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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.tensor;
import java.util.Optional;
/**
* @author bratseth
*/
class TensorParser {
static Tensor tensorFrom(String tensorString, Optional<TensorType> explicitType) {
Optional<TensorType> type;
String valueString;
tensorString = tensorString.trim();
if (tensorString.startsWith("tensor")) {
int colonIndex = tensorString.indexOf(':');
String typeString = tensorString.substring(0, colonIndex);
TensorType typeFromString = TensorTypeParser.fromSpec(typeString);
if (explicitType.isPresent() && ! explicitType.get().equals(typeFromString))
throw new IllegalArgumentException("Got tensor with type string '" + typeString + "', but was " +
"passed type " + explicitType.get());
type = Optional.of(typeFromString);
valueString = tensorString.substring(colonIndex + 1);
}
else {
type = explicitType;
valueString = tensorString;
}
valueString = valueString.trim();
if (valueString.startsWith("{")) {
return tensorFromSparseValueString(valueString, type);
}
else if (valueString.startsWith("[")) {
return tensorFromDenseValueString(valueString, type);
}
else {
if (explicitType.isPresent() && ! explicitType.get().equals(TensorType.empty))
throw new IllegalArgumentException("Got a zero-dimensional tensor value ('" + tensorString +
"') where type " + explicitType.get() + " is required");
try {
return Tensor.Builder.of(TensorType.empty).cell(Double.parseDouble(tensorString)).build();
}
catch (NumberFormatException e) {
throw new IllegalArgumentException("Excepted a number or a string starting by {, [ or tensor(...):, got '" +
tensorString + "'");
}
}
}
/** Derives the tensor type from the first address string in the given tensor string */
private static TensorType typeFromSparseValueString(String valueString) {
String s = valueString.substring(1).trim(); // remove tensor start
int firstKeyOrTensorEnd = s.indexOf('}');
if (firstKeyOrTensorEnd < 0)
throw new IllegalArgumentException("Excepted a number or a string starting by {, [ or tensor(...):, got '" +
valueString + "'");
String addressBody = s.substring(0, firstKeyOrTensorEnd).trim();
if (addressBody.isEmpty()) return TensorType.empty; // Empty tensor
if ( ! addressBody.startsWith("{")) return TensorType.empty; // Single value tensor
addressBody = addressBody.substring(1, addressBody.length()); // remove key start
if (addressBody.isEmpty()) return TensorType.empty; // Empty key
TensorType.Builder builder = new TensorType.Builder(TensorType.Value.DOUBLE);
for (String elementString : addressBody.split(",")) {
String[] pair = elementString.split(":");
if (pair.length != 2)
throw new IllegalArgumentException("Expecting argument elements to be on the form dimension:label, " +
"got '" + elementString + "'");
builder.mapped(pair[0].trim());
}
return builder.build();
}
private static Tensor tensorFromSparseValueString(String valueString, Optional<TensorType> type) {
try {
valueString = valueString.trim();
Tensor.Builder builder = Tensor.Builder.of(type.orElse(typeFromSparseValueString(valueString)));
return fromCellString(builder, valueString);
}
catch (NumberFormatException e) {
throw new IllegalArgumentException("Excepted a number or a string starting by { or tensor(, got '" +
valueString + "'");
}
}
private static Tensor tensorFromDenseValueString(String valueString, Optional<TensorType> type) {
if (type.isEmpty())
throw new IllegalArgumentException("The dense tensor form requires an explicit tensor type " +
"on the form 'tensor(dimensions):...");
if (type.get().dimensions().stream().anyMatch(d -> ( d.size().isEmpty())))
throw new IllegalArgumentException("The dense tensor form requires a tensor type containing " +
"only dense dimensions with a given size");
IndexedTensor.BoundBuilder builder = (IndexedTensor.BoundBuilder)IndexedTensor.Builder.of(type.get());
// Since we know the dimensions the brackets are just syntactic sugar
long[] indexes = new long[builder.type().rank()];
int currentChar;
int nextNumberEnd = 0;
while ((currentChar = nextStartCharIndex(nextNumberEnd + 1, valueString)) < valueString.length()) {
nextNumberEnd = nextStopCharIndex(currentChar, valueString);
if (currentChar == nextNumberEnd) return builder.build();
if (builder.type().valueType() == TensorType.Value.DOUBLE)
builder.cellByDirectIndex(nextCellIndex(indexes, builder), Double.parseDouble(valueString.substring(currentChar, nextNumberEnd)));
else if (builder.type().valueType() == TensorType.Value.FLOAT)
builder.cellByDirectIndex(nextCellIndex(indexes, builder), Float.parseFloat(valueString.substring(currentChar, nextNumberEnd)));
else
throw new IllegalArgumentException(builder.type().valueType() + " is not supported");
}
return builder.build();
}
// -----
/**
* Advance to the next cell in left-adjac ent order.
