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+/* CSSParser.java --
+ Copyright (C) 2005 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING. If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package javax.swing.text.html;
+
+import java.io.*;
+
+/**
+ * Parses a CSS document. This works by way of a delegate that implements the
+ * CSSParserCallback interface. The delegate is notified of the following
+ * events:
+ * - Import statement: handleImport
+ * - Selectors handleSelector. This is invoked for each string. For example if
+ * the Reader contained p, bar , a {}, the delegate would be notified 4 times,
+ * for 'p,' 'bar' ',' and 'a'.
+ * - When a rule starts, startRule
+ * - Properties in the rule via the handleProperty. This
+ * is invoked one per property/value key, eg font size: foo;, would cause the
+ * delegate to be notified once with a value of 'font size'.
+ * - Values in the rule via the handleValue, this is notified for the total value.
+ * - When a rule ends, endRule
+ *
+ * @author Lillian Angel (langel@redhat.com)
+ */
+class CSSParser
+{
+
+ /**
+ * Receives all information about the CSS document structure while parsing it.
+ * The methods are invoked by parser.
+ */
+ static interface CSSParserCallback
+ {
+ /**
+ * Handles the import statment in the document.
+ *
+ * @param imp - the import string
+ */
+ public abstract void handleImport(String imp);
+
+ /**
+ * Called when the start of a rule is encountered.
+ */
+ public abstract void startRule();
+
+ /**
+ * Called when the end of a rule is encountered.
+ */
+ public abstract void endRule();
+
+ /**
+ * Handles the selector of a rule.
+ *
+ * @param selector - the selector in the rule
+ */
+ public abstract void handleSelector(String selector);
+
+ /**
+ * Handles the properties in the document.
+ *
+ * @param property - the property in the document.
+ */
+ public abstract void handleProperty(String property);
+
+ /**
+ * Handles the values in the document.
+ *
+ * @param value - the value to handle.
+ */
+ public abstract void handleValue(String value);
+
+ }
+
+ /**
+ * The identifier of the rule.
+ */
+ private static final int IDENTIFIER = 1;
+
+ /**
+ * The open bracket.
+ */
+ private static final int BRACKET_OPEN = 2;
+
+ /**
+ * The close bracket.
+ */
+ private static final int BRACKET_CLOSE = 3;
+
+ /**
+ * The open brace.
+ */
+ private static final int BRACE_OPEN = 4;
+
+ /**
+ * The close brace.
+ */
+ private static final int BRACE_CLOSE = 5;
+
+ /**
+ * The open parentheses.
+ */
+ private static final int PAREN_OPEN = 6;
+
+ /**
+ * The close parentheses.
+ */
+ private static final int PAREN_CLOSE = 7;
+
+ /**
+ * The end of the document.
+ */
+ private static final int END = -1;
+
+ /**
+ * The character mapping in the document.
+ */
+ // FIXME: What is this used for?
+ private static final char[] charMapping = null;
+
+ /**
+ * Set to true if one character has been read ahead.
+ */
+ private boolean didPushChar;
+
+ /**
+ * The read ahead character.
+ */
+ private int pushedChar;
+
+ /**
+ * Used to indicate blocks.
+ */
+ private int[] unitStack;
+
+ /**
+ * Number of valid blocks.
+ */
+ private int stackCount;
+
+ /**
+ * Holds the incoming CSS rules.
+ */
+ private Reader reader;
+
+ /**
+ * Set to true when the first non @ rule is encountered.
+ */
+ private boolean encounteredRuleSet;
+
+ /**
+ * The call back used to parse.
+ */
+ private CSSParser.CSSParserCallback callback;
+
+ /**
+ * nextToken() inserts the string here.
+ */
+ private char[] tokenBuffer;
+
+ /**
+ * Current number of chars in tokenBufferLength.
+ */
+ private int tokenBufferLength;
+
+ /**
+ * Set to true if any whitespace is read.
+ */
+ private boolean readWS;
+
+ /**
+ * Constructor
+ */
+ CSSParser()
+ {
+ tokenBuffer = new char[10];
+ }
+
+ /**
+ * Appends a character to the token buffer.
+ *
+ * @param c - the character to append
+ */
+ private void append(char c)
+ {
+ if (tokenBuffer.length >= tokenBufferLength)
+ {
+ char[] temp = new char[tokenBufferLength * 2];
+ if (tokenBuffer != null)
+ System.arraycopy(tokenBuffer, 0, temp, 0, tokenBufferLength);
+
+ temp[tokenBufferLength] = c;
+ tokenBuffer = temp;
+ }
+ else
+ tokenBuffer[tokenBufferLength] = c;
+ tokenBufferLength++;
+ }
+
+ /**
+ * Fetches the next token.
