1 files changed, 147 insertions, 0 deletions
diff --git a/jlox/src/com/craftinginterpreters/lox/AstPrinter.java b/jlox/src/com/craftinginterpreters/lox/AstPrinter.java
new file mode 100644
index 0000000..4c120d3
--- /dev/null
+++ b/jlox/src/com/craftinginterpreters/lox/AstPrinter.java
@@ -0,0 +1,147 @@
+package com.craftinginterpreters.lox;
+
+import java.util.List;
+
+/**
+ * AstPrinter
+ */
+class AstPrinter implements Expr.Visitor<String>, Stmt.Visitor<String> {
+    String print(Expr expr) {
+        return expr.accept(this);
+    }
+
+    @Override
+    public String visitCallExpr(Expr.Call expr) {
+        StringBuilder builder = new StringBuilder();
+
+        builder.append(print(expr.callee));
+        builder.append(parenthesizeExpr("", expr.arguments));
+
+        return builder.toString();
+    }
+
+    @Override
+    public String visitBinaryExpr(Expr.Binary expr) {
+        return parenthesizeExpr(expr.operator.lexeme, expr.left, expr.right);
+    }
+
+    @Override
+    public String visitGroupingExpr(Expr.Grouping expr) {
+        return parenthesizeExpr("group", expr.expression);
+    }
+
+    @Override
+    public String visitLiteralExpr(Expr.Literal expr) {
+        if (expr.value == null)
+            return "nil";
+        return expr.value.toString();
+    }
+
+    @Override
+    public String visitLogicalExpr(Expr.Logical expr) {
+        return parenthesizeExpr(expr.operator.type.toString(), expr.left, expr.right);
+    }
+
+    @Override
+    public String visitUnaryExpr(Expr.Unary expr) {
+        return parenthesizeExpr(expr.operator.lexeme, expr.right);
+    }
+
+    @Override
+    public String visitVariableExpr(Expr.Variable expr) {
+        return expr.name.lexeme;
+    }
+
+    @Override
+    public String visitAssignExpr(Expr.Assign expression) {
+        return parenthesizeExpr(expression.name.lexeme + " = ", expression.value);
+    }
+
+    @Override
+    public String visitVarStmt(Stmt.Var statement) {
+        return parenthesizeExpr("define " + statement.name.lexeme + " = ", statement.initializer);
+    }
+
+    @Override
+    public String visitWhileStmt(Stmt.While statement) {
+        StringBuilder builder = new StringBuilder();
+
+        builder.append('(');
+        builder.append(parenthesizeExpr("while", statement.condition));
+        builder.append(parenthesizeStmt("do", statement.body));
+        builder.append(')');
+
+        return builder.toString();
+    }
+
+    @Override
+    public String visitPrintStmt(Stmt.Print statement) {
+        return parenthesizeExpr("print", statement.expression);
+    }
+
+    @Override
+    public String visitExpressionStmt(Stmt.Expression expression) {
+        return expression.expression.accept(this);
+    }
+
+    @Override
+    public String visitIfStmt(Stmt.If stmt) {
+        StringBuilder builder = new StringBuilder();
+
+        builder.append("(");
+        builder.append(parenthesizeExpr("if", stmt.condition));
+        builder.append(parenthesizeStmt("then", stmt.thenBranch));
+
+        if (stmt.elseBranch != null) {
+            builder.append(parenthesizeStmt("else", stmt.elseBranch));
+        }
+        return builder.toString();
+    }
+
+    @Override
+    public String visitBlockStmt(Stmt.Block block) {
+        return parenthesizeStmt("", block.statements);
+    }
+
+    private String parenthesizeExpr(String name, Expr... exprs) {
+        return parenthesizeExpr(name, exprs);
+    }
+
+    private String parenthesizeExpr(String name, List<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();
+    }
+
+    private String parenthesizeStmt(String name, List<Stmt> statements) {
+        StringBuilder builder = new StringBuilder();
+
+        builder.append("(").append(name);
+        for (Stmt statement : statements) {
+            builder.append(" ");
+            builder.append(statement.accept(this));
+        }
+        builder.append(")");
+
+        return builder.toString();
+    }
+
+    private String parenthesizeStmt(String name, Stmt... statements) {
+        return parenthesizeStmt(name, statements);
+    }
+
+    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));
+    }
+}