Package org.apache.tapestry.parse

Source Code of org.apache.tapestry.parse.TemplateParser$Tag

// Copyright 2004, 2005 The Apache Software Foundation
//
// 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 org.apache.tapestry.parse;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.hivemind.ApplicationRuntimeException;
import org.apache.hivemind.Location;
import org.apache.hivemind.Resource;
import org.apache.hivemind.impl.LocationImpl;
import org.apache.oro.text.regex.MalformedPatternException;
import org.apache.oro.text.regex.MatchResult;
import org.apache.oro.text.regex.Pattern;
import org.apache.oro.text.regex.PatternMatcher;
import org.apache.oro.text.regex.Perl5Compiler;
import org.apache.oro.text.regex.Perl5Matcher;
import org.apache.tapestry.util.IdAllocator;

/**
* Parses Tapestry templates, breaking them into a series of
* {@link org.apache.tapestry.parse.TemplateToken tokens}. Although often referred to as an "HTML
* template", there is no real requirement that the template be HTML. This parser can handle any
* reasonable SGML derived markup (including XML), but specifically works around the ambiguities of
* HTML reasonably.
* <p>
* Deployed as the tapestry.parse.TemplateParser service, using the threaded model.
* <p>
* Dynamic markup in Tapestry attempts to be invisible. Components are arbitrary tags containing a
* <code>jwcid</code> attribute. Such components must be well balanced (have a matching close tag,
* or end the tag with "<code>/&gt;</code>".
* <p>
* Generally, the id specified in the template is matched against an component defined in the
* specification. However, implicit components are also possible. The jwcid attribute uses the
* syntax "<code>@Type</code>" for implicit components. Type is the component type, and may include a library id
*       prefix. Such a component is anonymous (but is given a unique id).
*       <p>
*       (The unique ids assigned start with a dollar sign, which is normally no allowed for
*       component ids ... this helps to make them stand out and assures that they do not conflict
*       with user-defined component ids. These ids tend to propagate into URLs and become HTML
*       element names and even JavaScript variable names ... the dollar sign is acceptible in these
*       contexts as well).
*       <p>
*       Implicit component may also be given a name using the syntax "
*       <code>componentId:@Type</code>". Such a component should <b>not </b> be defined in the
*       specification, but may still be accessed via
*       {@link org.apache.tapestry.IComponent#getComponent(String)}.
*       <p>
*       Both defined and implicit components may have additional attributes defined, simply by
*       including them in the template. They set formal or informal parameters of the component to
*       static strings.
*       {@link org.apache.tapestry.spec.IComponentSpecification#getAllowInformalParameters()}, if
*       false, will cause such attributes to be simply ignored. For defined components, conflicting
*       values defined in the template are ignored.
*       <p>
*       Attributes in component tags will become formal and informal parameters of the
*       corresponding component. Most attributes will be
*       <p>
*       The parser removes the body of some tags (when the corresponding component doesn't
*       {@link org.apache.tapestry.spec.IComponentSpecification#getAllowBody() allow a body}, and
*       allows portions of the template to be completely removed.
*       <p>
*       The parser does a pretty thorough lexical analysis of the template, and reports a great
*       number of errors, including improper nesting of tags.
*       <p>
*       The parser supports <em>invisible localization</em>: The parser recognizes HTML of the
*       form: <code>&lt;span key="<i>value</i>"&gt; ... &lt;/span&gt;</code> and converts them
*       into a {@link TokenType#LOCALIZATION}token. You may also specifify a <code>raw</code>
*       attribute ... if the value is <code>true</code>, then the localized value is sent to the
*       client without filtering, which is appropriate if the value has any markup that should not
*       be escaped.
* @author Howard Lewis Ship, Geoff Longman
*/

public class TemplateParser implements ITemplateParser
{
    /**
     * A "magic" component id that causes the tag with the id and its entire body to be ignored
     * during parsing.
     */

    private static final String REMOVE_ID = "$remove$";

    /**
     * A "magic" component id that causes the tag to represent the true content of the template. Any
     * content prior to the tag is discarded, and any content after the tag is ignored. The tag
     * itself is not included.
     */

    private static final String CONTENT_ID = "$content$";

    /**
     * The attribute, checked for in &lt;span&gt; tags, that signfies that the span is being used as
     * an invisible localization.
     *
     * @since 2.0.4
     */

    public static final String LOCALIZATION_KEY_ATTRIBUTE_NAME = "key";

    /**
     * Used with {@link #LOCALIZATION_KEY_ATTRIBUTE_NAME}to indicate a string that should be
     * rendered "raw" (without escaping HTML). If not specified, defaults to "false". The value must
     * equal "true" (caselessly).
     *
     * @since 2.3
     */

    public static final String RAW_ATTRIBUTE_NAME = "raw";

