Here comes a rudimentary parser. This is capable for parsing the
default.css from Swing, so it should be enough for a start.
Next thing will be to wire this into javax.swing.text.html in order to
enable stylesheet support in Swing HTML.
2006-08-21 Roman Kennke <[EMAIL PROTECTED]>
* gnu/javax/swing/text/html/css/CSSParser.java:
New class.
* gnu/javax/swing/text/html/css/CSSParserCallback.java:
New interface.
* gnu/javax/swing/text/html/css/CSSParserException.java:
New exception.
* gnu/javax/swing/text/html/css/CSSScanner.java:
Adjusted API comments. Made all constants package private.
(EOF): New constant field.
(parseBuffer): Made package private.
(tokenEnd): Made package private.
(CSSScanner): Initialize lookahead buffer with -1.
(main): Print out to System.out rather then System.err.
(nextToken): Push back character after IDENT.
/Roman
Index: gnu/javax/swing/text/html/css/CSSParser.java
===================================================================
RCS file: gnu/javax/swing/text/html/css/CSSParser.java
diff -N gnu/javax/swing/text/html/css/CSSParser.java
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ gnu/javax/swing/text/html/css/CSSParser.java 21 Aug 2006 20:44:14 -0000
@@ -0,0 +1,470 @@
+/* CSSParser.java -- A parser for CSS stylesheets
+ Copyright (C) 2006 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 gnu.javax.swing.text.html.css;
+
+import java.io.BufferedInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+
+/**
+ * A parser for CSS stylesheets.
+ *
+ * This parser is based on the simple CSS grammar describe in
+ *
+ * http://www.w3.org/TR/CSS21/syndata.html .
+ *
+ * @author Roman Kennke ([EMAIL PROTECTED])
+ */
+// TODO: Maybe use more restrictive grammar:
+// http://www.w3.org/TR/CSS21/grammar.html#q1
+public class CSSParser
+{
+
+ /**
+ * The scanner used to read the input streams into more usable tokens.
+ */
+ private CSSScanner scanner;
+
+ /**
+ * The parser callback.
+ */
+ private CSSParserCallback callback;
+
+ /**
+ * One lookahead token.
+ */
+ private int lookahead;
+
+ /**
+ * The parse error.
+ */
+ private String error;
+
+ /**
+ * Creates a new CSSParser that parses the specified input.
+ *
+ * @param in the source to parse
+ */
+ public CSSParser(Reader in, CSSParserCallback cb)
+ {
+ scanner = new CSSScanner(in);
+ callback = cb;
+ lookahead = -1;
+ }
+
+ /**
+ * Parses the input source specified in the constructor.
+ *
+ * @throws IOException if an IO or parse error occurs
+ */
+ public void parse()
+ throws IOException
+ {
+ boolean success = parseStylesheet();
+ if (! success)
+ {
+ throw new CSSParserException(error);
+ }
+ }
+
+ /**
+ * Parses a stylesheet.
+ *
+ * @return <code>true</code> if the stylesheet could be parsed successfully,
+ * <code>false</code> otherwise
+ *
+ * @throws IOException if an IO or parse error occurs
+ */
+ private boolean parseStylesheet()
+ throws IOException
+ {
+ int token = peekToken();
+ while (token != CSSScanner.EOF && (token == CSSScanner.CDC
+ || token == CSSScanner.CDO || token == CSSScanner.S
+ || parseStatement()))
+ {
+ if (token == CSSScanner.CDC || token == CSSScanner.CDO
+ || token == CSSScanner.S)
+ readToken();
+ token = peekToken();
+ }
+ // Last token must be EOF for valid stylesheets, I'd think.
+ return token == CSSScanner.EOF;
+ }
+
+ /**
+ * Parses a CSS statement.
+ * @return <code>true</code> if the stylesheet could be parsed successfully,
+ * <code>false</code> otherwise
+ *
+ * @throws IOException if an IO or parse error occurs
+ */
+ private boolean parseStatement()
+ throws IOException
+ {
+ return parseRuleset() || parseAtRule();
+ }
+
+ /**
+ * Parses a CSS rule set.
