/*
 * Copyright 2002-2018 the original author or authors.
 *
 * 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
 *
 *      https://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
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package org.springframework.expression.common;

import org.springframework.core.convert.TypeDescriptor;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.Expression;
import org.springframework.expression.TypedValue;
import org.springframework.lang.Nullable;

Represents a template expression broken into pieces. Each piece will be an Expression but pure text parts to the template will be represented as LiteralExpression objects. An example of a template expression might be:
"Hello ${getName()}"
which will be represented as a CompositeStringExpression of two parts. The first part being a LiteralExpression representing 'Hello ' and the second part being a real expression that will call getName() when invoked.
Author:Andy Clement, Juergen Hoeller
Since:3.0
/** * Represents a template expression broken into pieces. Each piece will be an Expression * but pure text parts to the template will be represented as LiteralExpression objects. * An example of a template expression might be: * * <pre class="code"> * &quot;Hello ${getName()}&quot; * </pre> * * which will be represented as a CompositeStringExpression of two parts. The first part * being a LiteralExpression representing 'Hello ' and the second part being a real * expression that will call {@code getName()} when invoked. * * @author Andy Clement * @author Juergen Hoeller * @since 3.0 */
public class CompositeStringExpression implements Expression { private final String expressionString;
The array of expressions that make up the composite expression.
/** The array of expressions that make up the composite expression. */
private final Expression[] expressions; public CompositeStringExpression(String expressionString, Expression[] expressions) { this.expressionString = expressionString; this.expressions = expressions; } @Override public final String getExpressionString() { return this.expressionString; } public final Expression[] getExpressions() { return this.expressions; } @Override public String getValue() throws EvaluationException { StringBuilder sb = new StringBuilder(); for (Expression expression : this.expressions) { String value = expression.getValue(String.class); if (value != null) { sb.append(value); } } return sb.toString(); } @Override @Nullable public <T> T getValue(@Nullable Class<T> expectedResultType) throws EvaluationException { Object value = getValue(); return ExpressionUtils.convertTypedValue(null, new TypedValue(value), expectedResultType); } @Override public String getValue(@Nullable Object rootObject) throws EvaluationException { StringBuilder sb = new StringBuilder(); for (Expression expression : this.expressions) { String value = expression.getValue(rootObject, String.class); if (value != null) { sb.append(value); } } return sb.toString(); } @Override @Nullable public <T> T getValue(@Nullable Object rootObject, @Nullable Class<T> desiredResultType) throws EvaluationException { Object value = getValue(rootObject); return ExpressionUtils.convertTypedValue(null, new TypedValue(value), desiredResultType); } @Override public String getValue(EvaluationContext context) throws EvaluationException { StringBuilder sb = new StringBuilder(); for (Expression expression : this.expressions) { String value = expression.getValue(context, String.class); if (value != null) { sb.append(value); } } return sb.toString(); } @Override @Nullable public <T> T getValue(EvaluationContext context, @Nullable Class<T> expectedResultType) throws EvaluationException { Object value = getValue(context); return ExpressionUtils.convertTypedValue(context, new TypedValue(value), expectedResultType); } @Override public String getValue(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException { StringBuilder sb = new StringBuilder(); for (Expression expression : this.expressions) { String value = expression.getValue(context, rootObject, String.class); if (value != null) { sb.append(value); } } return sb.toString(); } @Override @Nullable public <T> T getValue(EvaluationContext context, @Nullable Object rootObject, @Nullable Class<T> desiredResultType) throws EvaluationException { Object value = getValue(context,rootObject); return ExpressionUtils.convertTypedValue(context, new TypedValue(value), desiredResultType); } @Override public Class<?> getValueType() { return String.class; } @Override public Class<?> getValueType(EvaluationContext context) { return String.class; } @Override public Class<?> getValueType(@Nullable Object rootObject) throws EvaluationException { return String.class; } @Override public Class<?> getValueType(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException { return String.class; } @Override public TypeDescriptor getValueTypeDescriptor() { return TypeDescriptor.valueOf(String.class); } @Override public TypeDescriptor getValueTypeDescriptor(@Nullable Object rootObject) throws EvaluationException { return TypeDescriptor.valueOf(String.class); } @Override public TypeDescriptor getValueTypeDescriptor(EvaluationContext context) { return TypeDescriptor.valueOf(String.class); } @Override public TypeDescriptor getValueTypeDescriptor(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException { return TypeDescriptor.valueOf(String.class); } @Override public boolean isWritable(@Nullable Object rootObject) throws EvaluationException { return false; } @Override public boolean isWritable(EvaluationContext context) { return false; } @Override public boolean isWritable(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException { return false; } @Override public void setValue(@Nullable Object rootObject, @Nullable Object value) throws EvaluationException { throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression"); } @Override public void setValue(EvaluationContext context, @Nullable Object value) throws EvaluationException { throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression"); } @Override public void setValue(EvaluationContext context, @Nullable Object rootObject, @Nullable Object value) throws EvaluationException { throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression"); } }