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Adds support for reading binary tagless types.
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@tgregg
tgregg committed Jun 28, 2024
1 parent ae23c9e commit a6a6a37
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Showing 6 changed files with 741 additions and 131 deletions.
210 changes: 140 additions & 70 deletions src/main/java/com/amazon/ion/impl/IonCursorBinary.java
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
import static com.amazon.ion.impl.IonTypeID.SYSTEM_SYMBOL_VALUE;
import static com.amazon.ion.impl.IonTypeID.TWO_ANNOTATION_FLEX_SYMS_LOWER_NIBBLE_1_1;
import static com.amazon.ion.impl.IonTypeID.TWO_ANNOTATION_SIDS_LOWER_NIBBLE_1_1;
import static com.amazon.ion.impl.IonTypeID.TYPE_IDS_1_1;
import static com.amazon.ion.util.IonStreamUtils.throwAsIonException;

/**
Expand Down Expand Up @@ -349,6 +350,11 @@ private static class RefillableState {
*/
private boolean isSystemInvocation = false;

/**
* The type of the current value, if tagless. Otherwise, null.
*/
PrimitiveType taglessType = null;

/**
* @return the given configuration's DataHandler, or null if that DataHandler is a no-op.
*/
Expand Down Expand Up @@ -1232,12 +1238,12 @@ private boolean uncheckedReadAnnotationWrapperHeader_1_1(IonTypeID valueTid) {
private boolean slowSkipNonPrefixedAnnotations_1_1(IonTypeID valueTid) {
if (valueTid.isInlineable) {
// Opcodes 0xE7 (one annotation FlexSym) and 0xE8 (two annotation FlexSyms)
if (slowSkipFlexSym_1_1()) {
if (slowSkipFlexSym_1_1(null) == FlexSymType.INCOMPLETE) {
return true;
}
if (valueTid.lowerNibble == TWO_ANNOTATION_FLEX_SYMS_LOWER_NIBBLE_1_1) {
// Opcode 0xE8 (two annotation FlexSyms)
return slowSkipFlexSym_1_1();
return slowSkipFlexSym_1_1(null) == FlexSymType.INCOMPLETE;
}
} else {
// Opcodes 0xE4 (one annotation SID) and 0xE5 (two annotation SIDs)
Expand Down Expand Up @@ -1544,46 +1550,127 @@ private long slowReadFlexSym_1_1(Marker markerToSet) {
return result;
}

/**
* FlexSym encoding types.
*/
private enum FlexSymType {
INCOMPLETE {
@Override
IonTypeID typeIdFor(int length) {
throw new IllegalStateException("The FlexSym is incomplete.");
}
},
INLINE_TEXT {
@Override
IonTypeID typeIdFor(int length) {
if (length <= 0xF) {
return TYPE_IDS_1_1[0xA0 | length];
}
return TYPE_IDS_1_1[OpCodes.VARIABLE_LENGTH_INLINE_SYMBOL & SINGLE_BYTE_MASK];
}
},
SYMBOL_ID {
@Override
IonTypeID typeIdFor(int length) {
if (length == 0) {
return TYPE_IDS_1_1[OpCodes.SYMBOL_ADDRESS_1_BYTE & SINGLE_BYTE_MASK];
}
if (length < 3) {
return TYPE_IDS_1_1[0xE0 | length];
}
return TYPE_IDS_1_1[OpCodes.SYMBOL_ADDRESS_MANY_BYTES & SINGLE_BYTE_MASK];
}
},
STRUCT_END {
@Override
IonTypeID typeIdFor(int length) {
throw new IllegalStateException("The special struct end FlexSym is not associated with a type ID.");
}
};

/**
* Classifies a special FlexSym (beginning with FlexInt zero) based on the byte that follows.
* @param specialByte the byte that followed FlexInt zero.
* @return the FlexSymType that corresponds to the given special byte.
*/
static FlexSymType classifySpecialFlexSym(int specialByte) {
if (specialByte < 0) {
return FlexSymType.INCOMPLETE;
}
if ((byte) specialByte == OpCodes.INLINE_SYMBOL_ZERO_LENGTH) {
return FlexSymType.SYMBOL_ID;
}
if ((byte) specialByte == OpCodes.STRING_ZERO_LENGTH) {
return FlexSymType.INLINE_TEXT;
}
if ((byte) specialByte == OpCodes.DELIMITED_END_MARKER) {
return FlexSymType.STRUCT_END;
}
throw new IonException("FlexSyms may only wrap symbol zero, empty string, or delimited end.");
}

