[Java] Class CompileStack

  • org.codehaus.groovy.classgen.asm.CompileStack
All Implemented Interfaces and Traits:
org.objectweb.asm.Opcodes
public class CompileStack
extends Object

This class is a helper for AsmClassGenerator. It manages different aspects of the code of a code block like handling labels, defining variables, and scopes. After a MethodNode is visited clear should be called, for initialization the method init should be used.

Some Notes:

  • every push method will require a later pop call
  • method parameters may define a category 2 variable, so don't ignore the type stored in the variable object
  • the index of the variable may not be as assumed when the variable is a parameter of a method because the parameter may be used in a closure, so don't ignore the stored variable index
  • the names of temporary variables can be ignored. The names are only used for debugging and do not conflict with each other or normal variables. For accessing, the index of the variable must be used.
  • never mix temporary and normal variables by changes to this class. While the name is very important for a normal variable, it is only a helper construct for temporary variables. That means for example a name for a temporary variable can be used multiple times without conflict. So mixing them both may lead to the problem that a normal or temporary variable is hidden or even removed. That must not happen!
See Also:
AsmClassGenerator
Authors:
Jochen Theodorou

Nested Class Summary

Nested classes
Modifiers Name Description
static class CompileStack.BlockRecorder
protected static class CompileStack.LabelRange

Methods Summary

Methods
Type Params Return Type Name and description
def CompileStack(WriterController wc)
void addExceptionBlock(org.objectweb.asm.Label start, org.objectweb.asm.Label end, org.objectweb.asm.Label goal, String sig)
void applyBlockRecorder()
void applyFinallyBlocks(org.objectweb.asm.Label label, boolean isBreakLabel)
void clear()
Clears the state of the class.
boolean containsVariable(String name)
@param name the name of the variable of interest
org.objectweb.asm.Label createLocalLabel(String name)
creates a new named label
int defineTemporaryVariable(Variable var, boolean store)
creates a temporary variable.
int defineTemporaryVariable(String name, boolean store)
creates a temporary variable.
int defineTemporaryVariable(String name, ClassNode node, boolean store)
creates a temporary variable.
BytecodeVariable defineVariable(Variable v, boolean initFromStack)
Defines a new Variable using an AST variable.
BytecodeVariable defineVariable(Variable v, ClassNode variableType, boolean initFromStack)
org.objectweb.asm.Label getBreakLabel()
org.objectweb.asm.Label getContinueLabel()
org.objectweb.asm.Label getLabel(String name)
Returns the label for the given name
org.objectweb.asm.Label getNamedBreakLabel(String name)
Used for break foo inside a loop to end the execution of the marked loop.
org.objectweb.asm.Label getNamedContinueLabel(String name)
Used for continue foo inside a loop to continue the execution of the marked loop.
VariableScope getScope()
BytecodeVariable getVariable(String variableName)
BytecodeVariable getVariable(String variableName, boolean mustExist)
Returns a normal variable.
boolean hasBlockRecorder()
void init(VariableScope el, Parameter[] parameters)
initializes this class for a MethodNode.
boolean isImplicitThis()
boolean isInSpecialConstructorCall()
boolean isLHS()
void pop()
void popBlockRecorderVisit(CompileStack.BlockRecorder finallyBlock)
void popImplicitThis()
void popLHS()
void pushBlockRecorder(CompileStack.BlockRecorder recorder)
void pushBlockRecorderVisit(CompileStack.BlockRecorder finallyBlock)
void pushBooleanExpression()
because a boolean Expression may not be evaluated completely it is important to keep the registers clean
void pushImplicitThis(boolean implicitThis)
void pushInSpecialConstructorCall()
void pushLHS(boolean lhs)
void pushLoop(VariableScope el, String labelName)
Should be called when descending into a loop that defines also a scope.
void pushLoop(VariableScope el, List<String> labelNames)
Should be called when descending into a loop that defines also a scope.
void pushLoop(String labelName)
Should be called when descending into a loop that does not define a scope.
void pushLoop(List<String> labelNames)
Should be called when descending into a loop that does not define a scope.
void pushState()
org.objectweb.asm.Label pushSwitch()
Creates a new break label and a element for the state stack so pop has to be called later
void pushVariableScope(VariableScope el)
Causes the state-stack to add an element and sets the given scope as new current variable scope.
void removeVar(int tempIndex)
void writeExceptionTable(CompileStack.BlockRecorder block, org.objectweb.asm.Label goal, String sig)

Inherited Methods Summary

Inherited Methods
Methods inherited from class Name
class Object wait, wait, wait, equals, toString, hashCode, getClass, notify, notifyAll

Method Detail

public def CompileStack(WriterController wc)

public void addExceptionBlock(org.objectweb.asm.Label start, org.objectweb.asm.Label end, org.objectweb.asm.Label goal, String sig)

public void applyBlockRecorder()

public void applyFinallyBlocks(org.objectweb.asm.Label label, boolean isBreakLabel)

public void clear()

Clears the state of the class. This method should be called after a MethodNode is visited. Note that a call to init will fail if clear is not called before

public boolean containsVariable(String name)

Parameters:
name - the name of the variable of interest
Returns:
true if a variable is already defined

public org.objectweb.asm.Label createLocalLabel(String name)

creates a new named label

public int defineTemporaryVariable(Variable var, boolean store)

creates a temporary variable.

