Add RGB(A) color decoding

core/src/main/kotlin/eu/iamgio/quarkdown/function/value/ValueFactory.kt

@@ -19,8 +19,6 @@ import eu.iamgio.quarkdown.function.value.data.Lambda
 import eu.iamgio.quarkdown.function.value.data.Range
 import eu.iamgio.quarkdown.lexer.Lexer
 import eu.iamgio.quarkdown.misc.color.Color
-import eu.iamgio.quarkdown.misc.color.decoder.ColorNameDecoder
-import eu.iamgio.quarkdown.misc.color.decoder.HexColorDecoder
 import eu.iamgio.quarkdown.misc.color.decoder.decode
 import eu.iamgio.quarkdown.pipeline.error.UnattachedPipelineException
 import eu.iamgio.quarkdown.util.iterator
@@ -158,15 +156,7 @@ object ValueFactory {
      */
     @FromDynamicType(Color::class)
     fun color(raw: String): ObjectValue<Color> {
-        val decoders =
-            arrayOf(
-                // #FF0000
-                HexColorDecoder,
-                // red
-                ColorNameDecoder,
-            )
-
-        return Color.decode(raw, *decoders)?.let(::ObjectValue)
+        return Color.decode(raw)?.let(::ObjectValue)
             ?: throw IllegalArgumentException("Invalid color: $raw")
     }
 

core/src/main/kotlin/eu/iamgio/quarkdown/misc/color/Color.kt

@@ -21,5 +21,8 @@ data class Color(
     /**
      * @see eu.iamgio.quarkdown.misc.color.decoder.decode
      */
-    companion object
+    companion object {
+        const val MAX_RGB = 255
+        const val MAX_ALPHA = 1.0
+    }
 }

core/src/main/kotlin/eu/iamgio/quarkdown/misc/color/decoder/ColorDecoder.kt

@@ -5,7 +5,7 @@ import eu.iamgio.quarkdown.misc.color.Color
 /**
  * A strategy to decode a [Color] from a raw string.
  */
-interface ColorDecoder {
+sealed interface ColorDecoder {
     /**
      * Decodes a [Color] from a raw string.
      * @param raw raw string
@@ -17,10 +17,10 @@ interface ColorDecoder {
 /**
  * Decodes a [Color] from a raw string using the first decoder that successfully decodes it.
  * @param raw raw string
- * @param decoders ordered list of decoders
+ * @param decoders ordered list of decoders. Defaults to all decoders.
  * @return a successfully decoded [Color], or `null` if no decoder can decode it
  */
 fun Color.Companion.decode(
     raw: String,
-    vararg decoders: ColorDecoder,
+    vararg decoders: ColorDecoder = arrayOf(HexColorDecoder, RgbColorDecoder, RgbaColorDecoder, ColorNameDecoder),
 ): Color? = decoders.firstNotNullOfOrNull { it.decode(raw) }

core/src/main/kotlin/eu/iamgio/quarkdown/misc/color/decoder/RgbaColorDecoder.kt

@@ -0,0 +1,50 @@
+package eu.iamgio.quarkdown.misc.color.decoder
+
+import eu.iamgio.quarkdown.misc.color.Color
+
+/**
+ * Given a regex match result, extracts RGB components from it.
+ * @return a list of red, green and blue components. Any can be `null` if the component is invalid.
+ */
+private fun extractRGBComponents(match: MatchResult): List<Int?> =
+    match.destructured.toList().map { component ->
+        component.toIntOrNull()?.takeIf { it <= Color.MAX_RGB }
+    }
+
+/**
+ * Decodes a [Color] from an RGB string (e.g. `rgb(255, 100, 25)`).
+ */
+object RgbColorDecoder : ColorDecoder {
+    override fun decode(raw: String): Color? {
+        if (!raw.startsWith("rgb(")) return null
+
+        val match = Regex("rgb\\((\\d{1,3}), ?(\\d{1,3}), ?(\\d{1,3})\\)").find(raw) ?: return null
+        val (r, g, b) = extractRGBComponents(match)
+
+        return if (r != null && g != null && b != null) {
+            Color(r, g, b)
+        } else {
+            null
+        }
+    }
+}
+
+/**
+ * Decodes a [Color] from an RGBA string (e.g. `rgba(255, 100, 25, 0.5)`).
+ */
+object RgbaColorDecoder : ColorDecoder {
+    override fun decode(raw: String): Color? {
+        if (!raw.startsWith("rgba(")) return null
+
+        val match = Regex("rgba\\((\\d{1,3}), ?(\\d{1,3}), ?(\\d{1,3}), ?([0-9.]+)\\)").find(raw) ?: return null
+        val (r, g, b) = extractRGBComponents(match)
+
+        val a = match.destructured.component4().toDoubleOrNull()?.takeIf { it <= Color.MAX_ALPHA }
+
+        return if (r != null && g != null && b != null && a != null) {
+            Color(r, g, b, a)
+        } else {
+            null
+        }
+    }
+}