+ *
+ * @return <code>true</code> if the ruleset could be parsed successfully,
+ * <code>false</code> otherwise
+ *
+ * @throws IOException if an IO or parse error occurs
+ */
+ private boolean parseRuleset()
+ throws IOException
+ {
+ StringBuilder selector = new StringBuilder();
+ parseSelector(selector);
+ callback.startStatement(selector.toString());
+ // Read any number of whitespace.
+ int token;
+ do
+ {
+ token = readToken();
+ } while (token == CSSScanner.S);
+ boolean ret = true;
+
+ if (token == CSSScanner.CURLY_LEFT)
+ {
+ // Read any number of whitespace.
+ do
+ {
+ token = readToken();
+ } while (token == CSSScanner.S);
+ lookahead = token;
+
+ // Maybe read declaration.
+ boolean decl = parseDeclaration();
+ token = peekToken();
+ while (token == CSSScanner.SEMICOLON)
+ {
+ readToken(); // Read the semicolon.
+ // Read any number of whitespace.
+ do
+ {
+ token = readToken();
+ } while (token == CSSScanner.S);
+ lookahead = token;
+
+ // Maybe read declaration.
+ parseDeclaration();
+ token = peekToken();
+ }
+ if (token != CSSScanner.CURLY_RIGHT)
+ {
+ error = "Expected right curly brace";
+ ret = false;
+ }
+ else
+ {
+ readToken();
+ // Read any number of whitespace.
+ do
+ {
+ token = readToken();
+ } while (token == CSSScanner.S);
+ lookahead = token;
+ callback.endStatement();
+ }
+ }
+ else
+ {
+ ret = false;
+ error = "Expected left curly brace";
+ }
+ return ret;
+ }
+
+ /**
+ * Parses a CSS declaration.
+ *
+ * @return <code>true</code> if the ruleset could be parsed successfully,
+ * <code>false</code> otherwise
+ *
+ * @throws IOException if an IO or parse error occurs
+ */
+ private boolean parseDeclaration()
+ throws IOException
+ {
+ // Maybe fetch one DELIM.
+ int token = readToken();
+ if (token == CSSScanner.DELIM)
+ token = readToken();
+
+ boolean ret = true;
+
+ // Parse property
+ String property = null;
+ if (token == CSSScanner.IDENT)
+ {
+ property = new String(scanner.parseBuffer, 0, scanner.tokenEnd);
+ // Read any number of whitespace.
+ do
+ {
+ token = readToken();
+ } while (token == CSSScanner.S);
+
+ // Read ':'.
+ if (token == CSSScanner.DELIM && scanner.parseBuffer[0] == ':')
+ {
+ // Read any number of whitespace.
+ do
+ {
+ token = readToken();
+ } while (token == CSSScanner.S);
+ lookahead = token;
+
+ StringBuilder value = new StringBuilder();
+ if (parseValue(value))
+ {
+ callback.declaration(property, value.toString());
+ }
+ else
+ {
+ ret = false;
+ error = "Error while reading the property value";
+ }
+ }
+ else
+ {
+ ret = false;
+ error = "Expected colon to separate property and value";
+ }
+
+ }
+ else
+ {
+ lookahead = token;
+ ret = false;
+ error = "Expected IDENT token for property";
+ }
+ return ret;
+ }
+
+ /**
+ * Parses a property value.
+ *
+ * @param s the string builder to read the value into
+ *
+ * @return <code>true</code> if the ruleset could be parsed successfully,
+ * <code>false</code> otherwise
+ *
+ * @throws IOException if an IO or parse error occurs
+ */
+ private boolean parseValue(StringBuilder s)
+ throws IOException
+ {
+ // FIXME: Handle block and ATKEYWORD.
+ return parseAny(s);
+ }
+
+ /**
+ * Parses a selector.
+ *
+ * @param sel the string buffer to put the selector into
+ *
+ * @return <code>true</code> if the ruleset could be parsed successfully,
+ * <code>false</code> otherwise
+ *
+ * @throws IOException if an IO or parse error occurs
+ */
+ private boolean parseSelector(StringBuilder sel)
+ throws IOException
+ {
+ // At least one any needs to be parsed.
