Class ExpressionParser

  • Direct Known Subclasses:
    QueryParser

    public class ExpressionParser
    extends java.lang.Object
    Parser for XPath expressions and XSLT patterns. This code was originally inspired by James Clark's xt but has been totally rewritten (several times)
    Author:
    Michael Kay
    • Constructor Detail

      • ExpressionParser

        public ExpressionParser()
        Create an expression parser
    • Method Detail

      • setCompileWithTracing

        public void setCompileWithTracing​(boolean trueOrFalse)
        Set whether trace hooks are to be included in the compiled code. To use tracing, it is necessary both to compile the code with trace hooks included, and to supply a TraceListener at run-time
        Parameters:
        trueOrFalse - true if trace code is to be compiled in, false otherwise
      • isCompileWithTracing

        public boolean isCompileWithTracing()
        Determine whether trace hooks are included in the compiled code.
        Returns:
        true if trace hooks are included, false if not.
      • getTokenizer

        public Tokenizer getTokenizer()
        Get the tokenizer (the lexical analyzer)
        Returns:
        the tokenizer (the lexical analyzer)
      • nextToken

        protected void nextToken()
                          throws XPathException
        Read the next token, catching any exception thrown by the tokenizer
        Throws:
        XPathException
      • expect

        protected void expect​(int token)
                       throws XPathException
        Expect a given token; fail if the current token is different. Note that this method does not read any tokens.
        Parameters:
        token - the expected token
        Throws:
        XPathException - if the current token is not the expected token
      • grumble

        protected void grumble​(java.lang.String message)
                        throws XPathException
        Report a syntax error (a static error with error code XP0003)
        Parameters:
        message - the error message
        Throws:
        XPathException - always thrown: an exception containing the supplied message
      • grumble

        protected void grumble​(java.lang.String message,
                               java.lang.String errorCode)
                        throws XPathException
        Report a static error
        Parameters:
        message - the error message
        errorCode - the error code
        Throws:
        XPathException - always thrown: an exception containing the supplied message
      • warning

        protected void warning​(java.lang.String message)
                        throws XPathException
        Output a warning message
        Parameters:
        message - the text of the message
        Throws:
        XPathException
      • getLanguage

        protected java.lang.String getLanguage()
        Get the current language (XPath or XQuery)
        Returns:
        a string representation of the language being parsed, for use in error messages
      • currentTokenDisplay

        protected java.lang.String currentTokenDisplay()
        Display the current token in an error message
        Returns:
        the display representation of the token
      • parse

        public Expression parse​(java.lang.String expression,
                                int start,
                                int terminator,
                                int lineNumber,
                                StaticContext env)
                         throws XPathException
        Parse a string representing an expression
        Parameters:
        expression - the expression expressed as a String
        start - offset within the string where parsing is to start
        terminator - character to treat as terminating the expression
        lineNumber - location of the start of the expression, for diagnostics
        env - the static context for the expression
        Returns:
        an Expression object representing the result of parsing
        Throws:
        XPathException - if the expression contains a syntax error
      • parsePattern

        public Pattern parsePattern​(java.lang.String pattern,
                                    StaticContext env)
                             throws XPathException
        Parse a string representing an XSLT pattern
        Parameters:
        pattern - the pattern expressed as a String
        env - the static context for the pattern
        Returns:
        a Pattern object representing the result of parsing
        Throws:
        XPathException - if the pattern contains a syntax error
      • parseSequenceType

        public SequenceType parseSequenceType​(java.lang.String input,
                                              StaticContext env)
                                       throws XPathException
        Parse a string representing a sequence type
        Parameters:
        input - the string, which should conform to the XPath SequenceType production
        env - the static context
        Returns:
        a SequenceType object representing the type
        Throws:
        XPathException - if any error is encountered
      • parseExpression

        protected Expression parseExpression()
                                      throws XPathException
        Parse a top-level Expression: ExprSingle ( ',' ExprSingle )*
        Returns:
        the Expression object that results from parsing
        Throws:
        XPathException - if the expression contains a syntax error
      • parseExprSingle

        protected Expression parseExprSingle()
                                      throws XPathException
        Parse an ExprSingle
        Returns:
        the resulting subexpression
        Throws:
        XPathException - if any error is encountered
      • parseTypeswitchExpression

        protected Expression parseTypeswitchExpression()
                                                throws XPathException
        Parse a Typeswitch Expression. This construct is XQuery-only, so the XPath version of this method throws an error unconditionally
        Returns:
        the expression that results from the parsing
        Throws:
        XPathException
      • parseValidateExpression

        protected Expression parseValidateExpression()
                                              throws XPathException
        Parse a Validate Expression. This construct is XQuery-only, so the XPath version of this method throws an error unconditionally
        Returns:
        the parsed expression; except that this version of the method always throws an exception
        Throws:
        XPathException
      • parseExtensionExpression

