ' + e.message);
                    }
            
                    return null;
                },
            
                /**
                 * Fetches the XPath-specified result for a given location in an XML node
                 * or document.
                 *
                 * @method _getXPathResult
                 * @param locator {String} The XPath location.
                 * @param context {Object} XML node or document to search within.
                 * @param xmldoc {Object} XML document to resolve namespace.
                 * @return {Object} Data collection or null.
                 * @static
                 * @protected
                 */
                _getXPathResult: function(locator, context, xmldoc) {
                    // Standards mode
                    if (! Lang.isUndefined(xmldoc.evaluate)) {
                        return xmldoc.evaluate(locator, context, xmldoc.createNSResolver(context.ownerDocument ? context.ownerDocument.documentElement : context.documentElement), 0, null);
            
                    }
                    // IE mode
                    else {
                        var values=[], locatorArray = locator.split(/\b\/\b/), i=0, l=locatorArray.length, location, subloc, m, isNth;
            
                        // XPath is supported
                        try {
                            // this fixes the IE 5.5+ issue where childnode selectors begin at 0 instead of 1
                            try {
                               xmldoc.setProperty("SelectionLanguage", "XPath");
                            } catch (e) {}
            
                            values = context.selectNodes(locator);
                        }
                        // Fallback for DOM nodes and fragments
                        catch (e) {
                            // Iterate over each locator piece
                            for (; i<l && context; i++) {
                                location = locatorArray[i];
            
                                // grab nth child []
                                if ((location.indexOf("[") > -1) && (location.indexOf("]") > -1)) {
                                    subloc = location.slice(location.indexOf("[")+1, location.indexOf("]"));
                                    //XPath is 1-based while DOM is 0-based
                                    subloc--;
                                    context = context.children[subloc];
                                    isNth = true;
                                }
                                // grab attribute value @
                                else if (location.indexOf("@") > -1) {
                                    subloc = location.substr(location.indexOf("@"));
                                    context = subloc ? context.getAttribute(subloc.replace('@', '')) : context;
                                }
                                // grab that last instance of tagName
                                else if (-1 < location.indexOf("//")) {
                                    subloc = context.getElementsByTagName(location.substr(2));
                                    context = subloc.length ? subloc[subloc.length - 1] : null;
                                }
                                // find the last matching location in children
                                else if (l != i + 1) {
                                    for (m=context.childNodes.length-1; 0 <= m; m-=1) {
                                        if (location === context.childNodes[m].tagName) {
                                            context = context.childNodes[m];
                                            m = -1;
                                        }
                                    }
                                }
                            }
            
                            if (context) {
                                // attribute
                                if (Lang.isString(context)) {
                                    values[0] = {value: context};
                                }
                                // nth child
                                else if (isNth) {
                                    values[0] = {value: context.innerHTML};
                                }
                                // all children
                                else {
                                    values = Y.Array(context.childNodes, 0, true);
                                }
                            }
                        }
            
                        // returning a mock-standard object for IE
                        return {
                            index: 0,
            
                            iterateNext: function() {
                                if (this.index >= this.values.length) {return undefined;}
                                var result = this.values[this.index];
                                this.index += 1;
                                return result;
                            },
            
                            values: values
                        };
                    }
                },
            
                /**
                 * Schema-parsed result field.
                 *
                 * @method _parseField
                 * @param field {String | Object} Required. Field definition.
                 * @param result {Object} Required. Schema parsed data object.
                 * @param context {Object} Required. XML node or document to search within.
                 * @static
                 * @protected
                 */
                _parseField: function(field, result, context) {
                    var key = field.key || field,
                        parsed;
            
                    if (field.schema) {
                        parsed = { results: [], meta: {} };
                        parsed = SchemaXML._parseResults(field.schema, context, parsed);
            
                        result[key] = parsed.results;
                    } else {
                        result[key] = SchemaXML._getLocationValue(field, context);
                    }
                },
            
                /**
                 * Parses results data according to schema
                 *
                 * @method _parseMeta
                 * @param xmldoc_in {Object} XML document parse.
                 * @param data_out {Object} In-progress schema-parsed data to update.
                 * @return {Object} Schema-parsed data.
                 * @static
                 * @protected
                 */
                _parseMeta: function(metaFields, xmldoc_in, data_out) {
                    if(Lang.isObject(metaFields)) {
                        var key,
                            xmldoc = xmldoc_in.ownerDocument || xmldoc_in;
            
                        for(key in metaFields) {
                            if (metaFields.hasOwnProperty(key)) {
                                data_out.meta[key] = SchemaXML._getLocationValue(metaFields[key], xmldoc);
                            }
                        }
                    }
                    return data_out;
                },
            
                /**
                 * Schema-parsed result to add to results list.
                 *
                 * @method _parseResult
                 * @param fields {Array} Required. A collection of field definition.
                 * @param context {Object} Required. XML node or document to search within.
                 * @return {Object} Schema-parsed data.
                 * @static
                 * @protected
                 */
                _parseResult: function(fields, context) {
                    var result = {}, j;
            
                    // Find each field value
                    for (j=fields.length-1; 0 <= j; j--) {
                        SchemaXML._parseField(fields[j], result, context);
                    }
            
                    return result;
                },
            
                /**
                 * Schema-parsed list of results from full data
                 *
                 * @method _parseResults
                 * @param schema {Object} Schema to parse against.
                 * @param context {Object} XML node or document to parse.
                 * @param data_out {Object} In-progress schema-parsed data to update.
                 * @return {Object} Schema-parsed data.
                 * @static
                 * @protected
                 */
                _parseResults: function(schema, context, data_out) {
                    if (schema.resultListLocator && Lang.isArray(schema.resultFields)) {
                        var xmldoc = context.ownerDocument || context,
                            fields = schema.resultFields,
                            results = [],
                            node, nodeList, i=0;
            
                        if (schema.resultListLocator.match(/^[:\-\w]+$/)) {
                            nodeList = context.getElementsByTagName(schema.resultListLocator);
            
                            // loop through each result node
                            for (i = nodeList.length - 1; i >= 0; --i) {
                                results[i] = SchemaXML._parseResult(fields, nodeList[i]);
                            }
                        } else {
                            nodeList = SchemaXML._getXPathResult(schema.resultListLocator, context, xmldoc);
            
                            // loop through the nodelist
                            while ((node = nodeList.iterateNext())) {
                                results[i] = SchemaXML._parseResult(fields, node);
                                i += 1;
                            }
                        }
            
                        if (results.length) {
                            data_out.results = results;
                        } else {
                            data_out.error = new Error("XML schema result nodes retrieval failure");
                        }
                    }
                    return data_out;
                }
            };
            
            Y.DataSchema.XML = Y.mix(SchemaXML, Y.DataSchema.Base);