tool/store/LayoutFileParser.java

/*
 * Copyright (C) 2015 The Android Open Source Project
 * 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.
 */

package android.databinding.tool.store;

import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.ParserRuleContext;
import org.antlr.v4.runtime.misc.NotNull;
import org.apache.commons.io.FileUtils;
import org.apache.commons.lang3.StringEscapeUtils;
import org.apache.commons.lang3.StringUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

import android.databinding.parser.XMLLexer;
import android.databinding.parser.XMLParser;
import android.databinding.parser.XMLParserBaseVisitor;
import android.databinding.tool.util.L;
import android.databinding.tool.util.ParserHelper;
import android.databinding.tool.util.Preconditions;
import android.databinding.tool.util.XmlEditor;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URISyntaxException;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

/**
 * Gets the list of XML files and creates a list of
 * {@link android.databinding.tool.store.ResourceBundle} that can be persistent or converted to
 * LayoutBinder.
 */
public class LayoutFileParser {

    private static final String XPATH_BINDING_LAYOUT = "/layout";

    private static final String LAYOUT_PREFIX = "@layout/";

    public ResourceBundle.LayoutFileBundle parseXml(File xml, String pkg, int minSdk)
            throws ParserConfigurationException, IOException, SAXException,
            XPathExpressionException {
        final String xmlNoExtension = ParserHelper.stripExtension(xml.getName());
        final String newTag = xml.getParentFile().getName() + '/' + xmlNoExtension;
        File original = stripFileAndGetOriginal(xml, newTag);
        if (original == null) {
            L.d("assuming the file is the original for %s", xml.getAbsoluteFile());
            original = xml;
        }
        return parseXml(original, pkg);
    }

    private ResourceBundle.LayoutFileBundle parseXml(File original, String pkg)
            throws IOException {
        final String xmlNoExtension = ParserHelper.stripExtension(original.getName());
        ANTLRInputStream inputStream = new ANTLRInputStream(new FileReader(original));
        XMLLexer lexer = new XMLLexer(inputStream);
        CommonTokenStream tokenStream = new CommonTokenStream(lexer);
        XMLParser parser = new XMLParser(tokenStream);
        XMLParser.DocumentContext expr = parser.document();
        XMLParser.ElementContext root = expr.element();
        if (!"layout".equals(root.elmName.getText())) {
            return null;
        }
        XMLParser.ElementContext data = getDataNode(root);
        XMLParser.ElementContext rootView = getViewNode(original, root);

        if (hasMergeInclude(rootView)) {
            L.e("Data binding does not support include elements as direct children of a " +
                    "merge element: %s", original.getPath());
            return null;
        }
        boolean isMerge = "merge".equals(rootView.elmName.getText());

        ResourceBundle.LayoutFileBundle bundle = new ResourceBundle.LayoutFileBundle(
                xmlNoExtension, original.getParentFile().getName(), pkg, isMerge);
        final String newTag = original.getParentFile().getName() + '/' + xmlNoExtension;
        parseData(original, data, bundle);
        parseExpressions(newTag, rootView, isMerge, bundle);
        return bundle;
    }

    private void parseExpressions(String newTag, final XMLParser.ElementContext rootView,
            final boolean isMerge, ResourceBundle.LayoutFileBundle bundle) {
        final List<XMLParser.ElementContext> bindingElements = new ArrayList<>();
        final List<XMLParser.ElementContext> otherElementsWithIds = new ArrayList<>();
        rootView.accept(new XMLParserBaseVisitor<Void>() {
            @Override
            public Void visitElement(@NotNull XMLParser.ElementContext ctx) {
                if (filter(ctx)) {
                    bindingElements.add(ctx);
                } else {
                    String name = ctx.elmName.getText();
                    if (!"include".equals(name) && !"fragment".equals(name) &&
                            attributeMap(ctx).containsKey("android:id")) {
                        otherElementsWithIds.add(ctx);
                    }
                }
                visitChildren(ctx);
                return null;
            }

            private boolean filter(XMLParser.ElementContext ctx) {
                if (isMerge) {
                    // account for XMLParser.ContentContext
                    if (ctx.getParent().getParent() == rootView) {
                        return true;
                    }
                } else if (ctx == rootView) {
                    return true;
                }
                if (hasIncludeChild(ctx)) {
                    return true;
                }
                if (XmlEditor.hasExpressionAttributes(ctx)) {
                    return true;
                }
                return false;
            }

            private boolean hasIncludeChild(XMLParser.ElementContext ctx) {
                for (XMLParser.ElementContext child : XmlEditor.elements(ctx)) {
                    if ("include".equals(child.elmName.getText())) {
                        return true;
                    }
                }
                return false;
            }
        });

