Package org.codehaus.janino
Class CodeContext
- java.lang.Object
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- org.codehaus.janino.CodeContext
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public class CodeContext extends java.lang.Object
The context of the compilation of a function (constructor or method). Manages generation of byte code, the exception table, generation of line number tables, allocation of local variables, determining of stack size and local variable table size and flow analysis.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static interface
CodeContext.FixUp
A throw-in interface that marksCodeContext.Offset
s as "fix-ups": During the execution offixUp()
, all "fix-ups" are invoked and can do last touches to the code attribute.class
CodeContext.Inserter
A class that implements an insertion point into a "Code" attribute.class
CodeContext.LineNumberOffset
AnCodeContext.Offset
who#s sole purpose is to later create a 'LneNumberTable' attribute.class
CodeContext.Offset
A class that represents an offset within a "Code" attribute.
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Constructor Summary
Constructors Constructor Description CodeContext(ClassFile classFile)
Create an empty "Code" attribute.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
addExceptionTableEntry(CodeContext.Offset startPc, CodeContext.Offset endPc, CodeContext.Offset handlerPc, java.lang.String catchTypeFd)
Add another entry to the "exception_table" of this code attribute (see JVMS 4.7.3).short
allocateLocalVariable(short size)
Allocate space for a local variable of the given size (1 or 2) on the local variable array.Java.LocalVariableSlot
allocateLocalVariable(short size, java.lang.String name, IClass type)
Allocate space for a local variable of the given size (1 or 2) on the local variable array.CodeContext.Inserter
currentInserter()
void
fixUpAndRelocate()
fixUp() all of the offsets and relocate() all relocatablesvoid
flowAnalysis(java.lang.String functionName)
Checks the code for consistency; updates the "maxStack" member.java.util.List
getAllLocalVars()
ClassFile
getClassFile()
TheClassFile
this context is related to.void
makeSpace(short lineNumber, int size)
Add space for size bytes at current offset.CodeContext.Inserter
newInserter()
Allocate anCodeContext.Inserter
, set it to the current offset, and insert it before the current offset.CodeContext.Offset
newOffset()
Creates and inserts anCodeContext.Offset
at the current inserter's current position.void
popInserter()
Replace the currentCodeContext.Inserter
with the remembered one (seepushInserter(CodeContext.Inserter)
).void
pushInserter(CodeContext.Inserter ins)
Remember the currentCodeContext.Inserter
, then replace it with the new one.void
restoreLocalVariables()
Restore the previous size of the local variables array.java.util.List
saveLocalVariables()
Remember the current size of the local variables array.protected void
storeCodeAttributeBody(java.io.DataOutputStream dos, short lineNumberTableAttributeNameIndex, short localVariableTableAttributeNameIndex)
protected ClassFile.AttributeInfo
storeLocalVariableTable(java.io.DataOutputStream dos, short localVariableTableAttributeNameIndex)
void
write(short lineNumber, byte b1)
Inserts a byte at the current insertion position.void
write(short lineNumber, byte[] b)
Inserts a sequence of bytes at the current insertion position.void
write(short lineNumber, byte b1, byte b2)
Inserts bytes at the current insertion position.void
write(short lineNumber, byte b1, byte b2, byte b3)
Inserts bytes at the current insertion position.void
write(short lineNumber, byte b1, byte b2, byte b3, byte b4)
Inserts bytes at the current insertion position.void
writeBranch(short lineNumber, int opcode, CodeContext.Offset dst)
void
writeOffset(short lineNumber, CodeContext.Offset src, CodeContext.Offset dst)
Writes a four-byte offset (as it is used in TABLESWITCH and LOOKUPSWITCH) into this code context.void
writeShort(short lineNumber, int v)
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Constructor Detail
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CodeContext
public CodeContext(ClassFile classFile)
Create an empty "Code" attribute.
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Method Detail
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allocateLocalVariable
public short allocateLocalVariable(short size)
Allocate space for a local variable of the given size (1 or 2) on the local variable array. As a side effect, the "max_locals" field of the "Code" attribute is updated. The only way to deallocate local variables is tosaveLocalVariables()
and laterrestoreLocalVariables()
.- Parameters:
size
- The number of slots to allocate (1 or 2)- Returns:
- The slot index of the allocated variable
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allocateLocalVariable
public Java.LocalVariableSlot allocateLocalVariable(short size, java.lang.String name, IClass type)
Allocate space for a local variable of the given size (1 or 2) on the local variable array. As a side effect, the "max_locals" field of the "Code" attribute is updated. The only way to deallocate local variables is tosaveLocalVariables()
and laterrestoreLocalVariables()
.- Parameters:
size
- Number of slots to use (1 or 2)name
- The variable name, if it's null, the variable won't be written to the localvariabletabletype
- The variable type. if the name isn't null, the type is needed to write to the localvariabletable
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saveLocalVariables
public java.util.List saveLocalVariables()
Remember the current size of the local variables array.