    /**
     * Attribute name used to identify components.
     *
     * @since 4.0
     */

    private String _componentAttributeName;

    private static final String PROPERTY_NAME_PATTERN = "_?[a-zA-Z]\\w*";

    /**
     * Pattern used to recognize ordinary components (defined in the specification).
     *
     * @since 3.0
     */

    public static final String SIMPLE_ID_PATTERN = "^(" + PROPERTY_NAME_PATTERN + ")$";

    /**
     * Pattern used to recognize implicit components (whose type is defined in the template).
     * Subgroup 1 is the id (which may be null) and subgroup 2 is the type (which may be qualified
     * with a library prefix). Subgroup 4 is the library id, Subgroup 5 is the simple component
     * type.
     *
     * @since 3.0
     */

    public static final String IMPLICIT_ID_PATTERN = "^(" + PROPERTY_NAME_PATTERN + ")?@((("
            + PROPERTY_NAME_PATTERN + "):)?(" + PROPERTY_NAME_PATTERN + "))$";

    private static final int IMPLICIT_ID_PATTERN_ID_GROUP = 1;

    private static final int IMPLICIT_ID_PATTERN_TYPE_GROUP = 2;

    private static final int IMPLICIT_ID_PATTERN_LIBRARY_ID_GROUP = 4;

    private static final int IMPLICIT_ID_PATTERN_SIMPLE_TYPE_GROUP = 5;

    private Pattern _simpleIdPattern;

    private Pattern _implicitIdPattern;

    private PatternMatcher _patternMatcher;

    private IdAllocator _idAllocator = new IdAllocator();

    private ITemplateParserDelegate _delegate;

    /**
     * Identifies the template being parsed; used with error messages.
     */

    private Resource _resourceLocation;

    /**
     * Shared instance of {@link Location}used by all {@link TextToken}instances in the template.
     */

    private Location _templateLocation;

    /**
     * Location with in the resource for the current line.
     */

    private Location _currentLocation;

    /**
     * Local reference to the template data that is to be parsed.
     */

    private char[] _templateData;

    /**
     * List of Tag
     */

    private List _stack = new ArrayList();

    private static class Tag
    {
        // The element, i.e., <jwc> or virtually any other element (via jwcid attribute)
        String _tagName;

        // If true, the tag is a placeholder for a dynamic element
        boolean _component;

        // If true, the body of the tag is being ignored, and the
        // ignore flag is cleared when the close tag is reached
        boolean _ignoringBody;

        // If true, then the entire tag (and its body) is being ignored
        boolean _removeTag;

        // If true, then the tag must have a balanced closing tag.
        // This is always true for components.
        boolean _mustBalance;

        // The line on which the start tag exists
        int _line;

        // If true, then the parse ends when the closing tag is found.
        boolean _content;

        Tag(String tagName, int line)
        {
            _tagName = tagName;
            _line = line;
        }

        boolean match(String matchTagName)
        {
            return _tagName.equalsIgnoreCase(matchTagName);
        }
    }

    /**
     * List of {@link TemplateToken}, this forms the ultimate response.
     */

    private List _tokens = new ArrayList();

    /**
     * The location of the 'cursor' within the template data. The advance() method moves this
     * forward.
     */

    private int _cursor;

    /**
     * The start of the current block of static text, or -1 if no block is active.
     */

    private int _blockStart;

    /**
     * The current line number; tracked by advance(). Starts at 1.
     */

    private int _line;

    /**
     * Set to true when the body of a tag is being ignored. This is typically used to skip over the
     * body of a tag when its corresponding component doesn't allow a body, or whe the special jwcid
     * of $remove$ is used.
     */

    private boolean _ignoring;

    /**
     * A {@link Map}of {@link String}s, used to store attributes collected while parsing a tag.
     */

    private Map _attributes = new HashMap();

    /**
     * A factory used to create template tokens.
     */

    private TemplateTokenFactory _factory;

    public TemplateParser()
    {
        Perl5Compiler compiler = new Perl5Compiler();

        try
        {
            _simpleIdPattern = compiler.compile(SIMPLE_ID_PATTERN);
            _implicitIdPattern = compiler.compile(IMPLICIT_ID_PATTERN);
        }
        catch (MalformedPatternException ex)
        {
            throw new ApplicationRuntimeException(ex);
        }

