Class ExpressionParser

java.lang.Object
net.sf.saxon.expr.ExpressionParser
Direct Known Subclasses:
QueryParser

public class ExpressionParser extends 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
  • Field Details

    • t

      protected Tokenizer t
    • env

      protected StaticContext env
    • rangeVariables

      protected Stack rangeVariables
    • nameChecker

      protected NameChecker nameChecker
    • scanOnly

      protected boolean scanOnly
    • compileWithTracing

      protected boolean compileWithTracing
    • language

      protected int language
    • XPATH

      protected static final int XPATH
      See Also:
    • XSLT_PATTERN

      protected static final int XSLT_PATTERN
      See Also:
    • SEQUENCE_TYPE

      protected static final int SEQUENCE_TYPE
      See Also:
    • XQUERY

      protected static final int XQUERY
      See Also:
  • Constructor Details

    • ExpressionParser

      public ExpressionParser()
      Create an expression parser
  • Method Details

    • 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(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(String message, 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(String message) throws XPathException
      Output a warning message
      Parameters:
      message - the text of the message
      Throws:
      XPathException
    • getLanguage

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

      public Expression parse(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(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(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(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 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(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(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(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(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, 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, 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, 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(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.