如何使用Gradle 2.10将ANTLR lexer语法导入另一个语法？

Question

我一直在通过特伦斯·帕尔（Terence Parr）的《权威的ANTLR 4参考》（The Definitive ANTLR 4 Reference）学习ANTLR 4，到目前为止，我一直在使用Gradle 2.10及其内置的ANTLR插件来关注它。然而，我在获取一些代码时遇到了一些困难，我从第4章38-41页改编了这些代码，以便与我的Gradle构建脚本正常工作。（我之所以使用Gradle，而不是直接使用ANTLR，是因为我想最终将ANTLR集成到一个Java web应用程序中，这是我为我的论文所做的，我强烈希望使用一个构建工具来实现这一点，这样我就可以自动化ANTLR到Java代码的生成过程，并轻松地管理我的依赖关系。）

我创建了两个ANTLR 4语法（我在这个问题的末尾粘贴了它们）：src/main/ANTLR/org/jbduncan/Expr。g4（标准语法）和src/main/antlr/org/jbduncan/CommonLexerRules。g4（词法语法），其中Expr。g4依赖于通用规则。g4通过导入CommonLexerRules语句。但是当我尝试在命令行中用我的构建运行gradlew generateGrammarSource时。gradle（也贴在这个问题的末尾以及我的gradle.properties），我得到了以下错误：

12:45:21: Executing external task 'generateGrammarSource'...
:generateGrammarSource
error(110): org\jbduncan\Expr.g4:3:7: can't find or load grammar CommonLexerRules
warning(125): org\jbduncan\Expr.g4:12:11: implicit definition of token NEWLINE in parser
warning(125): org\jbduncan\Expr.g4:13:6: implicit definition of token ID in parser
warning(125): org\jbduncan\Expr.g4:19:6: implicit definition of token INT in parser
:generateGrammarSource FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':generateGrammarSource'.
> There was 1 error during grammar generation

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED

Total time: 3.166 secs
There was 1 error during grammar generation
12:45:24: External task execution finished 'generateGrammarSource'.

看一下这个错误消息，在我看来，Gradle的ANTLR插件能够找到Expr. g4，但不知何故却找不到通用规则. g4。

我尝试使用几个外部Gradle插件来解决这个错误(https://github.com/melix/antlr4-gradle-plugin和https://github.com/Abnaxos/gradle-antlr4-plugin)而不是内置的，但当我尝试每一个，他们介绍了自己的问题，我无法解决。

使用直接从ANTLR网站下载的ANTLR 4.5.2 jar确实让我可以毫无问题地编译我的两个语法，但正如我之前讨论的那样，这对我来说是一个非常不可取的选择，因为我必须手动编译我的语法，而我相信Gradle可以为我自动完成。

我的问题是：我如何解决上面的错误，并让Gradle将我的lexer语法导入我的其他语法？

建筑格拉德尔

apply plugin: 'java'
apply plugin: 'application'
apply plugin: 'antlr'

sourceCompatibility = 1.8
targetCompatibility = 1.8

[compileJava, compileTestJava]*.options*.encoding = 'UTF-8'

group = 'org.jbduncan'
version = '1.0-SNAPSHOT'
mainClassName = 'org.jbduncan.Application'

repositories {
    jcenter()
}

dependencies {
    antlr "org.antlr:antlr4:$antlrVersion"
    compile "com.google.guava:guava:$guavaVersion"
    testCompile "com.google.guava:guava-testlib:$guavaVersion"
    testCompile "com.google.truth:truth:$truthVersion"
    testCompile "junit:junit:$junitVersion"
}

// Send all generated source code to a directory other than build/, to workaround an issue in
// IntelliJ IDEA where it fails to recognise source files in build/.
def generatedJavaSourcesDir = 'src/generated/java'

generateGrammarSource {
    arguments += ['-visitor']
    outputDirectory = file(generatedJavaSourcesDir)
}

sourceSets {
    main {
        java {
            srcDir generatedJavaSourcesDir
        }
    }
}

clean {
    delete generatedJavaSourcesDir
}

task wrapper(type: Wrapper) {
    distributionUrl = "http://services.gradle.org/distributions/gradle-$gradleVersion-bin.zip"
}

gradle.properties

gradleVersion=2.10

# Dependency versions
antlrVersion=4.5
guavaVersion=19.0
junitVersion=4.12
truthVersion=0.28

src/main/antlr/org/jbduncan/Expr。g4

grammar Expr;

import CommonLexerRules; // includes all rules from CommonLexerRules.g4

@header {
    package org.jbduncan;
}

/** The start rule; begin parsing here. */
prog: stat+;

stat: expr NEWLINE # printExpr
    | ID '=' expr NEWLINE # assign
    | NEWLINE # blank
    ;

expr: expr op=('*'|'/') expr # MulDiv
    | expr op=('+'|'-') expr # AddSub
    | INT # int
    | ID # id
    | '(' expr ')' # parens
    ;

MUL: '*'; // assigns token name to '*' used above in grammar
DIV: '/';
ADD: '+';
SUB: '-';

src/main/antlr/org/jbduncan/CommonLexerRules。g4

lexer grammar CommonLexerRules; // note "lexer grammar"

ID: [a-zA-Z]+ ; // match identifiers
INT: [0-9]+ ; // match integers
NEWLINE: '\r'? '\n' ; // return newlines to parser (is end-statement signal)
WS: [ \t] -> skip ; // toss out whitespace

src/main/java/org/jbduncan/Application。JAVA

package org.jbduncan;

import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.tree.ParseTree;

import html" target="_blank">java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

public final class Application {
  public static void main(String[] args) throws IOException {
    String inputFile = (args.length > 0) ? args[0] : null;

    InputStream inputStream = (inputFile == null) ? System.in : new FileInputStream(inputFile);
    ANTLRInputStream input = new ANTLRInputStream(inputStream);
    ExprLexer lexer = new ExprLexer(input);
    CommonTokenStream tokens = new CommonTokenStream(lexer);
    ExprParser parser = new ExprParser(tokens);
    ParseTree tree = parser.prog(); // parse; start at prog

    System.out.println(tree.toStringTree(parser)); // print tree as text
  }
}

Answer 1

在Gradle论坛上发布了我的问题后，我终于找到了答案：

generateGrammarSource {
  arguments << "-lib" << "src/main/antlr/org/jbduncan" 
}

其中，“src/main/antlr/org/jbduncan”是一个包含antlr的路径。g4库。