com.saxonica.bytecode.util
Class CompilerService

java.lang.Object
  com.saxonica.bytecode.util.CompilerService

public class CompilerService
extends Object

Controlling/service class for compilation of expressions to Java bytecode

Nested Class Summary

static class	CompilerService.GeneratedClassInfo
class	CompilerService.GeneratedExpression sub-class GeneratedExpression - used to keep track of ExpressionCompiler classes that need to generate a method
static class	CompilerService.StaticSubClasses
static class	CompilerService.StaticVariableInfo

Field Summary

HashMap<com.saxonica.bytecode.util.CompilerService.ObjectIdentityWrapper,CompilerService.StaticSubClasses>	cClassMap
static int	tracePoint

Constructor Summary

CompilerService(Configuration config)

Method Summary

void	addNewMethod(ExpressionCompiler ec, Expression e) The methods adds the
CompilerService.StaticVariableInfo	allocateStaticVariableInfo(Object value) Create a StaticVariableInfo containing the information needed to allow a static reference to a given object to be added as a static field in the currently-being-compiled class
boolean	canCompileToLoop(Expression expr) Ask if an expression can be compiled using the compileToLoop() method
void	compileToBoolean(Expression expr) Generate bytecode to evaluate an expression leaving a boolean on the stack.
CompiledExpression	compileToByteCode(Expression expr, String objectName, int evaluationModes) Compile a top-level expression to bytecode, and return the resulting expression
void	compileToItem(Expression expr) Generate bytecode to evaluate an expression leaving either an Item or null on the stack (null indicating that the expression evaluated to an empty sequence).
void	compileToIterator(Expression expr) Generate bytecode to evaluate an expression leaving a SequenceIterator on the stack
void	compileToLoop(Expression expr, LoopBodyGenerator bodyGen)
void	compileToPrimitive(Expression expr, Class requiredClass, OnEmpty onEmpty) Compile an expression that returns a singleton (or empty) result of type xs:double, xs:float, xs:string, xs:untypedAtomic.
void	compileToPush(Expression expr) Generate bytecode to evaluate an expression by writing events to the current SequenceReceiver (leaving nothing on the stack at execution time)
void	compileToValueRepresentation(Expression expression) Compile code to evaluate a variable reference, or any other expresssion, leaving a ValueRepresentation on the stack
void	generateGetContext() Generate code to load the current XPathContext, leaving it on the top of the stack
void	generateGetReceiver() Generate code to load the current Receiver, leaving it on the top of the stack
Class	getCompiledClass(Object expr)
Configuration	getConfiguration() Get the Configuration used by this CompilerService
CompilerService.GeneratedClassInfo	getCurrentClass()
Generator	getCurrentGenerator()
GeneratedMethodInfo	getCurrentMethod()
Stack<GeneratedMethodInfo>	getCurrentMethods()
int	getFlags() Get the flag options used by the ClassWriter
int	getUniqueNumber() Get a unique number which is different from any other number allocated by a call on this method, for the same CompilerService instance
void	initNewMethod(Generator ga, boolean holdReceiverAsLocal) Initialize context information for a new method.
boolean	isDisplayByteCode()
boolean	isInRangeForInt(Expression exp)
boolean	isInRangeForLong(Expression exp)
static boolean	isLanguagePrimitiveType(AtomicType targetType)
Class	makeClass(org.objectweb.asm.ClassWriter writer, String className) Having written the bytecode for all the methods for a class, create the Class itself so it can be used
String	makeValidJavaName(String name) Given a candidate Java name, make it into a valid Java name
void	popCurrentMethodInfo()
void	popReceiverInfo() Generate code to reinstate the previous current receiver by popping it from the receiver stack.
void	pushNewClassInfo(String className, Class superclass, org.objectweb.asm.ClassWriter cw)
void	pushNewMethodInfo(Generator ga, boolean contextIsArgument, int contextVariablePosition)
void	pushNewReceiverInfo(Generator ga) Generate code to set a new current receiver on the top of the receiver stack.
void	setCompiledClass(Object expr, Class clss)

