100 lines
2.8 KiB
Java
100 lines
2.8 KiB
Java
package tool;
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import java.io.IOException;
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import java.io.PrintWriter;
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import java.nio.charset.Charset;
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import java.util.Arrays;
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import java.util.List;
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public class GenerateAST {
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public static void main(String[] args) throws IOException {
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if (args.length != 1) {
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System.err.println("Usage: generate_ast <output directory>");
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System.exit(64);
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}
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String outputDir = args[0];
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defineAST(
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outputDir,
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"Expr",
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Arrays.asList(
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"Binary : Expr left, Token operator, Expr right",
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"Grouping : Expr expression",
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"Literal : Object value",
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"Unary : Token operator, Expr right"));
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}
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private static void defineAST(String outputDir, String baseName, List<String> types)
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throws IOException {
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String path = outputDir + "/" + baseName + ".java";
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PrintWriter writer = new PrintWriter(path, Charset.defaultCharset());
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writer.println("package lox;");
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writer.println();
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writer.println("import java.util.List;");
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writer.println();
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writer.println("abstract class " + baseName + " {");
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defineVisitor(writer, baseName, types);
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for (String type : types) {
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String className = type.split(":")[0].trim();
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String fields = type.split(":")[1].trim();
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defineType(writer, baseName, className, fields);
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}
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writer.println(" abstract <R> R accept(Visitor<R> visitor);");
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writer.println("}");
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writer.close();
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}
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private static void defineVisitor(PrintWriter writer, String baseName, List<String> types) {
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writer.println(" interface Visitor<R> {");
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for (String type : types) {
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String typeName = type.split(":")[0].trim();
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writer.println(
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" R visit"
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+ typeName
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+ baseName
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+ "("
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+ typeName
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+ " "
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+ baseName.toLowerCase()
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+ ");");
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}
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writer.println(" }");
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writer.println();
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}
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private static void defineType(
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PrintWriter writer, String baseName, String className, String fieldList) {
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writer.println(" static class " + className + " extends " + baseName + " {");
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writer.println(" " + className + "(" + fieldList + ") {");
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String[] fields = fieldList.split(", ");
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for (String field : fields) {
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String name = field.split(" ")[1];
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writer.println(" this." + name + " = " + name + ";");
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}
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writer.println(" }");
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writer.println();
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writer.println(" @Override");
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writer.println(" <R> R accept(Visitor<R> visitor) {");
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writer.println(" return visitor.visit" + className + baseName + "(this);");
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writer.println(" }");
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writer.println();
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for (String field : fields) {
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writer.println(" final " + field + ";");
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}
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writer.println(" }");
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writer.println();
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}
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}
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