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A library for core classes (Graph, Vertex, Edge, etc.)
package io.konig.formula;
/*
* #%L
* Konig Core
* %%
* Copyright (C) 2015 - 2017 Gregory McFall
* %%
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* #L%
*/
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.openrdf.model.Literal;
import org.openrdf.model.URI;
import org.openrdf.model.impl.URIImpl;
import org.openrdf.rio.RDFHandlerException;
import org.openrdf.rio.RDFParseException;
import io.konig.core.Context;
import io.konig.core.KonigException;
import io.konig.core.LocalNameService;
import io.konig.core.Term;
import io.konig.core.Term.Kind;
import io.konig.core.util.IriTemplate;
import io.konig.core.util.ValueFormat.Element;
import io.konig.core.util.ValueFormat.ElementType;
import io.konig.rio.turtle.NamespaceMap;
import io.konig.rio.turtle.SeaTurtleParser;
public class FormulaParser {
private static final Set KEYWORD = new HashSet<>();
static {
KEYWORD.add("IF");
KEYWORD.add("COUNT");
KEYWORD.add("SUM");
KEYWORD.add("AVG");
KEYWORD.add("DAY");
KEYWORD.add("MONTH");
KEYWORD.add("YEAR");
KEYWORD.add("CONCAT");
KEYWORD.add("STRPOS");
KEYWORD.add("SUBSTR");
KEYWORD.add("BOUND");
KEYWORD.add("UNIX_TIME");
KEYWORD.add("CASE");
KEYWORD.add("WHEN");
KEYWORD.add("THEN");
KEYWORD.add("ELSE");
KEYWORD.add("END");
KEYWORD.add("DISTINCT");
KEYWORD.add("IN");
KEYWORD.add("NOT");
KEYWORD.add("AND");
KEYWORD.add("OR");
KEYWORD.add("WHERE");
}
private PropertyOracle propertyOracle;
private LocalNameService localNameService;
private NamespaceMap namespaceMap;
public FormulaParser() {
}
public QuantifiedExpression quantifiedExpression(String formula, URI...terms) throws RDFParseException, IOException {
StringBuilder builder = new StringBuilder();
for (URI term : terms) {
builder.append("@term ");
builder.append(term.getLocalName());
builder.append(" <");
builder.append(term.stringValue());
builder.append(">\n");
}
builder.append(formula);
return quantifiedExpression(builder.toString());
}
public FormulaParser(PropertyOracle propertyOracle) {
this.propertyOracle = propertyOracle;
}
public FormulaParser(PropertyOracle propertyOracle, LocalNameService localNameService) {
this.propertyOracle = propertyOracle;
this.localNameService = localNameService;
}
public FormulaParser(PropertyOracle propertyOracle, LocalNameService localNameService, NamespaceMap nsMap) {
this.propertyOracle = propertyOracle;
this.localNameService = localNameService;
this.namespaceMap = nsMap;
}
public PropertyOracle getPropertyOracle() {
return propertyOracle;
}
public LocalNameService getLocalNameService() {
return localNameService;
}
public NamespaceMap getNamespaceMap() {
return namespaceMap;
}
public QuantifiedExpression quantifiedExpression(String text) throws RDFParseException, IOException {
StringReader reader = new StringReader(text);
return quantifiedExpression(reader);
}
public QuantifiedExpression quantifiedExpression(Reader reader) throws RDFParseException, IOException {
Worker worker = new Worker(reader);
worker.setDefaultNamespaceMap(namespaceMap);
try {
return worker.quantifiedExpression();
} catch (RDFHandlerException e) {
throw new KonigException(e);
}
}
public Expression expression(String text) throws RDFParseException, IOException {
StringReader reader = new StringReader(text);
return expression(reader);
}
public Expression expression(Reader reader) throws RDFParseException, IOException {
Worker worker = new Worker(reader);
try {
return worker.formula();
} catch (RDFHandlerException e) {
throw new KonigException(e);
}
}
private class Worker extends SeaTurtleParser {
private Worker(Reader reader) {
initParse(reader, "");
}
private Expression formula() throws RDFParseException, IOException, RDFHandlerException {
prologue();
return expression();
}
private QuantifiedExpression quantifiedExpression() throws RDFParseException, IOException, RDFHandlerException {
prologue();
Expression e = expression();
// List statementList = whereClause();
