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/*
* Copyright (c) 2013, SRI International
* All rights reserved.
* Licensed under the The BSD 3-Clause License;
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://opensource.org/licenses/BSD-3-Clause
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* Neither the name of the aic-expresso nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.sri.ai.expresso.core;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import com.google.common.annotations.Beta;
import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;
import com.sri.ai.expresso.ExpressoConfiguration;
import com.sri.ai.expresso.api.Expression;
import com.sri.ai.expresso.api.ExpressionAndSyntacticContext;
import com.sri.ai.expresso.api.Symbol;
import com.sri.ai.expresso.api.SyntaxLeaf;
import com.sri.ai.expresso.api.SyntaxTree;
import com.sri.ai.expresso.helper.Expressions;
import com.sri.ai.grinder.api.Registry;
import com.sri.ai.grinder.core.AbstractNonQuantifiedExpression;
import com.sri.ai.util.AICUtilConfiguration;
import com.sri.ai.util.Util;
import com.sri.ai.util.math.Rational;
/**
* An (atomic) {@link Expression} representing a symbol.
*
* @author braz
*/
@Beta
public class DefaultSymbol extends AbstractNonQuantifiedExpression implements Symbol {
private static final long serialVersionUID = 1L;
private SyntaxLeaf syntxLeaf;
@Override
public Object getValue() {
return syntxLeaf.getValue();
}
@Override
public boolean isStringLiteral() {
return syntxLeaf.isStringLiteral();
}
@Override
public Iterator getImmediateSubExpressionsAndContextsIterator() {
return Util.iterator();
}
@Override
public Object getSyntacticFormType() {
return Symbol.SYNTACTIC_FORM_TYPE;
}
@Override
public SyntaxTree getSyntaxTree() {
return syntxLeaf;
}
@Override
public Expression replaceSymbol(Expression symbol, Expression newSymbol, Registry registry) {
Expression result = this;
if (this.equals(symbol)) {
result = newSymbol;
}
return result;
}
@Override
public Expression clone() {
return Expressions.makeSymbol(getValue());
}
@Override
public boolean booleanValue() {
if (getSyntaxTree().getLabel() instanceof Boolean) {
return ((Boolean) getSyntaxTree().getLabel()).booleanValue();
}
throw new Error("Expression.intValue() invoked on " + this + ", which is not a boolean.");
}
@Override
public int intValue() {
if (getSyntaxTree().getLabel() instanceof Number) {
return ((Number) getSyntaxTree().getLabel()).intValue();
}
throw new Error("Expression.intValue() invoked on " + this + ", which is not a number.");
}
@Override
public long longValue() {
if (getSyntaxTree().getLabel() instanceof Number) {
return ((Number) getSyntaxTree().getLabel()).longValue();
}
throw new Error("Expression.longValue() invoked on " + this + ", which is not a number.");
}
@Override
public int intValueExact() throws ArithmeticException {
if (getSyntaxTree().getLabel() instanceof Rational) {
return ((Rational) getSyntaxTree().getLabel()).intValueExact();
}
throw new Error("Expression.intValueExact() invoked on " + this + ", which is not a number.");
}
@Override
public double doubleValue() {
if (getSyntaxTree().getLabel() instanceof Number) {
return ((Number) getSyntaxTree().getLabel()).doubleValue();
}
throw new Error("Expression.doubleValue() invoked on " + this + ", which is not a number.");
}
@Override
public Rational rationalValue() {
if (getSyntaxTree().getLabel() instanceof Number) {
return (Rational) getSyntaxTree().getLabel();
}
// throw new Error("Expression.rationalValue() invoked on " + this + ", which is not a number.");
return null; // returning null for consistency with rationalValue() behavior for other expressions
}
public static Symbol createSymbol(Object value) {
return createSymbol(value, false);
}
public static Symbol createSymbol(Object value, boolean isStringLiteral) {
Symbol result = null;
// If global symbol table to be used and the symbol's value is not
// an expression - i.e. quoted expressions of the form:
//
// as these need to be instantiated each time in order to be
// parsed correctly.
if (useGlobalSymbolTable && !(value instanceof Expression)) {
if (isStringLiteral) {
result = globalStringLiteralTable.getIfPresent(value);
}
else {
result = globalSymbolTable.getIfPresent(value);
}
if (result == null) {
result = new DefaultSymbol(value, isStringLiteral);
if (!(!cacheNumericSymbols && result.getValue() instanceof Number)) {
if (isStringLiteral) {
globalStringLiteralTable.put(value, result);
}
else {
globalSymbolTable.put(value, result);
}
}
}
}
else {
result = new DefaultSymbol(value, isStringLiteral);
}
return result;
}
// Note: End users can only instantiate Symbols via the factory method.
private DefaultSymbol(Object value, boolean isStringLiteral) {
syntxLeaf = DefaultSyntaxLeaf.createSyntaxLeaf(value, isStringLiteral);
}
public static void flushGlobalSymbolTable() {
if (AICUtilConfiguration.isRecordCacheStatistics()) {
System.out.println("Global Symbol Table Cache Stats="+globalSymbolTable.stats());
System.out.println("Global String Literal Table Cache Stats="+globalStringLiteralTable.stats());
}
// Causes relevant flags to be reset.