+ *
+ * @param c - the character to fetch.
+ * @return the location
+ * @throws IOException - any i/o error encountered while reading
+ */
+ private int nextToken(char c) throws IOException
+ {
+ readWS = false;
+ int next = readWS();
+
+ switch (next)
+ {
+ case '\"':
+ if (tokenBufferLength > 0)
+ tokenBufferLength--;
+ return IDENTIFIER;
+ case '\'':
+ if (tokenBufferLength > 0)
+ tokenBufferLength--;
+ return IDENTIFIER;
+ case '(':
+ return PAREN_OPEN;
+ case ')':
+ return PAREN_CLOSE;
+ case '{':
+ return BRACE_OPEN;
+ case '}':
+ return BRACE_CLOSE;
+ case '[':
+ return BRACKET_OPEN;
+ case ']':
+ return BRACKET_CLOSE;
+ case -1:
+ return END;
+ default:
+ pushChar(next);
+ getIdentifier(c);
+ return IDENTIFIER;
+ }
+ }
+
+ /**
+ * Reads a character from the stream.
+ *
+ * @return the number of characters read or -1 if end of stream is reached.
+ * @throws IOException - any i/o encountered while reading
+ */
+ private int readChar() throws IOException
+ {
+ if (didPushChar)
+ {
+ didPushChar = false;
+ return pushedChar;
+ }
+ return reader.read();
+ }
+
+ /**
+ * Parses the the contents of the reader using the
+ * callback.
+ *
+ * @param reader - the reader to read from
+ * @param callback - the callback instance
+ * @param parsingDeclaration - true if parsing a declaration
+ * @throws IOException - any i/o error from the reader
+ */
+ void parse(Reader reader, CSSParser.CSSParserCallback callback,
+ boolean parsingDeclaration)
+ throws IOException
+ {
+ this.reader = reader;
+ this.callback = callback;
+
+ try
+ {
+ if (!parsingDeclaration)
+ while(getNextStatement())
+ ;
+ else
+ parseDeclarationBlock();
+ }
+ catch (IOException ioe)
+ {
+ // Nothing to do here.
+ }
+ }
+
+ /**
+ * Skips any white space, returning the character after the white space.
+ *
+ * @return the character after the whitespace
+ * @throws IOException - any i/o error from the reader
+ */
+ private int readWS() throws IOException
+ {
+ int next = readChar();
+ while (Character.isWhitespace((char) next))
+ {
+ readWS = true;
+ int tempNext = readChar();
+ if (tempNext == END)
+ return next;
+ next = tempNext;
+ }
+
+ // Its all whitespace
+ return END;
+ }
+
+ /**
+ * Gets the next statement, returning false if the end is reached.
+ * A statement is either an At-rule, or a ruleset.
+ *
+ * @return false if the end is reached
+ * @throws IOException - any i/o error from the reader
+ */
+ private boolean getNextStatement() throws IOException
+ {
+ int c = nextToken((char) 0);
+ switch (c)
+ {
+ case PAREN_OPEN:
+ case BRACE_OPEN:
+ case BRACKET_OPEN:
+ parseTillClosed(c);
+ break;
+ case BRACKET_CLOSE:
+ case BRACE_CLOSE:
+ case PAREN_CLOSE:
+ throw new IOException("Not a proper statement.");
+ case IDENTIFIER:
+ if (tokenBuffer[0] == ('@'))
+ parseAtRule();
+ else
+ parseRuleSet();
+ break;
+ case END:
+ return false;
+ }
+ return true;
+ }
+
+ /**
+ * Parses an @ rule, stopping at a matching brace pair, or ;.
+ *
+ * @throws IOException - any i/o error from the reader
+ */
+ private void parseAtRule() throws IOException
+ {
+ // An At-Rule begins with the "@" character followed immediately by a keyword.
+ // Following the keyword separated by a space is an At-rule statement appropriate
+ // to the At-keyword used. If the At-Rule is a simple declarative statement
+ // (charset, import, fontdef), it is terminated by a semi-colon (";".)
+ // If the At-Rule is a conditional or informative statement (media, page, font-face),
+ // it is followed by optional arguments and then a style declaration block inside matching
+ // curly braces ("{", "}".) At-Rules are sometimes nestable, depending on the context.
