From d46a344b15fde5fabdb0917f321d3169242edc55 Mon Sep 17 00:00:00 2001
From: Jakob Odersky <jodersky@gmail.com>
Date: Mon, 23 Mar 2015 12:01:38 +0100
Subject: generate bindings only when needed

---
 .../com/github/jodersky/mavlink/Generator.scala     | 21 ++++++++++++---------
 .../github/jodersky/mavlink/sbt/SbtMavlink.scala    | 16 ++++++++--------
 project/Build.scala                                 |  2 +-
 3 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/mavlink-library/src/main/scala/com/github/jodersky/mavlink/Generator.scala b/mavlink-library/src/main/scala/com/github/jodersky/mavlink/Generator.scala
index 9b5b447..4f8b207 100644
--- a/mavlink-library/src/main/scala/com/github/jodersky/mavlink/Generator.scala
+++ b/mavlink-library/src/main/scala/com/github/jodersky/mavlink/Generator.scala
@@ -21,18 +21,21 @@ class Generator(dialect: Dialect) {
   }
 
   /**
-   * Generates Scala code implementing MAVLink.
-   * @return a list containing proposed Scala file names pointing to their contents
+   * Represents a generator's target file
+   * @param path the path of the generated file
+   * @param generate contents of the generated file
    */
-  def generate(): List[(String, String)] = {
-    val context = Context(dialect.version)
+  case class Target(path: String, generate: () => String)
 
+  def targets: List[Target] = {
+    val context = Context(dialect.version)
     List(
-      "org/mavlink/Assembler.scala" -> org.mavlink.txt.Assembler(context).body,
-      "org/mavlink/Crc.scala" -> org.mavlink.txt.Crc(context).body,
-      "org/mavlink/Packet.scala" -> org.mavlink.txt.Packet(context, maxPayloadLength, extraCrcs).body,
-      "org/mavlink/Parser.scala" -> org.mavlink.txt.Parser(context).body,
-      "org/mavlink/messages/messages.scala" -> org.mavlink.messages.txt.messages(context, dialect.messages).body
+      Target("org/mavlink/Assembler.scala", () => org.mavlink.txt.Assembler(context).body),
+      Target("org/mavlink/Crc.scala", () => org.mavlink.txt.Crc(context).body),
+      Target("org/mavlink/Packet.scala", () => org.mavlink.txt.Packet(context, maxPayloadLength, extraCrcs).body),
+      Target("org/mavlink/Parser.scala", () => org.mavlink.txt.Parser(context).body),
+      Target("org/mavlink/messages/messages.scala", () => org.mavlink.messages.txt.messages(context, dialect.messages).body)
     )
   }
+
 }
\ No newline at end of file
diff --git a/mavlink-plugin/src/main/scala/com/github/jodersky/mavlink/sbt/SbtMavlink.scala b/mavlink-plugin/src/main/scala/com/github/jodersky/mavlink/sbt/SbtMavlink.scala
index 613538c..e1b044b 100644
--- a/mavlink-plugin/src/main/scala/com/github/jodersky/mavlink/sbt/SbtMavlink.scala
+++ b/mavlink-plugin/src/main/scala/com/github/jodersky/mavlink/sbt/SbtMavlink.scala
@@ -38,20 +38,20 @@ object SbtMavlink extends AutoPlugin {
 
     val dialectDefinition = XML.loadFile(dialectDefinitionFile)
     val dialect = (new Parser(reporter)).parseDialect(dialectDefinition)
-    val pathToSource = (new Generator(dialect)).generate()
+    val targets = (new Generator(dialect)).targets
 
     val outDirectory = mavlinkTarget.value
 
-    streams.value.log.info("Generating mavlink files...")
+    val files = for (tgt <- targets) yield {
+      val file = outDirectory / tgt.path
 
-    val files = for ((path, source) <- pathToSource) yield {
-      val file = outDirectory / path
-      streams.value.log.info("Generating " + file)
-      IO.write(file, source)
+      if (dialectDefinitionFile.lastModified > file.lastModified) {
+        streams.value.log.info("Generating mavlink binding " + file)
+        IO.write(file, tgt.generate())
+      }
       file.getAbsoluteFile
     }
-    
-    streams.value.log.info("Done generating mavlink files")
+
     files
   }
 
diff --git a/project/Build.scala b/project/Build.scala
index 4ab6a80..0f7acc2 100644
--- a/project/Build.scala
+++ b/project/Build.scala
@@ -10,7 +10,7 @@ object ApplicationBuild extends Build {
     scalaVersion := "2.10.4",
     scalacOptions ++= Seq("-feature", "-deprecation"),
     organization := "com.github.jodersky",
-    version := "0.2-SNAPSHOT"
+    version := "0.3-SNAPSHOT"
   ) ++ publishSettings
 
   lazy val root = (
-- 
cgit v1.2.3