        _patternMatcher = new Perl5Matcher();
    }

    /**
     * Parses the template data into an array of {@link TemplateToken}s.
     * <p>
     * The parser is <i>decidedly </i> not threadsafe, so care should be taken that only a single
     * thread accesses it.
     *
     * @param templateData
     *            the HTML template to parse. Some tokens will hold a reference to this array.
     * @param delegate
     *            object that "knows" about defined components
     * @param resourceLocation
     *            a description of where the template originated from, used with error messages.
     */

    public TemplateToken[] parse(char[] templateData, ITemplateParserDelegate delegate,
            Resource resourceLocation) throws TemplateParseException
    {
        try
        {
            beforeParse(templateData, delegate, resourceLocation);

            parse();

            return (TemplateToken[]) _tokens.toArray(new TemplateToken[_tokens.size()]);
        }
        finally
        {
            afterParse();
        }
    }

    /**
     * perform default initialization of the parser.
     */

    protected void beforeParse(char[] templateData, ITemplateParserDelegate delegate,
            Resource resourceLocation)
    {
        _templateData = templateData;
        _resourceLocation = resourceLocation;
        _templateLocation = new LocationImpl(resourceLocation);
        _delegate = delegate;
        _ignoring = false;
        _line = 1;
        _componentAttributeName = delegate.getComponentAttributeName();
    }

    /**
     * Perform default cleanup after parsing completes.
     */

    protected void afterParse()
    {
        _delegate = null;
        _templateData = null;
        _resourceLocation = null;
        _templateLocation = null;
        _currentLocation = null;
        _stack.clear();
        _tokens.clear();
        _attributes.clear();
        _idAllocator.clear();
    }

    /**
     * Used by the parser to report problems in the parse. Parsing <b>must </b> stop when a problem
     * is reported.
     * <p>
     * The default implementation simply throws an exception that contains the message and location
     * parameters.
     * <p>
     * Subclasses may override but <b>must </b> ensure they throw the required exception.
     *
     * @param message
     * @param location
     * @param line
     *            ignored by the default impl
     * @param cursor
     *            ignored by the default impl
     * @throws TemplateParseException
     *             always thrown in order to terminate the parse.
     */

    protected void templateParseProblem(String message, Location location, int line, int cursor)
            throws TemplateParseException
    {
        throw new TemplateParseException(message, location);
    }

    /**
     * Used by the parser to report tapestry runtime specific problems in the parse. Parsing <b>must
     * </b> stop when a problem is reported.
     * <p>
     * The default implementation simply rethrows the exception.
     * <p>
     * Subclasses may override but <b>must </b> ensure they rethrow the exception.
     *
     * @param exception
     * @param line
     *            ignored by the default impl
     * @param cursor
     *            ignored by the default impl
     * @throws ApplicationRuntimeException
     *             always rethrown in order to terminate the parse.
     */

    protected void templateParseProblem(ApplicationRuntimeException exception, int line, int cursor)
            throws ApplicationRuntimeException
    {
        throw exception;
    }

    /**
     * Give subclasses access to the parse results.
     */
    protected List getTokens()
    {
        if (_tokens == null)
            return Collections.EMPTY_LIST;

        return _tokens;
    }

    /**
     * Checks to see if the next few characters match a given pattern.
     */

    private boolean lookahead(char[] match)
    {
        try
        {
            for (int i = 0; i < match.length; i++)
            {
                if (_templateData[_cursor + i] != match[i])
                    return false;
            }

            // Every character matched.

            return true;
        }
        catch (IndexOutOfBoundsException ex)
        {
            return false;
        }
    }

    private static final char[] COMMENT_START = new char[]
    { '<', '!', '-', '-' };

    private static final char[] COMMENT_END = new char[]
    { '-', '-', '>' };

    private static final char[] CLOSE_TAG = new char[]
    { '<', '/' };

    protected void parse() throws TemplateParseException
    {
        _cursor = 0;
        _blockStart = -1;
        int length = _templateData.length;

        while (_cursor < length)
        {
            if (_templateData[_cursor] != '<')
            {
                if (_blockStart < 0 && !_ignoring)
                    _blockStart = _cursor;

                advance();
                continue;
            }

            // OK, start of something.

            if (lookahead(CLOSE_TAG))
            {
                closeTag();
                continue;
            }

            if (lookahead(COMMENT_START))
            {
                skipComment();
                continue;
            }

            // The start of some tag.

            startTag();
        }

        // Usually there's some text at the end of the template (after the last closing tag) that
        // should
        // be added. Often the last few tags are static tags so we definately
        // need to end the text block.