+ boolean ret = parseAny(sel);
+ if (ret)
+ {
+ while (parseAny(sel));
+ }
+ return ret;
+ }
+
+ /**
+ * Parses the any rule. If s is not null, then the contents of the
+ * tokens is appended verbatim.
+ *
+ * @param s the string builder to append to
+ *
+ * @return <code>true</code> if the ruleset could be parsed successfully,
+ * <code>false</code> otherwise
+ *
+ * @throws IOException if an IO or parse error occurs
+ */
+ private boolean parseAny(StringBuilder s)
+ throws IOException
+ {
+ int token = peekToken();
+ boolean ret = false;
+ if (token == CSSScanner.IDENT || token == CSSScanner.NUMBER
+ || token == CSSScanner.PERCENTAGE || token == CSSScanner.DIMENSION
+ || token == CSSScanner.STRING || token == CSSScanner.DELIM
+ || token == CSSScanner.URI || token == CSSScanner.HASH
+ || token == CSSScanner.UNICODE_RANGE || token == CSSScanner.INCLUDES
+ || token == CSSScanner.DASHMATCH)
+ {
+ if (s != null)
+ s.append(scanner.parseBuffer, 0, scanner.tokenEnd);
+ readToken();
+ ret = true;
+ }
+ else if (token == CSSScanner.FUNCTION)
+ System.err.println("Implement parseAny for FUNCTION");
+ else if (token == CSSScanner.PAREN_LEFT)
+ System.err.println("Implement parseAny for (");
+ else if (token == CSSScanner.BRACE_LEFT)
+ System.err.println("Implement parseAny for [");
+
+ // Parse any following whitespace too.
+ token = peekToken();
+ while (token == CSSScanner.S)
+ {
+ if (s != null)
+ s.append(scanner.parseBuffer, 0, scanner.tokenEnd);
+ readToken();
+ token = peekToken();
+ }
+ return ret;
+ }
+
+ /**
+ * Parses a CSS at-rule.
+ *
+ * @return <code>true</code> if the at-rule could be parsed successfully,
+ * <code>false</code> otherwise
+ *
+ * @throws IOException if an IO or parse error occurs
+ */
+ private boolean parseAtRule()
+ throws IOException
+ {
+ // FIXME: Implement.
+ return false;
+ }
+
+ /**
+ * Reads the next token, and skips the comments.
+ *
+ * @return the next non-comment token
+ */
+ private int readToken()
+ throws IOException
+ {
+ int token;
+ if (lookahead == -1)
+ {
+ do
+ {
+ token = scanner.nextToken();
+ } while (token == CSSScanner.COMMENT);
+ }
+ else
+ {
+ token = lookahead;
+ lookahead = -1;
+ }
+ return token;
+ }
+
+ /**
+ * Returns the next token to be read, without really reading it. The next
+ * call to readToken() will return the same token again.
+ *
+ * @return the next token to be read, without really reading it
+ */
+ private int peekToken()
+ throws IOException
+ {
+ int token;
+ if (lookahead == -1)
+ {
+ do
+ {
+ token = scanner.nextToken();
+ } while (token == CSSScanner.COMMENT);
+ lookahead = token;
+ }
+ else
+ token = lookahead;
+ return token;
+ }
+
+ /**
+ * For testing, we read in the default.css in javax/swing/text/html
+ *
+ * @param args
+ */
+ public static void main(String[] args)
+ {
+ try
+ {
+ String name = "/javax/swing/text/html/default.css";
+ InputStream in = CSSScanner.class.getResourceAsStream(name);
+ BufferedInputStream bin = new BufferedInputStream(in);
+ InputStreamReader r = new InputStreamReader(bin);
+ CSSParserCallback cb = new CSSParserCallback()
+ {
+ public void startStatement(String selector)
+ {
+ System.out.println("startStatement: " + selector);
+ }
+ public void endStatement()
+ {
+ System.out.println("endStatement");
+ }
+ public void declaration(String property, String value)
+ {
+ System.out.println("declaration: " + property + ", " + value);
+ }
+ };
+ CSSParser p = new CSSParser(r, cb);
+ p.parse();
+ }
+ catch (IOException ex)
+ {
+ ex.printStackTrace();
+ }
+ }
+
+}
Index: gnu/javax/swing/text/html/css/CSSParserCallback.java
===================================================================
RCS file: gnu/javax/swing/text/html/css/CSSParserCallback.java
diff -N gnu/javax/swing/text/html/css/CSSParserCallback.java
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ gnu/javax/swing/text/html/css/CSSParserCallback.java 21 Aug 2006 20:44:14 -0000
@@ -0,0 +1,81 @@
+/* CSSParserCallback.java -- Callback for parsing CSS
+ Copyright (C) 2006 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 gnu.javax.swing.text.html.css;
+
+/**
+ * Defines the callback that is used by the CSSParser to notify the
+ * backend of the parsing process.
