From 5d0435110262ec4b0d138b0169998e472a957870 Mon Sep 17 00:00:00 2001
From: Giorgio Garofalo <giogar2705@gmail.com>
Date: Sat, 23 Nov 2024 17:05:08 +0100
Subject: [PATCH] Add `.range` function

---
 .../kotlin/eu/iamgio/quarkdown/stdlib/Math.kt | 22 +++++++++++++++++++
 .../iamgio/quarkdown/test/FullPipelineTest.kt | 12 ++++++++--
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/stdlib/src/main/kotlin/eu/iamgio/quarkdown/stdlib/Math.kt b/stdlib/src/main/kotlin/eu/iamgio/quarkdown/stdlib/Math.kt
index 090e2443..754ff26e 100644
--- a/stdlib/src/main/kotlin/eu/iamgio/quarkdown/stdlib/Math.kt
+++ b/stdlib/src/main/kotlin/eu/iamgio/quarkdown/stdlib/Math.kt
@@ -3,6 +3,8 @@ package eu.iamgio.quarkdown.stdlib
 import eu.iamgio.quarkdown.function.reflect.annotation.Name
 import eu.iamgio.quarkdown.function.value.BooleanValue
 import eu.iamgio.quarkdown.function.value.NumberValue
+import eu.iamgio.quarkdown.function.value.ObjectValue
+import eu.iamgio.quarkdown.function.value.data.Range
 import kotlin.math.PI
 import kotlin.math.pow
 
@@ -22,6 +24,7 @@ val Math: Module =
         ::cos,
         ::tan,
         ::isEven,
+        ::range,
     )
 
 // Basic operations
@@ -105,3 +108,22 @@ fun tan(x: Number) = NumberValue(kotlin.math.tan(x.toFloat()))
  */
 @Name("iseven")
 fun isEven(x: Number) = BooleanValue(x.toInt() % 2 == 0)
+
+/**
+ * Creates a range of numbers, which can also be iterated through.
+ * The behavior of an open range is delegated to the consumer.
+ * For instance, using a left-open range with [forEach] will make the loop start from 1.
+ * The difference between this function and the built-in `..` operator is that the latter
+ * does not allow for dynamic evaluation, hence both ends must be literals.
+ * This function allows evaluating ends dynamically: for instance, `.range from:{1} to:{.sum {1} {2}}`.
+ * Floating-point numbers are truncated to integers.
+ * @property start start of the range (inclusive). If `null`, the range is infinite on the left end
+ * @property end end of the range (inclusive). If `null`, the range is infinite on the right end. [end] > [start]
+ */
+fun range(
+    @Name("from") start: Number? = null,
+    @Name("to") end: Number? = null,
+): ObjectValue<Range> =
+    ObjectValue(
+        Range(start?.toInt(), end?.toInt()),
+    )
diff --git a/test/src/test/kotlin/eu/iamgio/quarkdown/test/FullPipelineTest.kt b/test/src/test/kotlin/eu/iamgio/quarkdown/test/FullPipelineTest.kt
index c569908c..1306e273 100644
--- a/test/src/test/kotlin/eu/iamgio/quarkdown/test/FullPipelineTest.kt
+++ b/test/src/test/kotlin/eu/iamgio/quarkdown/test/FullPipelineTest.kt
@@ -610,6 +610,14 @@ class FullPipelineTest {
             assertEquals("<p><strong>N:</strong> 1</p><p><strong>N:</strong> 2</p><p><strong>N:</strong> 3</p>", it)
         }
 
+        execute(".foreach {2..4}\n  **N:** .1") {
+            assertEquals("<p><strong>N:</strong> 2</p><p><strong>N:</strong> 3</p><p><strong>N:</strong> 4</p>", it)
+        }
+
+        execute(".foreach {.range from:{2} to:{4}}\n  **N:** .1") {
+            assertEquals("<p><strong>N:</strong> 2</p><p><strong>N:</strong> 3</p><p><strong>N:</strong> 4</p>", it)
+        }
+
         execute(
             """
             ## Title
@@ -623,7 +631,7 @@ class FullPipelineTest {
 
         execute(
             """
-            .foreach {..2}
+            .foreach {.range to:{.sum {1} {1}}}
                 ## Hello .1
                 .foreach {..1}
                     **Hi**!
@@ -646,7 +654,7 @@ class FullPipelineTest {
         execute(
             """
             .foreach {..2}
-                .foreach {..2}
+                .foreach {.range to:{2}}
                     .foreach {..2}
                         ## Title 2
                     # Title 1