        addTextToken(_templateData.length - 1);
    }

    /**
     * Advance forward in the document until the end of the comment is reached. In addition, skip
     * any whitespace following the comment.
     */

    private void skipComment() throws TemplateParseException
    {
        int length = _templateData.length;
        int startLine = _line;

        if (_blockStart < 0 && !_ignoring)
            _blockStart = _cursor;

        while (true)
        {
            if (_cursor >= length)
                templateParseProblem(ParseMessages.commentNotEnded(startLine), new LocationImpl(
                        _resourceLocation, startLine), startLine, _cursor);

            if (lookahead(COMMENT_END))
                break;

            // Not the end of the comment, advance over it.

            advance();
        }

        _cursor += COMMENT_END.length;
        advanceOverWhitespace();
    }

    private void addTextToken(int end)
    {
        // No active block to add to.

        if (_blockStart < 0)
            return;

        if (_blockStart <= end)
        {
            // This seems odd, shouldn't the location be the current location? I guess
            // no errors are ever reported for a text token.

            TemplateToken token = _factory.createTextToken(
                    _templateData,
                    _blockStart,
                    end,
                    _templateLocation);

            _tokens.add(token);
        }

        _blockStart = -1;
    }

    private static final int WAIT_FOR_ATTRIBUTE_NAME = 0;

    private static final int COLLECT_ATTRIBUTE_NAME = 1;

    private static final int ADVANCE_PAST_EQUALS = 2;

    private static final int WAIT_FOR_ATTRIBUTE_VALUE = 3;

    private static final int COLLECT_QUOTED_VALUE = 4;

    private static final int COLLECT_UNQUOTED_VALUE = 5;

    private void startTag() throws TemplateParseException
    {
        int cursorStart = _cursor;
        int length = _templateData.length;
        String tagName = null;
        boolean endOfTag = false;
        boolean emptyTag = false;
        int startLine = _line;
        Location startLocation = new LocationImpl(_resourceLocation, startLine);

        tagBeginEvent(startLine, _cursor);

        advance();

        // Collect the element type

        while (_cursor < length)
        {
            char ch = _templateData[_cursor];

            if (ch == '/' || ch == '>' || Character.isWhitespace(ch))
            {
                tagName = new String(_templateData, cursorStart + 1, _cursor - cursorStart - 1);

                break;
            }

            advance();
        }

        String attributeName = null;
        int attributeNameStart = -1;
        int attributeValueStart = -1;
        int state = WAIT_FOR_ATTRIBUTE_NAME;
        char quoteChar = 0;

        _attributes.clear();

        // Collect each attribute

        while (!endOfTag)
        {
            if (_cursor >= length)
            {
                String message = (tagName == null) ? ParseMessages.unclosedUnknownTag(startLine)
                        : ParseMessages.unclosedTag(tagName, startLine);

                templateParseProblem(message, startLocation, startLine, cursorStart);
            }

            char ch = _templateData[_cursor];

            switch (state)
            {
                case WAIT_FOR_ATTRIBUTE_NAME:

                    // Ignore whitespace before the next attribute name, while
                    // looking for the end of the current tag.

                    if (ch == '/')
                    {
                        emptyTag = true;
                        advance();
                        break;
                    }

                    if (ch == '>')
                    {
                        endOfTag = true;
                        break;
                    }

                    if (Character.isWhitespace(ch))
                    {
                        advance();
                        break;
                    }

                    // Found non-whitespace, assume its the attribute name.
                    // Note: could use a check here for non-alpha.

                    attributeNameStart = _cursor;
                    state = COLLECT_ATTRIBUTE_NAME;
                    advance();
                    break;

                case COLLECT_ATTRIBUTE_NAME:

                    // Looking for end of attribute name.

                    if (ch == '=' || ch == '/' || ch == '>' || Character.isWhitespace(ch))
                    {
                        attributeName = new String(_templateData, attributeNameStart, _cursor
                                - attributeNameStart);

                        state = ADVANCE_PAST_EQUALS;
                        break;
                    }

                    // Part of the attribute name

                    advance();
                    break;

                case ADVANCE_PAST_EQUALS:

                    // Looking for the '=' sign. May hit the end of the tag, or (for bare
                    // attributes),
                    // the next attribute name.

                    if (ch == '/' || ch == '>')
                    {
                        // A bare attribute, which is not interesting to
                        // us.

