Set up basic ANTLR grammar for Fix

Generate Java sources after edit: `./gradlew generateGrammarSource`

See metafacture/metafacture-fix#298

Author: fsteeg

metafacture-fix/src/main/antlr/org/metafacture/fix/parser/Fix.g

@@ -0,0 +1,55 @@
+/*
+ *  Copyright 2024 Fabian Steeg, hbz
+ *
+ *  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.
+ */
+
+grammar Fix;
+
+options {
+language = Java;
+output = AST;
+ASTLabelType = CommonTree;
+}
+
+@header {
+package org.metafacture.fix.parser;
+}
+
+@lexer::header {
+package org.metafacture.fix.parser;
+}
+
+fix	: expression*;
+
+expression	: (doExpr | unless | ifExpr | methodCall | COMMENT) WS*;
+
+methodCall	: ID '(' (ID|option) (',' (ID|option))* ')';
+
+doExpr	: 'do' methodCall expression* 'end';
+
+unless	: 'unless' methodCall expression* 'end';
+
+ifExpr	: 'if' methodCall expression* elsIf* elseExpr? 'end';
+
+elsIf	: 'elsif' methodCall expression*;
+
+elseExpr	: 'else' expression*;
+
+option	: ID ':' ID;
+
+ID	: ('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')*;
+
+COMMENT	: '#' ~('\n'|'\r')* '\r'? '\n' {$channel=HIDDEN;};
+
+WS	: (' '| '\t'| '\r'| '\n') {$channel=HIDDEN;};

metafacture-fix/src/test/java/org/metafacture/fix/FixGrammarTest.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2024 Fabian Steeg, hbz
+ *
+ * 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 org.metafacture.fix;
+
+import static org.junit.Assert.assertEquals;
+
+import org.metafacture.fix.parser.FixLexer;
+import org.metafacture.fix.parser.FixParser;
+
+import org.antlr.runtime.ANTLRInputStream;
+import org.antlr.runtime.CommonTokenStream;
+import org.antlr.runtime.RecognitionException;
+import org.antlr.runtime.tree.Tree;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Tests for the Fix grammar.
+ *
+ * @author Fabian Steeg
+ */
+public final class FixGrammarTest {
+
+    @Test
+    public void parseSimpleFix() {
+        assertEquals("add_field ( test )", parseToString("add_field(test)"));
+    }
+
+    @Test
+    public void parseSimpleFixWithOption() {
+        assertEquals("add_field ( test1 , option : test2 )", parseToString("add_field(test1,option:test2)"));
+    }
+
+    @Test
+    public void parseFixWithIf() {
+        assertEquals("if some ( test1 ) add ( something ) elsif some ( test2 ) add ( somethingElse , opt : one ) else add ( anotherThing , opt : two ) end",
+                parseToString(
+                    "if some(test1)",
+                    "  add(something)",
+                    "elsif some(test2)",
+                    "  add(somethingElse, opt: one)",
+                    "else",
+                    "  add(anotherThing, opt: two)",
+                    "  # comment",
+                    "end"));
+    }
+
+    @Test
+    public void parseError() {
+        assertEquals("<unexpected: [@3,14:14='<EOF>',<-1>,1:14], resync=add_field(> <mismatched token: [@3,14:14='<EOF>',<-1>,1:14], resync=test>",
+                parseToString("add_field(test"));
+    }
+
+    private String parseToString(final String... fixLines) {
+        try {
+            final ByteArrayInputStream fixInput = createInputStream(String.join("\n", fixLines));
+            final FixLexer lexer = new FixLexer(new ANTLRInputStream(fixInput));
+            final FixParser parser = new FixParser(new CommonTokenStream(lexer));
+            return ((Tree) parser.fix().getTree()).toStringTree();
+        } catch (IOException | RecognitionException e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
+
+    private ByteArrayInputStream createInputStream(final String string) {
+        return new ByteArrayInputStream(string.getBytes(StandardCharsets.UTF_8));
+    }
+
+}