diff options
Diffstat (limited to 'src/org/unitConverter/expressionParser')
| -rw-r--r-- | src/org/unitConverter/expressionParser/ExpressionParser.java | 398 | ||||
| -rw-r--r-- | src/org/unitConverter/expressionParser/package-info.java | 23 |
2 files changed, 0 insertions, 421 deletions
diff --git a/src/org/unitConverter/expressionParser/ExpressionParser.java b/src/org/unitConverter/expressionParser/ExpressionParser.java deleted file mode 100644 index 804ea87..0000000 --- a/src/org/unitConverter/expressionParser/ExpressionParser.java +++ /dev/null @@ -1,398 +0,0 @@ -/** - * Copyright (C) 2019 Adrien Hopkins - * - * This program is free software: you can redistribute it and/or modify - * it under the terms of the GNU Affero General Public License as published by - * the Free Software Foundation, either version 3 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU Affero General Public License for more details. - * - * You should have received a copy of the GNU Affero General Public License - * along with this program. If not, see <https://www.gnu.org/licenses/>. - */ -package org.unitConverter.expressionParser; - -import java.util.ArrayDeque; -import java.util.Deque; -import java.util.HashMap; -import java.util.Map; -import java.util.Objects; -import java.util.function.BinaryOperator; -import java.util.function.Function; -import java.util.function.UnaryOperator; - -/** - * An object that can parse expressions with unary or binary operators. - * - * @author Adrien Hopkins - * @param <T> - * type of object that exists in parsed expressions - * @since 2019-03-14 - */ -// TODO: possibly make this class non-final? -public final class ExpressionParser<T> { - /** - * A builder that can create {@code ExpressionParser<T>} instances. - * - * @author Adrien Hopkins - * @param <T> - * type of object that exists in parsed expressions - * @since 2019-03-17 - */ - public static final class Builder<T> { - /** - * A function that obtains a parseable object from a string. For example, an integer {@code ExpressionParser} - * would use {@code Integer::parseInt}. - * - * @since 2019-03-14 - */ - private final Function<String, T> objectObtainer; - - /** - * A map mapping operator strings to operator functions, for unary operators. - * - * @since 2019-03-14 - */ - private final Map<String, PriorityUnaryOperator<T>> unaryOperators; - - /** - * A map mapping operator strings to operator functions, for binary operators. - * - * @since 2019-03-14 - */ - private final Map<String, PriorityBinaryOperator<T>> binaryOperators; - - /** - * Creates the {@code Builder}. - * - * @param objectObtainer - * a function that can turn strings into objects of the type handled by the parser. - * @throws NullPointerException - * if {@code objectObtainer} is null - * @since 2019-03-17 - */ - public Builder(final Function<String, T> objectObtainer) { - this.objectObtainer = Objects.requireNonNull(objectObtainer, "objectObtainer must not be null."); - this.unaryOperators = new HashMap<>(); - this.binaryOperators = new HashMap<>(); - } - - /** - * Adds a binary operator to the builder. - * - * @param text - * text used to reference the operator, like '+' - * @param operator - * operator to add - * @param priority - * operator's priority, which determines which operators are applied first - * @return this builder - * @throws NullPointerException - * if {@code text} or {@code operator} is null - * @since 2019-03-17 - */ - public Builder<T> addBinaryOperator(final String text, final BinaryOperator<T> operator, final int priority) { - Objects.requireNonNull(text, "text must not be null."); - Objects.requireNonNull(operator, "operator must not be null."); - - // Unfortunately, I cannot use a lambda because the PriorityBinaryOperator requires arguments. - final PriorityBinaryOperator<T> priorityOperator = new PriorityBinaryOperator<T>(priority) { - @Override - public T apply(final T t, final T u) { - return operator.apply(t, u); - } - - }; - this.binaryOperators.put(text, priorityOperator); - return this; - } - - /** - * Adds a unary operator to the builder. - * - * @param text - * text used to reference the operator, like '-' - * @param operator - * operator to add - * @param priority - * operator's priority, which determines which operators are applied first - * @return this builder - * @throws NullPointerException - * if {@code text} or {@code operator} is null - * @since 2019-03-17 - */ - public Builder<T> addUnaryOperator(final String text, final UnaryOperator<T> operator, final int priority) { - Objects.requireNonNull(text, "text must not be null."); - Objects.requireNonNull(operator, "operator must not be null."); - - // Unfortunately, I cannot use a lambda because the PriorityUnaryOperator requires arguments. - final PriorityUnaryOperator<T> priorityOperator = new PriorityUnaryOperator<T>(priority) { - @Override - public T apply(final T t) { - return operator.apply(t); - } - }; - this.unaryOperators.put(text, priorityOperator); - return this; - } - - /** - * @return an {@code ExpressionParser<T>} instance with the properties given to this builder - * @since 2019-03-17 - */ - public ExpressionParser<T> build() { - return new ExpressionParser<>(this.objectObtainer, this.unaryOperators, this.binaryOperators); - } - } - - /** - * A binary operator with a priority field that determines which operators apply first. - * - * @author Adrien Hopkins - * @param <T> - * type of operand and result - * @since 2019-03-17 - */ - private static abstract class PriorityBinaryOperator<T> - implements BinaryOperator<T>, Comparable<PriorityBinaryOperator<T>> { - /** - * The operator's priority. Higher-priority operators are applied before lower-priority operators - */ - private final int priority; - - /** - * Creates the {@code PriorityBinaryOperator}. - * - * @param priority - * operator's priority - * @since 2019-03-17 - */ - public PriorityBinaryOperator(final int priority) { - this.priority = priority; - } - - /** - * Compares this object to another by priority. - */ - @Override - public int compareTo(final PriorityBinaryOperator<T> o) { - if (this.priority < o.priority) - return -1; - else if (this.priority > o.priority) - return 1; - else - return 0; - } - } - - /** - * A unary operator with a priority field that determines which operators apply first. - * - * @author Adrien Hopkins - * @param <T> - * type of operand and result - * @since 2019-03-17 - */ - private static abstract class PriorityUnaryOperator<T> - implements UnaryOperator<T>, Comparable<PriorityUnaryOperator<T>> { - /** - * The operator's priority. Higher-priority operators are applied before lower-priority operators - */ - private final int priority; - - /** - * Creates the {@code PriorityUnaryOperator}. - * - * @param priority - * operator's priority - * @since 2019-03-17 - */ - public PriorityUnaryOperator(final int priority) { - this.priority = priority; - } - - /** - * Compares this object to another by priority. - */ - @Override - public int compareTo(final PriorityUnaryOperator<T> o) { - if (this.priority < o.priority) - return -1; - else if (this.priority > o.priority) - return 1; - else - return 0; - } - } - - /** - * The types of tokens that are available. - * - * @author Adrien Hopkins - * @since 2019-03-14 - */ - private static enum TokenType { - OBJECT, UNARY_OPERATOR, BINARY_OPERATOR; - } - - /** - * A function that obtains a parseable object from a string. For example, an integer {@code ExpressionParser} would - * use {@code Integer::parseInt}. - * - * @since 2019-03-14 - */ - private final Function<String, T> objectObtainer; - - /** - * A map mapping operator strings to operator functions, for unary operators. - * - * @since 2019-03-14 - */ - private final Map<String, PriorityUnaryOperator<T>> unaryOperators; - - /** - * A map mapping operator strings to operator functions, for binary operators. - * - * @since 2019-03-14 - */ - private final Map<String, PriorityBinaryOperator<T>> binaryOperators; - - /** - * Creates the {@code ExpressionParser}. - * - * @param objectObtainer - * function to get objects from strings - * @param unaryOperators - * operators available to the parser - * @since 2019-03-14 - */ - private ExpressionParser(final Function<String, T> objectObtainer, - final Map<String, PriorityUnaryOperator<T>> unaryOperators, - final Map<String, PriorityBinaryOperator<T>> binaryOperators) { - this.objectObtainer = objectObtainer; - this.unaryOperators = unaryOperators; - this.binaryOperators = binaryOperators; - } - - /** - * Converts a given mathematical expression to reverse Polish notation (operators after operands). - * <p> - * For example,<br> - * {@code 2 * (3 + 4)}<br> - * becomes<br> - * {@code 