com.google.template.soy.soytree.ExprUnion.java Source code

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Here is the source code for com.google.template.soy.soytree.ExprUnion.java

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/*
 * Copyright 2011 Google Inc.
 *
 * 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.
 */

package com.google.template.soy.soytree;

import com.google.common.collect.Lists;
import com.google.template.soy.basetree.CopyState;
import com.google.template.soy.exprtree.ExprNode;
import com.google.template.soy.exprtree.ExprRootNode;

import java.util.List;

import javax.annotation.Nullable;

/**
 * Represents a Soy expression in either V2 or V1 syntax.
 *
 * <p> Important: Do not use outside of Soy code (treat as superpackage-private).
 *
 * If this expression is in V2 syntax, then {@link #getExpr()} will return a nonnull expression
 * tree. If this expression is in V1 syntax, then {@code #getExpr()} will return null. In either
 * case, the expression text can be obtained from {@link #getExprText()}.
 *
 */
public final class ExprUnion {

    /**
     * Utility to create a list of {@code ExprUnion}s from a list of expression trees.
     * @param exprs The list of expression trees.
     * @return A new list of corresponding {@code ExprUnion}s.
     */
    public static List<ExprUnion> createList(List<? extends ExprRootNode> exprs) {
        List<ExprUnion> exprUnions = Lists.newArrayListWithCapacity(exprs.size());
        for (ExprRootNode expr : exprs) {
            exprUnions.add(new ExprUnion(expr));
        }
        return exprUnions;
    }

    /** The expression tree, or null if the expression is in V1 syntax. */
    @Nullable
    private final ExprRootNode expr;

    /** The V1 expression text, or null if the expression is in V2 syntax. */
    @Nullable
    private final String exprText;

    /**
     * Constructor for an instance that represents a V2 expression.
     * @param expr The expression tree.
     */
    public ExprUnion(ExprNode expr) {
        this(new ExprRootNode(expr));
    }

    /**
     * Constructor for an instance that represents a V2 expression.
     * @param expr The expression tree.
     */
    public ExprUnion(ExprRootNode expr) {
        this.expr = expr;
        this.exprText = null;
    }

    /**
     * Constructor for an instance that represents an expression in V1 syntax.
     * @param exprTextV1 The text of the V1 expression.
     */
    public ExprUnion(String exprTextV1) {
        this.expr = null;
        this.exprText = exprTextV1;
    }

    private ExprUnion(ExprUnion orig, CopyState copyState) {
        this.expr = orig.expr != null ? orig.expr.copy(copyState) : null;
        this.exprText = orig.exprText;
    }

    /**
     * Returns the expression tree if the expression is in V2 syntax, else null.
     */
    public ExprRootNode getExpr() {
        return expr;
    }

    /**
     * Returns the expression text. This method works for both V2 and V1 expressions.
     */
    public String getExprText() {
        return (expr != null) ? expr.toSourceString() : exprText;
    }

    /**
     * Returns a (deep) clone of this object.
     */
    public ExprUnion copy(CopyState copyState) {
        return new ExprUnion(this, copyState);
    }

}