From 80faff86f5e58273cf94cac2b0110118de75bae9 Mon Sep 17 00:00:00 2001
From: Pekka Laiho <pekka.i.laiho@gmail.com>
Date: Thu, 28 May 2020 17:10:00 +0700
Subject: [PATCH] split code to multiple classes

---
 bootstrap.php     |  10 ++
 repl.php          |   2 +-
 src/Evaller.php   |  79 ++++++++++++++
 src/Lisp.php      | 267 +++-------------------------------------------
 src/Printer.php   |  57 ++++++++++
 src/Reader.php    |  67 ++++++++++++
 src/Tokenizer.php |  75 +++++++++++++
 7 files changed, 303 insertions(+), 254 deletions(-)
 create mode 100644 src/Evaller.php
 create mode 100644 src/Printer.php
 create mode 100644 src/Reader.php
 create mode 100644 src/Tokenizer.php

diff --git a/bootstrap.php b/bootstrap.php
index 229c1af..4ce26a4 100644
--- a/bootstrap.php
+++ b/bootstrap.php
@@ -10,3 +10,13 @@ function ml_get_env(): MadLisp\Env
 
     return $env;
 }
+
+function ml_get_lisp(): MadLisp\Lisp
+{
+    $tokenizer = new MadLisp\Tokenizer();
+    $reader = new MadLisp\Reader();
+    $eval = new MadLisp\Evaller();
+    $printer = new MadLisp\Printer();
+
+    return new MadLisp\Lisp($tokenizer, $reader, $eval, $printer);
+}
diff --git a/repl.php b/repl.php
index 8f33df7..191265e 100644
--- a/repl.php
+++ b/repl.php
@@ -2,7 +2,7 @@
 require('bootstrap.php');
 
 $env = ml_get_env();
-$lisp = new MadLisp\Lisp();
+$lisp = ml_get_lisp();
 
 while (true) {
     $input = readline('> ');
diff --git a/src/Evaller.php b/src/Evaller.php
new file mode 100644
index 0000000..8c51ea2
--- /dev/null
+++ b/src/Evaller.php
@@ -0,0 +1,79 @@
+<?php
+namespace MadLisp;
+
+use Closure;
+
+class Evaller
+{
+    public function eval(array $expressions, Env $env): array
+    {
+        $results = [];
+
+        foreach ($expressions as $expr) {
+            $results[] = $this->doEval($expr, $env);
+        }
+
+        return $results;
+    }
+
+    public function doEval($expr, Env $env)
+    {
+        if ($expr instanceof MList && $expr->count() > 0) {
+            $first = $expr->get(0);
+
+            if ($first instanceof Symbol) {
+                // Special built-in features
+                if ($first->getName() == 'env') {
+                    return $env;
+                } elseif ($first->getName() == 'quote') {
+                    if ($expr->count() != 2) {
+                        throw new MadLispException("quote requires exactly 1 argument");
+                    }
+
+                    return $expr->get(1);
+                } elseif ($first->getName() == 'if') {
+                    if ($expr->count() != 4) {
+                        throw new MadLispException("if requires exactly 3 arguments");
+                    }
+
+                    // Eval condition
+                    $result = $this->doEval($expr->get(1), $env);
+
+                    // Eval true or false branch and return it
+                    if ($result == true) {
+                        return $this->doEval($expr->get(2), $env);
+                    } else {
+                        return $this->doEval($expr->get(3), $env);
+                    }
+                }
+
+                // Normal symbol, fetch from env
+                $first = $env->get($first->getName());
+            }
+
+            if (!($first instanceof Closure)) {
+                throw new MadLispException("first argument of list is not function");
+            }
+
+            $args = array_slice($expr->getData(), 1);
+
+            // Evaluate args
+            $args = array_map(fn ($a) => $this->doEval($a, $env), $args);
+
+            // Call func and return result
+            return $first(...$args);
+        } elseif ($expr instanceof Hash) {
+            // Hash: return new hash with all items evaluated
+            $items = [];
+            foreach ($expr->getData() as $key => $val) {
+                $items[$key] = $this->doEval($val, $env);
+            }
+            return new Hash($items);
+        } elseif ($expr instanceof Symbol) {
+            return $env->get($expr->getName());
+        }
+
+        // Return the expression unchanged
+        return $expr;
+    }
+}
diff --git a/src/Lisp.php b/src/Lisp.php
index ee51467..91c7bca 100644
--- a/src/Lisp.php
+++ b/src/Lisp.php
@@ -1,268 +1,29 @@
 <?php
 namespace MadLisp;
 
