content: /*
   * Copyright (C) 2019 The Android Open Source Project
   *
   * 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 android.database.sqlite;
  
  import android.annotation.NonNull;
  import android.annotation.Nullable;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Locale;
  import java.util.function.Consumer;
  
  /**
   * SQL Tokenizer specialized to extract tokens from SQL (snippets).
   * <p>
   * Based on sqlite3GetToken() in tokenzie.c in SQLite.
   * <p>
   * Source for v3.8.6 (which android uses): http://www.sqlite.org/src/artifact/ae45399d6252b4d7
   * (Latest source as of now: http://www.sqlite.org/src/artifact/78c8085bc7af1922)
   * <p>
   * Also draft spec: http://www.sqlite.org/draft/tokenreq.html
   *
   * @hide
   */
  public class SQLiteTokenizer {
      private static boolean isAlpha(char ch) {
          return ('a' <= ch && ch <= 'z') || ('A' <= ch && ch <= 'Z') || (ch == '_');
      }
  
      private static boolean isNum(char ch) {
          return ('0' <= ch && ch <= '9');
      }
  
      private static boolean isAlNum(char ch) {
          return isAlpha(ch) || isNum(ch);
      }
  
      private static boolean isAnyOf(char ch, String set) {
          return set.indexOf(ch) >= 0;
      }
  
      private static IllegalArgumentException genException(String message, String sql) {
          throw new IllegalArgumentException(message + " in '" + sql + "'");
      }
  
      private static char peek(String s, int index) {
          return index < s.length() ? s.charAt(index) : '\0';
      }
  
      public static final int OPTION_NONE = 0;
  
      /**
       * Require that SQL contains only tokens; any comments or values will result
       * in an exception.
       */
      public static final int OPTION_TOKEN_ONLY = 1 << 0;
  
      /**
       * Tokenize the given SQL, returning the list of each encountered token.
       *
       * @throws IllegalArgumentException if invalid SQL is encountered.
       */
      public static List<String> tokenize(@Nullable String sql, int options) {
          final ArrayList<String> res = new ArrayList<>();
          tokenize(sql, options, res::add);
          return res;
      }
  
      /**
       * Tokenize the given SQL, sending each encountered token to the given
       * {@link Consumer}.
       *
       * @throws IllegalArgumentException if invalid SQL is encountered.
       */
      public static void tokenize(@Nullable String sql, int options, Consumer<String> checker) {
          if (sql == null) {
              return;
          }
          int pos = 0;
          final int len = sql.length();
          while (pos < len) {
              final char ch = peek(sql, pos);
  
              // Regular token.
              if (isAlpha(ch)) {
                  final int start = pos;
                  pos++;
                  while (isAlNum(peek(sql, pos))) {
                      pos++;
                  }
                  final int end = pos;
  
                  final String token = sql.substring(start, end);
                  checker.accept(token);
  
                  continue;
              }
  
              // Handle quoted tokens
              if (isAnyOf(ch, "'\"`")) {
                  final int quoteStart = pos;
                  pos++;
  
                  for (;;) {
                      pos = sql.indexOf(ch, pos);
                      if (pos < 0) {
                          throw genException("Unterminated quote", sql);
                      }
                      if (peek(sql, pos + 1) != ch) {
                          break;
                      }
                      // Quoted quote char -- e.g. "abc""def" is a single string.
                      pos += 2;
                  }
                  final int quoteEnd = pos;
                  pos++;
  
                  if (ch != '\'') {
                      // Extract the token
                      final String tokenUnquoted = sql.substring(quoteStart + 1, quoteEnd);
  
                      final String token;
  
                      // Unquote if needed. i.e. "aa""bb" -> aa"bb
                      if (tokenUnquoted.indexOf(ch) >= 0) {
                          token = tokenUnquoted.replaceAll(
                                  String.valueOf(ch) + ch, String.valueOf(ch));
                      } else {
                          token = tokenUnquoted;
                      }
                      checker.accept(token);
                  } else {
                      if ((options &= OPTION_TOKEN_ONLY) != 0) {
                          throw genException("Non-token detected", sql);
                      }
                  }
                  continue;
              }
              // Handle tokens enclosed in [...]
              if (ch == '[') {
                  final int quoteStart = pos;
                  pos++;
  
                  pos = sql.indexOf(']', pos);
                  if (pos < 0) {
                      throw genException("Unterminated quote", sql);
                  }
                  final int quoteEnd = pos;
                  pos++;
  
                  final String token = sql.substring(quoteStart + 1, quoteEnd);
  
                  checker.accept(token);
                  continue;
              }
              if ((options &= OPTION_TOKEN_ONLY) != 0) {
                  throw genException("Non-token detected", sql);
              }
  
              // Detect comments.
              if (ch == '-' && peek(sql, pos + 1) == '-') {
                  pos += 2;
                  pos = sql.indexOf('\n', pos);
                  if (pos < 0) {
                      // We disallow strings ending in an inline comment.
                      throw genException("Unterminated comment", sql);
                  }
                  pos++;
  
                  continue;
              }
              if (ch == '/' && peek(sql, pos + 1) == '*') {
                  pos += 2;
                  pos = sql.indexOf("*/", pos);
                  if (pos < 0) {
                      throw genException("Unterminated comment", sql);
                  }
                  pos += 2;
  
                  continue;
              }
  
              // Semicolon is never allowed.
              if (ch == ';') {
                  throw genException("Semicolon is not allowed", sql);
              }
  
