com.saxonica.bytecode
Class CountCompiler

java.lang.Object
  com.saxonica.bytecode.ExpressionCompiler
      com.saxonica.bytecode.ToItemCompiler
          com.saxonica.bytecode.CountCompiler

public class CountCompiler
extends ToItemCompiler

Generate bytecode for a call to the count() function

Constructor Summary

CountCompiler()

Method Summary

void	compileToItem(CompilerService compiler, Expression expression) Generate bytecode to evaluate the expression as an Item Precondition: none.
void	compileToPrimitive(CompilerService compiler, Expression expression, Class requiredClass, OnEmpty onEmpty) Generate bytecode to evaluate the expression leaving a plain Java value on the stack.
static boolean	maybeLastPositionFinder(Expression expression)

Methods inherited from class com.saxonica.bytecode.ToItemCompiler

compileToBoolean, compileToIterator, compileToPush, returnZeroLengthStringIfNull

Methods inherited from class com.saxonica.bytecode.ExpressionCompiler

allocateStatic, compileItemFromInt, compileItemFromString, compileToLoop, generateMethod, getConfiguration, handleEmptyStringResult, setConfiguration, throwXPathException, throwXPathException, unboxItem, verify, visitAnnotation, visitLineNumber

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CountCompiler

public CountCompiler()

Method Detail

compileToPrimitive

public void compileToPrimitive(CompilerService compiler,
                               Expression expression,
                               Class requiredClass,
                               OnEmpty onEmpty)
                        throws CannotCompileException

Description copied from class: ExpressionCompiler

Generate bytecode to evaluate the expression leaving a plain Java value on the stack. This method must only be called if the static type of the expressionis such that the value is known to be representable by a value of the specified class; the cardinality must be either exactly-one or zero-or-one.

Overrides:

compileToPrimitive in class ExpressionCompiler

Parameters:

compiler - the compiler service

expression - the expression to be compiled

requiredClass - the class of the Java value that is to be left on the stack if the generated code exits normally. This must be one of Integer.TYPE, Double.TYPE, Float.TYPE, BigDecimal.class, CharSequence.class.

onEmpty - defines the action to be taken if the expression evaluates to the empty sequence. May be null if the expression is known statically not to evaluate to an empty sequence. If the return class is a primitive type (double, float, etc) this must be an instance of OnEmpty.UnwindAndJump

Throws:

CannotCompileException

compileToItem

public void compileToItem(CompilerService compiler,
                          Expression expression)
                   throws CannotCompileException

Generate bytecode to evaluate the expression as an Item Precondition: none. Postcondition: the stack contains either an item (the result of the expression), or null (representing an empty sequence).

Specified by:

compileToItem in class ExpressionCompiler

Parameters:

compiler - the compiler service

expression - the expression to be compiled

Throws:

CannotCompileException

maybeLastPositionFinder

public static boolean maybeLastPositionFinder(Expression expression)