/**
* Gets the most appropriate IonTypeID for a FlexSym of this type and the given length.
* @param length the length of the FlexSym.
* @return an Ion 1.1 IonTypeID with appropriate values for 'length' and 'isInlineable'.
*/
abstract IonTypeID typeIdFor(int length);
}

/**
* Skips a FlexSym. After this method returns, `peekIndex` points to the first byte after the end of the FlexSym.
* @param markerToSet the method returns `INLINE_TEXT, will have `startIndex` and `endIndex` set to the bounds of
* the inline UTF-8 byte sequence.
* @return the type of FlexSym that was skipped.
*/
private void uncheckedSkipFlexSym_1_1() {
private FlexSymType uncheckedSkipFlexSym_1_1(Marker markerToSet) {
long result = uncheckedReadFlexInt_1_1();
if (result == 0) {
peekIndex++;
markerToSet.startIndex = peekIndex + 1;
markerToSet.endIndex = markerToSet.startIndex;
return FlexSymType.classifySpecialFlexSym(buffer[(int) peekIndex++] & SINGLE_BYTE_MASK);
} else if (result < 0) {
peekIndex -= result;
markerToSet.startIndex = peekIndex;
markerToSet.endIndex = peekIndex - result;
peekIndex = markerToSet.endIndex;
return FlexSymType.INLINE_TEXT;
}
return FlexSymType.SYMBOL_ID;
}

/**
* Skips a FlexSym, ensuring enough space is available in the buffer. After this method returns, `peekIndex` points
* to the first byte after the end of the FlexSym.
* @return true if there are not enough bytes in the stream to complete the FlexSym; otherwise, false.
* @param markerToSet if non-null and the method returns `INLINE_TEXT`, will have `startIndex` and `endIndex` set
* to the bounds of the inline UTF-8 byte sequence.
* @return INCOMPLETE if there are not enough bytes in the stream to complete the FlexSym; otherwise, the type
* of FlexSym that was skipped.
*/
private boolean slowSkipFlexSym_1_1() {
private FlexSymType slowSkipFlexSym_1_1(Marker markerToSet) {
long result = slowReadFlexUInt_1_1();
if (result < 0) {
return true;
return FlexSymType.INCOMPLETE;
}
if (buffer[(int) peekIndex - 1] < 0) {
// Sign extension.
result |= ~(-1 >>> Long.numberOfLeadingZeros(result));
}
if (result == 0) {
int nextByte = slowReadByte();
if (nextByte < 0) {
return true;
}
if ((byte) nextByte != OpCodes.INLINE_SYMBOL_ZERO_LENGTH && (byte) nextByte != OpCodes.STRING_ZERO_LENGTH && (byte) nextByte != OpCodes.DELIMITED_END_MARKER) {
throw new IonException("FlexSyms may only wrap symbol zero, empty string, or delimited end.");
FlexSymType flexSymType = FlexSymType.classifySpecialFlexSym(slowReadByte());
if (markerToSet != null && flexSymType != FlexSymType.INCOMPLETE) {
markerToSet.startIndex = peekIndex;
markerToSet.endIndex = peekIndex;
}
return false;
return flexSymType;
} else if (result < 0) {
if (markerToSet != null) {
markerToSet.startIndex = peekIndex;
markerToSet.endIndex = peekIndex - result;
}
peekIndex -= result;
return false;
return FlexSymType.INLINE_TEXT;
}
return false;
return FlexSymType.SYMBOL_ID;
}

/**
Expand Down Expand Up @@ -1970,6 +2057,7 @@ private void reset() {
annotationSequenceMarker.endIndex = -1;
macroInvocationId = -1;
isSystemInvocation = false;
taglessType = null;
}

/**
Expand Down Expand Up @@ -2850,64 +2938,55 @@ private boolean slowSkipToNextToken() {
}

/**
* Reads the length of the FlexSym that starts at the given position.
* @param position the start position of the FlexSym.
* @return the length of the FlexSym.
*/
private long uncheckedReadLengthOfFlexSym_1_1(long position) {
uncheckedSkipFlexSym_1_1();
long lengthOfFlexSym = (int) (peekIndex - position);
peekIndex = position;
return lengthOfFlexSym;
}

