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Merge pull request #2400 from hborchardt/spdx-expressions
Implement SPDX expressions
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128 changes: 128 additions & 0 deletions
128
src/main/java/org/dependencytrack/parser/spdx/expression/SpdxExpressionParser.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,128 @@ | ||
| /* | ||
| * This file is part of Dependency-Track. | ||
| * | ||
| * 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. | ||
| * | ||
| * SPDX-License-Identifier: Apache-2.0 | ||
| * Copyright (c) Steve Springett. All Rights Reserved. | ||
| */ | ||
| package org.dependencytrack.parser.spdx.expression; | ||
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| import java.util.ArrayDeque; | ||
| import java.util.Iterator; | ||
| import java.util.List; | ||
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| import org.dependencytrack.parser.spdx.expression.model.SpdxOperator; | ||
| import org.dependencytrack.parser.spdx.expression.model.SpdxExpression; | ||
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| /** | ||
| * This class parses SPDX expressions according to | ||
| * https://spdx.github.io/spdx-spec/v2-draft/SPDX-license-expressions/ into a tree of | ||
| * SpdxExpressions and SpdxExpressionOperations | ||
| * | ||
| * @author hborchardt | ||
| * @since 4.8.0 | ||
| */ | ||
| public class SpdxExpressionParser { | ||
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| /** | ||
| * Reads in a SPDX expression and returns a parsed tree of SpdxExpressionOperators and license | ||
| * ids. | ||
| * | ||
| * @param spdxExpression | ||
| * spdx expression string | ||
| * @return parsed SpdxExpression tree, or SpdxExpression.INVALID if an error has occurred during | ||
| * parsing | ||
| */ | ||
| public SpdxExpression parse(final String spdxExpression) { | ||
| // operators are surrounded by spaces or brackets. Let's make our life easier and surround brackets by spaces. | ||
| var _spdxExpression = spdxExpression.replace("(", " ( ").replace(")", " ) ").split(" "); | ||
| if (_spdxExpression.length == 1) { | ||
| return new SpdxExpression(spdxExpression); | ||
| } | ||
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| // Shunting yard algorithm to convert SPDX expression to reverse polish notation | ||
| // specify list of infix operators | ||
| List<String> infixOperators = List.of(SpdxOperator.OR.getToken(), SpdxOperator.AND.getToken(), | ||
| SpdxOperator.WITH.getToken()); | ||
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| ArrayDeque<String> operatorStack = new ArrayDeque<>(); | ||
| ArrayDeque<String> outputQueue = new ArrayDeque<>(); | ||
| Iterator<String> it = List.of(_spdxExpression).iterator(); | ||
| while(it.hasNext()) { | ||
| var token = it.next(); | ||
| if (token.length() == 0) { | ||
| continue; | ||
| } | ||
| if (infixOperators.contains(token)) { | ||
| int opPrecedence = SpdxOperator.valueOf(token).getPrecedence(); | ||
| for (String o2; (o2 = operatorStack.peek()) != null && !o2.equals("(") | ||
| && SpdxOperator.valueOf(o2).getPrecedence() > opPrecedence;) { | ||
| outputQueue.push(operatorStack.pop()); | ||
| } | ||
| ; | ||
| operatorStack.push(token); | ||
| } else if (token.equals("(")) { | ||
| operatorStack.push(token); | ||
| } else if (token.equals(")")) { | ||
| for (String o2; (o2 = operatorStack.peek()) == null || !o2.equals("(");) { | ||
| if (o2 == null) { | ||
| // Mismatched parentheses | ||
| return SpdxExpression.INVALID; | ||
| } | ||
| outputQueue.push(operatorStack.pop()); | ||
| } | ||
| ; | ||
| String leftParens = operatorStack.pop(); | ||
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| if (!"(".equals(leftParens)) { | ||
| // Mismatched parentheses | ||
| return SpdxExpression.INVALID; | ||
| } | ||
| // no function tokens implemented | ||
| } else { | ||
| outputQueue.push(token); | ||
| } | ||
| } | ||
| for (String o2; (o2 = operatorStack.peek()) != null;) { | ||
| if ("(".equals(o2)) { | ||
| // Mismatched parentheses | ||
| return SpdxExpression.INVALID; | ||
| } | ||
| outputQueue.push(operatorStack.pop()); | ||
| } | ||
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| // convert RPN stack into tree | ||
| // this is easy because all infix operators have two arguments | ||
| ArrayDeque<SpdxExpression> expressions = new ArrayDeque<>(); | ||
| SpdxExpression expr = null; | ||
| while (!outputQueue.isEmpty()) { | ||
| var token = outputQueue.pollLast(); | ||
| if (infixOperators.contains(token)) { | ||
| var rhs = expressions.pop(); | ||
| var lhs = expressions.pop(); | ||
| expr = new SpdxExpression(SpdxOperator.valueOf(token), List.of(lhs, rhs)); | ||
| } else { | ||
| if (token.endsWith("+")) { | ||
| // trailing `+` is not a whitespace-delimited operator - process it separately | ||
| expr = new SpdxExpression(SpdxOperator.PLUS, | ||
| List.of(new SpdxExpression(token.substring(0, token.length() - 1)))); | ||
| } else { | ||
| expr = new SpdxExpression(token); | ||
| } | ||
| } | ||
| expressions.push(expr); | ||
| } | ||
| return expr; | ||
| } | ||
| } |
69 changes: 69 additions & 0 deletions
69
src/main/java/org/dependencytrack/parser/spdx/expression/model/SpdxExpression.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,69 @@ | ||
| /* | ||
| * This file is part of Dependency-Track. | ||
| * | ||
| * 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. | ||
| * | ||
| * SPDX-License-Identifier: Apache-2.0 | ||
| * Copyright (c) Steve Springett. All Rights Reserved. | ||
| */ | ||
| package org.dependencytrack.parser.spdx.expression.model; | ||
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| import java.util.List; | ||
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| /** | ||
| * A node of an SPDX expression tree. If it is a leaf node, it contains a spdxLicenseId. If it is an | ||
| * inner node, containss an operation. | ||
| * | ||
| * @author hborchardt | ||
| * @since 4.8.0 | ||
| */ | ||
| public class SpdxExpression { | ||
| public static final SpdxExpression INVALID = new SpdxExpression(null); | ||
| public SpdxExpression(String spdxLicenseId) { | ||
| this.spdxLicenseId = spdxLicenseId; | ||
| } | ||
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| public SpdxExpression(SpdxOperator operator, List<SpdxExpression> arguments) { | ||
| this.operation = new SpdxExpressionOperation(operator, arguments); | ||
| } | ||
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| private SpdxExpressionOperation operation; | ||
| private String spdxLicenseId; | ||
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| public SpdxExpressionOperation getOperation() { | ||
| return operation; | ||
| } | ||
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| public void setOperation(SpdxExpressionOperation operation) { | ||
| this.operation = operation; | ||
| } | ||
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| public String getSpdxLicenseId() { | ||
| return spdxLicenseId; | ||
| } | ||
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| public void setSpdxLicenseId(String spdxLicenseId) { | ||
| this.spdxLicenseId = spdxLicenseId; | ||
| } | ||
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| @Override | ||
| public String toString() { | ||
| if (this == INVALID) { | ||
| return "INVALID"; | ||
| } | ||
| if (spdxLicenseId != null) { | ||
| return spdxLicenseId; | ||
| } | ||
| return operation.toString(); | ||
| } | ||
| } |
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