        protected Expression parseExtensionExpression()
                                               throws XPathException
        Parse an Extension Expression This construct is XQuery-only, so the XPath version of this method throws an error unconditionally
        Returns:
        the parsed expression; except that this version of the method always throws an exception
        Throws:
        XPathException
      • parseForExpression

        protected Expression parseForExpression()
                                         throws XPathException
        Parse a FOR expression: for $x in expr (',' $y in expr)* 'return' expr
        Returns:
        the resulting subexpression
        Throws:
        XPathException - if any error is encountered
      • parseMappingExpression

        protected Expression parseMappingExpression()
                                             throws XPathException
        Parse a mapping expression. This is a common routine that handles XPath 'for' expressions and quantified expressions.

        Syntax:
        (for|some|every) $x in expr (',' $y in expr)* (return|satisfies) expr

        On entry, the current token indicates whether a for, some, or every expression is expected.

        Returns:
        the resulting subexpression
        Throws:
        XPathException - if any error is encountered
      • parseSequenceType

        protected SequenceType parseSequenceType()
                                          throws XPathException
        Parse the sequence type production. The QName must be the name of a built-in schema-defined data type.
        Returns:
        the resulting subexpression
        Throws:
        XPathException - if any error is encountered
      • parseRelativePath

        protected Expression parseRelativePath()
                                        throws XPathException
        Parse a relative path (a sequence of steps). Called when the current token immediately follows a separator (/ or //), or an implicit separator (XYZ is equivalent to ./XYZ)
        Returns:
        the resulting subexpression
        Throws:
        XPathException - if any error is encountered
      • parseRemainingPath

        protected Expression parseRemainingPath​(Expression start)
                                         throws XPathException
        Parse the remaining steps of an absolute path expression (one starting in "/" or "//"). Note that the token immediately after the "/" or "//" has already been read, and in the case of "/", it has been confirmed that we have a path expression starting with "/" rather than a standalone "/" expression.
        Parameters:
        start - the initial implicit expression: root() in the case of "/", root()/descendant-or-self::node in the case of "//"
        Returns:
        the completed path expression
        Throws:
        XPathException
      • parseStepExpression

        protected Expression parseStepExpression()
                                          throws XPathException
        Parse a step (including an optional sequence of predicates)
        Returns:
        the resulting subexpression
        Throws:
        XPathException - if any error is encountered
      • makeStringLiteral

        protected Literal makeStringLiteral​(java.lang.String currentTokenValue)
                                     throws XPathException
        Method to make a string literal from a token identified as a string literal. This is trivial in XPath, but in XQuery the method is overridden to identify pseudo-XML character and entity references. Note that the job of handling doubled string delimiters is done by the tokenizer.
        Parameters:
        currentTokenValue - the token as read (excluding quotation marks)
        Returns:
        The string value of the string literal
        Throws:
        XPathException
      • parseConstructor

        protected Expression parseConstructor()
                                       throws XPathException
        Parse a node constructor. This is allowed only in XQuery, so the method throws an error for XPath.
        Returns:
        the expression that results from the parsing
        Throws:
        XPathException
      • parseNodeTest

        protected NodeTest parseNodeTest​(short nodeType)
                                  throws XPathException
        Parse a NodeTest. One of QName, prefix:*, *:suffix, *, text(), node(), comment(), or processing-instruction(literal?), or element(~,~), attribute(~,~), etc.
        Parameters:
        nodeType - the node type being sought if one is specified
        Returns:
        the resulting NodeTest object
        Throws:
        XPathException - if any error is encountered
      • parseFunctionCall

        protected Expression parseFunctionCall()
                                        throws XPathException
        Parse a function call. function-name '(' ( Expression (',' Expression )* )? ')'
        Returns:
        the resulting subexpression
        Throws:
        XPathException - if any error is encountered
      • declareRangeVariable

        protected void declareRangeVariable​(Binding declaration)
                                     throws XPathException
        Declare a range variable (record its existence within the parser). A range variable is a variable declared within an expression, as distinct from a variable declared in the context.
        Parameters:
        declaration - the variable declaration to be added to the stack
        Throws:
        XPathException - if any error is encountered
      • undeclareRangeVariable

        protected void undeclareRangeVariable()
        Note when the most recently declared range variable has gone out of scope
      • getRangeVariableStack

        public java.util.Stack getRangeVariableStack()
        Get the range variable stack. Used when parsing a nested subexpression inside an attribute constructor
        Returns:
        the stack used for locally-declared variables
      • setRangeVariableStack

        public void setRangeVariableStack​(java.util.Stack stack)
        Set the range variable stack. Used when parsing a nested subexpression inside an attribute constructor.
        Parameters:
        stack - the stack to be used for local variables declared within the expression
      • makeNameCode