        final HashMap<XMLParser.ElementContext, String> nodeTagMap =
                new HashMap<XMLParser.ElementContext, String>();
        L.d("number of binding nodes %d", bindingElements.size());
        int tagNumber = 0;
        for (XMLParser.ElementContext parent : bindingElements) {
            final Map<String, String> attributes = attributeMap(parent);
            String nodeName = parent.elmName.getText();
            String viewName = null;
            String includedLayoutName = null;
            final String id = attributes.get("android:id");
            final String tag;
            final String originalTag = attributes.get("android:tag");
            if ("include".equals(nodeName)) {
                // get the layout attribute
                final String includeValue = attributes.get("layout");
                if (StringUtils.isEmpty(includeValue)) {
                    L.e("%s must include a layout", parent);
                }
                if (!includeValue.startsWith(LAYOUT_PREFIX)) {
                    L.e("included value (%s) must start with %s.",
                            includeValue, LAYOUT_PREFIX);
                }
                // if user is binding something there, there MUST be a layout file to be
                // generated.
                String layoutName = includeValue.substring(LAYOUT_PREFIX.length());
                includedLayoutName = layoutName;
                final ParserRuleContext myParentContent = parent.getParent();
                Preconditions.check(myParentContent instanceof XMLParser.ContentContext,
                        "parent of an include tag must be a content context but it is %s",
                        myParentContent.getClass().getCanonicalName());
                final ParserRuleContext grandParent = myParentContent.getParent();
                Preconditions.check(grandParent instanceof XMLParser.ElementContext,
                        "grandparent of an include tag must be an element context but it is %s",
                        grandParent.getClass().getCanonicalName());
                //noinspection SuspiciousMethodCalls
                tag = nodeTagMap.get(grandParent);
            } else if ("fragment".equals(nodeName)) {
                L.e("fragments do not support data binding expressions.");
                continue;
            } else {
                viewName = getViewName(parent);
                // account for XMLParser.ContentContext
                if (rootView == parent || (isMerge && parent.getParent().getParent() == rootView)) {
                    tag = newTag + "_" + tagNumber;
                } else {
                    tag = "binding_" + tagNumber;
                }
                tagNumber++;
            }
            final ResourceBundle.BindingTargetBundle bindingTargetBundle =
                    bundle.createBindingTarget(id, viewName, true, tag, originalTag,
                            new Location(parent));
            nodeTagMap.put(parent, tag);
            bindingTargetBundle.setIncludedLayout(includedLayoutName);

            for (XMLParser.AttributeContext attr : XmlEditor.expressionAttributes(parent)) {
                String value = escapeQuotes(attr.attrValue.getText(), true);
                if (value.charAt(0) == '@' && value.charAt(1) == '{' &&
                        value.charAt(value.length() - 1) == '}') {
                    final String strippedValue = value.substring(2, value.length() - 1);
                    bindingTargetBundle.addBinding(escapeQuotes(attr.attrName.getText(), false)
                            , strippedValue);
                }
            }
        }

        for (XMLParser.ElementContext elm : otherElementsWithIds) {
            final String id = attributeMap(elm).get("android:id");
            final String className = getViewName(elm);
            bundle.createBindingTarget(id, className, true, null, null, new Location(elm));
        }
    }

    private String getViewName(XMLParser.ElementContext elm) {
        String viewName = elm.elmName.getText();
        if ("view".equals(viewName)) {
            String classNode = attributeMap(elm).get("class");
            if (StringUtils.isEmpty(classNode)) {
                L.e("No class attribute for 'view' node");
            }
            viewName = classNode;
        }
        return viewName;
    }

    private void parseData(File xml, XMLParser.ElementContext data,
            ResourceBundle.LayoutFileBundle bundle) {
        if (data == null) {
            return;
        }
        for (XMLParser.ElementContext imp : filter(data, "import")) {
            final Map<String, String> attrMap = attributeMap(imp);
            String type = attrMap.get("type");
            String alias = attrMap.get("alias");
            Preconditions.check(StringUtils.isNotBlank(type), "Type of an import cannot be empty."
                    + " %s in %s", imp.toStringTree(), xml);
            if (StringUtils.isEmpty(alias)) {
                final String[] split = StringUtils.split(type, '.');
                alias = split[split.length - 1];
            }
            bundle.addImport(alias, type, new Location(imp));
        }

        for (XMLParser.ElementContext variable : filter(data, "variable")) {
            final Map<String, String> attrMap = attributeMap(variable);
            String type = attrMap.get("type");
            String name = attrMap.get("name");
            Preconditions.checkNotNull(type, "variable must have a type definition %s in %s",
                    variable.toStringTree(), xml);
            Preconditions.checkNotNull(name, "variable must have a name %s in %s",
                    variable.toStringTree(), xml);
            bundle.addVariable(name, type, new Location(variable));
        }
        final String className = attributeMap(data).get("class");
        if (StringUtils.isNotBlank(className)) {
            bundle.setBindingClass(className);
        }
    }

    private XMLParser.ElementContext getDataNode(XMLParser.ElementContext root) {
        final List<XMLParser.ElementContext> data = filter(root, "data");
        if (data.size() == 0) {
            return null;
        }
        Preconditions.check(data.size() == 1, "XML layout can have only 1 data tag");
        return data.get(0);
    }

    private XMLParser.ElementContext getViewNode(File xml, XMLParser.ElementContext root) {
        final List<XMLParser.ElementContext> view = filterNot(root, "data");
        Preconditions.check(view.size() == 1, "XML layout %s must have 1 view but has %s. root"
                        + " children count %s", xml, view.size(), root.getChildCount());
        return view.get(0);
    }