*
* On rightmost vs. leftmost adjacency:
* A dense tensor is laid out with the rightmost dimension as adjacent numbers,
* but when we parse a dense tensor we encounter numbers in the leftmost-adjacent order, since
* that is the most natural way to write it: tensor(x,y)[[1,2],[3,4]]
* should mean {{x:0, y:0}:1, {x:1, y:0}:2, {x:0, y:1}:3, {x:1, y:1}:4}.
* Therefore we need to convert the encounter order (numberIndex) from left-adjacent to right-adjacent.
*/
private static long nextCellIndex(long[] indexes, IndexedTensor.BoundBuilder builder) {
long cellIndex = IndexedTensor.toValueIndex(indexes, builder.sizes());
// Find next dimension to advance
int nextInDimension = 0;
while (nextInDimension < indexes.length && indexes[nextInDimension] + 1 >= builder.sizes().size(nextInDimension)) {
indexes[nextInDimension] = 0;
nextInDimension++;
}
if (nextInDimension < indexes.length)
indexes[nextInDimension]++;
else // there is no next - become invalid
indexes[0]++;
return cellIndex;
}
/** Returns the position of the next character that should contain a number, or if none the string length */
private static int nextStartCharIndex(int charIndex, String valueString) {
for (; charIndex < valueString.length(); charIndex++) {
if (valueString.charAt(charIndex) == ']') continue;
if (valueString.charAt(charIndex) == '[') continue;
if (valueString.charAt(charIndex) == ',') continue;
if (valueString.charAt(charIndex) == ' ') continue;
return charIndex;
}
return valueString.length();
}
private static int nextStopCharIndex(int charIndex, String valueString) {
while (charIndex < valueString.length()) {
if (valueString.charAt(charIndex) == ',') return charIndex;
if (valueString.charAt(charIndex) == ']') return charIndex;
charIndex++;
}
throw new IllegalArgumentException("Malformed tensor value '" + valueString +
"': Expected a ',' or ']' after position " + charIndex);
}
private static Tensor fromCellString(Tensor.Builder builder, String s) {
int index = 1;
index = skipSpace(index, s);
while (index + 1 < s.length()) {
int keyOrTensorEnd = s.indexOf('}', index);
TensorAddress.Builder addressBuilder = new TensorAddress.Builder(builder.type());
if (keyOrTensorEnd < s.length() - 1) { // Key end: This has a key - otherwise TensorAddress is empty
addLabels(s.substring(index, keyOrTensorEnd + 1), addressBuilder);
index = keyOrTensorEnd + 1;
index = skipSpace(index, s);
if ( s.charAt(index) != ':')
throw new IllegalArgumentException("Expecting a ':' after " + s.substring(index) + ", got '" + s + "'");
index++;
}
int valueEnd = s.indexOf(',', index);
if (valueEnd < 0) { // last value
valueEnd = s.indexOf('}', index);
if (valueEnd < 0)
throw new IllegalArgumentException("A tensor string must end by '}'");
}
TensorAddress address = addressBuilder.build();
Double value = asDouble(address, s.substring(index, valueEnd).trim());
builder.cell(address, value);
index = valueEnd+1;
index = skipSpace(index, s);
}
return builder.build();
}
private static int skipSpace(int index, String s) {
while (index < s.length() && s.charAt(index) == ' ')
index++;
return index;
}
/** Creates a tenor address from a string on the form {dimension1:label1,dimension2:label2,...} */
private static void addLabels(String mapAddressString, TensorAddress.Builder builder) {
mapAddressString = mapAddressString.trim();
if ( ! (mapAddressString.startsWith("{") && mapAddressString.endsWith("}")))
throw new IllegalArgumentException("Expecting a tensor address enclosed in {}, got '" + mapAddressString + "'");
String addressBody = mapAddressString.substring(1, mapAddressString.length() - 1).trim();
if (addressBody.isEmpty()) return;
for (String elementString : addressBody.split(",")) {
String[] pair = elementString.split(":");
if (pair.length != 2)
throw new IllegalArgumentException("Expecting argument elements on the form dimension:label, " +
"got '" + elementString + "'");
String dimension = pair[0].trim();
builder.add(dimension, pair[1].trim());
}
}
private static Double asDouble(TensorAddress address, String s) {
try {
return Double.valueOf(s);
}
catch (NumberFormatException e) {
throw new IllegalArgumentException("At " + address + ": Expected a floating point number, got '" + s + "'");
}
}
}
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