Parameters:
var - defines type and name
store - defines if the toplevel argument of the stack should be stored
Returns:
the index used for this temporary variable

public int defineTemporaryVariable(String name, boolean store)

creates a temporary variable.

Parameters:
name - defines type and name
store - defines if the top-level argument of the stack should be stored
Returns:
the index used for this temporary variable

public int defineTemporaryVariable(String name, ClassNode node, boolean store)

creates a temporary variable.

Parameters:
name - defines the name
node - defines the node
store - defines if the top-level argument of the stack should be stored
Returns:
the index used for this temporary variable

public BytecodeVariable defineVariable(Variable v, boolean initFromStack)

Defines a new Variable using an AST variable.

Parameters:
initFromStack - if true the last element of the stack will be used to initialize the new variable. If false null will be used.

public BytecodeVariable defineVariable(Variable v, ClassNode variableType, boolean initFromStack)

public org.objectweb.asm.Label getBreakLabel()

public org.objectweb.asm.Label getContinueLabel()

public org.objectweb.asm.Label getLabel(String name)

Returns the label for the given name

public org.objectweb.asm.Label getNamedBreakLabel(String name)

Used for break foo inside a loop to end the execution of the marked loop. This method will return the break label of the loop if there is one found for the name. If not, the current break label is returned.

public org.objectweb.asm.Label getNamedContinueLabel(String name)

Used for continue foo inside a loop to continue the execution of the marked loop. This method will return the break label of the loop if there is one found for the name. If not, getLabel is used.

public VariableScope getScope()

public BytecodeVariable getVariable(String variableName)

public BytecodeVariable getVariable(String variableName, boolean mustExist)

Returns a normal variable.

If mustExist is true and the normal variable doesn't exist, then this method will throw a GroovyBugError. It is not the intention of this method to let this happen! And the exception should not be used for flow control - it is just acting as an assertion. If the exception is thrown then it indicates a bug in the class using CompileStack. This method can also not be used to return a temporary variable. Temporary variables are not normal variables.

Parameters:
variableName - name of the variable
mustExist - throw exception if variable does not exist
Returns:
the normal variable or null if not found (and mustExist not true)

public boolean hasBlockRecorder()

public void init(VariableScope el, Parameter[] parameters)

initializes this class for a MethodNode. This method will automatically define variables for the method parameters and will create references if needed. The created variables can be accessed by calling getVariable().

public boolean isImplicitThis()

public boolean isInSpecialConstructorCall()

public boolean isLHS()

public void pop()

public void popBlockRecorderVisit(CompileStack.BlockRecorder finallyBlock)

public void popImplicitThis()

public void popLHS()

public void pushBlockRecorder(CompileStack.BlockRecorder recorder)

public void pushBlockRecorderVisit(CompileStack.BlockRecorder finallyBlock)

public void pushBooleanExpression()

because a boolean Expression may not be evaluated completely it is important to keep the registers clean

public void pushImplicitThis(boolean implicitThis)

public void pushInSpecialConstructorCall()

public void pushLHS(boolean lhs)

public void pushLoop(VariableScope el, String labelName)

Should be called when descending into a loop that defines also a scope. Calls pushVariableScope and prepares labels for a loop structure. Creates a element for the state stack so pop has to be called later, TODO:

Deprecate:

public void pushLoop(VariableScope el, List<String> labelNames)

Should be called when descending into a loop that defines also a scope. Calls pushVariableScope and prepares labels for a loop structure. Creates a element for the state stack so pop has to be called later

public void pushLoop(String labelName)

Should be called when descending into a loop that does not define a scope. Creates a element for the state stack so pop has to be called later, TODO:

Deprecate:

public void pushLoop(List<String> labelNames)

Should be called when descending into a loop that does not define a scope. Creates a element for the state stack so pop has to be called later

public void pushState()

public org.objectweb.asm.Label pushSwitch()

Creates a new break label and a element for the state stack so pop has to be called later

public void pushVariableScope(VariableScope el)

Causes the state-stack to add an element and sets the given scope as new current variable scope. Creates a element for the state stack so pop has to be called later

public void removeVar(int tempIndex)

public void writeExceptionTable(CompileStack.BlockRecorder block, org.objectweb.asm.Label goal, String sig)

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Licensed under the Apache license.
https://docs.groovy-lang.org/2.4.21/html/gapi/org/codehaus/groovy/classgen/asm/CompileStack.html