com.google.template.soy.jssrc.dsl.Concatenation.java Source code

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Here is the source code for com.google.template.soy.jssrc.dsl.Concatenation.java

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/*
 * Copyright 2018 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.jssrc.dsl;

import com.google.auto.value.AutoValue;
import com.google.common.collect.ImmutableList;
import com.google.errorprone.annotations.Immutable;
import com.google.template.soy.exprtree.Operator;
import com.google.template.soy.exprtree.Operator.Associativity;

/**
 * Represents the concatenation of many chunks via the {@code +} operator.
 *
 * <p>This could be represented as a nested sequence of {@link BinaryOperation} chunks, but the
 * compiler tends to create very large concatenations (thousands of nodes) and the naive recursive
 * formatting algorithm can cause stack overflow errors.
 */
@AutoValue
@Immutable
abstract class Concatenation extends Operation {

    static Concatenation create(Iterable<? extends Expression> parts) {
        ImmutableList.Builder<Statement> initialStatements = ImmutableList.builder();
        ImmutableList.Builder<Expression> partsBuilder = ImmutableList.builder();
        for (Expression part : parts) {
            initialStatements.addAll(part.initialStatements());
            if (part instanceof Concatenation) {
                partsBuilder.addAll(((Concatenation) part).parts());
            } else if (part instanceof BinaryOperation) {
                BinaryOperation binaryOp = (BinaryOperation) part;
                if (binaryOp.operator().equals(Operator.PLUS.getTokenString())) {
                    partsBuilder.add(binaryOp.arg1());
                    partsBuilder.add(binaryOp.arg2());
                } else {
                    partsBuilder.add(part);
                }
            } else {
                partsBuilder.add(part);
            }
        }
        return new AutoValue_Concatenation(initialStatements.build(), partsBuilder.build());
    }

    abstract ImmutableList<Expression> parts();

    @Override
    int precedence() {
        return Operator.PLUS.getPrecedence();
    }

    @Override
    Associativity associativity() {
        return Operator.PLUS.getAssociativity();
    }

    @Override
    public void collectRequires(RequiresCollector collector) {
        for (Expression part : parts()) {
            part.collectRequires(collector);
        }
    }

    @Override
    void doFormatOutputExpr(FormattingContext ctx) {
        if (parts().isEmpty()) {
            ctx.append("''");
        } else if (parts().size() == 1) {
            ctx.appendOutputExpression(parts().get(0));
        } else {
            formatOperand(parts().get(0), OperandPosition.LEFT, ctx);
            for (int i = 1; i < parts().size(); i++) {
                ctx.append(" + ");
                formatOperand(parts().get(i), OperandPosition.RIGHT, ctx);
            }
        }
    }

    @Override
    void doFormatInitialStatements(FormattingContext ctx) {
        for (Expression part : parts()) {
            ctx.appendInitialStatements(part);
        }
    }
}