| // 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; |
| |
| import com.google.devtools.build.lib.events.Location; |
| import java.util.List; |
| |
| /** Syntax node for an index expression. e.g. obj[field], but not obj[from:to] */ |
| public final class SliceExpression extends Expression { |
| |
| private final Expression obj; |
| private final Expression start; |
| private final Expression end; |
| private final Expression step; |
| |
| public SliceExpression(Expression obj, Expression start, Expression end, Expression step) { |
| this.obj = obj; |
| this.start = start; |
| this.end = end; |
| this.step = step; |
| } |
| |
| public Expression getObject() { |
| return obj; |
| } |
| |
| public Expression getStart() { |
| return start; |
| } |
| |
| public Expression getEnd() { |
| return end; |
| } |
| |
| public Expression getStep() { |
| return step; |
| } |
| |
| @Override |
| public String toString() { |
| return String.format("%s[%s:%s%s]", |
| obj, |
| start, |
| // Omit `end` if it's a literal `None` (default value) |
| ((end instanceof Identifier) && (((Identifier) end).getName().equals("None"))) ? "" : end, |
| // Omit `step` if it's an integer literal `1` (default value) |
| ((step instanceof IntegerLiteral) && (((IntegerLiteral) step).value.equals(1))) |
| ? "" : ":" + step |
| ); |
| } |
| |
| @Override |
| Object doEval(Environment env) throws EvalException, InterruptedException { |
| Object objValue = obj.eval(env); |
| Object startValue = start.eval(env); |
| Object endValue = end.eval(env); |
| Object stepValue = step.eval(env); |
| Location loc = getLocation(); |
| |
| if (objValue instanceof SkylarkList) { |
| SkylarkList<Object> list = (SkylarkList<Object>) objValue; |
| Object slice = list.getSlice(startValue, endValue, stepValue, loc); |
| return SkylarkType.convertToSkylark(slice, env); |
| } else if (objValue instanceof String) { |
| String string = (String) objValue; |
| List<Integer> indices = EvalUtils.getSliceIndices(startValue, endValue, stepValue, |
| string.length(), loc); |
| char[] result = new char[indices.size()]; |
| char[] original = ((String) objValue).toCharArray(); |
| int resultIndex = 0; |
| for (int originalIndex : indices) { |
| result[resultIndex] = original[originalIndex]; |
| ++resultIndex; |
| } |
| return new String(result); |
| } |
| |
| throw new EvalException( |
| loc, |
| Printer.format( |
| "Type %s has no operator [:](%s, %s, %s)", |
| EvalUtils.getDataTypeName(objValue), |
| EvalUtils.getDataTypeName(startValue), |
| EvalUtils.getDataTypeName(endValue), |
| EvalUtils.getDataTypeName(stepValue))); |
| } |
| |
| @Override |
| public void accept(SyntaxTreeVisitor visitor) { |
| visitor.visit(this); |
| } |
| |
| @Override |
| void validate(ValidationEnvironment env) throws EvalException { |
| obj.validate(env); |
| } |
| } |