Pretty printer

Implement pretty printer and a test to confirm basics are working

.phpunit.result.cache

@@ -1 +1 @@
-{"version":1,"defects":[],"times":{"Tests\\ScannerTest::it_expects_single_token_when_source_is_empty":0.005}}
+{"version":1,"defects":{"Tests\\AstPrinterTest::it_expects_to_pretty_print_tree":7},"times":{"Tests\\ScannerTest::it_expects_single_token_when_source_is_empty":0.005,"Tests\\AstPrinterTest::it_expects_to_pretty_print_tree":0.03,"Tests\\AstPrinterTest::it_expects_missing_parenthesis_and_additional_space_not_to_match":0.004,"Tests\\AstPrinterTest::it_expects_the_printed_expression_to_match_exactly":0.002}}

src/AstPrinter.php

@@ -0,0 +1,112 @@
+<?php
+
+namespace Waffle;
+
+use Waffle\Grammar\Expr;
+use Waffle\Grammar\Expressions\Assign;
+use Waffle\Grammar\Expressions\Binary;
+use Waffle\Grammar\Expressions\Call;
+use Waffle\Grammar\Expressions\EThis;
+use Waffle\Grammar\Expressions\Get;
+use Waffle\Grammar\Expressions\Grouping;
+use Waffle\Grammar\Expressions\Literal;
+use Waffle\Grammar\Expressions\Logical;
+use Waffle\Grammar\Expressions\Set;
+use Waffle\Grammar\Expressions\Super;
+use Waffle\Grammar\Expressions\Unary;
+use Waffle\Grammar\Expressions\Variable;
+
+class AstPrinter implements Grammar\Expressions\Visitor
+{
+ public function printExpr(Expr $expr): string
+ {
+ return $expr->accept($this);
+ }
+
+ public function visitAssignExpr(Assign $expr)
+ {
+ // TODO: Implement visitAssignExpr() method.
+ }
+
+ public function visitBinaryExpr(Binary $expr)
+ {
+ return $this->parenthesize(
+ $expr->operator->lexeme,
+ $expr->left,
+ $expr->right
+ );
+ }
+
+ public function visitCallExpr(Call $expr)
+ {
+ // TODO: Implement visitCallExpr() method.
+ }
+
+ public function visitGetExpr(Get $expr)
+ {
+ // TODO: Implement visitGetExpr() method.
+ }
+
+ public function visitGroupingExpr(Grouping $expr)
+ {
+ return $this->parenthesize(
+ "group",
+ $expr->expression
+ );
+ }
+
+ public function visitLiteralExpr(Literal $expr)
+ {
+ if (is_null($expr->value)) {
+ return "nil";
+ }
+ return (string)$expr->value;
+ }
+
+ public function visitLogicalExpr(Logical $expr)
+ {
+ // TODO: Implement visitLogicalExpr() method.
+ }
+
+ public function visitSetExpr(Set $expr)
+ {
+ // TODO: Implement visitSetExpr() method.
+ }
+
+ public function visitSuperExpr(Super $expr)
+ {
+ // TODO: Implement visitSuperExpr() method.
+ }
+
+ public function visitThisExpr(EThis $expr)
+ {
+ // TODO: Implement visitThisExpr() method.
+ }
+
+ public function visitUnaryExpr(Unary $expr)
+ {
+ return $this->parenthesize(
+ $expr->operator->lexeme,
+ $expr->right
+ );
+ }
+
+ public function visitVariableExpr(Variable $variable)
+ {
+ // TODO: Implement visitVariableExpr() method.
+ }
+
+ private function parenthesize(string $name, Expr...$exprs): string
+ {
+ $parts = [];
+ $parts[] = "(";
+ $parts[] = $name;
+ foreach ($exprs as $expr) {
+ $parts[] = " ";
+ $parts[] = $expr->accept($this);
+ }
+ $parts[] = ")";
+
+ return implode($parts);
+ }
+}

src/Grammar/Expressions/Binary.php

@@ -3,13 +3,14 @@
 namespace Waffle\Grammar\Expressions;
 
 use Waffle\Grammar\Expr;
+use Waffle\Token;
 
 class Binary extends Expr
 {
  public function __construct(
- private readonly Expr $left,
- private readonly Token $operator,
- private readonly Expr $right
+ public readonly Expr $left,
+ public readonly Token $operator,
+ public readonly Expr $right
  ) {
  }
 

src/Grammar/Expressions/This.php → src/Grammar/Expressions/EThis.php

@@ -5,7 +5,7 @@
 use Waffle\Grammar\Expr;
 use Waffle\Token;
 
-class This extends Expr
+class EThis extends Expr
 {
  public function __construct(
  private readonly Token $keyword

src/Grammar/Expressions/Grouping.php

@@ -7,7 +7,7 @@
 class Grouping extends Expr
 {
  public function __construct(
- private readonly Expr $grouping
+ public readonly Expr $expression
  ) {
  }
 

src/Grammar/Expressions/Literal.php

@@ -7,7 +7,7 @@
 class Literal extends Expr
 {
  public function __construct(
- private readonly mixed $value
+ public readonly mixed $value
  ) {
  }
 

src/Grammar/Expressions/Unary.php

@@ -8,8 +8,8 @@
 class Unary extends Expr
 {
  public function __construct(
- private readonly Token $operator,
- private readonly Expr $right
+ public readonly Token $operator,
+ public readonly Expr $right
  ) {
  }
 

src/Grammar/Expressions/Visitor.php

@@ -22,7 +22,7 @@ public function visitSetExpr(Set $expr);
 
  public function visitSuperExpr(Super $expr);
 
- public function visitThisExpr(This $expr);
+ public function visitThisExpr(EThis $expr);
 
  public function visitUnaryExpr(Unary $expr);
 

src/Token.php

@@ -8,11 +8,10 @@ class Token implements Stringable
 {
  public function __construct(
  private TokenType $type,
- private string $lexeme,
+ public readonly string $lexeme,
  private mixed $literal,
  private int $line
- )
- {
+ ) {
  }
 
  public function __toString(): string

tests/AstPrinterTest.php

@@ -0,0 +1,52 @@
+<?php
+
+namespace Tests;
+
+use PHPUnit\Framework\TestCase;
+use Waffle\AstPrinter;
+use Waffle\Grammar\Expr;
+use Waffle\Grammar\Expressions\Binary;
+use Waffle\Grammar\Expressions\Grouping;
+use Waffle\Grammar\Expressions\Literal;
+use Waffle\Grammar\Expressions\Unary;
+use Waffle\Token;
+use Waffle\TokenType;
+
+class AstPrinterTest extends TestCase
+{
+ private AstPrinter $printer;
+ private Expr $expr;
+
+ protected function setUp(): void
+ {
+ $this->printer = new AstPrinter();
+ $this->expr = new Binary(
+ new Unary(
+ new Token(TokenType::MINUS, "-", null, 1),
+ new Literal(123)
+ ),
+ new Token(TokenType::STAR, "*", null, 1),
+ new Grouping(
+ new Literal(45.67)
+ )
+ );
+ }
+
+ /** @test */
+ public function it_expects_missing_parenthesis_and_additional_space_not_to_match(): void
+ {
+ $this->assertNotEquals(
+ "* (- 123) (group 45.67) )",
+ $this->printer->printExpr($this->expr)
+ );
+ }
+
+ /** @test */
+ public function it_expects_the_printed_expression_to_match_exactly(): void
+ {
+ $this->assertEquals(
+ "(* (- 123) (group 45.67))",
+ $this->printer->printExpr($this->expr)
+ );
+ }
+}