        public final int makeNameCode​(java.lang.String qname,
                                      boolean useDefault)
                               throws XPathException
        Make a NameCode, using the static context for namespace resolution
        Parameters:
        qname - The name as written, in the form "[prefix:]localname"
        useDefault - Defines the action when there is no prefix. If true, use the default namespace URI for element names. If false, use no namespace URI (as for attribute names).
        Returns:
        the namecode, which can be used to identify this name in the name pool
        Throws:
        XPathException - if the name is invalid, or the prefix undeclared
      • makeNameCodeSilently

        public final int makeNameCodeSilently​(java.lang.String qname,
                                              boolean useDefault)
                                       throws XPathException,
                                              QNameException
        Make a NameCode, using the static context for namespace resolution. This variant of the method does not call "grumble" to report any errors to the ErrorListener, it only reports errors by throwing exceptions. This allows the caller to control the message output.
        Parameters:
        qname - The name as written, in the form "[prefix:]localname"
        useDefault - Defines the action when there is no prefix. If true, use the default namespace URI for element names. If false, use no namespace URI (as for attribute names).
        Returns:
        the namecode, which can be used to identify this name in the name pool
        Throws:
        XPathException - if the name is invalid, or the prefix undeclared
        QNameException
      • makeStructuredQName

        public final StructuredQName makeStructuredQName​(java.lang.String qname,
                                                         boolean useDefault)
                                                  throws XPathException
        Make a Structured QName, using the static context for namespace resolution
        Parameters:
        qname - The name as written, in the form "[prefix:]localname"
        useDefault - Defines the action when there is no prefix. If true, use the default namespace URI for element names. If false, use no namespace URI (as for attribute names).
        Returns:
        the namecode, which can be used to identify this name in the name pool
        Throws:
        XPathException - if the name is invalid, or the prefix undeclared
      • makeNameTest

        public NameTest makeNameTest​(short nodeType,
                                     java.lang.String qname,
                                     boolean useDefault)
                              throws XPathException
        Make a NameTest, using the static context for namespace resolution
        Parameters:
        nodeType - the type of node required (identified by a constant in class Type)
        qname - the lexical QName of the required node
        useDefault - true if the default namespace should be used when the QName is unprefixed
        Returns:
        a NameTest, representing a pattern that tests for a node of a given node kind and a given name
        Throws:
        XPathException - if the QName is invalid
      • makeNamespaceTest

        public NamespaceTest makeNamespaceTest​(short nodeType,
                                               java.lang.String prefix)
                                        throws XPathException
        Make a NamespaceTest (name:*)
        Parameters:
        nodeType - integer code identifying the type of node required
        prefix - the namespace prefix
        Returns:
        the NamespaceTest, a pattern that matches all nodes in this namespace
        Throws:
        XPathException - if the namespace prefix is not declared
      • makeLocalNameTest

        public LocalNameTest makeLocalNameTest​(short nodeType,
                                               java.lang.String localName)
                                        throws XPathException
        Make a LocalNameTest (*:name)
        Parameters:
        nodeType - the kind of node to be matched
        localName - the requred local name
        Returns:
        a LocalNameTest, a pattern which matches all nodes of a given local name, regardless of namespace
        Throws:
        XPathException - if the local name is invalid
      • setLocation

        protected void setLocation​(Expression exp)
        Set location information on an expression. At present this consists of a simple line number. Needed mainly for XQuery.
        Parameters:
        exp - the expression whose location information is to be set
      • setLocation

        protected void setLocation​(Expression exp,
                                   int offset)
        Set location information on an expression. At present only the line number is retained. Needed mainly for XQuery. This version of the method supplies an explicit offset (character position within the expression or query), which the tokenizer can convert to a line number and column number.
        Parameters:
        exp - the expression whose location information is to be set
        offset - the character position within the expression (ignoring newlines)
      • makeTracer

        protected Expression makeTracer​(int startOffset,
                                        Expression exp,
                                        int construct,
                                        StructuredQName qName)
        If tracing, wrap an expression in a trace instruction
        Parameters:
        startOffset - the position of the expression in the soruce
        exp - the expression to be wrapped
        construct - integer constant identifying the kind of construct
        qName - the name of the construct (if applicable)
        Returns:
        the expression that does the tracing
      • isKeyword

        protected boolean isKeyword​(java.lang.String s)
        Test whether the current token is a given keyword.
        Parameters:
        s - The string to be compared with the current token
        Returns:
        true if they are the same
      • setScanOnly

        public void setScanOnly​(boolean scanOnly)
        Set that we are parsing in "scan only"
        Parameters:
        scanOnly - true if parsing is to proceed in scan-only mode. In this mode namespace bindings are not yet known, so no attempt is made to look up namespace prefixes.