Damien Martin-Guillerez | f88f4d8 | 2015-09-25 13:56:55 +0000 | [diff] [blame] | 1 | // Copyright 2014 The Bazel Authors. All rights reserved. |
Han-Wen Nienhuys | d08b27f | 2015-02-25 16:45:20 +0100 | [diff] [blame] | 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | package com.google.devtools.build.lib.analysis; |
| 16 | |
| 17 | import com.google.common.base.CharMatcher; |
tomlu | a155b53 | 2017-11-08 20:12:47 +0100 | [diff] [blame] | 18 | import com.google.common.base.Preconditions; |
Han-Wen Nienhuys | d08b27f | 2015-02-25 16:45:20 +0100 | [diff] [blame] | 19 | import com.google.common.base.Strings; |
dannark | a8d7357 | 2018-06-21 17:46:06 -0700 | [diff] [blame] | 20 | import com.google.common.collect.ImmutableMap; |
Han-Wen Nienhuys | d08b27f | 2015-02-25 16:45:20 +0100 | [diff] [blame] | 21 | import com.google.common.collect.Iterables; |
| 22 | import com.google.devtools.build.lib.actions.Artifact; |
Lukacs Berki | 6e91eb9 | 2015-09-21 09:12:37 +0000 | [diff] [blame] | 23 | import com.google.devtools.build.lib.cmdline.Label; |
Lukacs Berki | a643436 | 2015-09-15 13:56:14 +0000 | [diff] [blame] | 24 | import com.google.devtools.build.lib.cmdline.LabelSyntaxException; |
Han-Wen Nienhuys | d08b27f | 2015-02-25 16:45:20 +0100 | [diff] [blame] | 25 | import com.google.devtools.build.lib.vfs.PathFragment; |
Han-Wen Nienhuys | d08b27f | 2015-02-25 16:45:20 +0100 | [diff] [blame] | 26 | import java.util.ArrayList; |
| 27 | import java.util.List; |
| 28 | import java.util.Map; |
Han-Wen Nienhuys | d08b27f | 2015-02-25 16:45:20 +0100 | [diff] [blame] | 29 | import javax.annotation.Nullable; |
| 30 | |
| 31 | /** |
| 32 | * Helper class encapsulating string scanning state used during "heuristic" |
| 33 | * expansion of labels embedded within rules. |
| 34 | */ |
| 35 | public final class LabelExpander { |
| 36 | /** |
| 37 | * An exception that is thrown when a label is expanded to zero or multiple |
| 38 | * files during expansion. |
| 39 | */ |
| 40 | public static class NotUniqueExpansionException extends Exception { |
| 41 | public NotUniqueExpansionException(int sizeOfResultSet, String labelText) { |
| 42 | super("heuristic label expansion found '" + labelText + "', which expands to " |
| 43 | + sizeOfResultSet + " files" |
| 44 | + (sizeOfResultSet > 1 |
| 45 | ? ", please use $(locations " + labelText + ") instead" |
| 46 | : "")); |
| 47 | } |
| 48 | } |
| 49 | |
| 50 | // This is a utility class, no need to instantiate. |
| 51 | private LabelExpander() {} |
| 52 | |
| 53 | /** |
| 54 | * CharMatcher to determine if a given character is valid for labels. |
| 55 | * |
| 56 | * <p>The Build Concept Reference additionally allows '=' and ',' to appear in labels, |
| 57 | * but for the purposes of the heuristic, this function does not, as it would cause |
| 58 | * "--foo=:rule1,:rule2" to scan as a single possible label, instead of three |
| 59 | * ("--foo", ":rule1", ":rule2"). |
| 60 | */ |
| 61 | private static final CharMatcher LABEL_CHAR_MATCHER = |
| 62 | CharMatcher.inRange('a', 'z') |
| 63 | .or(CharMatcher.inRange('A', 'Z')) |
| 64 | .or(CharMatcher.inRange('0', '9')) |
Googler | 7cf2460 | 2016-07-25 15:36:55 +0000 | [diff] [blame] | 65 | .or(CharMatcher.anyOf(":/_.-+" + PathFragment.SEPARATOR_CHAR)) |
| 66 | .precomputed(); |
Han-Wen Nienhuys | d08b27f | 2015-02-25 16:45:20 +0100 | [diff] [blame] | 67 | |
| 68 | /** |
| 69 | * Expands all references to labels embedded within a string using the |
| 70 | * provided expansion mapping from labels to artifacts. |
| 71 | * |
| 72 | * <p>Since this pass is heuristic, references to non-existent labels (such |
| 73 | * as arbitrary words) or invalid labels are simply ignored and are unchanged |
| 74 | * in the output. However, if the heuristic discovers a label, which |
| 75 | * identifies an existing target producing zero or multiple files, an error |
| 76 | * is reported. |
| 77 | * |
| 78 | * @param expression the expression to expand. |
| 79 | * @param labelMap the mapping from labels to artifacts, whose relative path |
| 80 | * is to be used as the expansion. |
| 81 | * @param labelResolver the {@code Label} that can resolve label strings |
| 82 | * to {@code Label} objects. The resolved label is either relative to |
| 83 | * {@code labelResolver} or is a global label (i.e. starts with "//"). |
| 84 | * @return the expansion of the string. |
| 85 | * @throws NotUniqueExpansionException if a label that is present in the |
| 86 | * mapping expands to zero or multiple files. |
| 87 | */ |