Methods inherited from class java.lang.Object

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

Field Detail

tracePoint

public static int tracePoint

cClassMap

public HashMap<com.saxonica.bytecode.util.CompilerService.ObjectIdentityWrapper,CompilerService.StaticSubClasses> cClassMap

Constructor Detail

CompilerService

public CompilerService(Configuration config)

Method Detail

isLanguagePrimitiveType

public static boolean isLanguagePrimitiveType(AtomicType targetType)

isDisplayByteCode

public boolean isDisplayByteCode()

addNewMethod

public void addNewMethod(ExpressionCompiler ec,
                         Expression e)

The methods adds the

Parameters:

ec - - The ExpressionCompiler that needs to generate a method

e - - The expression represented by the Expressioncompiler

compileToValueRepresentation

public void compileToValueRepresentation(Expression expression)
                                  throws CannotCompileException

Compile code to evaluate a variable reference, or any other expresssion, leaving a ValueRepresentation on the stack

Parameters:

expression - the expression to be compiled

Throws:

CannotCompileException - if the expression cannot be compiled

getCompiledClass

public Class getCompiledClass(Object expr)

setCompiledClass

public void setCompiledClass(Object expr,
                             Class clss)

getUniqueNumber

public int getUniqueNumber()

Get a unique number which is different from any other number allocated by a call on this method, for the same CompilerService instance

Returns:

a unique number

pushNewReceiverInfo

public void pushNewReceiverInfo(Generator ga)

Generate code to set a new current receiver on the top of the receiver stack.

Runtime precondition: the new receiver is on the top of the bytecode stack

Runtime postcondition: the new receiver is now the current receiver; the previous current receiver has been added to the receiver stack. The top entry from the bytecode stack has been consumed.

Parameters:

ga - the code generator

popReceiverInfo

public void popReceiverInfo()

Generate code to reinstate the previous current receiver by popping it from the receiver stack.

Runtime precondition: there is a non-empty receiver stack

Runtime postcondition: the top entry in the receiver stack has been removed from the receiver stack and is now the current receiver.

pushNewMethodInfo

public void pushNewMethodInfo(Generator ga,
                              boolean contextIsArgument,
                              int contextVariablePosition)

initNewMethod

public void initNewMethod(Generator ga,
                          boolean holdReceiverAsLocal)

Initialize context information for a new method. On entry, the XPathContext object must be on the top of stack.

Parameters:

ga - the code generator

holdReceiverAsLocal - true if a local variable on the bytecode stack is to be allocated to hold the current receiver; if false, the receiver is obtained via the context when required

pushNewClassInfo

public void pushNewClassInfo(String className,
                             Class superclass,
                             org.objectweb.asm.ClassWriter cw)

getCurrentMethods

public Stack<GeneratedMethodInfo> getCurrentMethods()

getCurrentMethod

public GeneratedMethodInfo getCurrentMethod()

getCurrentClass

public CompilerService.GeneratedClassInfo getCurrentClass()

getConfiguration

public Configuration getConfiguration()

Get the Configuration used by this CompilerService

Returns:

the Saxon Configuration

getFlags

public int getFlags()

Get the flag options used by the ClassWriter

Returns:

the flags set

compileToByteCode

public CompiledExpression compileToByteCode(Expression expr,
                                            String objectName,
                                            int evaluationModes)

Compile a top-level expression to bytecode, and return the resulting expression

Parameters:

expr - The expression to be compiled

objectName - The name of the object (e.g. function) being compiled

evaluationModes - The evaluation modes for which code is generated. Currently a subset of Expression.PROCESS_METHOD, Expression.ITERATE_METHOD, Expression.EVALUATE_METHOD. If no code is generated for a given evaluation method, the fallback implementation from the superclass is used.