-use Closure;
-
 class Lisp
 {
-    public function tokenize(string $a): array
+    protected Tokenizer $tokenizer;
+    protected Reader $reader;
+    protected Evaller $eval;
+    protected Printer $printer;
+
+    public function __construct(Tokenizer $tokenizer, Reader $reader, Evaller $eval, Printer $printer)
     {
-        $tokens = [];
-        $current = '';
-        $string = false;
-        $parens = 0;
-
-        $addCurrent = function () use (&$tokens, &$current) {
-            if ($current !== '') {
-                $tokens[] = $current;
-                $current = '';
-            }
-        };
-
-        for ($i = 0; $i < strlen($a); $i++) {
-            $c = substr($a, $i, 1);
-
-            if ($string) {
-                // Inside string, add all characters
-                $current .= $c;
-
-                // Stop at "
-                if ($c == '"') {
-                    $addCurrent();
-                    $string = false;
-                }
-            } else {
-                // Not inside string
-
-                if ($c == '"') {
-                    // Start of string
-                    $addCurrent();
-                    $current .= $c;
-                    $string = true;
-                } elseif ($c == ' ' || $c == "\t" || $c == "\n" || $c == "\r") {
-                    // Whitespace is ignored
-                    $addCurrent();
-                } elseif ($c == '(') {
-                    // Start of list
-                    $addCurrent();
-                    $tokens[] = '(';
-                    $parens++;
-                } elseif ($c == ')') {
-                    // End of list
-                    if ($parens == 0) {
-                        throw new MadLispException("unexpected closing parenthesis");
-                    }
-                    $addCurrent();
-                    $tokens[] = ')';
-                    $parens--;
-                } else {
-                    // All other characters
-                    $current .= $c;
-                }
-            }
-        }
-
-        // Add last also
-        $addCurrent();
-
-        // Check for errors
-        if ($parens != 0) {
-            throw new MadLispException("missing closing parenthesis");
-        } elseif ($string) {
-            throw new MadLispException("unterminated string");
-        }
-
-        return $tokens;
-    }
-
-    public function parse(array $tokens): array
-    {
-        $result = [];
-        $index = 0;
-
-        while ($index < count($tokens)) {
-            $result[] = $this->readForm($tokens, $index);
-        }
-
-        return $result;
-    }
-
-    public function read(string $code): array
-    {
-        $tokens = $this->tokenize($code);
-
-        $expressions = $this->parse($tokens);
-
-        return $expressions;
-    }
-
-    public function eval($expr, Env $env)
-    {
-        if ($expr instanceof MList && $expr->count() > 0) {
-            $first = $expr->get(0);
-
-            if ($first instanceof Symbol) {
-                // Special built-in features
-                if ($first->getName() == 'env') {
-                    return $env;
-                } elseif ($first->getName() == 'quote') {
-                    if ($expr->count() != 2) {
-                        throw new MadLispException("quote requires exactly 1 argument");
-                    }
-
-                    return $expr->get(1);
-                } elseif ($first->getName() == 'if') {
-                    if ($expr->count() != 4) {
-                        throw new MadLispException("if requires exactly 3 arguments");
-                    }
-
-                    // Eval condition
-                    $result = $this->eval($expr->get(1), $env);
-
-                    // Eval true or false branch and return it
-                    if ($result == true) {
-                        return $this->eval($expr->get(2), $env);
-                    } else {
-                        return $this->eval($expr->get(3), $env);
-                    }
-                }
-
-                // Normal symbol, fetch from env
-                $first = $env->get($first->getName());
-            }
-
-            if (!($first instanceof Closure)) {
-                throw new MadLispException("first argument of list is not function");
-            }
-
-            $args = array_slice($expr->getData(), 1);
-
-            // Evaluate args
-            $args = array_map(fn ($a) => $this->eval($a, $env), $args);
-
-            // Call func and return result
-            return $first(...$args);
-        } elseif ($expr instanceof Hash) {
-            // Hash: return new hash with all items evaluated
-            $items = [];
-            foreach ($expr->getData() as $key => $val) {
-                $items[$key] = $this->eval($val, $env);
-            }
-            return new Hash($items);
-        } elseif ($expr instanceof Symbol) {
-            return $env->get($expr->getName());
-        }
-
-        // Return the expression unchanged
-        return $expr;
-    }
-
-    public function print(array $items): void
-    {
-        for ($i = 0; $i < count($items); $i++) {
-            if ($i > 0) {
-                print(' ');
-            }
-            $this->doPrint($items[$i]);
-        }
+        $this->tokenizer = $tokenizer;
+        $this->reader = $reader;
+        $this->eval = $eval;
+        $this->printer = $printer;
     }
 