core/src/main/kotlin/eu/iamgio/quarkdown/parser/InlineTokenParser.kt

@@ -42,6 +42,8 @@ import eu.iamgio.quarkdown.lexer.tokens.TextSymbolToken
 import eu.iamgio.quarkdown.lexer.tokens.UrlAutolinkToken
 import eu.iamgio.quarkdown.misc.color.Color
 import eu.iamgio.quarkdown.misc.color.decoder.HexColorDecoder
+import eu.iamgio.quarkdown.misc.color.decoder.RgbColorDecoder
+import eu.iamgio.quarkdown.misc.color.decoder.RgbaColorDecoder
 import eu.iamgio.quarkdown.misc.color.decoder.decode
 import eu.iamgio.quarkdown.util.iterator
 import eu.iamgio.quarkdown.util.nextOrNull
@@ -225,8 +227,8 @@ class InlineTokenParser(private val context: MutableContext) : InlineTokenVisito
         // Additional content brought by the code span.
         // If null, no additional content is present.
         val content: CodeSpan.ContentInfo? =
-            // Color decoding.
-            Color.decode(text, HexColorDecoder)?.let(CodeSpan::ColorContent)
+            // Color decoding. Named colors are disabled due to performance reasons.
+            Color.decode(text, HexColorDecoder, RgbColorDecoder, RgbaColorDecoder)?.let(CodeSpan::ColorContent)
 
         return CodeSpan(text, content)
     }

core/src/test/kotlin/eu/iamgio/quarkdown/ValueFactoryTest.kt

@@ -117,8 +117,14 @@ class ValueFactoryTest {
         assertEquals(Color(0, 0, 0), ValueFactory.color("#000000").unwrappedValue)
         assertEquals(Color(0, 0, 0), ValueFactory.color("BLACK").unwrappedValue)
         assertEquals(Color(145, 168, 50), ValueFactory.color("#91a832").unwrappedValue)
+        assertEquals(Color(145, 168, 50), ValueFactory.color("rgb(145, 168, 50)").unwrappedValue)
+        assertEquals(Color(120, 111, 93), ValueFactory.color("rgb(120,111,93)").unwrappedValue)
+        assertEquals(Color(120, 111, 93, 0.5), ValueFactory.color("rgba(120, 111, 93, 0.5)").unwrappedValue)
         assertFails { ValueFactory.color("abc") }
         assertFails { ValueFactory.color("#hello") }
+        assertFails { ValueFactory.color("rgb(300, 200, 200)") }
+        assertFails { ValueFactory.color("rgb(300, 200, 200, 0.8)") }
+        assertFails { ValueFactory.color("rgba(100, 200, 200, 1.5)") }
     }
 
     @Test

test/src/test/kotlin/eu/iamgio/quarkdown/test/FullPipelineTest.kt

@@ -312,6 +312,19 @@ class FullPipelineTest {
             assertFalse(attributes.hasCode)
         }
 
+        execute("`rgba(200, 100, 50, 0.5)`") {
+            assertEquals(
+                "<p>" +
+                    "<span class=\"codespan-content\">" +
+                    "<code>rgba(200, 100, 50, 0.5)</code>" +
+                    "<span style=\"background-color: rgba(200, 100, 50, 0.5);\" class=\"color-preview\"></span>" +
+                    "</span>" +
+                    "</p>",
+                it,
+            )
+            assertFalse(attributes.hasCode)
+        }
+
         execute("```\nprintln(\"Hello, world!\")\n```") {
             assertEquals("<pre><code>println(&quot;Hello, world!&quot;)</code></pre>", it)
             assertTrue(attributes.hasCode)