1 files changed, 58 insertions, 0 deletions
diff --git a/buildSrc/src/main/kotlin/androidx/build/docs/ConcatenateFilesTask.kt b/buildSrc/src/main/kotlin/androidx/build/docs/ConcatenateFilesTask.kt
new file mode 100644
index 00000000000..d97c7019df8
--- /dev/null
+++ b/buildSrc/src/main/kotlin/androidx/build/docs/ConcatenateFilesTask.kt
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package androidx.build.docs
+
+import org.gradle.api.Action
+import org.gradle.api.DefaultTask
+import org.gradle.api.tasks.TaskAction
+import org.gradle.api.tasks.OutputFile
+import java.io.File
+import java.util.SortedMap
+
+open class ConcatenateFilesTask : DefaultTask() {
+    private var keyedInputs: MutableMap<String, File> = mutableMapOf()
+
+    @get:OutputFile
+    lateinit var Output: File
+
+    // Adds the given input file
+    // The order that files are concatenated in is based on sorting the corresponding keys
+    fun addInput(key: String, inputFile: File) {
+        if (this.keyedInputs.containsKey(key)) {
+            throw IllegalArgumentException("Key $key already exists")
+        }
+        this.inputs.file(inputFile)
+        this.keyedInputs[key] = inputFile
+    }
+
+    @TaskAction
+    fun aggregate() {
+        val destFile = this.Output
+
+        // sort the input files to make sure this task always concatenates them in the same order
+        val sortedInputs = this.keyedInputs.toSortedMap()
+
+        val inputFiles = sortedInputs.values
+        if (inputFiles.contains(destFile)) {
+            throw IllegalArgumentException("Output file $destFile is also an input file")
+        }
+
+        val text = inputFiles.joinToString(separator = "") { file -> file.readText() }
+        this.project.logger.info("Joining ${inputFiles.count()} files, and storing the result in ${destFile.path}")
+        destFile.writeText(text)
+    }
+}