List statementList = null;
return new QuantifiedExpression(e, statementList);
}
// private List whereClause() throws IOException, RDFParseException {
// List list = null;
// skipSpace();
// if (tryWord("WHERE")) {
// list = new ArrayList<>();
// Triple triple = null;
// while ((triple=tryTriple()) != null) {
// list.add(triple);
// }
// }
// return list;
// }
// private Triple tryTriple() throws RDFParseException, IOException {
// Triple triple = null;
// PathTerm subject = tryPathTerm();
// if (subject != null) {
// PathTerm term = pathTerm();
// if (!(term instanceof IriValue)) {
// throw new RDFParseException("Expected curie, iri, or local name");
// }
// IriValue predicate = (IriValue) term;
// PathTerm object = pathTerm();
// assertNext('.');
// triple = new Triple(subject, predicate, object);
//
// }
// return triple;
// }
private Expression expression() throws RDFParseException, IOException, RDFHandlerException {
Expression e = conditionalOrExpression();
e.getContext().compile();
return e;
}
private BareExpression expr() throws RDFParseException, RDFHandlerException, IOException {
ConditionalOrExpression e = conditionalOrExpression();
return new BareExpression(e);
}
private ConditionalOrExpression conditionalOrExpression() throws RDFParseException, IOException, RDFHandlerException {
ConditionalOrExpression or = new ConditionalOrExpression();
or.setContext(getContext());
ConditionalAndExpression and = conditionalAndExpression();
or.add(and);
while ((and=tryConditionalAndExpression()) != null) {
or.add(and);
}
return or;
}
private ConditionalAndExpression tryConditionalAndExpression() throws IOException, RDFParseException, RDFHandlerException {
if (tryWord("WHERE")) {
unread("WHERE");
return null;
}
ConditionalAndExpression and = null;
ValueLogical value = tryValueLogical();
if (value != null) {
and = new ConditionalAndExpression();
and.add(value);
skipSpace();
while (tryWord("&&") || isWord("AND")) {
value = valueLogical();
and.add(value);
}
}
return and;
}
private boolean isString(String text) throws IOException {
StringBuilder buffer = buffer();
for (int i=0; i' :
operator = tryWord("=") ? BinaryOperator.GREATER_THAN_OR_EQUAL : BinaryOperator.GREATER_THAN;
break;
case '!' :
operator = tryWord("=") ? BinaryOperator.NOT_EQUAL : null;
break;
}
if (operator == null) {
unread(c);
} else {
right = numericExpression();
}
binary = new BinaryRelationalExpression(operator, left, right);
}
return binary;
}
private NumericExpression numericExpression() throws RDFParseException, IOException, RDFHandlerException {
NumericExpression numeric = tryNumericExpression();
if (numeric == null) {
fail("Expected a NumericExpression");
}
return numeric;
}
private NumericExpression tryNumericExpression() throws IOException, RDFParseException, RDFHandlerException {
return tryAdditiveExpression();
}
private AdditiveExpression tryAdditiveExpression() throws IOException, RDFParseException, RDFHandlerException {
GeneralAdditiveExpression expr = null;
MultiplicativeExpression left = tryMultiplicativeExpression();
if (left != null) {
expr = new GeneralAdditiveExpression(left);
for (;;) {
skipSpace();
int c = read();
AdditiveOperator operator = null;
switch (c) {
case '+' :
operator = AdditiveOperator.PLUS;
break;
case '-' :
operator = AdditiveOperator.MINUS;
break;
}
if (operator == null) {
unread(c);
break;
}
skipSpace();
MultiplicativeExpression right = multiplicativeExpression();
Addend addend = new Addend(operator, right);
expr.add(addend);
}
}
return expr;
}
private MultiplicativeExpression multiplicativeExpression() throws RDFParseException, IOException, RDFHandlerException {
MultiplicativeExpression mult = tryMultiplicativeExpression();
if (mult == null) {
fail("Expected MultiplicativeExpression");
}
return mult;
}
private MultiplicativeExpression tryMultiplicativeExpression() throws IOException, RDFParseException, RDFHandlerException {
MultiplicativeExpression mult = null;
UnaryExpression left = tryUnaryExpression();
if (left != null) {