                        state = WAIT_FOR_ATTRIBUTE_NAME;
                        break;
                    }

                    if (Character.isWhitespace(ch))
                    {
                        advance();
                        break;
                    }

                    if (ch == '=')
                    {
                        state = WAIT_FOR_ATTRIBUTE_VALUE;
                        quoteChar = 0;
                        attributeValueStart = -1;
                        advance();
                        break;
                    }

                    // Otherwise, an HTML style "bare" attribute (such as <select multiple>).
                    // We aren't interested in those (we're just looking for the id or jwcid
                    // attribute).

                    state = WAIT_FOR_ATTRIBUTE_NAME;
                    break;

                case WAIT_FOR_ATTRIBUTE_VALUE:

                    if (ch == '/' || ch == '>')
                        templateParseProblem(ParseMessages.missingAttributeValue(
                                tagName,
                                _line,
                                attributeName), getCurrentLocation(), _line, _cursor);

                    // Ignore whitespace between '=' and the attribute value. Also, look
                    // for initial quote.

                    if (Character.isWhitespace(ch))
                    {
                        advance();
                        break;
                    }

                    if (ch == '\'' || ch == '"')
                    {
                        quoteChar = ch;

                        state = COLLECT_QUOTED_VALUE;
                        advance();
                        attributeValueStart = _cursor;
                        attributeBeginEvent(attributeName, _line, attributeValueStart);
                        break;
                    }

                    // Not whitespace or quote, must be start of unquoted attribute.

                    state = COLLECT_UNQUOTED_VALUE;
                    attributeValueStart = _cursor;
                    attributeBeginEvent(attributeName, _line, attributeValueStart);
                    break;

                case COLLECT_QUOTED_VALUE:

                    // Start collecting the quoted attribute value. Stop at the matching quote
                    // character,
                    // unless bare, in which case, stop at the next whitespace.

                    if (ch == quoteChar)
                    {
                        String attributeValue = new String(_templateData, attributeValueStart,
                                _cursor - attributeValueStart);

                        _attributes.put(attributeName, attributeValue);
                        attributeEndEvent(_cursor);

                        // Advance over the quote.
                        advance();
                        state = WAIT_FOR_ATTRIBUTE_NAME;
                        break;
                    }

                    advance();
                    break;

                case COLLECT_UNQUOTED_VALUE:

                    // An unquoted attribute value ends with whitespace
                    // or the end of the enclosing tag.

                    if (ch == '/' || ch == '>' || Character.isWhitespace(ch))
                    {
                        String attributeValue = new String(_templateData, attributeValueStart,
                                _cursor - attributeValueStart);

                        _attributes.put(attributeName, attributeValue);
                        attributeEndEvent(_cursor);

                        state = WAIT_FOR_ATTRIBUTE_NAME;
                        break;
                    }

                    advance();
                    break;
            }
        }

        tagEndEvent(_cursor);

        // Check for invisible localizations

        String localizationKey = findValueCaselessly(LOCALIZATION_KEY_ATTRIBUTE_NAME, _attributes);
        String jwcId = findValueCaselessly(_componentAttributeName, _attributes);

        if (localizationKey != null && tagName.equalsIgnoreCase("span") && jwcId == null)
        {
            if (_ignoring)
                templateParseProblem(
                        ParseMessages.componentMayNotBeIgnored(tagName, startLine),
                        startLocation,
                        startLine,
                        cursorStart);

            // If the tag isn't empty, then create a Tag instance to ignore the
            // body of the tag.

            if (!emptyTag)
            {
                Tag tag = new Tag(tagName, startLine);

                tag._component = false;
                tag._removeTag = true;
                tag._ignoringBody = true;
                tag._mustBalance = true;

                _stack.add(tag);

                // Start ignoring content until the close tag.

                _ignoring = true;
            }
            else
            {
                // Cursor is at the closing carat, advance over it and any whitespace.
                advance();
                advanceOverWhitespace();
            }

            // End any open block.

            addTextToken(cursorStart - 1);

            boolean raw = checkBoolean(RAW_ATTRIBUTE_NAME, _attributes);

            Map attributes = filter(_attributes, new String[]
            { LOCALIZATION_KEY_ATTRIBUTE_NAME, RAW_ATTRIBUTE_NAME });

            TemplateToken token = _factory.createLocalizationToken(
                    tagName,
                    localizationKey,
                    raw,
                    attributes,
                    startLocation);

            _tokens.add(token);

            return;
        }

        if (jwcId != null)
        {
            processComponentStart(tagName, jwcId, emptyTag, startLine, cursorStart, startLocation);
            return;
        }

        // A static tag (not a tag without a jwcid attribute).
        // We need to record this so that we can match close tags later.

        if (!emptyTag)
        {
            Tag tag = new Tag(tagName, startLine);
            _stack.add(tag);
        }

        // If there wasn't an active block, then start one.

        if (_blockStart < 0 && !_ignoring)
            _blockStart = cursorStart;

        advance();
    }

    /**
     * Processes a tag that is the open tag for a component (but also handles the $remove$ and
     * $content$ tags).
     */

