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author | Tom Willemse | 2020-10-28 22:56:15 -0700 |
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committer | Tom Willemse | 2020-10-28 22:56:15 -0700 |
commit | 2e15e8bab840b6d13d1463709e3125bb2910dbab (patch) | |
tree | 41e805a0726990c175be46763b0bb029f7608856 /src/com/craftinginterpreters/tool/GenerateAst.java | |
parent | 5fcfc5a01582c6159593eaaf23ec0109d1230130 (diff) | |
download | crafting-interpreters-2e15e8bab840b6d13d1463709e3125bb2910dbab.tar.gz crafting-interpreters-2e15e8bab840b6d13d1463709e3125bb2910dbab.zip |
Add GenerateAst and AstPrinter
Diffstat (limited to 'src/com/craftinginterpreters/tool/GenerateAst.java')
-rw-r--r-- | src/com/craftinginterpreters/tool/GenerateAst.java | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/src/com/craftinginterpreters/tool/GenerateAst.java b/src/com/craftinginterpreters/tool/GenerateAst.java new file mode 100644 index 0000000..5e79d2f --- /dev/null +++ b/src/com/craftinginterpreters/tool/GenerateAst.java @@ -0,0 +1,88 @@ +package com.craftinginterpreters.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); + + writer.println("package com.craftinginterpreters.lox;"); + writer.println(); + writer.println("import java.util.List;"); + writer.println(); + writer.println("abstract class " + baseName + " {"); + + defineVisitor(writer, baseName, types); + + for (String type : types) { + String className = type.split(":")[0].trim(); + String fields = type.split(":")[1].trim(); + defineType(writer, baseName, className, fields); + } + + // The base accept() method + writer.println(); + writer.println(" abstract <R> R accept(Visitor<R> visitor);"); + + writer.println("}"); + writer.close(); + } + + private static void defineVisitor(PrintWriter writer, String baseName, List<String> types) { + writer.println(" interface Visitor<R> {"); + + for (String type : types) { + String typeName = type.split(":")[0].trim(); + writer.println(" R visit" + typeName + baseName + "(" + typeName + " " + baseName.toLowerCase() + ");"); + } + + writer.println(" }"); + } + + private static void defineType(PrintWriter writer, String baseName, String className, String fieldList) { + writer.println(" static class " + className + " extends " + baseName + " {"); + + // Constructor + writer.println(" " + className + "(" + fieldList + ") {"); + + // Store parameters in fields. + String[] fields = fieldList.split(", "); + for (String field : fields) { + String name = field.split(" ")[1]; + writer.println(" this." + name + " = " + name + ";"); + } + + writer.println(" }"); + + // Visitor pattern. + writer.println(); + writer.println(" @Override"); + writer.println(" <R> R accept(Visitor<R> visitor) {"); + writer.println(" return visitor.visit" + className + baseName + "(this);"); + writer.println(" }"); + + // Fields + writer.println(); + for (String field : fields) { + writer.println(" final " + field + ";"); + } + + writer.println(" }"); + } +} |