mult = new MultiplicativeExpression(left);
for (;;) {
MultiplicativeOperator operator = null;
skipSpace();
int c = read();
switch(c) {
case '*' :
operator = MultiplicativeOperator.MULTIPLY;
break;
case '/' :
operator = MultiplicativeOperator.DIVIDE;
break;
}
if (operator == null) {
unread(c);
break;
}
UnaryExpression right = unaryExpression();
mult.add(new Factor(operator, right));
}
}
return mult;
}
private UnaryExpression unaryExpression() throws RDFParseException, IOException, RDFHandlerException {
UnaryExpression unary = tryUnaryExpression();
if (unary == null) {
fail("Expected UnaryExpression");
}
return unary;
}
private UnaryExpression tryUnaryExpression() throws IOException, RDFParseException, RDFHandlerException {
skipSpace();
int c = read();
UnaryOperator operator = null;
if (c == '!') {
int d = peek();
if (d == '=') {
return null;
}
operator = UnaryOperator.NOT;
} else {
unread(c);
}
PrimaryExpression primary = tryPrimaryExpression();
if (operator != null && primary==null) {
fail("Expected PrimaryExpression");
}
return primary==null ? null : new UnaryExpression(operator, primary);
}
private PrimaryExpression tryPrimaryExpression() throws IOException, RDFParseException, RDFHandlerException {
PrimaryExpression primary = null;
primary =
(primary=tryBrackettedExpression()) != null ? primary :
(primary=tryBuiltInCall()) != null ? primary :
(primary=tryCase()) != null ? primary :
(primary=tryLiteralFormula()) != null ? primary :
(primary=tryPath()) != null ? primary :
(primary=tryIri()) != null ? primary :
null;
return primary;
}
/**
* Return one of fully-qualified IRI, CURIE, or localName registered with the LocalNameService.
* @throws IOException
* @throws RDFParseException
* @throws RDFHandlerException
*/
private PrimaryExpression tryIri() throws IOException, RDFParseException, RDFHandlerException {
PrimaryExpression result = null;
return
(result=tryFullIri()) != null ? result :
(result=tryCurieOrLocalName()) != null ? result :
null;
}
private PathTerm tryCurieOrLocalName() throws IOException, RDFParseException {
int c = next();
if (Character.isLetter(c)) {
StringBuilder buffer = buffer();
do {
buffer.appendCodePoint(c);
c = read();
} while (Character.isLetterOrDigit(c) || c=='_');
String predicate = buffer.toString();
if (c == ':') {
String prefix = predicate;
c = read();
if (Character.isLetterOrDigit(c)) {
buffer = buffer();
do {
buffer.appendCodePoint(c);
c = read();
} while (Character.isLetterOrDigit(c) || c=='_');
String localName = buffer.toString();
unread(c);
Context context = getContext();
boolean ok = context.getTerm(prefix)!= null;
if (!ok && namespaceMap!=null) {
String namespace = namespaceMap.get(prefix);
if (namespace != null) {
Term term = context.addTerm(prefix, namespace);
term.setKind(Kind.NAMESPACE);
ok = true;
}
}
if (!ok) {
throw new RDFParseException("Namespace not defined for prefix: " + prefix);
}
return new CurieValue(getContext(), prefix, localName);
} else {
fail("Expected a letter after ':' in CURIE");
}
} else {
unread(c);
if (KEYWORD.contains(predicate.toUpperCase())) {
unread(predicate);
return null;
}
String localName = predicate;
Context context = getContext();
Term term = context.getTerm(localName);
if (term == null) {
if (localNameService != null) {
Set iriOptions = localNameService.lookupLocalName(localName);
if (iriOptions.size()==1) {
URI id = iriOptions.iterator().next();
term = new Term(localName, id.stringValue(), Kind.ANY);
context.add(term);
} else if (iriOptions.isEmpty()) {
String msg = MessageFormat.format("Local name not found: {0}", localName);
fail(msg);
} else {
StringBuilder builder = new StringBuilder();
builder.append("Local name \"");
builder.append(localName);
builder.append("\" is ambiguous. Could be one of");
for (URI iri : iriOptions) {
builder.append("\n ");
builder.append(iri.stringValue());
}
fail(builder.toString());
}
}
}
return new LocalNameTerm(context, predicate);
}
} else {
unread(c);
}
return null;
}
private PrimaryExpression tryFullIri() throws RDFParseException, IOException, RDFHandlerException {