    private List<XMLParser.ElementContext> filter(XMLParser.ElementContext root,
            String name) {
        List<XMLParser.ElementContext> result = new ArrayList<>();
        if (root == null) {
            return result;
        }
        final XMLParser.ContentContext content = root.content();
        if (content == null) {
            return result;
        }
        for (XMLParser.ElementContext child : XmlEditor.elements(root)) {
            if (name.equals(child.elmName.getText())) {
                result.add(child);
            }
        }
        return result;
    }

    private List<XMLParser.ElementContext> filterNot(XMLParser.ElementContext root,
            String name) {
        List<XMLParser.ElementContext> result = new ArrayList<>();
        if (root == null) {
            return result;
        }
        final XMLParser.ContentContext content = root.content();
        if (content == null) {
            return result;
        }
        for (XMLParser.ElementContext child : XmlEditor.elements(root)) {
            if (!name.equals(child.elmName.getText())) {
                result.add(child);
            }
        }
        return result;
    }

    private boolean hasMergeInclude(XMLParser.ElementContext rootView) {
        return "merge".equals(rootView.elmName.getText()) && filter(rootView, "include").size() > 0;
    }

    private File stripFileAndGetOriginal(File xml, String binderId)
            throws ParserConfigurationException, IOException, SAXException,
            XPathExpressionException {
        L.d("parsing resource file %s", xml.getAbsolutePath());
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document doc = builder.parse(xml);
        XPathFactory xPathFactory = XPathFactory.newInstance();
        XPath xPath = xPathFactory.newXPath();
        final XPathExpression commentElementExpr = xPath
                .compile("//comment()[starts-with(., \" From: file:\")][last()]");
        final NodeList commentElementNodes = (NodeList) commentElementExpr
                .evaluate(doc, XPathConstants.NODESET);
        L.d("comment element nodes count %s", commentElementNodes.getLength());
        if (commentElementNodes.getLength() == 0) {
            L.d("cannot find comment element to find the actual file");
            return null;
        }
        final Node first = commentElementNodes.item(0);
        String actualFilePath = first.getNodeValue().substring(" From:".length()).trim();
        L.d("actual file to parse: %s", actualFilePath);
        File actualFile = urlToFile(new java.net.URL(actualFilePath));
        if (!actualFile.canRead()) {
            L.d("cannot find original, skipping. %s", actualFile.getAbsolutePath());
            return null;
        }

        // now if file has any binding expressions, find and delete them
        // TODO we should rely on namespace to avoid parsing file twice
        boolean changed = isBindingLayout(doc, xPath);
        if (changed) {
            stripBindingTags(xml, binderId);
        }
        return actualFile;
    }

    private boolean isBindingLayout(Document doc, XPath xPath) throws XPathExpressionException {
        return !get(doc, xPath, XPATH_BINDING_LAYOUT).isEmpty();
    }

    private List<Node> get(Document doc, XPath xPath, String pattern)
            throws XPathExpressionException {
        final XPathExpression expr = xPath.compile(pattern);
        return toList((NodeList) expr.evaluate(doc, XPathConstants.NODESET));
    }

    private List<Node> toList(NodeList nodeList) {
        List<Node> result = new ArrayList<Node>();
        for (int i = 0; i < nodeList.getLength(); i++) {
            result.add(nodeList.item(i));
        }
        return result;
    }

    private void stripBindingTags(File xml, String newTag) throws IOException {
        String res = XmlEditor.strip(xml, newTag);
        if (res != null) {
            L.d("file %s has changed, overwriting %s", xml.getName(), xml.getAbsolutePath());
            FileUtils.writeStringToFile(xml, res);
        }
    }

    public static File urlToFile(URL url) throws MalformedURLException {
        try {
            return new File(url.toURI());
        } catch (IllegalArgumentException e) {
            MalformedURLException ex = new MalformedURLException(e.getLocalizedMessage());
            ex.initCause(e);
            throw ex;
        } catch (URISyntaxException e) {
            return new File(url.getPath());
        }
    }

    private static Map<String, String> attributeMap(XMLParser.ElementContext root) {
        final Map<String, String> result = new HashMap<>();
        for (XMLParser.AttributeContext attr : XmlEditor.attributes(root)) {
            result.put(escapeQuotes(attr.attrName.getText(), false),
                    escapeQuotes(attr.attrValue.getText(), true));
        }
        return result;
    }

    private static String escapeQuotes(String textWithQuotes, boolean unescapeValue) {
        char first = textWithQuotes.charAt(0);
        int start = 0, end = textWithQuotes.length();
        if (first == '"' || first == '\'') {
            start = 1;
        }
        char last = textWithQuotes.charAt(textWithQuotes.length() - 1);
        if (last == '"' || last == '\'') {
            end -= 1;
        }
        String val = textWithQuotes.substring(start, end);
        if (unescapeValue) {
            return StringEscapeUtils.unescapeXml(val);
        } else {
            return val;
        }
    }
}