Returns:

The compiled expression if compilation was possible; otherwise null

compileToIterator

public void compileToIterator(Expression expr)
                       throws CannotCompileException

Generate bytecode to evaluate an expression leaving a SequenceIterator on the stack

Parameters:

expr - the expression to be evaluated

Throws:

CannotCompileException - if the expression cannot be compiled

compileToPush

public void compileToPush(Expression expr)
                   throws CannotCompileException

Generate bytecode to evaluate an expression by writing events to the current SequenceReceiver (leaving nothing on the stack at execution time)

Parameters:

expr - the expression to be evaluated

Throws:

CannotCompileException - if the expression cannot be compiled

compileToItem

public void compileToItem(Expression expr)
                   throws CannotCompileException

Generate bytecode to evaluate an expression leaving either an Item or null on the stack (null indicating that the expression evaluated to an empty sequence).

Parameters:

expr - the expression to be evaluated

Throws:

CannotCompileException - if the expression cannot be compiled

compileToBoolean

public void compileToBoolean(Expression expr)
                      throws CannotCompileException

Generate bytecode to evaluate an expression leaving a boolean on the stack. The boolean represents the effective boolean value of the result of the evaluation. This method must be implemented for all expressions except where it is statically known that the expression has no effective boolean value

Parameters:

expr - the expression to be evaluated

Throws:

CannotCompileException - if the expression cannot be compiled

isInRangeForInt

public boolean isInRangeForInt(Expression exp)

isInRangeForLong

public boolean isInRangeForLong(Expression exp)

compileToPrimitive

public void compileToPrimitive(Expression expr,
                               Class requiredClass,
                               OnEmpty onEmpty)
                        throws CannotCompileException

Compile an expression that returns a singleton (or empty) result of type xs:double, xs:float, xs:string, xs:untypedAtomic. An ExpressionCompiler must support this method if the expression is known statically to return one of these types. The code generated will leave an "unboxed" result on the bytecode stack: specifically a double, a float, a String or CharSequence.

Parameters:

expr - the expression to be compiled

requiredClass - the required class. For an expression with static type xs:double, this will be Double.TYPE; for xs:float it will be Float.TYPE; for xs:string and xs:untypedAtomic it may be either String.class or CharSequence.class. The expression compiler MUST generate code that leaves this class of value on the top of the bytecode stack. For an expression whose static type is xs:integer, the requiredClass may be Integer.TYPE or Long.TYPE, provided that either (a) the expression is known always to deliver a value in the range of an int or long respectively, or (b) that any other value would exceed system limits in the context where it is used (for example, if it is used as an index into a sequence then it cannot exceed a 32-bit integer). All expressions that have a static type of xs:integer must therefore implement this method.

onEmpty - action to be taken when the expression returns an empty result.

Throws:

CannotCompileException - if the expression cannot be compiled

canCompileToLoop

public boolean canCompileToLoop(Expression expr)

Ask if an expression can be compiled using the compileToLoop() method

Parameters:

expr - the expression in question

Returns:

true if it can be compiled to a loop

compileToLoop

public void compileToLoop(Expression expr,
                          LoopBodyGenerator bodyGen)
                   throws CannotCompileException

Throws:

CannotCompileException

getCurrentGenerator

public Generator getCurrentGenerator()

popCurrentMethodInfo

public void popCurrentMethodInfo()

generateGetContext

public void generateGetContext()

Generate code to load the current XPathContext, leaving it on the top of the stack

generateGetReceiver

public void generateGetReceiver()

Generate code to load the current Receiver, leaving it on the top of the stack

makeClass

public Class makeClass(org.objectweb.asm.ClassWriter writer,
                       String className)

Having written the bytecode for all the methods for a class, create the Class itself so it can be used

Parameters:

writer - the writer that was used to create the class

className - the name of the class

Returns:

the constructed Class object

allocateStaticVariableInfo

public CompilerService.StaticVariableInfo allocateStaticVariableInfo(Object value)

Create a StaticVariableInfo containing the information needed to allow a static reference to a given object to be added as a static field in the currently-being-compiled class

Parameters:

value - the object to be referenced

Returns:

a StaticVariableInfo object, which will have been queued for later addition to the class

makeValidJavaName

public String makeValidJavaName(String name)

Given a candidate Java name, make it into a valid Java name

Parameters:

name - a candidate Java name

Returns:

a valid Java name