feat(spdx-utils): Make simplify() remove redundant choices

Extract flattening to a function and reuse it to either flatten an only choice, or the original expression. Signed-off-by: Sebastian Schuberth <[email protected]>
oss-review-toolkit · Dec 18, 2024 · 8965839 · 8965839
1 parent c208a15
commit 8965839
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Showing 2 changed files with 29 additions and 2 deletions.
diff --git a/utils/spdx/src/main/kotlin/SpdxExpression.kt b/utils/spdx/src/main/kotlin/SpdxExpression.kt
@@ -249,13 +249,13 @@ class SpdxCompoundExpression(
     override fun normalize(mapDeprecated: Boolean) =
         SpdxCompoundExpression(operator, children.map { it.normalize(mapDeprecated) })
 
-    override fun simplify(): SpdxExpression {
+    private fun flatten(): SpdxExpression {
         val flattenedChildren = children.flatMapTo(mutableSetOf()) { child ->
             val simplifiedChild = child.simplify()
 
             if (simplifiedChild is SpdxCompoundExpression && simplifiedChild.operator == operator) {
                 // Inline nested children of the same operator.
-                simplifiedChild.children.map { it.simplify() }
+                simplifiedChild.children.map { if (it is SpdxCompoundExpression) it.flatten() else it }
             } else {
                 setOf(simplifiedChild)
             }
@@ -264,6 +264,12 @@ class SpdxCompoundExpression(
         return flattenedChildren.singleOrNull() ?: SpdxCompoundExpression(operator, flattenedChildren)
     }
 
+    override fun simplify(): SpdxExpression =
+        // Eliminate redundant choices by creating the set of unique choices and using the choice if there is only one.
+        validChoices().singleOrNull()?.let {
+            if (it is SpdxCompoundExpression) it.flatten() else it
+        } ?: flatten()
+
     override fun sorted(): SpdxExpression {
         /**
          * Get all transitive children of this expression that are concatenated with the same operator as this compound

diff --git a/utils/spdx/src/test/kotlin/SpdxCompoundExpressionTest.kt b/utils/spdx/src/test/kotlin/SpdxCompoundExpressionTest.kt
@@ -87,5 +87,26 @@ class SpdxCompoundExpressionTest : WordSpec({
             // Compare string representations to not rely on semantic equality.
             expression.simplify().toString() shouldBe "MIT"
         }
+
+        "remove redundant choices with a nested expression at the beginning" {
+            val expression = "(Apache-2.0 OR MIT) AND MIT AND Apache-2.0 AND Apache-2.0 AND MIT".toSpdx()
+
+            // Compare string representations to not rely on semantic equality.
+            expression.simplify().sorted().toString() shouldBe "Apache-2.0 AND MIT"
+        }
+
+        "remove redundant choices with a nested expression in the middle" {
+            val expression = "Apache-2.0 AND (Apache-2.0 OR MIT) AND MIT AND MIT".toSpdx()
+
+            // Compare string representations to not rely on semantic equality.
+            expression.simplify().sorted().toString() shouldBe "Apache-2.0 AND MIT"
+        }
+
+        "remove redundant choices with a nested expression at the end" {
+            val expression = "MIT AND Apache-2.0 AND Apache-2.0 AND MIT AND (Apache-2.0 OR MIT)".toSpdx()
+
+            // Compare string representations to not rely on semantic equality.
+            expression.simplify().sorted().toString() shouldBe "Apache-2.0 AND MIT"
+        }
     }
 })