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restoreLocalVariables
public void restoreLocalVariables()
Restore the previous size of the local variables array. This MUST to be called for every call to saveLocalVariables as it closes the variable extent for all the active local variables in the current block.
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storeCodeAttributeBody
protected void storeCodeAttributeBody(java.io.DataOutputStream dos, short lineNumberTableAttributeNameIndex, short localVariableTableAttributeNameIndex) throws java.io.IOException
- Parameters:
dos
-lineNumberTableAttributeNameIndex
- 0 == don't generate a "LineNumberTable" attribute- Throws:
java.io.IOException
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storeLocalVariableTable
protected ClassFile.AttributeInfo storeLocalVariableTable(java.io.DataOutputStream dos, short localVariableTableAttributeNameIndex)
- Returns:
- A
ClassFile.LocalVariableTableAttribute
for thisCodeContext
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flowAnalysis
public void flowAnalysis(java.lang.String functionName)
Checks the code for consistency; updates the "maxStack" member. Notice: On inconsistencies, a "RuntimeException" is thrown (KLUDGE).
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fixUpAndRelocate
public void fixUpAndRelocate()
fixUp() all of the offsets and relocate() all relocatables
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write
public void write(short lineNumber, byte[] b)
Inserts a sequence of bytes at the current insertion position. CreatesCodeContext.LineNumberOffset
s as necessary.- Parameters:
lineNumber
- The line number that corresponds to the byte code, or -1b
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write
public void write(short lineNumber, byte b1)
Inserts a byte at the current insertion position. CreatesCodeContext.LineNumberOffset
s as necessary.This method is an optimization to avoid allocating small byte[] and ease GC load.
- Parameters:
lineNumber
- The line number that corresponds to the byte code, or -1b1
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write
public void write(short lineNumber, byte b1, byte b2)
Inserts bytes at the current insertion position. CreatesCodeContext.LineNumberOffset
s as necessary.This method is an optimization to avoid allocating small byte[] and ease GC load.
- Parameters:
lineNumber
- The line number that corresponds to the byte code, or -1b1
-b2
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write
public void write(short lineNumber, byte b1, byte b2, byte b3)
Inserts bytes at the current insertion position. CreatesCodeContext.LineNumberOffset
s as necessary.This method is an optimization to avoid allocating small byte[] and ease GC load.
- Parameters:
lineNumber
- The line number that corresponds to the byte code, or -1b1
-b2
-b3
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write
public void write(short lineNumber, byte b1, byte b2, byte b3, byte b4)
Inserts bytes at the current insertion position. CreatesCodeContext.LineNumberOffset
s as necessary.This method is an optimization to avoid allocating small byte[] and ease GC load.
- Parameters:
lineNumber
- The line number that corresponds to the byte code, or -1b1
-b2
-b3
-b4
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makeSpace
public void makeSpace(short lineNumber, int size)
Add space for size bytes at current offset. CreatesCodeContext.LineNumberOffset
s as necessary.- Parameters:
lineNumber
- The line number that corresponds to the byte code, or -1size
- The size in bytes to inject
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writeShort
public void writeShort(short lineNumber, int v)
- Parameters:
lineNumber
- The line number that corresponds to the byte code, or -1
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writeBranch
public void writeBranch(short lineNumber, int opcode, CodeContext.Offset dst)
- Parameters:
lineNumber
- The line number that corresponds to the byte code, or -1
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writeOffset
public void writeOffset(short lineNumber, CodeContext.Offset src, CodeContext.Offset dst)
Writes a four-byte offset (as it is used in TABLESWITCH and LOOKUPSWITCH) into this code context.
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newOffset
public CodeContext.Offset newOffset()
Creates and inserts anCodeContext.Offset
at the current inserter's current position.
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newInserter
public CodeContext.Inserter newInserter()
Allocate anCodeContext.Inserter
, set it to the current offset, and insert it before the current offset. In clear text, this means that you can continue writing to the "Code" attribute, thenpushInserter(CodeContext.Inserter)
theCodeContext.Inserter
, then write again (which inserts bytes into the "Code" attribute at the previously remembered position), and thenpopInserter()
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currentInserter
public CodeContext.Inserter currentInserter()
- Returns:
- The current inserter
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pushInserter
public void pushInserter(CodeContext.Inserter ins)
Remember the currentCodeContext.Inserter
, then replace it with the new one.
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popInserter
public void popInserter()
Replace the currentCodeContext.Inserter
with the remembered one (seepushInserter(CodeContext.Inserter)
).
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addExceptionTableEntry
public void addExceptionTableEntry(CodeContext.Offset startPc, CodeContext.Offset endPc, CodeContext.Offset handlerPc, java.lang.String catchTypeFd)
Add another entry to the "exception_table" of this code attribute (see JVMS 4.7.3).- Parameters:
catchTypeFd
- null == "finally" clause
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getAllLocalVars
public java.util.List getAllLocalVars()
- Returns:
- All the local variables that are allocated in any block in this
CodeContext
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