    /**
     * Notify that the beginning of a tag has been detected.
     * <p>
     * Default implementation does nothing.
     */
    protected void tagBeginEvent(int startLine, int cursorPosition)
    {
    }

    /**
     * Notify that the end of the current tag has been detected.
     * <p>
     * Default implementation does nothing.
     */
    protected void tagEndEvent(int cursorPosition)
    {
    }

    /**
     * Notify that the beginning of an attribute value has been detected.
     * <p>
     * Default implementation does nothing.
     */
    protected void attributeBeginEvent(String attributeName, int startLine, int cursorPosition)
    {
    }

    /**
     * Notify that the end of the current attribute value has been detected.
     * <p>
     * Default implementation does nothing.
     */
    protected void attributeEndEvent(int cursorPosition)
    {
    }

    private void processComponentStart(String tagName, String jwcId, boolean emptyTag,
            int startLine, int cursorStart, Location startLocation) throws TemplateParseException
    {
        if (jwcId.equalsIgnoreCase(CONTENT_ID))
        {
            processContentTag(tagName, startLine, cursorStart, emptyTag);

            return;
        }

        boolean isRemoveId = jwcId.equalsIgnoreCase(REMOVE_ID);

        if (_ignoring && !isRemoveId)
            templateParseProblem(
                    ParseMessages.componentMayNotBeIgnored(tagName, startLine),
                    startLocation,
                    startLine,
                    cursorStart);

        String type = null;
        boolean allowBody = false;

        if (_patternMatcher.matches(jwcId, _implicitIdPattern))
        {
            MatchResult match = _patternMatcher.getMatch();

            jwcId = match.group(IMPLICIT_ID_PATTERN_ID_GROUP);
            type = match.group(IMPLICIT_ID_PATTERN_TYPE_GROUP);

            String libraryId = match.group(IMPLICIT_ID_PATTERN_LIBRARY_ID_GROUP);
            String simpleType = match.group(IMPLICIT_ID_PATTERN_SIMPLE_TYPE_GROUP);

            // If (and this is typical) no actual component id was specified,
            // then generate one on the fly.
            // The allocated id for anonymous components is
            // based on the simple (unprefixed) type, but starts
            // with a leading dollar sign to ensure no conflicts
            // with user defined component ids (which don't allow dollar signs
            // in the id).

            if (jwcId == null)
                jwcId = _idAllocator.allocateId("$" + simpleType);

            try
            {
                allowBody = _delegate.getAllowBody(libraryId, simpleType, startLocation);
            }
            catch (ApplicationRuntimeException e)
            {
                // give subclasses a chance to handle and rethrow
                templateParseProblem(e, startLine, cursorStart);
            }

        }
        else
        {
            if (!isRemoveId)
            {
                if (!_patternMatcher.matches(jwcId, _simpleIdPattern))
                    templateParseProblem(
                            ParseMessages.componentIdInvalid(tagName, startLine, jwcId),
                            startLocation,
                            startLine,
                            cursorStart);

                if (!_delegate.getKnownComponent(jwcId))
                    templateParseProblem(
                            ParseMessages.unknownComponentId(tagName, startLine, jwcId),
                            startLocation,
                            startLine,
                            cursorStart);

                try
                {
                    allowBody = _delegate.getAllowBody(jwcId, startLocation);
                }
                catch (ApplicationRuntimeException e)
                {
                    // give subclasses a chance to handle and rethrow
                    templateParseProblem(e, startLine, cursorStart);
                }
            }
        }

        // Ignore the body if we're removing the entire tag,
        // of if the corresponding component doesn't allow
        // a body.

        boolean ignoreBody = !emptyTag && (isRemoveId || !allowBody);

        if (_ignoring && ignoreBody)
            templateParseProblem(ParseMessages.nestedIgnore(tagName, startLine), new LocationImpl(
                    _resourceLocation, startLine), startLine, cursorStart);

        if (!emptyTag)
            pushNewTag(tagName, startLine, isRemoveId, ignoreBody);

        // End any open block.

        addTextToken(cursorStart - 1);

        if (!isRemoveId)
        {
            addOpenToken(tagName, jwcId, type, startLocation);

            if (emptyTag)
                _tokens.add(_factory.createCloseToken(tagName, getCurrentLocation()));
        }

        advance();
    }

    private void pushNewTag(String tagName, int startLine, boolean isRemoveId, boolean ignoreBody)
    {
        Tag tag = new Tag(tagName, startLine);

        tag._component = !isRemoveId;
        tag._removeTag = isRemoveId;

        tag._ignoringBody = ignoreBody;

        _ignoring = tag._ignoringBody;

        tag._mustBalance = true;

