ANTLR: Multiple Input Sources

ANTLR is a powerful language recognition tool that can be used to generate parsers and lexers. In some cases, we may need to handle multiple input sources. This article will explain how to handle multiple input sources in ANTLR.

In ANTLR, we can use various input sources, including files, strings, and standard input. When we need to handle multiple input sources, we can use the multiple input option provided by ANTLR.

To handle multiple input sources in ANTLR, we need to do the following steps:

1. Define multiple input sources: We can use the ANTLRInputStream class provided by ANTLR to define multiple input sources. Each input source needs to instantiate an ANTLRInputStream object.

2. Create multiple lexers: For each input source, we need to create a separate lexer. We can use the lexer class generated by ANTLR to create lexer objects.

3. Parse multiple input sources: For each input source, we use the corresponding lexer to parse the input source. We can use the parser class generated by ANTLR to parse the input source.

Here is an example code that demonstrates how to handle multiple input sources in ANTLR:

ANTLRInputStream input1 = new ANTLRInputStream(new FileInputStream("input1.txt"));
Lexer lexer1 = new MyLexer(input1);
CommonTokenStream tokens1 = new CommonTokenStream(lexer1);
MyParser parser1 = new MyParser(tokens1);
parser1.startRule();

ANTLRInputStream input2 = new ANTLRInputStream(new FileInputStream("input2.txt"));
Lexer lexer2 = new MyLexer(input2);
CommonTokenStream tokens2 = new CommonTokenStream(lexer2);
MyParser parser2 = new MyParser(tokens2);
parser2.startRule();

In the above code, we define two input sources: input1.txt and input2.txt. For each input source, we create a lexer object and a parser object. Then, we use the parser object to parse each input source.

In summary, handling multiple input sources in ANTLR is straightforward. We simply define multiple input sources, create the corresponding lexer and parser, and then use the parser to parse each input source. By utilizing the multiple input option provided by ANTLR, we can easily handle multiple input sources.