     public function rep(string $input, Env $env): void
     {
-        $expressions = $this->read($input);
+        $tokens = $this->tokenizer->tokenize($input);
 
-        $results = array_map(fn ($expr) => $this->eval($expr, $env), $expressions);
+        $expressions = $this->reader->read($tokens);
 
-        $this->print($results);
-    }
+        $results = $this->eval->eval($expressions, $env);
 
-    private function doPrint($a): void
-    {
-        if ($a instanceof Closure) {
-            print('<function>');
-        } elseif ($a instanceof MList) {
-            print('(');
-            for ($i = 0; $i < $a->count(); $i++) {
-                if ($i > 0) {
-                    print(' ');
-                }
-                $this->doPrint($a->get($i));
-            }
-            print(')');
-        } elseif ($a instanceof Hash) {
-            print('{');
-            $keys = array_keys($a->getData());
-            for ($i = 0; $i < count($keys); $i++) {
-                if ($i > 0) {
-                    print(' ');
-                }
-                $this->doPrint($keys[$i]);
-                print(':');
-                $this->doPrint($a->get($keys[$i]));
-            }
-            print('}');
-        } elseif ($a instanceof Symbol) {
-            print($a->getName());
-        } elseif ($a === true) {
-            print('true');
-        } elseif ($a === false) {
-            print('false');
-        } elseif ($a === null) {
-            print('null');
-        } elseif (is_string($a)) {
-            print('"' . $a . '"');
-        } else {
-            print($a);
-        }
-    }
-
-    private function readForm(array $tokens, int &$index)
-    {
-        if ($tokens[$index] == '(') {
-            return $this->readList($tokens, $index);
-        } else {
-            return $this->readAtom($tokens, $index);
-        }
-    }
-
-    private function readList(array $tokens, int &$index): MList
-    {
-        $result = [];
-
-        // start tag
-        $index++;
-
-        while ($tokens[$index] != ')') {
-            $result[] = $this->readForm($tokens, $index);
-        }
-
-        // end tag
-        $index++;
-
-        return new MList($result);
-    }
-
-    private function readAtom(array $tokens, int &$index)
-    {
-        $a = $tokens[$index++];
-
-        if ($a === 'true') {
-            return true;
-        } elseif ($a === 'false') {
-            return false;
-        } elseif ($a === 'null') {
-            return null;
-        } elseif (substr($a, 0, 1) === '"') {
-            // string
-            return substr($a, 1, strlen($a) - 2);
-        } elseif (is_numeric($a)) {
-            if (filter_var($a, FILTER_VALIDATE_INT) !== false) {
-                return intval($a);
-            } else {
-                return floatval($a);
-            }
-        } else {
-            return new Symbol($a);
-        }
+        $this->printer->print($results);
     }
 }
diff --git a/src/Printer.php b/src/Printer.php
new file mode 100644
index 0000000..f3d4d0d
--- /dev/null
+++ b/src/Printer.php
@@ -0,0 +1,57 @@
+<?php
+namespace MadLisp;
+
+use Closure;
+
+class Printer
+{
+    public function print(array $items): void
+    {
+        for ($i = 0; $i < count($items); $i++) {
+            if ($i > 0) {
+                print(' ');
+            }
+            $this->doPrint($items[$i]);
+        }
+    }
+
+    private function doPrint($a): void
+    {
+        if ($a instanceof Closure) {
+            print('<function>');
+        } elseif ($a instanceof MList) {
+            print('(');
+            for ($i = 0; $i < $a->count(); $i++) {
+                if ($i > 0) {
+                    print(' ');
+                }
+                $this->doPrint($a->get($i));
+            }
+            print(')');
+        } elseif ($a instanceof Hash) {
+            print('{');
+            $keys = array_keys($a->getData());
+            for ($i = 0; $i < count($keys); $i++) {
+                if ($i > 0) {
+                    print(' ');
+                }
+                $this->doPrint($keys[$i]);
+                print(':');
+                $this->doPrint($a->get($keys[$i]));
+            }
+            print('}');
+        } elseif ($a instanceof Symbol) {
+            print($a->getName());
+        } elseif ($a === true) {