+ *
+ * @author Roman Kennke ([EMAIL PROTECTED])
+ */
+public interface CSSParserCallback
+{
+
+ /**
+ * Signals the beginning of a statement.
+ *
+ * A CSS statement is build up like follows:
+ * <pre>
+ * <selector> {
+ * ... declarations...
+ * }
+ * </pre>
+ *
+ * After startStatement(), the callback will receive zero to n callbacks
+ * to declaration, followed by an endStatement() call.
+ *
+ * @param selector the selector of the statement.
+ */
+ void startStatement(String selector);
+
+ /**
+ * Signals the end of a statement.
+ */
+ void endStatement();
+
+ /**
+ * Signals the parsing of one declaration, which defines a mapping
+ * from a property to a value.
+ *
+ * @param property the property
+ * @param value the value
+ */
+ void declaration(String property, String value);
+
+}
Index: gnu/javax/swing/text/html/css/CSSParserException.java
===================================================================
RCS file: gnu/javax/swing/text/html/css/CSSParserException.java
diff -N gnu/javax/swing/text/html/css/CSSParserException.java
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ gnu/javax/swing/text/html/css/CSSParserException.java 21 Aug 2006 20:44:15 -0000
@@ -0,0 +1,62 @@
+/* CSSParserException.java -- The CSS parser exception
+ Copyright (C) 2006 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 gnu.javax.swing.text.html.css;
+
+import java.io.IOException;
+
+/**
+ * This exception is raised when the CSS parser hits a syntax error.
+ *
+ * @author Roman Kennke ([EMAIL PROTECTED])
+ */
+public class CSSParserException
+ extends IOException
+{
+
+ /**
+ * Creates a new CSSParserException.
+ *
+ * @param message the exception message
+ */
+ public CSSParserException(String message)
+ {
+ super(message);
+ }
+
+}
Index: gnu/javax/swing/text/html/css/CSSScanner.java
===================================================================
RCS file: /cvsroot/classpath/classpath/gnu/javax/swing/text/html/css/CSSScanner.java,v
retrieving revision 1.3
diff -u -1 -2 -r1.3 CSSScanner.java
--- gnu/javax/swing/text/html/css/CSSScanner.java 21 Aug 2006 10:27:44 -0000 1.3
+++ gnu/javax/swing/text/html/css/CSSScanner.java 21 Aug 2006 20:44:15 -0000
@@ -36,84 +36,92 @@
exception statement from your version. */
package gnu.javax.swing.text.html.css;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
/**
- * A parser for CSS stylesheets. This is based on the grammar from:
+ * A tokenizer for CSS stylesheets. This is based on the scanner definition
+ * from:
*
- * http://www.w3.org/TR/CSS21/syndata.html
+ * http://www.w3.org/TR/CSS21/syndata.html#tokenization
*
* @author Roman Kennke ([EMAIL PROTECTED])
*/
+// TODO: Maybe implement more restrictive scanner:
+// http://www.w3.org/TR/CSS21/grammar.html#q2
class CSSScanner
{
// The tokens. This list is taken from:
// http://www.w3.org/TR/CSS21/syndata.html#tokenization
- private static final int IDENT = 1;
- private static final int ATKEYWORD = 2;
- private static final int STRING = 3;
- private static final int INVALID = 4;
- private static final int HASH = 5;
- private static final int NUMBER = 6;
- private static final int PERCENTAGE = 7;
- private static final int DIMENSION = 8;
