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SPL(Structured Process Language) A programming language specially for structured data computing.
package com.scudata.dm.cursor;
import com.scudata.array.IArray;
import com.scudata.dm.ComputeStack;
import com.scudata.dm.Context;
import com.scudata.dm.DataStruct;
import com.scudata.dm.Record;
import com.scudata.dm.Sequence;
import com.scudata.dm.Table;
import com.scudata.dm.op.Operation;
import com.scudata.dm.op.Select;
import com.scudata.expression.Expression;
/**
* ???ڶ??α??????
* xjoinx(csi:Fi,xi;??)
* @author RunQian
*
*/
public class XJoinxCursor extends ICursor {
private ICursor []cursors; // ?α?????
private Expression []exps; // ???˱???ʽ
private DataStruct ds; // ????????ݽṹ
private boolean isLeft = false; // ?Ƿ???????
private boolean isEnd = false; // ?Ƿ?ȡ??????
private Sequence []tables; // ÿ???α?ȡ???????ݻ???
private int []currents; // ÿ???α굱ǰ????????????
private Record record; // ???ڼ???
/**
* ????????α?
* @param cursors ?α?????
* @param exps ???˱???ʽ
* @param names ?ֶ???????
* @param fltOpts ????ѡ??
* @param opt ѡ??
* @param ctx ??????????
*/
public XJoinxCursor(ICursor []cursors, Expression []exps, String []names, String[] fltOpts, String opt, Context ctx) {
this.cursors = cursors;
this.exps = exps;
this.ctx = ctx;
this.isLeft = opt != null && opt.indexOf('1') != -1;
int tcount = cursors.length;
if (names == null) {
names = new String[tcount];
}
ds = new DataStruct(names);
setDataStruct(ds);
for (int i = 0; i < tcount; ++i) {
if (exps[i] != null) {
cursors[i].addOperation(new Select(exps[i], fltOpts[i]), ctx);
}
}
}
// ???м???ʱ??Ҫ?ı???????
// ?̳???????õ??˱???ʽ????Ҫ?????????????½???????ʽ
public void resetContext(Context ctx) {
if (this.ctx != ctx) {
for (ICursor cursor : cursors) {
cursor.resetContext(ctx);
}
exps = Operation.dupExpressions(exps, ctx);
super.resetContext(ctx);
}
}
private void init() {
if (tables != null) {
return;
}
int tcount = cursors.length;
tables = new Sequence[tcount];
currents = new int[tcount];
record = new Record(ds);
ComputeStack stack = ctx.getComputeStack();
stack.push(record);
try {
for (int i = 0; i < tcount; ++i) {
currents[i] = 1;
tables[i] = cursors[i].fetch(FETCHCOUNT);
if (tables[i] == null) {
break;
} else if (tables[i].length() == 0) {
tables[i] = null;
break;
} else {
record.setNormalFieldValue(i, tables[i].getMem(1));
}
}
} finally {
stack.pop();
}
}
private boolean next(int t) {
Sequence []tables = this.tables;
int []currents = this.currents;
if (tables[t].length() < ++currents[t]) {
tables[t] = cursors[t].fetch(FETCHCOUNT);
if (tables[t] != null && tables[t].length() > 0) {
currents[t] = 1;
record.setNormalFieldValue(t, tables[t].getMem(1));
return true;
} else if (t > 0) {
if (next(t - 1)) {
cursors[t].reset();
tables[t] = cursors[t].fetch(FETCHCOUNT);
if (tables[t] != null && tables[t].length() > 0) {
currents[t] = 1;
record.setNormalFieldValue(t, tables[t].getMem(1));
return true;
} else {
tables[t] = null;
record.setNormalFieldValue(t, null);
return false;
}
} else {
//record.setNormalFieldValue(t, null);
return false;
}
} else {
return false;
}
} else {
record.setNormalFieldValue(t, tables[t].getMem(currents[t]));
return true;
}
}
private Record getRecord() {
Sequence []tables = this.tables;
if (tables == null) {
return null;
}
int []currents = this.currents;
int last = tables.length - 1;
Next:
while (true) {
if (tables[last] != null) {
record.setNormalFieldValue(last, tables[last].getMem(currents[last]));
Record r = new Record(ds, record.getFieldValues());
if (tables[last].length() < ++currents[last]) {
tables[last] = cursors[last].fetch(FETCHCOUNT);
if (tables[last] != null && tables[last].length() > 0) {
currents[last] = 1;
} else {
if (next(last - 1)) {
cursors[last].reset();
tables[last] = cursors[last].fetch(FETCHCOUNT);
currents[last] = 1;
}
}
}
return r;
}
for (int i = last - 1; i >= 0; --i) {
if (tables[i] != null) {
if (isLeft) {
Record r = new Record(ds);
for (int j = 0; j <= i; ++j) {
r.setNormalFieldValue(j, record.getNormalFieldValue(j));
}
if (next(i)) {
for (int j = i + 1; j <= last; ++j) {
cursors[j].reset();
tables[j] = cursors[j].fetch(FETCHCOUNT);
if (tables[j] != null && tables[j].length() > 0) {
record.setNormalFieldValue(j, tables[j].getMem(1));
currents[j] = 1;
} else {
tables[j] = null;
break;
}
}
}
return r;
} else {
if (next(i)) {
for (int j = i + 1; j <= last; ++j) {
cursors[j].reset();
tables[j] = cursors[j].fetch(FETCHCOUNT);
if (tables[j] != null && tables[j].length() > 0) {
record.setNormalFieldValue(j, tables[j].getMem(1));
currents[j] = 1;
} else {
tables[j] = null;
break;
}
}
}
continue Next;
}
}
}
return null;
}
}
/**
* ??ȡָ???????????ݷ???
* @param n ????
* @return Sequence
*/
protected Sequence get(int n) {
if (isEnd || n < 1) return null;
init();
Table newTable;
if (n > INITSIZE) {
newTable = new Table(ds, INITSIZE);
} else {
newTable = new Table(ds, n);
}
IArray mems = newTable.getMems();
ComputeStack stack = ctx.getComputeStack();
stack.push(record);
try {
for (int i = 0; i < n; ++i) {
Record r = getRecord();
if (r != null) {
mems.add(r);
} else {
break;
}
}
} finally {
stack.pop();
}
if (newTable.length() > 0) {
return newTable;
} else {
return null;
}
}
/**
* ????ָ????????????
* @param n ????
* @return long ʵ????????????
*/
protected long skipOver(long n) {
if (isEnd || n < 1) return 0;
init();
ComputeStack stack = ctx.getComputeStack();
stack.push(record);
try {
for (int i = 0; i < n; ++i) {
Record r = getRecord();
if (r == null) {
return i;
}
}
} finally {
stack.pop();
}
return n;
}
/**
* ?ر??α?
*/
public synchronized void close() {
super.close();
for (int i = 0, count = cursors.length; i < count; ++i) {
cursors[i].close();
}
tables = null;
currents = null;
record = null;
isEnd = true;
}
/**
* ?????α?
* @return ?????Ƿ?ɹ???true???α???Դ?ͷ????ȡ????false???????Դ?ͷ????ȡ??
*/
public boolean reset() {
close();
for (int i = 0, count = cursors.length; i < count; ++i) {
if (!cursors[i].reset()) {
return false;
}
}
isEnd = false;
return true;
}
}