if (
isString("=0) {
Context context = getContext();
IriTemplate template = new IriTemplate(context, iriText);
if (namespaceMap != null && localNameService!=null) {
for (Element e : template.toList()) {
if (e.getType() == ElementType.VARIABLE) {
String text = e.getText();
int colon = text.indexOf(':');
if (colon > 0) {
String prefix = text.substring(0, colon);
String namespaceURI = namespaceMap.get(prefix);
if (namespaceURI == null) {
throw new RDFHandlerException("namespace prefix not defined: " + prefix);
}
context.add(new Term(prefix, namespaceURI, Kind.NAMESPACE));
String localName = text.substring(colon+1);
context.addTerm(localName, text);
} else {
Set set = localNameService.lookupLocalName(text);
if (set.size() > 1) {
StringBuilder builder = new StringBuilder();
builder.append("Local name '");
builder.append(text);
builder.append("' is ambiguous. Possible values include: ");
for (URI uri : set) {
builder.append("\n ");
builder.append(uri.stringValue());
}
throw new RDFHandlerException(builder.toString());
} else if (set.isEmpty()) {
throw new RDFHandlerException("Local name not known: " + text);
}
URI uri = set.iterator().next();
context.addTerm(text, uri.stringValue());
}
}
}
}
return new IriTemplateExpression(template);
}
return new FullyQualifiedIri(new URIImpl(iriText));
}
return null;
}
private IfFunction tryIfFunction() throws IOException, RDFParseException, RDFHandlerException {
skipSpace();
if (tryCaseInsensitiveWord("IF") != null){
skipSpace();
int c = read();
if (c != '(') {
unread(c);
} else {
skipSpace();
Expression condition = expr();
read(',');
Expression whenTrue = expr();
read(',');
Expression whenFalse = expr();
assertNext(')');
return new IfFunction(condition, whenTrue, whenFalse);
}
}
return null;
}
private BuiltInCall tryBuiltInCall() throws IOException, RDFParseException, RDFHandlerException {
BuiltInCall call =
(call=tryIfFunction()) !=null ? call :
(call=trySetFunction(FunctionModel.SUM)) != null ? call :
(call=trySetFunction(FunctionModel.AVG)) != null ? call :
(call=trySetFunction(FunctionModel.COUNT)) != null ? call :
(call=tryGenericFunction(FunctionModel.DAY)) != null ? call :
(call=tryGenericFunction(FunctionModel.MONTH)) != null ? call :
(call=tryGenericFunction(FunctionModel.YEAR)) != null ? call :
(call=tryGenericFunction(FunctionModel.CONCAT)) != null ? call :
(call=tryGenericFunction(FunctionModel.SUBSTR)) != null ? call :
(call=tryGenericFunction(FunctionModel.STRPOS)) != null ? call :
(call=tryGenericFunction(FunctionModel.UNIX_TIME)) != null ? call :
(call=tryGenericFunction(FunctionModel.IRI)) != null ? call :
(call=tryGenericFunction(FunctionModel.STRIP_SPACES)) != null ? call :
(call=tryBoundFunction()) != null ? call :
null;
return call;
}
private SetFunctionExpression trySetFunction(FunctionModel model) throws IOException, RDFParseException, RDFHandlerException {
skipSpace();
String functionName = model.getName();
String name = tryCaseInsensitiveWord(functionName);
if (name != null) {
int c = next();
if (c != '(') {
unread(c);
unread(name);
} else {
skipSpace();
boolean distinct = tryCaseInsensitiveWord("DISTINCT") != null;
if (distinct) {
skipSpace();
}
List argList = argList();
assertNext(')');
return new SetFunctionExpression(model, distinct, argList);
}
}
return null;
}
private BoundFunction tryBoundFunction() throws IOException, RDFParseException, RDFHandlerException {
if (tryWord("BOUND")) {
int c = next();
if (c != '(') {
unread(c);
unread("BOUND");
} else {
PathExpression arg = tryPath();
if (arg == null) {
fail("Expected variable or path as argument to BOUND function");
}
assertNext(')');
return new BoundFunction(arg);
}
}
return null;
}
private BuiltInCall tryGenericFunction(FunctionModel model) throws IOException, RDFParseException, RDFHandlerException {
skipSpace();
String functionName = model.getName();
String name = tryCaseInsensitiveWord(functionName);
if (name != null) {
int c = next();
if (c != '(') {
unread(c);
unread(name);
} else {
