From 427327003d639c943fd770734b13db9bb14fa8d6 Mon Sep 17 00:00:00 2001
From: Pekka Laiho <pekka.i.laiho@gmail.com>
Date: Tue, 16 Jun 2020 20:38:46 +0700
Subject: [PATCH] handle special characters correctly in printing

---
 README.md       |  2 +-
 run.php         |  6 +++---
 src/Lisp.php    | 10 +++++-----
 src/Printer.php | 22 +++++++++++++++-------
 4 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/README.md b/README.md
index 0fb0c54..51ba2e2 100644
--- a/README.md
+++ b/README.md
@@ -135,7 +135,7 @@ Name  | Example | Example result | Description
 ----- | ------- | -------------- | -----------
 doc   | `(doc +)` | `"Return the sum of all arguments."` | Show description of a built-in function.
 read  | `(read "(+ 1 2 3)")` | `(+ 1 2 3)` | Read a string as code and return the expression.
-print | `(print "hello world")` | `"hello world"null` | Print expression on the screen. Print returns null (which is shown due to the extra print in repl).
+print | `(print "hello world")` | `"hello world"null` | Print expression on the screen. Print returns null (which is shown due to the extra print in repl). Give optional second argument as `true` to show strings in readable format.
 error | `(error "invalid value")` | `error: invalid value` | Throw an exception with message as argument.
 
 ### Collection functions
diff --git a/run.php b/run.php
index 1b27934..e2c8fe8 100644
--- a/run.php
+++ b/run.php
@@ -17,7 +17,7 @@ function ml_repl($lisp, $env)
         $input = readline('> ');
 
         try {
-            $lisp->rep($input, $env);
+            $lisp->rep($input, $env, true);
 
             if ($input) {
                 readline_add_history($input);
@@ -42,10 +42,10 @@ function ml_run()
     list($lisp, $env) = ml_get_lisp($debug);
 
     if (array_key_exists('e', $args)) {
-        $lisp->rep($args['e'], $env);
+        $lisp->rep($args['e'], $env, false);
     } elseif (array_key_exists('f', $args)) {
         $input = "(load \"{$args['f']}\")";
-        $lisp->rep($input, $env);
+        $lisp->rep($input, $env, false);
     } elseif (array_key_exists('r', $args)) {
         ml_repl($lisp, $env);
     } else {
diff --git a/src/Lisp.php b/src/Lisp.php
index 163b27f..6ede8ed 100644
--- a/src/Lisp.php
+++ b/src/Lisp.php
@@ -16,7 +16,7 @@ class Lisp
         $this->printer = $printer;
     }
 
-    public function rep(string $input, Env $env): void
+    public function rep(string $input, Env $env, bool $printReadable): void
     {
         $tokens = $this->tokenizer->tokenize($input);
 
@@ -24,7 +24,7 @@ class Lisp
 
         $result = $this->eval->eval($expr, $env);
 
-        $this->printer->print($result);
+        $this->printer->print($result, $printReadable);
     }
 
     public function register(Env $env): void
@@ -43,9 +43,9 @@ class Lisp
             fn (string $a) => $this->reader->read($this->tokenizer->tokenize($a))
         ));
 
-        $env->set('print', new CoreFunc('print', 'Print argument.', 1, 1,
-            function ($a) {
-                $this->printer->print($a);
+        $env->set('print', new CoreFunc('print', 'Print argument. Give second argument as true to show strings in readable format.', 1, 2,
+            function ($a, bool $readable = false) {
+                $this->printer->print($a, $readable);
                 return null;
             }
         ));
diff --git a/src/Printer.php b/src/Printer.php
index e1b4d95..34099bc 100644
--- a/src/Printer.php
+++ b/src/Printer.php
@@ -3,21 +3,21 @@ namespace MadLisp;
 
 class Printer
 {
-    public function print($ast): void
+    public function print($ast, bool $readable = true): void
     {
-        print($this->doPrint($ast));
+        print($this->doPrint($ast, $readable));
     }
 
-    private function doPrint($a): string
+    private function doPrint($a, bool $readable): string
     {
         if ($a instanceof Func) {
             return '<function>';
         } elseif ($a instanceof MList) {
-            return '(' . implode(' ', array_map(fn ($b) => $this->doPrint($b), $a->getData())) . ')';
+            return '(' . implode(' ', array_map(fn ($b) => $this->doPrint($b, $readable), $a->getData())) . ')';
         } elseif ($a instanceof Vector) {
-            return '[' . implode(' ', array_map(fn ($b) => $this->doPrint($b), $a->getData())) . ']';
+            return '[' . implode(' ', array_map(fn ($b) => $this->doPrint($b, $readable), $a->getData())) . ']';
         } elseif ($a instanceof Hash) {
-            return '{' . implode(' ', array_map(fn ($key, $val) => $this->doPrint($key) . ':' . $this->doPrint($val),
+            return '{' . implode(' ', array_map(fn ($key, $val) => $this->doPrint($key, $readable) . ':' . $this->doPrint($val, $readable),
                                                 array_keys($a->getData()), array_values($a->getData()))) . '}';
         } elseif ($a instanceof Symbol) {
             return $a->getName();
@@ -28,7 +28,15 @@ class Printer
         } elseif ($a === null) {
             return 'null';
         } elseif (is_string($a)) {
-            return '"' . $a . '"';
+            if ($readable) {
+                $a = str_replace("\\", "\\\\", $a);
+                $a = str_replace("\n", "\\n", $a);
+                $a = str_replace("\r", "\\r", $a);
+                $a = str_replace("\"", "\\\"", $a);
+                return '"' . $a . '"';
+            } else {
+                return $a;
+            }
         } else {
             return $a;
         }