        _stack.add(tag);
    }

    private void processContentTag(String tagName, int startLine, int cursorStart, boolean emptyTag)
            throws TemplateParseException
    {
        if (_ignoring)
            templateParseProblem(
                    ParseMessages.contentBlockMayNotBeIgnored(tagName, startLine),
                    new LocationImpl(_resourceLocation, startLine),
                    startLine,
                    cursorStart);

        if (emptyTag)
            templateParseProblem(
                    ParseMessages.contentBlockMayNotBeEmpty(tagName, startLine),
                    new LocationImpl(_resourceLocation, startLine),
                    startLine,
                    cursorStart);

        _tokens.clear();
        _blockStart = -1;

        Tag tag = new Tag(tagName, startLine);

        tag._mustBalance = true;
        tag._content = true;

        _stack.clear();
        _stack.add(tag);

        advance();
    }

    private void addOpenToken(String tagName, String jwcId, String type, Location location)
    {
        OpenToken token = _factory.createOpenToken(tagName, jwcId, type, location);
        _tokens.add(token);

        if (_attributes.isEmpty())
            return;

        Iterator i = _attributes.entrySet().iterator();
        while (i.hasNext())
        {
            Map.Entry entry = (Map.Entry) i.next();

            String key = (String) entry.getKey();

            if (key.equalsIgnoreCase(_componentAttributeName))
                continue;

            String value = (String) entry.getValue();

            addAttributeToToken(token, key, value);
        }
    }

    /**
     * Adds the attribute to the token (identifying prefixes and whatnot is now done downstream).
     *
     * @since 3.0
     */

    private void addAttributeToToken(OpenToken token, String name, String attributeValue)
    {
        token.addAttribute(name, convertEntitiesToPlain(attributeValue));
    }

    /**
     * Invoked to handle a closing tag, i.e., &lt;/foo&gt;. When a tag closes, it will match against
     * a tag on the open tag start. Preferably the top tag on the stack (if everything is well
     * balanced), but this is HTML, not XML, so many tags won't balance.
     * <p>
     * Once the matching tag is located, the question is ... is the tag dynamic or static? If
     * static, then the current text block is extended to include this close tag. If dynamic, then
     * the current text block is ended (before the '&lt;' that starts the tag) and a close token is
     * added.
     * <p>
     * In either case, the matching static element and anything above it is removed, and the cursor
     * is left on the character following the '&gt;'.
     */

    private void closeTag() throws TemplateParseException
    {
        int cursorStart = _cursor;
        int length = _templateData.length;
        int startLine = _line;

        Location startLocation = getCurrentLocation();

        _cursor += CLOSE_TAG.length;

        int tagStart = _cursor;

        while (true)
        {
            if (_cursor >= length)
                templateParseProblem(
                        ParseMessages.incompleteCloseTag(startLine),
                        startLocation,
                        startLine,
                        cursorStart);

            char ch = _templateData[_cursor];

            if (ch == '>')
                break;

            advance();
        }

        String tagName = new String(_templateData, tagStart, _cursor - tagStart);

        int stackPos = _stack.size() - 1;
        Tag tag = null;

        while (stackPos >= 0)
        {
            tag = (Tag) _stack.get(stackPos);

            if (tag.match(tagName))
                break;

            if (tag._mustBalance)
                templateParseProblem(ParseMessages.improperlyNestedCloseTag(
                        tagName,
                        startLine,
                        tag._tagName,
                        tag._line), startLocation, startLine, cursorStart);

            stackPos--;
        }

        if (stackPos < 0)
            templateParseProblem(
                    ParseMessages.unmatchedCloseTag(tagName, startLine),
                    startLocation,
                    startLine,
                    cursorStart);

        // Special case for the content tag

        if (tag._content)
        {
            addTextToken(cursorStart - 1);

            // Advance the cursor right to the end.

            _cursor = length;
            _stack.clear();
            return;
        }

        // When a component closes, add a CLOSE tag.
        if (tag._component)
        {
            addTextToken(cursorStart - 1);

            _tokens.add(_factory.createCloseToken(tagName, getCurrentLocation()));
        }
        else
        {
            // The close of a static tag. Unless removing the tag
            // entirely, make sure the block tag is part of a text block.

            if (_blockStart < 0 && !tag._removeTag && !_ignoring)
                _blockStart = cursorStart;
        }

        // Remove all elements at stackPos or above.

        for (int i = _stack.size() - 1; i >= stackPos; i--)
            _stack.remove(i);

        // Advance cursor past '>'

        advance();

        // If editting out the tag (i.e., $remove$) then kill any whitespace.
        // For components that simply don't contain a body, removeTag will
        // be false.

        if (tag._removeTag)
            advanceOverWhitespace();