/**
* Reads the length of the FlexSym that starts at the given position, ensuring enough bytes are available in the
* stream.
* @param position the start position of the FlexSym.
* Reads the length and type of the FlexSym that starts at the given position, ensuring enough bytes are available
* in the stream. After this method returns with a value greater than or equal to zero, `valueTid` and
* `valueMarker.typeId` will be set to the IonTypeID that most closely corresponds to the length and type of the
* FlexSym.
* @return the length of the FlexSym, or -1 if not enough bytes are available in the stream to determine the length.
*/
private long slowReadLengthOfFlexSym_1_1(long position) {
if (slowSkipFlexSym_1_1()) {
return -1;
private long readFlexSymLengthAndType_1_1() {
FlexSymType flexSymType;
if (isSlowMode) {
flexSymType = slowSkipFlexSym_1_1(valueMarker);
if (flexSymType == FlexSymType.INCOMPLETE) {
return -1;
}
} else {
flexSymType = uncheckedSkipFlexSym_1_1(valueMarker);
}
int lengthOfFlexSym = (int) (peekIndex - position);
peekIndex = position;
int lengthOfFlexSym = (int) (peekIndex - valueMarker.startIndex);
peekIndex = valueMarker.startIndex;
valueTid = flexSymType.typeIdFor(lengthOfFlexSym);
valueMarker.typeId = valueTid;
return lengthOfFlexSym;
}

/**
* Calculates the length of a variable-length primitive value.
* @param primitiveType the variable-length primitive type of the tagless value that starts at `peekIndex`.
* @return the length of the value.
*/
private long uncheckedCalculateTaglessLength(PrimitiveType primitiveType) {
switch (primitiveType) {
case FLEX_UINT:
case FLEX_INT:
return uncheckedReadLengthOfFlexUInt_1_1(peekIndex);
case COMPACT_SYMBOL:
return uncheckedReadLengthOfFlexSym_1_1(peekIndex);
default:
throw new IllegalStateException("Length is built into the primitive type's IonTypeID.");
}
}

/**
* Calculates the length of a variable-length primitive value, ensuring enough bytes are available in the stream.
* Calculates the length and type of variable-length primitive value, ensuring enough bytes are available in the
* stream.
* @param primitiveType the variable-length primitive type of the tagless value that starts at `peekIndex`.
* @return the length of the value, or -1 if not enough bytes are available in the stream to determine the length.
*/
private long slowCalculateTaglessLength(PrimitiveType primitiveType) {
private long calculateTaglessLengthAndType(PrimitiveType primitiveType) {
// TODO length calculation for these types could be deferred until they are consumed to avoid duplicate
// work. This would trade some added complexity for a potential performance gain that would need to be
// quantified.
long length;
switch (primitiveType) {
case FLEX_UINT:
case FLEX_INT:
return slowReadLengthOfFlexUInt_1_1(peekIndex);
length = isSlowMode ? slowReadLengthOfFlexUInt_1_1(peekIndex) : uncheckedReadLengthOfFlexUInt_1_1(peekIndex);
break;
case COMPACT_SYMBOL:
return slowReadLengthOfFlexSym_1_1(peekIndex);
length = readFlexSymLengthAndType_1_1();
break;
default:
throw new IllegalStateException("Length is built into the primitive type's IonTypeID.");
}
if (length >= 0) {
valueMarker.endIndex = peekIndex + length;
}
return length;
}

/**
Expand Down Expand Up @@ -2938,24 +3017,15 @@ public Event nextTaglessValue(PrimitiveType primitiveType) {
reportConsumedData();
}
reset();
taglessType = primitiveType;
valueTid = primitiveType.typeID;
valueMarker.typeId = valueTid;
valueMarker.startIndex = peekIndex;
valuePreHeaderIndex = peekIndex;
if (valueTid.variableLength) {
// TODO length calculation for these types could be deferred until they are consumed to avoid duplicate
// work. This would trade some added complexity for a potential performance gain that would need to be
// quantified.
long length;
if (isSlowMode) {
length = slowCalculateTaglessLength(primitiveType);
if (length < 0) {
return event;
}
} else {
length = uncheckedCalculateTaglessLength(primitiveType);
if (calculateTaglessLengthAndType(primitiveType) < 0) {
return event;
}
valueMarker.endIndex = peekIndex + length;
} else {
valueMarker.endIndex = peekIndex + valueTid.length;
}
Expand Down
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