ParamStore.java

/*
 * Copyright 2013 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.data.internal;

import com.google.template.soy.data.SoyAbstractValue;
import com.google.template.soy.data.SoyRecord;
import com.google.template.soy.data.SoyValue;
import com.google.template.soy.data.SoyValueProvider;
import java.io.IOException;
import javax.annotation.Nonnull;

/**
 * Internal-use param store for passing data in subtemplate calls.
 *
 * <p>Important: Do not use outside of Soy code (treat as superpackage-private).
 *
 */
public abstract class ParamStore extends SoyAbstractValue implements SoyRecord {

  /**
   * Sets a field (i.e. param) in this ParamStore.
   *
   * @param name The field name to set.
   * @param valueProvider A provider of the field value.
   */
  public abstract ParamStore setField(String name, @Nonnull SoyValueProvider valueProvider);

  @Override
  public SoyValue getField(String name) {
    SoyValueProvider valueProvider = getFieldProvider(name);
    return (valueProvider != null) ? valueProvider.resolve() : null;
  }

  // -----------------------------------------------------------------------------------------------
  // SoyValue.

  @Override
  public boolean coerceToBoolean() {
    throw new UnsupportedOperationException();
  }

  @Override
  public String coerceToString() {
    throw new UnsupportedOperationException();
  }

  @Override
  public void render(Appendable appendable) throws IOException {
    throw new UnsupportedOperationException();
  }

  @Override
  public boolean equals(Object other) {
    throw new UnsupportedOperationException();
  }

  // -----------------------------------------------------------------------------------------------
  // Empty instance.

  public static final ParamStore EMPTY_INSTANCE =
      new ParamStore() {
        @Override
        public ParamStore setField(String name, @Nonnull SoyValueProvider valueProvider) {
          throw new UnsupportedOperationException();
        }

        @Override
        public boolean hasField(String name) {
          return false;
        }

        @Override
        public SoyValueProvider getFieldProvider(String name) {
          return null;
        }

        @Override
        public SoyValue getField(String name) {
          return null;
        }
      };
}