+            print('true');
+        } elseif ($a === false) {
+            print('false');
+        } elseif ($a === null) {
+            print('null');
+        } elseif (is_string($a)) {
+            print('"' . $a . '"');
+        } else {
+            print($a);
+        }
+    }
+}
diff --git a/src/Reader.php b/src/Reader.php
new file mode 100644
index 0000000..98ea869
--- /dev/null
+++ b/src/Reader.php
@@ -0,0 +1,67 @@
+<?php
+namespace MadLisp;
+
+class Reader
+{
+    public function read(array $tokens): array
+    {
+        $result = [];
+        $index = 0;
+
+        while ($index < count($tokens)) {
+            $result[] = $this->readForm($tokens, $index);
+        }
+
+        return $result;
+    }
+
+    private function readForm(array $tokens, int &$index)
+    {
+        if ($tokens[$index] == '(') {
+            return $this->readList($tokens, $index);
+        } else {
+            return $this->readAtom($tokens, $index);
+        }
+    }
+
+    private function readList(array $tokens, int &$index): MList
+    {
+        $result = [];
+
+        // start tag
+        $index++;
+
+        while ($tokens[$index] != ')') {
+            $result[] = $this->readForm($tokens, $index);
+        }
+
+        // end tag
+        $index++;
+
+        return new MList($result);
+    }
+
+    private function readAtom(array $tokens, int &$index)
+    {
+        $a = $tokens[$index++];
+
+        if ($a === 'true') {
+            return true;
+        } elseif ($a === 'false') {
+            return false;
+        } elseif ($a === 'null') {
+            return null;
+        } elseif (substr($a, 0, 1) === '"') {
+            // string
+            return substr($a, 1, strlen($a) - 2);
+        } elseif (is_numeric($a)) {
+            if (filter_var($a, FILTER_VALIDATE_INT) !== false) {
+                return intval($a);
+            } else {
+                return floatval($a);
+            }
+        } else {
+            return new Symbol($a);
+        }
+    }
+}
diff --git a/src/Tokenizer.php b/src/Tokenizer.php
new file mode 100644
index 0000000..1e48127
--- /dev/null
+++ b/src/Tokenizer.php
@@ -0,0 +1,75 @@
+<?php
+namespace MadLisp;
+
+class Tokenizer
+{
+    public function tokenize(string $a): array
+    {
+        $tokens = [];
+        $current = '';
+        $string = false;
+        $parens = 0;
+
+        $addCurrent = function () use (&$tokens, &$current) {
+            if ($current !== '') {
+                $tokens[] = $current;
+                $current = '';
+            }
+        };
+
+        for ($i = 0; $i < strlen($a); $i++) {
+            $c = substr($a, $i, 1);
+
+            if ($string) {
+                // Inside string, add all characters
+                $current .= $c;
+
+                // Stop at "
+                if ($c == '"') {
+                    $addCurrent();
+                    $string = false;
+                }
+            } else {
+                // Not inside string
+
+                if ($c == '"') {
+                    // Start of string
+                    $addCurrent();
+                    $current .= $c;
+                    $string = true;
+                } elseif ($c == ' ' || $c == "\t" || $c == "\n" || $c == "\r") {
+                    // Whitespace is ignored
+                    $addCurrent();
+                } elseif ($c == '(') {
+                    // Start of list
+                    $addCurrent();
+                    $tokens[] = '(';
+                    $parens++;
+                } elseif ($c == ')') {
+                    // End of list
+                    if ($parens == 0) {
+                        throw new MadLispException("unexpected closing parenthesis");
+                    }
+                    $addCurrent();
+                    $tokens[] = ')';
+                    $parens--;
+                } else {
+                    // All other characters
+                    $current .= $c;
+                }
+            }
+        }
+
+        // Add last also
+        $addCurrent();
+
+        // Check for errors
+        if ($parens != 0) {
+            throw new MadLispException("missing closing parenthesis");
+        } elseif ($string) {
+            throw new MadLispException("unterminated string");
+        }
+
+        return $tokens;
+    }
+}