skipSpace();
List argList = argList();
assertNext(')');
return new FunctionExpression(model, argList);
}
}
return null;
}
private CaseStatement tryCase() throws IOException, RDFParseException, RDFHandlerException {
skipSpace();
String name = tryCaseInsensitiveWord("CASE");
if (name != null) {
Expression caseCondition = null;
skipSpace();
String when = tryCaseInsensitiveWord("WHEN");
if (when == null) {
caseCondition = expression();
} else {
unread(when);
}
List whenThenList = whenThenList();
Expression elseClause = null;
if (tryCaseInsensitiveWord("ELSE") != null) {
elseClause = expression();
}
skipSpace();
assertIgnoreCase("END");
return new CaseStatement(caseCondition, whenThenList, elseClause);
}
return null;
}
private List whenThenList() throws IOException, RDFParseException, RDFHandlerException {
List list = new ArrayList<>();
for (;;) {
skipSpace();
if (tryCaseInsensitiveWord("WHEN") != null) {
skipSpace();
Expression when = expression();
skipSpace();
assertIgnoreCase("THEN");
Expression then = expression();
list.add(new WhenThenClause(when, then));
} else {
break;
}
}
if (list.isEmpty()) {
throw new RDFParseException("CASE statement is missing WHEN...THEN clause");
}
return list;
}
private List argList() throws IOException, RDFParseException, RDFHandlerException {
List result = new ArrayList<>();
int c=0;
do {
Expression arg = expr();
result.add(arg);
c = next();
} while (c==',');
unread(c);
return result;
}
private PathExpression tryPath() throws RDFParseException, IOException, RDFHandlerException {
int next = next();
if (next != '?' && next!='$') {
unread(next);
return null;
}
PathExpression path = new PathExpression();
if (next == '?') {
unread(next);
VariableTerm var = variable();
path.add(new DirectionStep(Direction.OUT, var));
}
next = peek();
while (next=='^' || next=='.' || next=='[') {
switch(next) {
case '.' :
path.add(outStep());
break;
case '^' :
path.add(inStep());
break;
case '[' :
path.add(hasStep());
}
skipSpace();
next = peek();
}
return path;
}
private PathStep hasStep() throws RDFParseException, RDFHandlerException, IOException {
List constraints = predicateObjectList();
return new HasPathStep(constraints);
}
private PathStep inStep() throws RDFParseException, IOException {
assertNext('^');
return new DirectionStep(Direction.IN, pathTerm());
}
private PathStep outStep() throws RDFParseException, IOException {
assertNext('.');
return new DirectionStep(Direction.OUT, pathTerm());
}
private List predicateObjectList() throws IOException, RDFParseException, RDFHandlerException {
assertNext('[');
List list = new ArrayList<>();
for (;;) {
PathExpression path = tryPath();
if (path == null) {
IriValue predicate = iriValue();
path = new PathExpression();
path.add(new DirectionStep(Direction.OUT, (PathTerm) predicate));
}
ObjectList objectList = objectList();
list.add(new PredicateObjectList(path, objectList));
int next = next();
if (next == ';') {
skipSpace();
next = peek();
if (next == ']') {
break;
}
} else if (next==']') {
break;
} else {
throw new RDFParseException("Invalid predicateObjectList");
}
}
return list;
}
private ObjectList objectList() throws RDFParseException, RDFHandlerException, IOException {
List list = new ArrayList<>();
for (;;) {
Expression e = expression();
list.add(e);
int next = next();
if (next != ',') {
unread(next);
break;
}
}
return new ObjectList(list);
}
private IriValue iriValue() throws RDFParseException, IOException {
IriValue result = null;
PathTerm term = tryPathTerm();
if (term instanceof IriValue) {
result = (IriValue) term;
} else {
fail("Expected IRI value");
}
return result;
}
private PathTerm pathTerm() throws RDFParseException, IOException {
PathTerm predicate = tryPathTerm();
if (predicate == null) {
fail("Expected a predicate");
}
return predicate;
}
private PathTerm tryPathTerm() throws RDFParseException, IOException {
String predicate = null;
skipSpace();
int c = read();
if (c == '<') {
String value = iriRef(c);
return new FullyQualifiedIri(new URIImpl(value));
}
