From 239c68f5ea2a094b6ab2eeb613999b2eb3d7bb49 Mon Sep 17 00:00:00 2001
From: Jack Cherng <jfcherng@gmail.com>
Date: Tue, 5 Mar 2024 16:30:48 +0800
Subject: [PATCH] feat: add new differ option: fullContextIfIdentical (#79)

Signed-off-by: Jack Cherng <jfcherng@gmail.com>
---
 README.md                         |  2 ++
 example/demo_base.php             |  2 ++
 src/Differ.php                    | 20 ++++++++++++++++++++
 src/Renderer/AbstractRenderer.php |  2 +-
 tests/Renderer/RendererTest.php   | 30 ++++++++++++++++++++++++++++++
 5 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 380c8936..b742a320 100644
--- a/README.md
+++ b/README.md
@@ -84,6 +84,8 @@ $differOptions = [
     'ignoreWhitespace' => false,
     // if the input sequence is too long, it will just gives up (especially for char-level diff)
     'lengthLimit' => 2000,
+    // if truthy, when inputs are identical, the whole inputs will be rendered in the output
+    'fullContextIfIdentical' => false,
 ];
 
 // the renderer class options
diff --git a/example/demo_base.php b/example/demo_base.php
index 3873df95..97170d22 100644
--- a/example/demo_base.php
+++ b/example/demo_base.php
@@ -24,6 +24,8 @@
     'ignoreWhitespace' => false,
     // if the input sequence is too long, it will just gives up (especially for char-level diff)
     'lengthLimit' => 2000,
+    // if truthy, when inputs are identical, the whole inputs will be rendered in the output
+    'fullContextIfIdentical' => false,
 ];
 
 // options for renderer class
diff --git a/src/Differ.php b/src/Differ.php
index 776d005f..54fddeba 100644
--- a/src/Differ.php
+++ b/src/Differ.php
@@ -119,6 +119,8 @@ final class Differ
         'ignoreWhitespace' => false,
         // if the input sequence is too long, it will just gives up (especially for char-level diff)
         'lengthLimit' => 2000,
+        // if truthy, when inputs are identical, the whole inputs will be rendered in the output
+        'fullContextIfIdentical' => false,
     ];
 
     /**
@@ -318,6 +320,15 @@ public function getGroupedOpcodes(): array
 
         $old = $this->old;
         $new = $this->new;
+
+        if ($this->oldNewComparison === 0 && $this->options['fullContextIfIdentical']) {
+            return [
+                [
+                    [SequenceMatcher::OP_EQ, 0, \count($old), 0, \count($new)],
+                ],
+            ];
+        }
+
         $this->getGroupedOpcodesPre($old, $new);
 
         $opcodes = $this->sequenceMatcher
@@ -344,6 +355,15 @@ public function getGroupedOpcodesGnu(): array
 
         $old = $this->old;
         $new = $this->new;
+
+        if ($this->oldNewComparison === 0 && $this->options['fullContextIfIdentical']) {
+            return [
+                [
+                    [SequenceMatcher::OP_EQ, 0, \count($old), 0, \count($new)],
+                ],
+            ];
+        }
+
         $this->getGroupedOpcodesGnuPre($old, $new);
 
         $opcodes = $this->sequenceMatcher
diff --git a/src/Renderer/AbstractRenderer.php b/src/Renderer/AbstractRenderer.php
index 992db662..d9e3ec42 100644
--- a/src/Renderer/AbstractRenderer.php
+++ b/src/Renderer/AbstractRenderer.php
@@ -183,7 +183,7 @@ final public function render(Differ $differ): string
     {
         $this->changesAreRaw = true;
         // the "no difference" situation may happen frequently
-        return $differ->getOldNewComparison() === 0
+        return $differ->getOldNewComparison() === 0 && !$differ->options['fullContextIfIdentical']
             ? $this->getResultForIdenticals()
             : $this->renderWorker($differ);
     }
diff --git a/tests/Renderer/RendererTest.php b/tests/Renderer/RendererTest.php
index 86af9cf3..e6f4dd6b 100644
--- a/tests/Renderer/RendererTest.php
+++ b/tests/Renderer/RendererTest.php
@@ -47,6 +47,36 @@ public function testSetOptionsWithLanguageArray(): void
         );
     }
 
+    /**
+     * Test the AbstractRenderer::setOptions with result for identicals.
+     *
+     * @covers \Jfcherng\Diff\Renderer\AbstractRenderer::setOptions
+     */
+    public function testSetOptionsWithFullContextIfIdentical(): void
+    {
+        $diffResult = DiffHelper::calculate(
+            "the 1st line\nthe 2nd line\nthe 3rd line",
+            "the 1st line\nthe 2nd line\nthe 3rd line",
+            'Unified',
+            ['fullContextIfIdentical' => true],
+            []
+        );
+
+        self::assertSame(
+            <<<'DIFF'
+@@ -1,3 +1,3 @@
+ the 1st line
+ the 2nd line
+ the 3rd line
+\ No newline at end of file
+
+DIFF
+            ,
+            $diffResult,
+            'Differ options: "fullContextIfIdentical" should work.'
+        );
+    }
+
     /**
      * Test the AbstractRenderer::setOptions with result for identicals.
      *