cobalt-lang/cobalt/tool/GenerateAst.java

67 lines
2.1 KiB
Java

package cobalt.tool;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.List;
public class GenerateAst {
public static void main(String[] args) throws IOException {
if (args.length != 1) {
System.err.println("Usage: generate_ast <output directory>");
System.exit(64);
}
String outputDir = args[0];
defineAst(outputDir, "Expr", Arrays.asList(
"Binary : Expr left, Token operator, Expr right",
"Grouping : Expr expression",
"Literal : Object value",
"Unary : Token operator, Expr right"
));
}
private static void defineAst(String outputDir, String baseName, List<String> types) throws IOException {
String path = outputDir + "/" + baseName + ".java";
PrintWriter writer = new PrintWriter(path, "UTF-8");
writer.println("package cobalt.lang");
writer.println();
writer.println("import java.util.List;");
writer.println();
writer.println("abstract class " + baseName + " {");
for (String type : types){
String className = type.split(":")[0].trim();
String fields = type.split(":")[1].trim();
defineType(writer, baseName, className, fields);
}
writer.println("}");
writer.close();
}
private static void defineType(PrintWriter writer, String baseName, String className, String fieldList) {
writer.println(" static class " + className + " extends " + baseName + " {");
// Constructor
writer.println(" " + className + "(" + fieldList + ") {");
String[] fields = fieldList.split(", ");
for (String field : fields) {
String name = field.split(" ")[1];
writer.println(" this." + name + " = " + name + ";");
}
writer.println(" }");
// Fields
writer.println();
for (String field : fields) {
writer.println(" final " + field + ";");
}
writer.println(" }");
}
}