| // Copyright 2014 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; |
| |
| |
| /** |
| * Base class for all expression nodes in the AST. |
| * |
| * <p>The only expressions permitted on the left-hand side of an assignment (such as 'lhs=rhs' or |
| * 'for lhs in expr') are identifiers, dot expressions (x.y), list expressions ([expr, ...]), tuple |
| * expressions ((expr, ...)), or parenthesized variants of those. In particular and unlike Python, |
| * slice expressions and starred expressions cannot appear on the LHS. TODO(bazel-team): Add support |
| * for assigning to slices (e.g. a[2:6] = [3]). |
| */ |
| public abstract class Expression extends Node { |
| |
| /** |
| * Kind of the expression. This is similar to using instanceof, except that it's more efficient |
| * and can be used in a switch/case. |
| */ |
| public enum Kind { |
| BINARY_OPERATOR, |
| COMPREHENSION, |
| CONDITIONAL, |
| DICT_EXPR, |
| DOT, |
| CALL, |
| IDENTIFIER, |
| INDEX, |
| INTEGER_LITERAL, |
| LIST_EXPR, |
| SLICE, |
| STRING_LITERAL, |
| UNARY_OPERATOR, |
| } |
| |
| /** |
| * Kind of the expression. This is similar to using instanceof, except that it's more efficient |
| * and can be used in a switch/case. |
| */ |
| public abstract Kind kind(); |
| |
| /** Parses an expression. */ |
| public static Expression parse(ParserInput input) throws SyntaxError { |
| return Parser.parseExpression(input); |
| } |
| |
| } |