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Rewrote the readers to use the CharBuffer iterator style
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@DavyLandman
DavyLandman committed Sep 20, 2024
1 parent 206676f commit 589aa9f
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Showing 2 changed files with 152 additions and 116 deletions.
258 changes: 152 additions & 106 deletions src/main/java/io/usethesource/vallang/impl/primitive/StringValue.java
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Original file line number Diff line number Diff line change
Expand Up @@ -27,15 +27,14 @@
import java.time.Duration;
import java.time.temporal.ChronoUnit;
import java.util.ArrayDeque;
import java.util.Collections;
import java.util.Deque;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.PrimitiveIterator;
import java.util.PrimitiveIterator.OfInt;

import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
import org.checkerframework.checker.nullness.qual.Nullable;

import io.usethesource.vallang.IString;
import io.usethesource.vallang.IValueFactory;
import io.usethesource.vallang.impl.persistent.ValueFactory;
Expand Down Expand Up @@ -286,6 +285,11 @@ public IString concat(IString other) {
public Reader asReader() {
return Reader.nullReader();
}

@Override
public Iterator<CharBuffer> iterateParts() {
return Collections.emptyIterator();
}
}

private static class FullUnicodeString extends AbstractString {
Expand Down Expand Up @@ -591,6 +595,11 @@ public int nextInt() {
}
};
}

@Override
public Iterator<CharBuffer> iterateParts() {
return Collections.singleton(CharBuffer.wrap(value)).iterator();
}
}

/**
Expand Down Expand Up @@ -650,6 +659,11 @@ public int nextInt() {
public Reader asReader() {
return new StringReader(value);
}

@Override
public Iterator<CharBuffer> iterateParts() {
return Collections.singleton(CharBuffer.wrap(value)).iterator();
}
}

/**
Expand Down Expand Up @@ -825,6 +839,8 @@ default AbstractString rotateRightLeft() {
default AbstractString rotateLeftRight() {
return (AbstractString) this;
}

Iterator<CharBuffer> iterateParts();
}

private abstract static class AbstractString implements IString, IStringTreeNode, IIndentableString {
Expand Down Expand Up @@ -980,6 +996,34 @@ protected final int hashCode(int prefixCode) {
}

abstract boolean hasNonBMPCodePoints();

public abstract Iterator<CharBuffer> iterateParts();

@Override
public Reader asReader() {
return new Reader() {
final Iterator<CharBuffer> parts = iterateParts();
CharBuffer currentBuffer = CharBuffer.allocate(0);

@Override
public int read(char[] cbuf, int off, int len) throws IOException {
var actualBuffer = currentBuffer;
while (!actualBuffer.hasRemaining()) {
if (!parts.hasNext()) {
return -1;
}
actualBuffer = currentBuffer = parts.next();
}
int actualLength = Math.min(len, actualBuffer.remaining());
actualBuffer.get(cbuf, off, actualLength);
return actualLength;
}

@Override
public void close() throws IOException {
}
};
}
}

private static class LazyConcatString extends AbstractString {
Expand Down Expand Up @@ -1163,47 +1207,8 @@ public void write(Writer w) throws IOException {
right.write(w);
}

@Override
public Reader asReader() {
return new Reader() {
private Reader currentReader = left.asReader();
private boolean readingRight = false;

private void continueRight() throws IOException {
assert !readingRight;
currentReader.close();
currentReader = right.asReader();
readingRight = true;
}


@Override
public int read(char[] cbuf, int off, int len) throws IOException {
int result = currentReader.read(cbuf, off, len);
if (result == -1 && !readingRight) {
continueRight();
return read(cbuf, off, len);
}
return result;
}

@Override
public int read() throws IOException {
int result = currentReader.read();
if (result == -1 && !readingRight) {
continueRight();
return read();
}
return result;
}

@Override
public void close() throws IOException {
currentReader.close();
}
};
}

@Override
public void indentedWrite(Writer w, Deque<IString> whitespace, boolean indentFirstLine) throws IOException {
left.indentedWrite(w, whitespace, indentFirstLine);
Expand Down Expand Up @@ -1262,6 +1267,49 @@ public int nextInt() {
};
}

