From 2e15e8bab840b6d13d1463709e3125bb2910dbab Mon Sep 17 00:00:00 2001 From: Tom Willemse Date: Wed, 28 Oct 2020 22:56:15 -0700 Subject: Add GenerateAst and AstPrinter --- src/CMakeLists.txt | 7 +- src/com/craftinginterpreters/lox/AstPrinter.java | 53 +++++++++++++ src/com/craftinginterpreters/tool/GenerateAst.java | 88 ++++++++++++++++++++++ 3 files changed, 146 insertions(+), 2 deletions(-) create mode 100644 src/com/craftinginterpreters/lox/AstPrinter.java create mode 100644 src/com/craftinginterpreters/tool/GenerateAst.java (limited to 'src') diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt index f664d96..cbd1efd 100644 --- a/src/CMakeLists.txt +++ b/src/CMakeLists.txt @@ -9,7 +9,10 @@ add_jar(Lox com/craftinginterpreters/lox/Lox.java com/craftinginterpreters/lox/TokenType.java com/craftinginterpreters/lox/Token.java + com/craftinginterpreters/lox/Expr.java + com/craftinginterpreters/lox/AstPrinter.java ENTRY_POINT com/craftinginterpreters/lox/Lox) -get_target_property(_jarFile Lox JAR_FILE) -get_target_property(_classDir Lox CLASSDIR) +add_jar(GenerateAst + com/craftinginterpreters/tool/GenerateAst.java + ENTRY_POINT com/craftinginterpreters/tool/GenerateAst) diff --git a/src/com/craftinginterpreters/lox/AstPrinter.java b/src/com/craftinginterpreters/lox/AstPrinter.java new file mode 100644 index 0000000..cb494f0 --- /dev/null +++ b/src/com/craftinginterpreters/lox/AstPrinter.java @@ -0,0 +1,53 @@ +package com.craftinginterpreters.lox; + +/** + * AstPrinter + */ +class AstPrinter implements Expr.Visitor { + String print(Expr expr) { + return expr.accept(this); + } + + @Override + public String visitBinaryExpr(Expr.Binary expr) { + return parenthesize(expr.operator.lexeme, expr.left, expr.right); + } + + @Override + public String visitGroupingExpr(Expr.Grouping expr) { + return parenthesize("group", expr.expression); + } + + @Override + public String visitLiteralExpr(Expr.Literal expr) { + if (expr.value == null) + return "nil"; + return expr.value.toString(); + } + + @Override + public String visitUnaryExpr(Expr.Unary expr) { + return parenthesize(expr.operator.lexeme, expr.right); + } + + private String parenthesize(String name, Expr... exprs) { + StringBuilder builder = new StringBuilder(); + + builder.append("(").append(name); + for (Expr expr : exprs) { + builder.append(" "); + builder.append(expr.accept(this)); + } + builder.append(")"); + + return builder.toString(); + } + + public static void main(String[] args) { + Expr expression = new Expr.Binary( + new Expr.Unary(new Token(TokenType.MINUS, "-", null, 1), new Expr.Literal(123)), + new Token(TokenType.STAR, "*", null, 1), new Expr.Grouping(new Expr.Literal(45.67))); + + System.out.println(new AstPrinter().print(expression)); + } +} 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 "); + 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 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 accept(Visitor visitor);"); + + writer.println("}"); + writer.close(); + } + + private static void defineVisitor(PrintWriter writer, String baseName, List types) { + writer.println(" interface Visitor {"); + + 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 accept(Visitor visitor) {"); + writer.println(" return visitor.visit" + className + baseName + "(this);"); + writer.println(" }"); + + // Fields + writer.println(); + for (String field : fields) { + writer.println(" final " + field + ";"); + } + + writer.println(" }"); + } +} -- cgit v1.2.3-54-g00ecf