+ // If any part of an At-Rule is not understood, it should be ignored.
+
+ // FIXME: Not Implemented
+ // call handleimport
+ }
+
+ /**
+ * Parses the next rule set, which is a selector followed by a declaration
+ * block.
+ *
+ * @throws IOException - any i/o error from the reader
+ */
+ private void parseRuleSet() throws IOException
+ {
+ // call parseDeclarationBlock
+ // call parse selectors
+ // call parse identifiers
+ // call startrule/endrule
+ // FIXME: Not Implemented
+ }
+
+ /**
+ * Parses a set of selectors, returning false if the end of the stream is
+ * reached.
+ *
+ * @return false if the end of stream is reached
+ * @throws IOException - any i/o error from the reader
+ */
+ private boolean parseSelectors() throws IOException
+ {
+ // FIXME: Not Implemented
+ // call handleselector
+ return false;
+ }
+
+ /**
+ * Parses a declaration block. Which a number of declarations followed by a
+ * })].
+ *
+ * @throws IOException - any i/o error from the reader
+ */
+ private void parseDeclarationBlock() throws IOException
+ {
+ // call parseDeclaration
+ // FIXME: Not Implemented
+ }
+
+ /**
+ * Parses a single declaration, which is an identifier a : and another identifier.
+ * This returns the last token seen.
+ *
+ * @returns the last token
+ * @throws IOException - any i/o error from the reader
+ */
+ private int parseDeclaration() throws IOException
+ {
+ // call handleValue
+ // FIXME: Not Implemented
+ return 0;
+ }
+
+ /**
+ * Parses identifiers until c is encountered, returning the ending token,
+ * which will be IDENTIFIER if c is found.
+ *
+ * @param c - the stop character
+ * @param wantsBlocks - true if blocks are wanted
+ * @return the ending token
+ * @throws IOException - any i/o error from the reader
+ */
+ private int parseIdentifiers(char c, boolean wantsBlocks) throws IOException
+ {
+ // FIXME: Not implemented
+ // call handleproperty?
+ return 0;
+ }
+
+ /**
+ * Parses till a matching block close is encountered. This is only appropriate
+ * to be called at the top level (no nesting).
+ *
+ * @param i - FIXME
+ * @throws IOException - any i/o error from the reader
+ */
+ private void parseTillClosed(int i) throws IOException
+ {
+ // FIXME: Not Implemented
+ }
+
+ /**
+ * Gets an identifier, returning true if the length of the string is greater
+ * than 0, stopping when c, whitespace, or one of {}()[] is hit.
+ *
+ * @param c - the stop character
+ * @return returns true if the length of the string > 0
+ * @throws IOException - any i/o error from the reader
+ */
+ private boolean getIdentifier(char c) throws IOException
+ {
+ // FIXME: Not Implemented
+ return false;
+ }
+
+ /**
+ * Reads till c is encountered, escaping characters as necessary.
+ *
+ * @param c - the stop character
+ * @throws IOException - any i/o error from the reader
+ */
+ private void readTill(char c) throws IOException
+ {
+ // FIXME: Not Implemented
+ }
+
+ /**
+ * Parses a comment block.
+ *
+ * @throws IOException - any i/o error from the reader
+ */
+ private void readComment() throws IOException
+ {
+ // Should ignore comments. Read until end of comment.
+ // FIXME: Not implemented
+ }
+
+ /**
+ * Called when a block start is encountered ({[.
+ *
+ * @param start of block
+ */
+ private void startBlock(int start)
+ {
+ // FIXME: Not Implemented
+ }
+
+ /**
+ * Called when an end block is encountered )]}
+ *
+ * @param end of block
+ */
+ private void endBlock(int end)
+ {
+ // FIXME: Not Implemented
+ }
+
+ /**
+ * Checks if currently in a block.
+ *
+ * @return true if currently in a block.
+ */
+ private boolean inBlock()
+ {
+ // FIXME: Not Implemented
+ return false;
+ }
+
+ /**
+ * Supports one character look ahead, this will throw if called twice in a row.
+ *
+ * @param c - the character to push.
+ * @throws IOException - if called twice in a row
+ */
+ private void pushChar(int c) throws IOException
+ {
+ if (didPushChar)
+ throw new IOException("pushChar called twice.");
+ didPushChar = true;
+ pushedChar = c;
+ }
+}