Fix filtering

api/src/main/kotlin/io/spine/protodata/plugin/Plugin.kt

@@ -157,7 +157,9 @@ public fun Plugin.render(
     renderers().forEach { r ->
         r.registerWith(codegenContext)
         r.withTypeConventions(conventionSet)
-        sources.forEach(r::renderSources)
+        sources.asSequence()
+            .filter { r.supports(it.label) }
+            .forEach { r.renderSources(it) }
     }
 }
 

api/src/main/kotlin/io/spine/protodata/renderer/Renderer.kt

@@ -34,6 +34,7 @@ import io.spine.protodata.type.TypeNameElement
 import io.spine.server.BoundedContext
 import io.spine.server.ContextAware
 import io.spine.server.query.QueryingClient
+import io.spine.tools.code.AnyLanguage
 import io.spine.tools.code.Language
 
 /**
@@ -61,11 +62,23 @@ protected constructor(
         sources.mergeBack(relevantFiles)
     }
 
+    /**
+     * Checks if this renderer supports a given source file set.
+     *
+     * By default, a renderer supports all source sets of the [supportedLanguage]. A renderer that
+     * supports [AnyLanguage] also supports any source file set.
+     *
+     * Note that, even if a source file set is supported, the renderer will still only receive
+     * a portion of it with the file that match the [language filter][Language.matches].
+     */
+    public open fun supports(label: SourceFileSetLabel): Boolean =
+        supportedLanguage == AnyLanguage || supportedLanguage == label.language
+
     /**
      * Makes changes to the given source set.
      *
-     * The source set is guaranteed to consist only of the files, containing the code in
-     * the [supportedLanguage].
+     * The source set is guaranteed to be [supported][supports] and to consist only of the files
+     * containing the code in the [supportedLanguage].
      *
      * This method may be called several times, if ProtoData is called with multiple source and
      * target directories.

api/src/main/kotlin/io/spine/protodata/renderer/SourceFile.kt

@@ -69,9 +69,7 @@ private constructor(
     /**
      * The FS path to the file relative to the source root.
      */
-    public val relativePath: Path,
-
-    private var changed: Boolean = false
+    public val relativePath: Path
 ) {
 
     private lateinit var sources: SourceFileSet
@@ -109,7 +107,7 @@ private constructor(
          *         the source code.
          */
         internal fun fromCode(relativePath: Path, code: String): SourceFile =
-            SourceFile(code, relativePath, changed = true)
+            SourceFile(code, relativePath)
     }
 
     /**
@@ -178,7 +176,6 @@ private constructor(
      */
     public fun overwrite(newCode: String) {
         this.code = newCode
-        this.changed = true
     }
 
     /**
@@ -215,15 +212,12 @@ private constructor(
     internal fun write(
         baseDir: Path,
         charset: Charset = Charsets.UTF_8,
-        forceWrite: Boolean = false
     ) {
-        if (changed || forceWrite) {
-            val targetPath = baseDir / relativePath
-            targetPath.toFile()
-                .parentFile
-                .mkdirs()
-            targetPath.writeText(code, charset, WRITE, TRUNCATE_EXISTING, CREATE)
-        }
+        val targetPath = baseDir / relativePath
+        targetPath.toFile()
+            .parentFile
+            .mkdirs()
+        targetPath.writeText(code, charset, WRITE, TRUNCATE_EXISTING, CREATE)
     }
 
     /**

api/src/main/kotlin/io/spine/protodata/renderer/SourceFileSet.kt

@@ -29,6 +29,7 @@ package io.spine.protodata.renderer
 import com.google.common.collect.ImmutableSet.toImmutableSet
 import io.spine.annotation.Internal
 import io.spine.protodata.TypeName
+import io.spine.protodata.renderer.SourceFileSet.Companion.create
 import io.spine.protodata.type.TypeConvention
 import io.spine.protodata.type.TypeNameElement
 import io.spine.server.query.Querying
@@ -39,7 +40,6 @@ import java.nio.charset.Charset
 import java.nio.file.Files.walk
 import java.nio.file.Path
 import java.util.*
-import kotlin.DeprecationLevel.ERROR
 import kotlin.io.path.absolutePathString
 import kotlin.io.path.exists
 import kotlin.io.path.isRegularFile
@@ -68,6 +68,8 @@ import kotlin.text.Charsets.UTF_8
 @Suppress("TooManyFunctions") // All part of the public API.
 public class SourceFileSet
 internal constructor(
+    public val label: SourceFileSetLabel,
+
     files: Set<SourceFile>,
 
     /**
@@ -79,7 +81,7 @@ internal constructor(
      * @see outputRoot
      */
     @get:JvmName("inputRoot")
-    public val inputRoot: Path,
+    public val inputRoot: Path?,
 
     /**
      * A directory where the source set should be placed after code generation.
@@ -97,8 +99,9 @@ internal constructor(
     internal lateinit var querying: Querying
 
     init {
-        require(inputRoot.absolutePathString() != outputRoot.absolutePathString()) {
-            "Input and output roots cannot be the same, but was '${inputRoot.absolutePathString()}'"
+        require(inputRoot?.absolutePathString() != outputRoot.absolutePathString()) {
+            "Input and output roots cannot be the same, " +
+                    "but was '${inputRoot!!.absolutePathString()}'"
         }
         val map = HashMap<Path, SourceFile>(files.size)
         this.files = files.associateByTo(map) { it.relativePath }
@@ -108,14 +111,6 @@ internal constructor(
     @Internal
     public companion object {
 
