| /* |
| * Copyright (C) 2014 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 com.android.calculator2; |
| |
| import android.content.Context; |
| import android.text.SpannableStringBuilder; |
| import android.text.TextUtils; |
| |
| public class CalculatorExpressionBuilder extends SpannableStringBuilder { |
| |
| private final CalculatorExpressionTokenizer mTokenizer; |
| private boolean mIsEdited; |
| |
| public CalculatorExpressionBuilder( |
| CharSequence text, CalculatorExpressionTokenizer tokenizer, boolean isEdited) { |
| super(text); |
| |
| mTokenizer = tokenizer; |
| mIsEdited = isEdited; |
| } |
| |
| @Override |
| public SpannableStringBuilder replace(int start, int end, CharSequence tb, int tbstart, |
| int tbend) { |
| if (start != length() || end != length()) { |
| mIsEdited = true; |
| return super.replace(start, end, tb, tbstart, tbend); |
| } |
| |
| String appendExpr = |
| mTokenizer.getNormalizedExpression(tb.subSequence(tbstart, tbend).toString()); |
| if (appendExpr.length() == 1) { |
| final String expr = mTokenizer.getNormalizedExpression(toString()); |
| switch (appendExpr.charAt(0)) { |
| case '.': |
| // don't allow two decimals in the same number |
| final int index = expr.lastIndexOf('.'); |
| if (index != -1 && TextUtils.isDigitsOnly(expr.substring(index + 1, start))) { |
| appendExpr = ""; |
| } |
| break; |
| case '+': |
| case '*': |
| case '/': |
| // don't allow leading operator |
| if (start == 0) { |
| appendExpr = ""; |
| break; |
| } |
| |
| // don't allow multiple successive operators |
| while (start > 0 && "+-*/".indexOf(expr.charAt(start - 1)) != -1) { |
| --start; |
| } |
| // fall through |
| case '-': |
| // don't allow -- or +- |
| if (start > 0 && "+-".indexOf(expr.charAt(start - 1)) != -1) { |
| --start; |
| } |
| |
| // mark as edited since operators can always be appended |
| mIsEdited = true; |
| break; |
| default: |
| break; |
| } |
| } |
| |
| // since this is the first edit replace the entire string |
| if (!mIsEdited && appendExpr.length() > 0) { |
| start = 0; |
| mIsEdited = true; |
| } |
| |
| appendExpr = mTokenizer.getLocalizedExpression(appendExpr); |
| return super.replace(start, end, appendExpr, 0, appendExpr.length()); |
| } |
| } |