2 3 4 + *}. - * - * @param expression - * @return - * @since 2019-03-17 - */ - private String convertExpressionToReversePolish(final String expression) { - Objects.requireNonNull(expression, "expression must not be null."); - - // TODO method stub org.unitConverter.expressionParser.ExpressionParser.convertExpressionToPolish(expression) - throw new UnsupportedOperationException(); - } - - /** - * Determines whether an inputted string is an object or an operator - * - * @param token - * string to input - * @return type of token it is - * @throws NullPointerException - * if {@code expression} is null - * @since 2019-03-14 - */ - private TokenType getTokenType(final String token) { - Objects.requireNonNull(token, "token must not be null."); - - if (this.unaryOperators.containsKey(token)) - return TokenType.UNARY_OPERATOR; - else if (this.binaryOperators.containsKey(token)) - return TokenType.BINARY_OPERATOR; - else - return TokenType.OBJECT; - } - - /** - * Parses an expression. - * - * @param expression - * expression to parse - * @return result - * @throws NullPointerException - * if {@code expression} is null - * @since 2019-03-14 - */ - public T parseExpression(final String expression) { - return this.parseReversePolishExpression(this.convertExpressionToReversePolish(expression)); - } - - /** - * Parses an expression expressed in reverse Polish notation. - * - * @param expression - * expression to parse - * @return result - * @throws NullPointerException - * if {@code expression} is null - * @since 2019-03-14 - */ - private T parseReversePolishExpression(final String expression) { - Objects.requireNonNull(expression, "expression must not be null."); - - final Deque<T> stack = new ArrayDeque<>(); - - // iterate over every item in the expression, then - for (final String item : expression.split(" ")) { - // choose a path based on what kind of thing was just read - switch (this.getTokenType(item)) { - - case BINARY_OPERATOR: - if (stack.size() < 2) - throw new IllegalStateException(String.format( - "Attempted to call binary operator %s with only %d arguments.", item, stack.size())); - - // get two arguments and operator, then apply! - final T o1 = stack.pop(); - final T o2 = stack.pop(); - final BinaryOperator<T> binaryOperator = this.binaryOperators.get(item); - - stack.push(binaryOperator.apply(o1, o2)); - break; - - case OBJECT: - // just add it to the stack - stack.push(this.objectObtainer.apply(item)); - break; - - case UNARY_OPERATOR: - if (stack.size() < 1) - throw new IllegalStateException(String.format( - "Attempted to call unary operator %s with only %d arguments.", item, stack.size())); - - // get one argument and operator, then apply! - final T o = stack.pop(); - final UnaryOperator<T> unaryOperator = this.unaryOperators.get(item); - - stack.push(unaryOperator.apply(o)); - break; - default: - throw new AssertionError( - String.format("Internal error: Invalid token type %s.", this.getTokenType(item))); - - } - } - - // return answer, or throw an exception if I can't - if (stack.size() > 1) - throw new IllegalStateException("Computation ended up with more than one answer."); - else if (stack.size() == 0) - throw new IllegalStateException("Computation ended up without an answer."); - return stack.pop(); - } -} diff --git a/src/org/unitConverter/expressionParser/package-info.java b/src/org/unitConverter/expressionParser/package-info.java deleted file mode 100644 index 28f0cae..0000000 --- a/src/org/unitConverter/expressionParser/package-info.java +++ /dev/null @@ -1,23 +0,0 @@ -/** - * Copyright (C) 2019 Adrien Hopkins - * - * This program is free software: you can redistribute it and/or modify - * it under the terms of the GNU Affero General Public License as published by - * the Free Software Foundation, either version 3 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU Affero General Public License for more details. - * - * You should have received a copy of the GNU Affero General Public License - * along with this program. If not, see <https://www.gnu.org/licenses/>. - */ -/** - * A module that is capable of parsing expressions of things, like mathematical expressions or unit expressions. - * - * @author Adrien Hopkins - * @since 2019-03-14 - */ -package org.unitConverter.expressionParser;
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