| 88 | public static <T extends Iterable<Artifact>> String expand(@Nullable String expression, |
| 89 | Map<Label, T> labelMap, Label labelResolver) throws NotUniqueExpansionException { |
| 90 | if (Strings.isNullOrEmpty(expression)) { |
| 91 | return ""; |
| 92 | } |
| 93 | Preconditions.checkNotNull(labelMap); |
| 94 | Preconditions.checkNotNull(labelResolver); |
| 95 | |
| 96 | int offset = 0; |
| 97 | StringBuilder result = new StringBuilder(); |
| 98 | while (offset < expression.length()) { |
| 99 | String labelText = scanLabel(expression, offset); |
| 100 | if (labelText != null) { |
| 101 | offset += labelText.length(); |
| 102 | result.append(tryResolvingLabelTextToArtifactPath(labelText, labelMap, labelResolver)); |
| 103 | } else { |
| 104 | result.append(expression.charAt(offset)); |
| 105 | offset++; |
| 106 | } |
| 107 | } |
| 108 | return result.toString(); |
| 109 | } |
| 110 | |
| 111 | /** |
| 112 | * Tries resolving a label text to a full label for the associated {@code |
| 113 | * Artifact}, using the provided mapping. |
| 114 | * |
| 115 | * <p>The method succeeds if the label text can be resolved to a {@code |
| 116 | * Label} object, which is present in the {@code labelMap} and maps to |
| 117 | * exactly one {@code Artifact}. |
| 118 | * |
| 119 | * @param labelText the text to resolve. |
| 120 | * @param labelMap the mapping from labels to artifacts, whose relative path |
| 121 | * is to be used as the expansion. |
| 122 | * @param labelResolver the {@code Label} that can resolve label strings |
| 123 | * to {@code Label} objects. The resolved label is either relative to |
| 124 | * {@code labelResolver} or is a global label (i.e. starts with "//"). |
| 125 | * @return an absolute label to an {@code Artifact} if the resolving was |
| 126 | * successful or the original label text. |
| 127 | * @throws NotUniqueExpansionException if a label that is present in the |
| 128 | * mapping expands to zero or multiple files. |
| 129 | */ |
| 130 | private static <T extends Iterable<Artifact>> String tryResolvingLabelTextToArtifactPath( |
| 131 | String labelText, Map<Label, T> labelMap, Label labelResolver) |
| 132 | throws NotUniqueExpansionException { |
| 133 | Label resolvedLabel = resolveLabelText(labelText, labelResolver); |
| 134 | if (resolvedLabel != null) { |
| 135 | Iterable<Artifact> artifacts = labelMap.get(resolvedLabel); |
| 136 | if (artifacts != null) { // resolvedLabel identifies an existing target |
| 137 | List<String> locations = new ArrayList<>(); |
| 138 | Artifact.addExecPaths(artifacts, locations); |
| 139 | int resultSetSize = locations.size(); |
| 140 | if (resultSetSize == 1) { |
| 141 | return Iterables.getOnlyElement(locations); // success! |
| 142 | } else { |
| 143 | throw new NotUniqueExpansionException(resultSetSize, labelText); |
| 144 | } |
| 145 | } |
| 146 | } |
| 147 | return labelText; |
| 148 | } |
| 149 | |
| 150 | /** |
| 151 | * Resolves a string to a label text. Uses {@code labelResolver} to do so. |
| 152 | * The result is either relative to {@code labelResolver} or is an absolute |
| 153 | * label. In case of an invalid label text, the return value is null. |
| 154 | */ |
| 155 | private static Label resolveLabelText(String labelText, Label labelResolver) { |
| 156 | try { |
dannark | a8d7357 | 2018-06-21 17:46:06 -0700 | [diff] [blame] | 157 | return labelResolver.getRelativeWithRemapping(labelText, ImmutableMap.of()); |
Lukacs Berki | a643436 | 2015-09-15 13:56:14 +0000 | [diff] [blame] | 158 | } catch (LabelSyntaxException e) { |
Han-Wen Nienhuys | d08b27f | 2015-02-25 16:45:20 +0100 | [diff] [blame] | 159 | // It's a heuristic, so quietly ignore "errors". Because Label.getRelative never |
| 160 | // returns null, we can use null to indicate an error. |
| 161 | return null; |
| 162 | } |
| 163 | } |
| 164 | |
| 165 | /** |
| 166 | * Scans the argument string from a given start position until the name of a |
| 167 | * potential label has been consumed, then returns the label text. If |
| 168 | * the expression contains no possible label starting at the start position, |
| 169 | * the return value is null. |
| 170 | */ |
| 171 | private static String scanLabel(String expression, int start) { |
| 172 | int offset = start; |
| 173 | while (offset < expression.length() && LABEL_CHAR_MATCHER.matches(expression.charAt(offset))) { |
| 174 | ++offset; |
| 175 | } |
| 176 | if (offset > start) { |
| 177 | return expression.substring(start, offset); |
| 178 | } else { |
| 179 | return null; |
| 180 | } |
| 181 | } |
| 182 | } |