Add test-tools module and matchers for content inside of it

1 files changed, 105 insertions, 0 deletions

diff --git a/test-tools/src/main/kotlin/matchers/content/contentMatchers.kt b/test-tools/src/main/kotlin/matchers/content/contentMatchers.kt
new file mode 100644
index 00000000..c4400646
--- /dev/null
+++ b/test-tools/src/main/kotlin/matchers/content/contentMatchers.kt
@@ -0,0 +1,105 @@
+package  org.jetbrains.dokka.test.tools.matchers.content
+
+import org.jetbrains.dokka.pages.ContentComposite
+import org.jetbrains.dokka.pages.ContentNode
+import org.jetbrains.dokka.pages.ContentText
+import kotlin.reflect.KClass
+import kotlin.reflect.full.cast
+
+sealed class MatcherElement
+
+class TextMatcher(val text: String) : MatcherElement()
+
+open class NodeMatcher<T: ContentNode>(
+    val kclass: KClass<T>,
+    val assertions: T.() -> Unit = {}
+): MatcherElement() {
+    open fun tryMatch(node: ContentNode) {
+        assertions(kclass.cast(node))
+    }
+}
+
+class CompositeMatcher<T : ContentComposite>(
+    kclass: KClass<T>,
+    private val children: List<MatcherElement>,
+    assertions: T.() -> Unit = {}
+) : NodeMatcher<T>(kclass, assertions) {
+    private val normalizedChildren: List<MatcherElement> by lazy {
+        children.fold(listOf<MatcherElement>()) { acc, e ->
+            when {
+                acc.lastOrNull() is Anything && e is Anything -> acc
+                acc.lastOrNull() is TextMatcher && e is TextMatcher ->
+                    acc.dropLast(1) + TextMatcher((acc.lastOrNull() as TextMatcher).text + e.text)
+                else -> acc + e
+            }
+        }
+    }
+
+    override fun tryMatch(node: ContentNode) {
+        super.tryMatch(node)
+        kclass.cast(node).children.fold(normalizedChildren.pop()) { acc, n -> acc.next(n) }.finish()
+    }
+}
+
+object Anything : MatcherElement()
+
+private sealed class MatchWalkerState {
+    abstract fun next(node: ContentNode): MatchWalkerState
+    abstract fun finish()
+}
+
+private class TextMatcherState(val text: String, val rest: List<MatcherElement>) : MatchWalkerState() {
+    override fun next(node: ContentNode): MatchWalkerState {
+        node as ContentText
+        return when {
+            text == node.text -> rest.pop()
+            text.startsWith(node.text) -> TextMatcherState(text.removePrefix(node.text), rest)
+            else -> throw AssertionError("Expected text: \"$text\", but found: \"${node.text}\"")
+        }
+    }
+
+    override fun finish() = throw AssertionError("\"$text\" was not found" + rest.messageEnd)
+}
+
+private object EmptyMatcherState : MatchWalkerState() {
+    override fun next(node: ContentNode): MatchWalkerState {
+        throw AssertionError("Unexpected $node")
+    }
+
+    override fun finish() = Unit
+}
+
+private class NodeMatcherState(
+    val matcher: NodeMatcher<*>,
+    val rest: List<MatcherElement>
+) : MatchWalkerState() {
+    override fun next(node: ContentNode): MatchWalkerState {
+        matcher.tryMatch(node)
+        return rest.pop()
+    }
+
+    override fun finish() = throw AssertionError("Composite of type ${matcher.kclass} was not found" + rest.messageEnd)
+}
+
+private class SkippingMatcherState(
+    val innerState: MatchWalkerState
+) : MatchWalkerState() {
+    override fun next(node: ContentNode): MatchWalkerState = runCatching { innerState.next(node) }.getOrElse { this }
+
+    override fun finish() = innerState.finish()
+}
+
+private fun List<MatcherElement>.pop(): MatchWalkerState = when (val head = firstOrNull()) {
+    is TextMatcher -> TextMatcherState(head.text, drop(1))
+    is NodeMatcher<*> -> NodeMatcherState(head, drop(1))
+    is Anything -> SkippingMatcherState(drop(1).pop())
+    null -> EmptyMatcherState
+}
+
+private val List<MatcherElement>.messageEnd: String
+    get() = filter { it !is Anything }
+        .count().takeIf { it > 0 }
+        ?.let { " and $it further matchers were not satisfied" } ?: ""
+
+// Creating this whole mechanism was most scala-like experience I had since I stopped using scala.
+// I don't know how I should feel about it.
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