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Squarespace template compiler
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/**
 * Copyright (c) 2014 SQUARESPACE, 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.squarespace.template;

import java.util.ArrayList;
import java.util.List;


/**
 * Mapping of fixed instruction identifiers.  Instructions which have variant
 * forms (predicates, variable references) are handled separately.
 */
public class InstructionTable {

  private static final int HASHMAP_BUCKETS = 32;

  private static final StringViewMap table = new StringViewMap<>(HASHMAP_BUCKETS);

  private static final List symbolList = new ArrayList<>();

  /**
   * Adds a mapping from the string identifier to the instruction type.
   */
  static void add(String str, InstructionType type) {
    add(str, type, true);
  }

  /**
   * Adds a mapping from the string identifier to the instruction type.
   */
  static void add(String str, InstructionType type, boolean isSymbol) {
    table.put(new StringView(str), type);
    if (isSymbol) {
      symbolList.add(str);
    }
  }

  static {
    add(".alternates", InstructionType.ALTERNATES_WITH, false);
    add(".ctx", InstructionType.CTXVAR);
    add(".end", InstructionType.END);
    add(".eval", InstructionType.EVAL);
    add(".if", InstructionType.IF);
    add(".include", InstructionType.INCLUDE);
    add(".inject", InstructionType.INJECT);
    add(".macro", InstructionType.MACRO);
    add(".meta-left", InstructionType.META_LEFT);
    add(".meta-right", InstructionType.META_RIGHT);
    add(".newline", InstructionType.NEWLINE);
    add(".or", InstructionType.OR_PREDICATE);
    add(".repeated", InstructionType.REPEATED, false);
    add(".section", InstructionType.SECTION);
    add(".space", InstructionType.SPACE);
    add(".tab", InstructionType.TAB);
    add(".var", InstructionType.BINDVAR);

    // Special-case for instructions containing whitespace (yeah).
    symbolList.add(".alternates with");
    symbolList.add(".repeated section");
  }

  /**
   * Used for debugging the internal table layout.
   */
  public static String dump() {
    try {
      return table.dump();
    } catch (Exception e) {
      throw new RuntimeException("Error dumping instruction table", e);
    }
  }

  /**
   * Returns the instruction table.
   */
  public static StringViewMap getTable() {
    return table;
  }

  /**
   * Returns the instruction type for the given symbol.
   */
  public static InstructionType get(StringView symbol) {
    return table.get(symbol);
  }

  /**
   * Returns all symbols registered in the table.
   */
  public static String[] getSymbols() {
    return symbolList.toArray(Constants.EMPTY_ARRAY_OF_STRING);
  }

}