if (Character.isLetter(c)) {
StringBuilder buffer = buffer();
do {
buffer.appendCodePoint(c);
c = read();
} while (Character.isLetter(c) || Character.isDigit(c) || c=='_');
predicate = buffer.toString();
if (c == ':') {
c = read();
if (Character.isLetter(c)) {
buffer = buffer();
do {
buffer.appendCodePoint(c);
c = read();
} while (Character.isLetter(c) || Character.isDigit(c) || c=='_');
String prefix = predicate;
String localName = buffer.toString();
unread(c);
Context context = getContext();
boolean ok = context.getTerm(prefix)!= null;
if (!ok && namespaceMap!=null) {
String namespace = namespaceMap.get(prefix);
if (namespace != null) {
Term term = context.addTerm(prefix, namespace);
term.setKind(Kind.NAMESPACE);
ok = true;
}
}
if (!ok) {
throw new RDFParseException("Namespace not defined for prefix: " + prefix);
}
return new CurieValue(getContext(), prefix, localName);
} else {
fail("Expected a letter");
}
}
}
unread(c);
if ("IN".equalsIgnoreCase(predicate)) {
unread(predicate);
predicate = null;
} else if ("NOT".equalsIgnoreCase(predicate)) {
unread(predicate);
predicate = null;
} else if ("THEN".equalsIgnoreCase(predicate)) {
unread(predicate);
predicate = null;
} else if ("WHEN".equalsIgnoreCase(predicate)) {
unread(predicate);
predicate = null;
} else if ("ELSE".equalsIgnoreCase(predicate)) {
unread(predicate);
predicate = null;
} else if ("END".equalsIgnoreCase(predicate)) {
unread(predicate);
predicate = null;
}
if (predicate == null) {
return null;
}
String localName = predicate;
Context context = getContext();
Term term = context.getTerm(localName);
if (term == null) {
if (localNameService != null) {
Set iriOptions = localNameService.lookupLocalName(localName);
if (iriOptions.size()==1) {
URI id = iriOptions.iterator().next();
term = new Term(localName, id.stringValue(), Kind.ANY);
context.add(term);
} else if (iriOptions.isEmpty()) {
String msg = MessageFormat.format("Local name not found: {0}", localName);
throw new RDFParseException(msg);
} else {
StringBuilder builder = new StringBuilder();
builder.append("Local name \"");
builder.append(localName);
builder.append("\" is ambiguous. Could be one of");
for (URI iri : iriOptions) {
builder.append("\n ");
builder.append(iri.stringValue());
}
throw new RDFParseException(builder.toString());
}
}
}
return new LocalNameTerm(context, predicate);
}
private VariableTerm variable() throws RDFParseException, IOException {
assertNext('?');
buffer = buffer();
int c = read();
do {
buffer.appendCodePoint(c);
c = read();
} while (Character.isLetter(c) || Character.isDigit(c) || c=='_');
unread(c);
String varName = buffer.toString();
Context context = getContext();
String termName = varName;
Term term = context.getTerm(termName);
if (term != null) {
String iri = context.expandIRI(termName);
return new VariableTerm(varName, new URIImpl(iri));
}
if (localNameService != null) {
Set set = localNameService.lookupLocalName(termName);
if (set.size() == 1) {
URI varId = set.iterator().next();
context.addTerm(termName, varId.stringValue());
return new VariableTerm(varName, varId);
}
}
VariableTerm result = new VariableTerm(varName);
context.addTerm(varName, result.getIri().stringValue());
return result;
}
private LiteralFormula tryLiteralFormula() throws RDFParseException, RDFHandlerException, IOException {
Literal literal = tryLiteral();
return literal == null ? null : new LiteralFormula(literal);
}
private BrackettedExpression tryBrackettedExpression() throws IOException, RDFParseException, RDFHandlerException {
BrackettedExpression bracket = null;
skipSpace();
int c = read();
if (c == '(') {
skipSpace();
Expression e = expression();
skipSpace();
assertNext(')');
bracket = new BrackettedExpression(e);
} else {
unread(c);
}
return bracket;
}
private ConditionalAndExpression conditionalAndExpression() throws RDFParseException, IOException, RDFHandlerException {
ConditionalAndExpression and = tryConditionalAndExpression();
if (and == null) {
fail("Expected ConditionalAndExpression" );
}
return and;
}
}
}