Github user mateiz commented on a diff in the pull request: https://github.com/apache/spark/pull/685#discussion_r12502555 --- Diff: mllib/src/main/scala/org/apache/spark/mllib/util/NumericParser.scala --- @@ -0,0 +1,153 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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 org.apache.spark.mllib.util + +import scala.collection.mutable.{ArrayBuffer, ListBuffer} + +private[mllib] object NumericTokenizer { + val NUMBER = -1 + val END = -2 +} + +import NumericTokenizer._ + +/** + * Simple tokenizer for a numeric structure consisting of three types: + * + * - number: a double in Java's floating number format + * - array: an array of numbers stored as `[v0,v1,...,vn]` + * - tuple: a list of numbers, arrays, or tuples stored as `(...)` + * + * @param s input string + * @param start start index + * @param end end index + */ +private[mllib] class NumericTokenizer(s: String, start: Int, end: Int) { + + /** + * Creates a tokenizer for the entire input string. + */ + def this(s: String) = this(s, 0, s.length) + + private var cur = start + private var allowComma = false + private var _value = Double.NaN + + /** + * Returns the most recent parsed number. + */ + def value: Double = _value + + /** + * Returns the next token, which could be any of the following: + * - '[', ']', '(', or ')'. + * - [[org.apache.spark.mllib.util.NumericTokenizer#NUMBER]], call value() to get its value. + * - [[org.apache.spark.mllib.util.NumericTokenizer#END]]. + */ + def next(): Int = { + if (cur < end) { + val c = s(cur) --- End diff -- Use `s.charAt(cur)` instead to avoid some temp objects from implicit conversion
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