@Override
public Iterator<CharBuffer> iterateParts() {
return new Iterator<> () {
final Deque<AbstractString> todo = new ArrayDeque<>(depth);
Iterator<CharBuffer> currentLeaf = leftmostLeafIteratorParts(todo, LazyConcatString.this);
@Override
public boolean hasNext() {
return currentLeaf.hasNext(); /* || !todo.isEmpty() is unnecessary due to post-condition of nextInt() */
}
@Override
public CharBuffer next() {
var next = currentLeaf.next();

if (!currentLeaf.hasNext() && !todo.isEmpty()) {
// now we back track to the previous node we went left from,
// take the right branch and continue with its first leaf:
currentLeaf = leftmostLeafIteratorParts(todo, todo.pop());
}

assert currentLeaf.hasNext() || todo.isEmpty();
return next;
}
};
}

/**
* Static helper function for the iterator() method.
*
* It finds the left-most leaf of the tree, and collects
* the path of nodes to this leaf as a side-effect in the todo
* stack.
*/
private static Iterator<CharBuffer> leftmostLeafIteratorParts(Deque<AbstractString> todo, IStringTreeNode start) {
IStringTreeNode cur = start;

while (cur.depth() > 1) {
todo.push(cur.right());
cur = cur.left();
}

return cur.iterateParts();
}

/**
* Static helper function for the iterator() method.
*
Expand Down Expand Up @@ -1390,6 +1438,69 @@ public int nextInt() {
};
}

@Override
public Iterator<CharBuffer> iterateParts() {
if (flattened != null) {
return flattened.iterateParts();
}
var indentBuffer = CharBuffer.wrap(indent.getValue());
return new Iterator<>() {
final Iterator<CharBuffer> content = wrapped.iterateParts();
CharBuffer active = CharBuffer.allocate(0);
boolean indentNext = indentFirstLine;

@Override
public boolean hasNext() {
return indentNext || content.hasNext() || active.hasRemaining();
}

private CharBuffer nextTillNewlineOrEndOfBuffer() {
int start = active.position();
int end = start + active.remaining();
int cur = start;
while (cur < end) {
if (active.get(cur) == NEWLINE) {
cur++;
indentNext = true;
break;
}
cur++;
}
if (cur != end) {
var result = active.duplicate();
result.limit(cur);
active.position(cur);
return result;
}
else {
// end of the buffer
var result = active;
if (content.hasNext()) {
active = content.next();
}
else {
// end of the stream
indentNext = false;
active = CharBuffer.allocate(0);
}
return result;
}
}

@Override
public CharBuffer next() {
if (indentNext) {
indentNext = false;
return indentBuffer.asReadOnlyBuffer();
}
// okay so no indent to send
// now we should give the next char-buffer till the next newline
return nextTillNewlineOrEndOfBuffer();
}

};
}

@Override
public IString reverse() {
return applyIndentation().reverse();
Expand Down Expand Up @@ -1438,71 +1549,6 @@ public void write(Writer w) throws IOException {
assert indents.isEmpty();
}

@Override
public Reader asReader() {
return new Reader() {
private final OfInt chars = iterator();
private char queuedLowSurrogate = 0;

@Override
public int read(char[] cbuf, int off, int len) throws IOException {
if (off < 0 || len < 0 || len > (cbuf.length - off)) {
throw new IndexOutOfBoundsException();
}
if (len == 0) {
return 0;
}

int pos = off;
int endPos = off + len;
char lowSurrogate = queuedLowSurrogate;
queuedLowSurrogate = 0;
while (pos < endPos) {
if (lowSurrogate != 0) {
cbuf[pos++] = lowSurrogate;
lowSurrogate = 0;
continue;
}
if (!chars.hasNext()) {
break;
}
int nextChar = chars.nextInt();
if (Character.isBmpCodePoint(nextChar)) {
cbuf[pos++] = (char)nextChar;
} else {
cbuf[pos++] = Character.highSurrogate(nextChar);
lowSurrogate = Character.lowSurrogate(nextChar);
}
}
queuedLowSurrogate = lowSurrogate;
int written = pos - off;
return written == 0 ? /* EOF */ -1 : written;
}

@Override
public int read() throws IOException {
if (queuedLowSurrogate != 0) {
int result = queuedLowSurrogate;
queuedLowSurrogate = 0;
return result;
}
if (chars.hasNext()) {
int nextChar = chars.nextInt();
if (Character.isBmpCodePoint(nextChar)) {
return nextChar;
} else {
queuedLowSurrogate = Character.lowSurrogate(nextChar);
return Character.highSurrogate(nextChar);
}
}
return -1;
}
@Override
public void close() throws IOException {
}
};
}

@Override
public void indentedWrite(Writer w, Deque<IString> whitespace, boolean indentFirstLine) throws IOException {
if (flattened != null) {
Expand Down
10 changes: 0 additions & 10 deletions src/test/java/io/usethesource/vallang/basic/LazyStringOperationsTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -231,16 +231,6 @@ public void neverRunOutOfStack(IValueFactory vf) throws IOException {
// TODO Auto-generated catch block
fail("unexpected IO:" + e);
}
try {
fromReader(v.asReader());
fail("this should run out of stack");
} catch (StackOverflowError e) {
// yes, that is what is expected
} catch (IOException e) {
// TODO Auto-generated catch block
fail("unexpected IO:" + e);
}

} finally {
StringValue.resetMaxFlatString();
StringValue.resetMaxUnbalance();
Expand Down

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