| // Copyright 2017 The Bazel Authors. All rights reserved. |
| // |
| // 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.google.devtools.build.lib.syntax; |
| |
| import com.google.devtools.build.lib.events.Location; |
| import java.io.IOException; |
| |
| /** Syntax node for a unary operator expression. */ |
| public final class UnaryOperatorExpression extends Expression { |
| |
| private final UnaryOperator operator; |
| |
| private final Expression operand; |
| |
| public UnaryOperatorExpression(UnaryOperator operator, Expression operand) { |
| this.operator = operator; |
| this.operand = operand; |
| } |
| |
| public UnaryOperator getOperator() { |
| return operator; |
| } |
| |
| public Expression getOperand() { |
| return operand; |
| } |
| |
| @Override |
| public void prettyPrint(Appendable buffer) throws IOException { |
| // TODO(bazel-team): Possibly omit parentheses when they are not needed according to operator |
| // precedence rules. This requires passing down more contextual information. |
| buffer.append(operator.toString()); |
| buffer.append('('); |
| operand.prettyPrint(buffer); |
| buffer.append(')'); |
| } |
| |
| @Override |
| public String toString() { |
| // All current and planned unary operators happen to be prefix operators. |
| // Non-symbolic operators have trailing whitespace built into their name. |
| // |
| // Note that this omits the parentheses for brevity, but is not correct in general due to |
| // operator precedence rules. For example, "(not False) in mylist" prints as |
| // "not False in mylist", which evaluates to opposite results in the case that mylist is empty. |
| return operator.toString() + operand; |
| } |
| |
| private static Object evaluate( |
| UnaryOperator operator, |
| Object value, |
| Location loc) |
| throws EvalException, InterruptedException { |
| switch (operator) { |
| case NOT: |
| return !EvalUtils.toBoolean(value); |
| |
| case MINUS: |
| if (!(value instanceof Integer)) { |
| throw new EvalException( |
| loc, |
| String.format( |
| "unsupported operand type for -: '%s'", EvalUtils.getDataTypeName(value))); |
| } |
| try { |
| return Math.negateExact((Integer) value); |
| } catch (ArithmeticException e) { |
| // Fails for -MIN_INT. |
| throw new EvalException(loc, e.getMessage()); |
| } |
| |
| default: |
| throw new AssertionError("Unsupported unary operator: " + operator); |
| } |
| } |
| |
| @Override |
| Object doEval(Environment env) throws EvalException, InterruptedException { |
| return evaluate(operator, operand.eval(env), getLocation()); |
| } |
| |
| @Override |
| public void accept(SyntaxTreeVisitor visitor) { |
| visitor.visit(this); |
| } |
| |
| @Override |
| public Kind kind() { |
| return Kind.UNARY_OPERATOR; |
| } |
| } |