-        @Deprecated(
-            "Use `create(..)` instead.",
-            replaceWith = ReplaceWith("create"),
-            level = ERROR
-        )
-        public fun from(inputRoot: Path, outputRoot: Path): SourceFileSet =
-            create(inputRoot, outputRoot)
-
         /**
          * Collects a source set from the given [input][inputRoot], assigning
          * the [output][outputRoot].
@@ -128,27 +123,29 @@ internal constructor(
          *         If different from the `sourceRoot`, the files in `sourceRoot`
          *         will not be changed.
          */
-        public fun create(inputRoot: Path, outputRoot: Path): SourceFileSet {
+        public fun create(
+            label: SourceFileSetLabel,
+            inputRoot: Path,
+            outputRoot: Path
+        ): SourceFileSet {
             val source = inputRoot.canonical()
             val target = outputRoot.canonical()
-            if (source != target) {
-                checkTarget(target)
-            }
+            checkTarget(target)
             val files = walk(source)
                 .filter { it.isRegularFile() }
                 .map { SourceFile.read(source.relativize(it), source) }
                 .collect(toImmutableSet())
-            return SourceFileSet(files, source, target)
+            return SourceFileSet(label, files, source, target)
         }
 
         /**
          * Creates an empty source set which can be appended with new files and
          * written to the given target directory.
          */
-        public fun empty(target: Path): SourceFileSet {
+        public fun empty(label: SourceFileSetLabel, target: Path): SourceFileSet {
             checkTarget(target)
             val files = setOf<SourceFile>()
-            return SourceFileSet(files, target, target)
+            return SourceFileSet(label, files, null, target)
         }
     }
 
@@ -249,9 +246,8 @@ internal constructor(
             it.rm(rootDir = outputRoot)
         }
         outputRoot.toFile().mkdirs()
-        val forceWriteFiles = inputRoot != outputRoot
         files.values.forEach {
-            it.write(outputRoot, charset, forceWriteFiles)
+            it.write(outputRoot, charset)
         }
     }
 
@@ -301,7 +297,7 @@ internal constructor(
  * matching the given [predicate].
  */
 internal fun SourceFileSet.subsetWhere(predicate: (SourceFile) -> Boolean) =
-    SourceFileSet(this.filter(predicate).toSet(), inputRoot, outputRoot)
+    SourceFileSet(this.label, this.filter(predicate).toSet(), inputRoot, outputRoot)
 
 /**
  * Obtains absolute [normalized][normalize] version of this path.

api/src/main/kotlin/io/spine/protodata/renderer/SourceFileSetLabel.kt

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2023, TeamDev. All rights reserved.
+ *
+ * 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
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.protodata.renderer
+
+import io.spine.tools.code.Language
+
+/**
+ * A label for a source file set.
+ *
+ * The label consists of the programming language that the files use and the name of the code
+ * generator that created the files.
+ *
+ * A label signifies the type of code structures found in the source files. This helps renderers
+ * that process those sources to know what to expect from the source file set before ever checking
+ * the contents of the files themselves.
+ */
+public data class SourceFileSetLabel(
+    public val language: Language,
+    public val generator: SourceGeneratorName = DefaultGenerator
+) {
+
+    /**
+     * Creates a new `SourceFileSetLabel` with the given language and a custom generator name.
+     */
+    public constructor(language: Language, generatorName: String)
+            : this(language, CustomGenerator(generatorName))
+
+    override fun toString(): String =
+        "${language.name}(${generator.name})"
+}

api/src/main/kotlin/io/spine/protodata/renderer/SourceGeneratorName.kt

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2023, TeamDev. All rights reserved.
+ *
+ * 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
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.protodata.renderer
+
+/**
+ * A name of a source code generator.
+ *
+ * This can be a `protoc` plugin or builtin, or a custom code generator tool.
+ */
+public sealed interface SourceGeneratorName {
+
+    public val name: String
+        get() = javaClass.simpleName.lowercase()
+}
+
+/**
+ * The default generator is the default way for the Protobuf compiler to generate source code for
+ * a given language.
+ *
+ * For example, in Java, the default generator, given a message `Foo`, would generate a message
+ * classes and auxiliary types, such as classes `Foo`, `Foo.Builder`, `Foo.Parser`,
+ * and the interface `FooOrBuilder`.
+ *
+ * Most ProtoData plugins will likely work with code generated by the default generator.
+ *
+ * Since the Protobuf compiler does not support all the existing programming languages,
+ * the `DefaultGenerator` is only defined for those languages that are supported, such as Java, JS,
+ * C++, etc. For other languages, as well as for other code generation scenarios,
+ * see [CustomGenerator].
+ */
+public object DefaultGenerator : SourceGeneratorName
+
+/**
+ * A name of a custom source code generator.
+ *
+ * May represent a Protobuf compiler plugin, or any other code generator.
+ *
+ * Conventionally, the name of the generator should coincide with the name of the directory where
+ * the generated files are placed. Users should follow this convention where possible, yet diverge
+ * when necessary. For example, Java gRPC stubs should be marked with the `grpc` name. However,
+ * files generated for Dart should be marked with the name `dart`, not `lib`.
+ */
+public class CustomGenerator(
+    override val name: String
+) : SourceGeneratorName

api/src/test/kotlin/io/spine/protodata/renderer/SourceFileSetSpec.kt

@@ -31,6 +31,7 @@ import io.kotest.matchers.shouldBe
 import io.kotest.matchers.shouldNotBe
 import io.spine.protodata.renderer.given.PlainTextConvention
 import io.spine.protodata.typeName
+import io.spine.tools.code.AnyLanguage
 import java.nio.file.Path
 import kotlin.io.path.Path
 import kotlin.io.path.div
@@ -62,7 +63,7 @@ class SourceFileSetSpec {
                 textFile.writeText("this is a non-empty file")
             }
         }
-        set = SourceFileSet.create(input, output)
+        set = SourceFileSet.create(SourceFileSetLabel(AnyLanguage), input, output)
     }
 
     @Test