| 1 | ------
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| 2 | Usage
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| 3 | ------
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| 4 | Gerwin Klein <[email protected]>
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| 5 | Régis Décamps <[email protected]>
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| 6 | ------
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| 7 | November 2, 2007
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| 8 | ------
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| 9 |
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| 10 |
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| 11 | About this project
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| 12 |
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| 13 | This sample project parses a grammar with JFlex.
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| 14 |
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| 15 | The project management is done with Maven.
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| 16 |
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| 17 | The project contains a simple grammar for the "Toy programming language".
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| 18 | It is the example from the JLex web site with some small
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| 19 | modifications, to make it a bit more readable.
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| 20 | It does nothing really useful, because there is no parser for
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| 21 | the toy programming language. It's just a demonstration how a
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| 22 | small simple scanner looks like.
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| 23 |
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| 24 |
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| 25 | * JFlex
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| 26 |
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| 27 | JFlex is a parser generator. Given a grammar, JFlex generate
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| 28 | Java (TM) code to parse documents that follow this grammar.
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| 29 |
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| 30 | * Maven
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| 31 |
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| 32 | Maven is a project management framework.
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| 33 | The project is described in as a POM (project object model,
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| 34 | stored into <<<pom.xml>>>).
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| 35 | This document isn't intended to be a tutorial on the use of Maven 2,
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| 36 | you should consult the {{{http://maven.apache.org/}Maven web site}}.
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| 37 |
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| 38 | The integration of JFlex and Maven is done with
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| 39 | {{{http://jflex.sourceforge.net/maven-flex-plugin/}maven-flex-plugin}}.
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| 40 |
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| 41 |
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| 42 | Usage
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| 43 |
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| 44 | * mvn generate-sources
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| 45 |
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| 46 | The maven-jflex-plugin will read the grammar
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| 47 | <<<src/main/jflex/simple.jflex>>>
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| 48 | and generate a Java scanner <<<Yylex.java>>>
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| 49 | in <<<target/generated-sources/flex>>>
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| 50 |
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| 51 | This is defined by the following section
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| 52 |
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| 53 | +---------
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| 54 | <build>
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| 55 | <plugins>
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| 56 | <plugin>
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| 57 | <groupId>de.jflex.maven.plugin</groupId>
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| 58 | <artifactId>maven-jflex-plugin</artifactId>
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| 59 | <version>0.2</version>
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| 60 | <executions>
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| 61 | <execution>
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| 62 | <goals>
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| 63 | <goal>generate</goal>
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| 64 | </goals>
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| 65 | </execution>
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| 66 | </executions>
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| 67 | </plugin>
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| 68 | </plugins>
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| 69 | </build>
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| 70 | +------------
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| 71 |
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| 72 | By default, the maven-jflex-plugin generates a scanner/parser for every file
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| 73 | in <<<src/main/jflex/>>>.
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| 74 |
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| 75 |
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| 76 | * mvn test
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| 77 |
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| 78 | This goal test the generated scanner (if required, the lexer will be
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| 79 | generated and all Java classes will be compiled)
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| 80 | by running all tests in <<<src/test/java>>>.
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| 81 |
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| 82 | There is only one test in <<<src/test/java/YylexTest.java>>>.
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| 83 | In this test,
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| 84 | the scanner is run with the input file <<<src/test/resources/test.txt>>>.
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| 85 |
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| 86 | By default, the scanner outputs debugging information about each
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| 87 | returned token to <<<System.out>>> until the end of file is reached,
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| 88 | or an error occurs.
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| 89 | But in the test, the output is redirected into <<<target/output.actual>>>.
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| 90 |
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| 91 | The test is successful if every line match
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| 92 | with <<<src/test/resources/output.good>>>,
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| 93 | which is the expected scanner debugging information.
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| 94 |
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| 95 |
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| 96 | References
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| 97 |
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| 98 | * {{{http://jflex.sourceforge.net/maven-flex-plugin/}maven-flex-plugin}}
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| 99 |
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| 100 | * {{{http://maven.apache.org/}Maven web site}}.
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