de.fub.bytecode.generic
Class FindPattern

java.lang.Object
  |
  +--de.fub.bytecode.generic.FindPattern

public class FindPattern

extends java.lang.Object

This class is an utility to search for given patterns, i.e., regular expressions in an instruction list. This can be used in order to implement a peep hole optimizer that looks for code patterns and replaces them with faster equivalents. This class internally uses the package gnu.regexp to search for regular expressions.

Version:

$Id: FindPattern.java,v 1.5 2001/10/11 11:59:27 dahm Exp $

Author:

M. Dahm

See Also:

Instruction, InstructionList, CodeConstraint

Constructor Summary

FindPattern(InstructionList il)

Method Summary

InstructionList	getInstructionList()
InstructionHandle[]	getMatch()
int	getMatchLength()
void	reread() Rereads the instruction list, e.g., after you've altered the list upon a match.
InstructionHandle	search(java.lang.String pattern) Start search beginning from the start of the given instruction list.
InstructionHandle	search(java.lang.String pattern, CodeConstraint constraint) Start search beginning from the start of the given instruction list.
InstructionHandle	search(java.lang.String pattern, InstructionHandle from) Start search beginning from `from'.
InstructionHandle	search(java.lang.String pattern, InstructionHandle from, CodeConstraint constraint) Search for the given pattern in the InstructionList.
void	setInstructionList(InstructionList il) Defines a new instruction list.

Methods inherited from class java.lang.Object

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

Constructor Detail

FindPattern

public FindPattern(InstructionList il)

Parameters:

il - instruction list to search for given patterns

Method Detail

reread

public final void reread()

Rereads the instruction list, e.g., after you've altered the list upon a match.

search

public final InstructionHandle search(java.lang.String pattern,
                                      InstructionHandle from,
                                      CodeConstraint constraint)

Search for the given pattern in the InstructionList. You may use the following special expressions in your pattern string which match instructions that belong to the denoted class. The `' are an escape and must not be omitted. You can use the Instruction names directly: `ILOAD_1', `GOTO', 'NOP', etc.. For convenience there exist some abbreviations for instructions that belong to the same group (underscores _ are used as some kind of wildcards): `Instruction', `BranchInstruction', `InvokeInstruction', `ReturnInstruction', `IfInstruction' correspond to their classes. `IF_ICMP__', `IF__', where __ stands for EQ, LE, etc. `xLOAD__', `xSTORE__', where x stands for I, D, F, L or A. __ is 0..3 or empty `PUSH' stands for any LDC, xCONST__, SIPUSH or BIPUSH instruction You must put the `' around these words or they can't be matched correctly. For the rest the usual (PERL) pattern matching rules apply.

Example pattern:

search("(`BranchInstruction')`NOP'((`IF_ICMP__'|`GOTO')+`ISTORE__'`Instruction')*");
 

Parameters:

pattern - the instruction pattern to search for, case is ignored

from - where to start the search in the instruction list

constraint - optional CodeConstraint to check the found code pattern for given constraints

Returns:

instruction handle or `null' if the matching fails

search

public final InstructionHandle search(java.lang.String pattern)

Start search beginning from the start of the given instruction list.

Parameters:

pattern - the instruction pattern to search for, case is ignored

Returns:

instruction handle or `null' if the matching fails

search

public final InstructionHandle search(java.lang.String pattern,
                                      InstructionHandle from)

Start search beginning from `from'.

Parameters:

pattern - the instruction pattern to search for, case is ignored

from - where to start the search in the instruction list

Returns:

instruction handle or `null' if the matching fails

search

public final InstructionHandle search(java.lang.String pattern,
                                      CodeConstraint constraint)

Start search beginning from the start of the given instruction list. Check found matches with the constraint object.

Parameters:

pattern - the instruction pattern to search for, case is ignored

constraint - constraints to be checked on matching code

Returns:

instruction handle or `null' if the match failed

getMatchLength

public final int getMatchLength()

Returns:

number of matched instructions, or -1 if the match did not succeed

getMatch

public final InstructionHandle[] getMatch()

Returns:

the matched piece of code as an array of instruction (handles)

setInstructionList

public final void setInstructionList(InstructionList il)

Defines a new instruction list. Automatically calls reread() to update the object.

Parameters:

il - the new instuction list

getInstructionList

public final InstructionList getInstructionList()

Returns:

the inquired instruction list