- private static final int URI = 9;
- private static final int UNICODE_RANGE = 10;
- private static final int CDO = 11;
- private static final int CDC = 12;
- private static final int SEMICOLON = 13;
- private static final int CURLY_LEFT = 14;
- private static final int CURLY_RIGHT = 15;
- private static final int PAREN_LEFT = 16;
- private static final int PAREN_RIGHT = 17;
- private static final int BRACE_LEFT = 16;
- private static final int BRACE_RIGHT = 17;
- private static final int S = 18;
- private static final int COMMENT = 19;
- private static final int FUNCTION = 20;
- private static final int INCLUDES = 21;
- private static final int DASHMATCH = 22;
- private static final int DELIM = 23;
+ static final int IDENT = 1;
+ static final int ATKEYWORD = 2;
+ static final int STRING = 3;
+ static final int INVALID = 4;
+ static final int HASH = 5;
+ static final int NUMBER = 6;
+ static final int PERCENTAGE = 7;
+ static final int DIMENSION = 8;
+ static final int URI = 9;
+ static final int UNICODE_RANGE = 10;
+ static final int CDO = 11;
+ static final int CDC = 12;
+ static final int SEMICOLON = 13;
+ static final int CURLY_LEFT = 14;
+ static final int CURLY_RIGHT = 15;
+ static final int PAREN_LEFT = 16;
+ static final int PAREN_RIGHT = 17;
+ static final int BRACE_LEFT = 16;
+ static final int BRACE_RIGHT = 17;
+ static final int S = 18;
+ static final int COMMENT = 19;
+ static final int FUNCTION = 20;
+ static final int INCLUDES = 21;
+ static final int DASHMATCH = 22;
+ static final int DELIM = 23;
+
+ // Additional tokens defined for convenience.
+ static final int EOF = -1;
/**
* The input source.
*/
private Reader in;
/**
* The parse buffer.
*/
- private char[] parseBuffer;
+ char[] parseBuffer;
/**
* The end index in the parseBuffer of the current token.
*/
- private int tokenEnd;
+ int tokenEnd;
/**
* The lookahead 'buffer'.
*/
private int[] lookahead;
CSSScanner(Reader r)
{
lookahead = new int[2];
+ lookahead[0] = -1;
+ lookahead[1] = -1;
parseBuffer = new char[2048];
in = r;
}
/**
* Fetches the next token. The actual character data is in the parseBuffer
* afterwards with the tokenStart at index 0 and the tokenEnd field
* pointing to the end of the token.
*
* @return the next token
*/
int nextToken()
@@ -299,24 +307,25 @@
}
break;
default:
// Handle IDENT that don't begin with '-'.
if (next == '_' || (next >= 'a' && next <= 'z')
|| (next >= 'A' && next <= 'Z') || next == '\\' || next > 177)
{
lookahead[0] = next;
readIdent();
int ch4 = read();
if (ch4 == -1 || ch4 != '(')
{
+ lookahead[0] = ch4;
token = IDENT;
}
else
{
parseBuffer[tokenEnd] = (char) ch4;
tokenEnd++;
token = FUNCTION;
}
}
else
{
parseBuffer[0] = (char) next;
@@ -687,22 +696,22 @@
{
try
{
String name = "/javax/swing/text/html/default.css";
InputStream in = CSSScanner.class.getResourceAsStream(name);
BufferedInputStream bin = new BufferedInputStream(in);
InputStreamReader r = new InputStreamReader(bin);
CSSScanner s = new CSSScanner(r);
int token;
do
{
token = s.nextToken();
- System.err.println("token: " + token + ": "
+ System.out.println("token: " + token + ": "
+ s.currentTokenString());
} while (token != -1);
}
catch (IOException ex)
{
ex.printStackTrace();
}
}
}