              // For this purpose, we can simply ignore other characters.
              // (Note it doesn't handle the X'' literal properly and reports this X as a token,
              // but that should be fine...)
              pos++;
          }
      }
  
      /**
       * Test if given token is a
       * <a href="https://www.sqlite.org/lang_keywords.html">SQLite reserved
       * keyword</a>.
       */
      public static boolean isKeyword(@NonNull String token) {
          switch (token.toUpperCase(Locale.US)) {
              case "ABORT": case "ACTION": case "ADD": case "AFTER":
              case "ALL": case "ALTER": case "ANALYZE": case "AND":
              case "AS": case "ASC": case "ATTACH": case "AUTOINCREMENT":
              case "BEFORE": case "BEGIN": case "BETWEEN": case "BINARY":
              case "BY": case "CASCADE": case "CASE": case "CAST":
              case "CHECK": case "COLLATE": case "COLUMN": case "COMMIT":
              case "CONFLICT": case "CONSTRAINT": case "CREATE": case "CROSS":
              case "CURRENT": case "CURRENT_DATE": case "CURRENT_TIME": case "CURRENT_TIMESTAMP":
              case "DATABASE": case "DEFAULT": case "DEFERRABLE": case "DEFERRED":
              case "DELETE": case "DESC": case "DETACH": case "DISTINCT":
              case "DO": case "DROP": case "EACH": case "ELSE":
              case "END": case "ESCAPE": case "EXCEPT": case "EXCLUDE":
              case "EXCLUSIVE": case "EXISTS": case "EXPLAIN": case "FAIL":
              case "FILTER": case "FOLLOWING": case "FOR": case "FOREIGN":
              case "FROM": case "FULL": case "GLOB": case "GROUP":
              case "GROUPS": case "HAVING": case "IF": case "IGNORE":
              case "IMMEDIATE": case "IN": case "INDEX": case "INDEXED":
              case "INITIALLY": case "INNER": case "INSERT": case "INSTEAD":
              case "INTERSECT": case "INTO": case "IS": case "ISNULL":
              case "JOIN": case "KEY": case "LEFT": case "LIKE":
              case "LIMIT": case "MATCH": case "NATURAL": case "NO":
              case "NOCASE": case "NOT": case "NOTHING": case "NOTNULL":
              case "NULL": case "OF": case "OFFSET": case "ON":
              case "OR": case "ORDER": case "OTHERS": case "OUTER":
              case "OVER": case "PARTITION": case "PLAN": case "PRAGMA":
              case "PRECEDING": case "PRIMARY": case "QUERY": case "RAISE":
              case "RANGE": case "RECURSIVE": case "REFERENCES": case "REGEXP":
              case "REINDEX": case "RELEASE": case "RENAME": case "REPLACE":
              case "RESTRICT": case "RIGHT": case "ROLLBACK": case "ROW":
              case "ROWS": case "RTRIM": case "SAVEPOINT": case "SELECT":
              case "SET": case "TABLE": case "TEMP": case "TEMPORARY":
              case "THEN": case "TIES": case "TO": case "TRANSACTION":
              case "TRIGGER": case "UNBOUNDED": case "UNION": case "UNIQUE":
              case "UPDATE": case "USING": case "VACUUM": case "VALUES":
              case "VIEW": case "VIRTUAL": case "WHEN": case "WHERE":
              case "WINDOW": case "WITH": case "WITHOUT":
                  return true;
              default:
                  return false;
          }
      }
  
      /**
       * Test if given token is a
       * <a href="https://www.sqlite.org/lang_corefunc.html">SQLite reserved
       * function</a>.
       */
      public static boolean isFunction(@NonNull String token) {
          switch (token.toLowerCase(Locale.US)) {
              case "abs": case "avg": case "char": case "coalesce":
              case "count": case "glob": case "group_concat": case "hex":
              case "ifnull": case "instr": case "length": case "like":
              case "likelihood": case "likely": case "lower": case "ltrim":
              case "max": case "min": case "nullif": case "random":
              case "randomblob": case "replace": case "round": case "rtrim":
              case "substr": case "sum": case "total": case "trim":
              case "typeof": case "unicode": case "unlikely": case "upper":
              case "zeroblob":
                  return true;
              default:
                  return false;
          }
      }
  
      /**
       * Test if given token is a
       * <a href="https://www.sqlite.org/datatype3.html">SQLite reserved type</a>.
       */
      public static boolean isType(@NonNull String token) {
          switch (token.toUpperCase(Locale.US)) {
              case "INT": case "INTEGER": case "TINYINT": case "SMALLINT":
              case "MEDIUMINT": case "BIGINT": case "INT2": case "INT8":
              case "CHARACTER": case "VARCHAR": case "NCHAR": case "NVARCHAR":
              case "TEXT": case "CLOB": case "BLOB": case "REAL":
              case "DOUBLE": case "FLOAT": case "NUMERIC": case "DECIMAL":
              case "BOOLEAN": case "DATE": case "DATETIME":
                  return true;
              default:
                  return false;
          }
      }
  }
  