5.4

Makefile

@@ -1,8 +1,10 @@
 
-.PHONY: build
+.PHONY: build-lox, build-tool
 
-build:
+build-lox:
 	javac -d build/classes src/com/craftinginterpreters/lox/*
+	
+build-tool:
 	javac -d build/classes src/com/craftinginterpreters/tool/*
 	
 lox:

jlox.iml

@@ -1,11 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module type="JAVA_MODULE" version="4">
-  <component name="NewModuleRootManager" inherit-compiler-output="true">
-    <exclude-output />
-    <content url="file://$MODULE_DIR$">
-      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
-    </content>
-    <orderEntry type="inheritedJdk" />
-    <orderEntry type="sourceFolder" forTests="false" />
-  </component>
-</module>

src/com/craftinginterpreters/lox/AstPrinter.java

@@ -0,0 +1,51 @@
+package com.craftinginterpreters.lox;
+
+class AstPrinter implements Expr.Visitor<String> {
+  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));
+  }
+}

src/com/craftinginterpreters/lox/Expr.java

@@ -1,6 +1,6 @@
 package com.craftinginterpreters.lox;
 
-import java.util.list;
+import java.util.List;
 
 abstract class Expr {
 	interface Visitor<R> {
@@ -12,8 +12,8 @@ abstract class Expr {
   static class Binary extends Expr {
     Binary(Expr left, Token operator, Expr right) {
     this.left = left;
-    this.Token = Token;
-    this.Expr = Expr;
+    this.operator = operator;
+    this.right = right;
     }
 
 	@Override
@@ -21,9 +21,9 @@ abstract class Expr {
 		return visitor.visitBinaryExpr(this);
 	}
 
-    final Expr left = Expr left;
-    final  Token operator =  Token operator;
-    final  Expr right =  Expr right;
+    final Expr left;
+    final Token operator;
+    final Expr right;
   }
   static class Grouping extends Expr {
     Grouping(Expr expression) {
@@ -35,7 +35,7 @@ abstract class Expr {
 		return visitor.visitGroupingExpr(this);
 	}
 
-    final Expr expression = Expr expression;
+    final Expr expression;
   }
   static class Literal extends Expr {
     Literal(Object value) {
@@ -47,12 +47,12 @@ abstract class Expr {
 		return visitor.visitLiteralExpr(this);
 	}
 
-    final Object value = Object value;
+    final Object value;
   }
   static class Unary extends Expr {
     Unary(Token operator, Expr right) {
     this.operator = operator;
-    this.Expr = Expr;
+    this.right = right;
     }
 
 	@Override
@@ -60,8 +60,8 @@ abstract class Expr {
 		return visitor.visitUnaryExpr(this);
 	}
 
-    final Token operator = Token operator;
-    final  Expr right =  Expr right;
+    final Token operator;
+    final Expr right;
   }
 
 	abstract <R> R accept(Visitor<R> visitor);

src/com/craftinginterpreters/tool/GenerateAst.java

@@ -26,7 +26,7 @@ public class GenerateAst {
 
         writer.println("package com.craftinginterpreters.lox;");
         writer.println();
-        writer.println("import java.util.list;");
+        writer.println("import java.util.List;");
         writer.println();
         writer.println("abstract class " + baseName + " {");
 
@@ -83,7 +83,7 @@ public class GenerateAst {
         // Fields
         writer.println();
         for (String field : fields) {
-            writer.println("    final " + field + " = " + field + ";");
+            writer.println("    final " + field + ";");
         }
 
         writer.println("  }");