        // If we were ignoring the body of the tag, then clear the ignoring
        // flag, since we're out of the body.

        if (tag._ignoringBody)
            _ignoring = false;
    }

    /**
     * Advances the cursor to the next character. If the end-of-line is reached, then increments the
     * line counter.
     */

    private void advance()
    {
        int length = _templateData.length;

        if (_cursor >= length)
            return;

        char ch = _templateData[_cursor];

        _cursor++;

        if (ch == '\n')
        {
            _line++;
            _currentLocation = null;
            return;
        }

        // A \r, or a \r\n also counts as a new line.

        if (ch == '\r')
        {
            _line++;
            _currentLocation = null;

            if (_cursor < length && _templateData[_cursor] == '\n')
                _cursor++;

            return;
        }

        // Not an end-of-line character.

    }

    private void advanceOverWhitespace()
    {
        int length = _templateData.length;

        while (_cursor < length)
        {
            char ch = _templateData[_cursor];
            if (!Character.isWhitespace(ch))
                return;

            advance();
        }
    }

    /**
     * Returns a new Map that is a copy of the input Map with some key/value pairs removed. A list
     * of keys is passed in and matching keys (caseless comparison) from the input Map are excluded
     * from the output map. May return null (rather than return an empty Map).
     */

    private Map filter(Map input, String[] removeKeys)
    {
        if (input == null || input.isEmpty())
            return null;

        Map result = null;

        Iterator i = input.entrySet().iterator();

        nextkey: while (i.hasNext())
        {
            Map.Entry entry = (Map.Entry) i.next();

            String key = (String) entry.getKey();

            for (int j = 0; j < removeKeys.length; j++)
            {
                if (key.equalsIgnoreCase(removeKeys[j]))
                    continue nextkey;
            }

            if (result == null)
                result = new HashMap(input.size());

            result.put(key, entry.getValue());
        }

        return result;
    }

    /**
     * Searches a Map for given key, caselessly. The Map is expected to consist of Strings for keys
     * and values. Returns the value for the first key found that matches (caselessly) the input
     * key. Returns null if no value found.
     */

    protected String findValueCaselessly(String key, Map map)
    {
        String result = (String) map.get(key);

        if (result != null)
            return result;

        Iterator i = map.entrySet().iterator();
        while (i.hasNext())
        {
            Map.Entry entry = (Map.Entry) i.next();

            String entryKey = (String) entry.getKey();

            if (entryKey.equalsIgnoreCase(key))
                return (String) entry.getValue();
        }

        return null;
    }

    /**
     * Conversions needed by {@link #convertEntitiesToPlain(String)}
     */

    private static final String[] CONVERSIONS =
    { "&lt;", "<", "&gt;", ">", "&quot;", "\"", "&amp;", "&" };

    /**
     * Provided a raw input string that has been recognized to be an expression, this removes excess
     * white space and converts &amp;amp;;, &amp;quot;; &amp;lt;; and &amp;gt;; to their normal
     * character values (otherwise its impossible to specify those values in expressions in the
     * template).
     */

    private String convertEntitiesToPlain(String input)
    {
        int inputLength = input.length();

        StringBuffer buffer = new StringBuffer(inputLength);

        int cursor = 0;

        outer: while (cursor < inputLength)
        {
            for (int i = 0; i < CONVERSIONS.length; i += 2)
            {
                String entity = CONVERSIONS[i];
                int entityLength = entity.length();
                String value = CONVERSIONS[i + 1];

                if (cursor + entityLength > inputLength)
                    continue;

                if (input.substring(cursor, cursor + entityLength).equals(entity))
                {
                    buffer.append(value);
                    cursor += entityLength;
                    continue outer;
                }
            }

            buffer.append(input.charAt(cursor));
            cursor++;
        }

        return buffer.toString().trim();
    }

    /**
     * Returns true if the map contains the given key (caseless search) and the value is "true"
     * (caseless comparison).
     */

    private boolean checkBoolean(String key, Map map)
    {
        String value = findValueCaselessly(key, map);

        if (value == null)
            return false;

        return value.equalsIgnoreCase("true");
    }

    /**
     * Gets the current location within the file. This allows the location to be created only as
     * needed, and multiple objects on the same line can share the same Location instance.
     *
     * @since 3.0
     */

    protected Location getCurrentLocation()
    {
        if (_currentLocation == null)
            _currentLocation = new LocationImpl(_resourceLocation, _line);

        return _currentLocation;
    }

    public void setFactory(TemplateTokenFactory factory)
    {
        _factory = factory;
    }

}
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Related Classes of org.apache.tapestry.parse.TemplateParser$Tag

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