useGlobalSymbolTable = ExpressoConfiguration.isUseGlobalSymbolTable();
cacheNumericSymbols = ExpressoConfiguration.isGlobalSymbolTableToCacheNumerics();
if (globalSymbolTable != null) {
globalSymbolTable.invalidateAll();
}
if (globalStringLiteralTable != null) {
globalStringLiteralTable.invalidateAll();
}
globalSymbolTable = newSymbolTable();
globalStringLiteralTable = newSymbolTable();
// Add well known symbols to the table
// The Booleans.
globalSymbolTable.put(true, SYMBOL_TRUE);
globalSymbolTable.put(Boolean.TRUE, SYMBOL_TRUE);
globalSymbolTable.put("true", SYMBOL_TRUE);
globalSymbolTable.put(false, SYMBOL_FALSE);
globalSymbolTable.put(Boolean.FALSE, SYMBOL_FALSE);
globalSymbolTable.put("false", SYMBOL_FALSE);
// Common Numbers
globalSymbolTable.put("0", SYMBOL_0);
globalSymbolTable.put(new Integer(0), SYMBOL_0);
globalSymbolTable.put(new Rational(0), SYMBOL_0);
globalSymbolTable.put("1", SYMBOL_1);
globalSymbolTable.put(new Integer(1), SYMBOL_1);
globalSymbolTable.put(new Rational(1), SYMBOL_1);
globalSymbolTable.put("2", SYMBOL_2);
globalSymbolTable.put(new Integer(2), SYMBOL_2);
globalSymbolTable.put(new Rational(2), SYMBOL_2);
globalSymbolTable.put("3", SYMBOL_3);
globalSymbolTable.put(new Integer(3), SYMBOL_3);
globalSymbolTable.put(new Rational(3), SYMBOL_3);
globalSymbolTable.put("4", SYMBOL_4);
globalSymbolTable.put(new Integer(4), SYMBOL_4);
globalSymbolTable.put(new Rational(4), SYMBOL_4);
globalSymbolTable.put("5", SYMBOL_5);
globalSymbolTable.put(new Integer(5), SYMBOL_5);
globalSymbolTable.put(new Rational(5), SYMBOL_5);
globalSymbolTable.put("6", SYMBOL_6);
globalSymbolTable.put(new Integer(6), SYMBOL_6);
globalSymbolTable.put(new Rational(6), SYMBOL_6);
globalSymbolTable.put("7", SYMBOL_7);
globalSymbolTable.put(new Integer(7), SYMBOL_7);
globalSymbolTable.put(new Rational(7), SYMBOL_7);
globalSymbolTable.put("8", SYMBOL_8);
globalSymbolTable.put(new Integer(8), SYMBOL_8);
globalSymbolTable.put(new Rational(8), SYMBOL_8);
globalSymbolTable.put("9", SYMBOL_9);
globalSymbolTable.put(new Integer(9), SYMBOL_9);
globalSymbolTable.put(new Rational(9), SYMBOL_9);
}
private static Cache newSymbolTable() {
CacheBuilder cb = CacheBuilder.newBuilder();
long maximumSize = ExpressoConfiguration.getGlobalSymbolTableMaximumSize();
// Note: a maximumSize of
// < 0 means no size restrictions
// = 0 means no cache
// > 0 means maximum size of cache
if (maximumSize >= 0L) {
cb.maximumSize(maximumSize);
}
if (AICUtilConfiguration.isRecordCacheStatistics()) {
cb.recordStats();
}
Cache result = cb.build();
return result;
}
//
// Commonly used symbol expressions
private static final Symbol SYMBOL_TRUE = Expressions.makeSymbol(true);
private static final Symbol SYMBOL_FALSE = Expressions.makeSymbol(false);
private static final Symbol SYMBOL_0 = Expressions.makeSymbol(new Rational(0));
private static final Symbol SYMBOL_1 = Expressions.makeSymbol(new Rational(1));
private static final Symbol SYMBOL_2 = Expressions.makeSymbol(new Rational(2));
private static final Symbol SYMBOL_3 = Expressions.makeSymbol(new Rational(3));
private static final Symbol SYMBOL_4 = Expressions.makeSymbol(new Rational(4));
private static final Symbol SYMBOL_5 = Expressions.makeSymbol(new Rational(5));
private static final Symbol SYMBOL_6 = Expressions.makeSymbol(new Rational(6));
private static final Symbol SYMBOL_7 = Expressions.makeSymbol(new Rational(7));
private static final Symbol SYMBOL_8 = Expressions.makeSymbol(new Rational(8));
private static final Symbol SYMBOL_9 = Expressions.makeSymbol(new Rational(9));
//
private static boolean useGlobalSymbolTable = ExpressoConfiguration.isUseGlobalSymbolTable();
private static boolean cacheNumericSymbols = ExpressoConfiguration.isGlobalSymbolTableToCacheNumerics();
private static Cache globalSymbolTable = newSymbolTable();
private static Cache globalStringLiteralTable = newSymbolTable();
static {
flushGlobalSymbolTable();
}
@Override
public String makeToString() {
return getSyntaxTree().toString();
}
@Override
public Expression getFunctor() {
return null;
}
@Override
public List getArguments() {
return Collections.emptyList();
}
@Override
public Expression set(int i, Expression newIthArgument) {
throw new Error("set(int, Expression) not defined for " + getClass());
}
}
