/*
* reserved comment block
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package com.sun.org.apache.bcel.internal.generic;
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/**
* SWITCH - Branch depending on int value, generates either LOOKUPSWITCH or
* TABLESWITCH instruction, depending on whether the match values (int[]) can be
* sorted with no gaps between the numbers.
*
* @version $Id: SWITCH.java,v 1.1.2.1 2005/07/31 23:44:40 jeffsuttor Exp $
* @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
*/
public final class SWITCH implements CompoundInstruction {
private int[] match;
private InstructionHandle[] targets;
private Select instruction;
private int match_length;
/**
* Template for switch() constructs. If the match array can be
* sorted in ascending order with gaps no larger than max_gap
* between the numbers, a TABLESWITCH instruction is generated, and
* a LOOKUPSWITCH otherwise. The former may be more efficient, but
* needs more space.
*
* Note, that the key array always will be sorted, though we leave
* the original arrays unaltered.
*
* @param match array of match values (case 2: ... case 7: ..., etc.)
* @param targets the instructions to be branched to for each case
* @param target the default target
* @param max_gap maximum gap that may between case branches
*/
public SWITCH(int[] match, InstructionHandle[] targets,
InstructionHandle target, int max_gap) {
this.match = (int[])match.clone();
this.targets = (InstructionHandle[])targets.clone();
if((match_length = match.length) < 2) // (almost) empty switch, or just default
instruction = new TABLESWITCH(match, targets, target);
else {
sort(0, match_length - 1);
if(matchIsOrdered(max_gap)) {
fillup(max_gap, target);
instruction = new TABLESWITCH(this.match, this.targets, target);
}
else
instruction = new LOOKUPSWITCH(this.match, this.targets, target);
}
}
public SWITCH(int[] match, InstructionHandle[] targets,
InstructionHandle target) {
this(match, targets, target, 1);
}
private final void fillup(int max_gap, InstructionHandle target) {
int max_size = match_length + match_length * max_gap;
int[] m_vec = new int[max_size];
InstructionHandle[] t_vec = new InstructionHandle[max_size];
int count = 1;
m_vec[0] = match[0];
t_vec[0] = targets[0];
for(int i=1; i < match_length; i++) {
int prev = match[i-1];
int gap = match[i] - prev;
for(int j=1; j < gap; j++) {
m_vec[count] = prev + j;
t_vec[count] = target;
count++;
}
m_vec[count] = match[i];
t_vec[count] = targets[i];
count++;
}
match = new int[count];
targets = new InstructionHandle[count];
System.arraycopy(m_vec, 0, match, 0, count);
System.arraycopy(t_vec, 0, targets, 0, count);
}
/**
* Sort match and targets array with QuickSort.
*/
private final void sort(int l, int r) {
int i = l, j = r;
int h, m = match[(l + r) / 2];
InstructionHandle h2;
do {
while(match[i] < m) i++;
while(m < match[j]) j--;
if(i <= j) {
h=match[i]; match[i]=match[j]; match[j]=h; // Swap elements
h2=targets[i]; targets[i]=targets[j]; targets[j]=h2; // Swap instructions, too
i++; j--;
}
} while(i <= j);
if(l < j) sort(l, j);
if(i < r) sort(i, r);
}
/**
* @return match is sorted in ascending order with no gap bigger than max_gap?
*/
private final boolean matchIsOrdered(int max_gap) {
for(int i=1; i < match_length; i++)
if(match[i] - match[i-1] > max_gap)
return false;
return true;
}
public final InstructionList getInstructionList() {
return new InstructionList(instruction);
}
public final Instruction getInstruction() {
return instruction;
}
}