Progress with macros

A short recap:
* Macro expansion now works finely for instance macro invocations
* Macros are now hidden behind -Xmacros
* Bodies of macros now have "import _context._" in their preamble
* Macros are now loaded from classpath, much like regular libraries
* Macros can now override methods (in that case macro expansion
  does not crash if macro is not found, it just falls back to super)

Review by @odersky.

9 files changed, 316 insertions, 1 deletions

diff --git a/test/files/macros/Printf.scala b/test/files/macros/Printf.scala
new file mode 100644
index 0000000000..4a88e5b069
--- /dev/null
+++ b/test/files/macros/Printf.scala
@@ -0,0 +1,39 @@
+// macros should be built separately from their clients, so simple "scalac Printf.scala Test.scala" won't work
+// 1) first build this file with "scalac -Xmacros Printf.scala"
+// 2) the build the test with "scalac -cp <output directory of compiling Printf.scala> Test.scala"
+
+object Printf extends App {
+  def macro printf(format: String, params: Any*) : String = {
+    var i = 0
+    def gensym(name: String) = { i += 1; newTermName(name + i) }
+
+    def createTempValDef(value: Tree, clazz: Class[_]): (Option[Tree], Tree) = {
+      val local = gensym("temp")
+      val tpe = if (clazz == classOf[Int]) Ident(newTypeName("Int"))
+        else if (clazz == classOf[String]) Select(Select(Ident(newTermName("java")), newTermName("lang")), newTypeName("String"))
+        else throw new Exception("unknown class " + clazz.toString)
+      (Some(ValDef(Modifiers(), local, tpe, value)), Ident(local))
+    }
+
+    def tree_printf(format: Tree, params: Tree*) = {
+      val Literal(Constant(s_format: String)) = format
+      val paramsStack = scala.collection.mutable.Stack(params: _*)
+      val parsed = s_format.split("(?<=%[\\w%])|(?=%[\\w%])") map {
+        case "%d" => createTempValDef(paramsStack.pop, classOf[Int])
+        case "%s" => createTempValDef(paramsStack.pop, classOf[String])
+        case "%%" => (None, Literal(Constant("%")))
+        case part => (None, Literal(Constant(part)))
+      }
+
+      val evals = for ((Some(eval), _) <- parsed if eval != None) yield eval
+      val prints = for ((_, ref) <- parsed) yield {
+        val print = Select(Select(Ident(newTermName("scala")), newTermName("Predef")), newTermName("print"))
+        Apply(print, List(ref))
+      }
+
+      Block((evals ++ prints).toList, Literal(Constant(())))
+    }
+
+    tree_printf(format, params: _*)
+  }
+}
diff --git a/test/files/macros/Test.scala b/test/files/macros/Test.scala
new file mode 100644
index 0000000000..d8cdcf6756
--- /dev/null
+++ b/test/files/macros/Test.scala
@@ -0,0 +1,8 @@
+// macros should be built separately from their clients, so simple "scalac Printf.scala Test.scala" won't work
+// 1) first build the printf macro with "scalac -Xmacros Printf.scala"
+// 2) the build this file with "scalac -cp <output directory of compiling Printf.scala> Test.scala"
+
+object Test extends App {
+  import Printf._
+  printf("hello %s", "world")
+}
\ No newline at end of file
diff --git a/test/files/macros/macros_v0001.bat b/test/files/macros/macros_v0001.bat
new file mode 100644
index 0000000000..3395d2e3c1
--- /dev/null
+++ b/test/files/macros/macros_v0001.bat
@@ -0,0 +1,40 @@
+@echo off

+

+set scalahome=%~dp0\..\..\..

+set scaladeps=%scalahome%\lib\jline.jar;%scalahome%\lib\fjbg.jar

+set scalalib=%scalahome%\build\pack\lib\scala-library.jar

+if not exist "%scalalib%" set scalalib=%scalahome%\build\locker\classes\library

+set scalacomp="%scalahome%\build\pack\lib\scala-compiler.jar"

+if not exist "%scalacomp%" set scalacomp=%scalahome%\build\locker\classes\compiler

+set stdcp=%scaladeps%;%scalalib%;%scalacomp%

+

+echo Compiling macros...

+set cp=%stdcp%

+call :scalac -Xmacros "%~dp0\Printf.scala"

+

+echo Compiling the program...

+set cp=%stdcp%;%~dp0.

+call :scalac "%~dp0\Test.scala"

+

+echo.

+echo NOW LOOK!!!

+echo ===============================================

+set cp=%stdcp%;%~dp0.

+call :scala Test

+echo.

+echo ===============================================

+goto :eof

+

+:scalac

+setlocal

+call set args=%*

+rem echo java -cp "%cp%" -Dscala.usejavacp=true scala.tools.nsc.Main %args%

+java -cp "%cp%" -Dscala.usejavacp=true scala.tools.nsc.Main %args%

+endlocal&goto :eof

+

+:scala

+setlocal

+call set args=%*

+rem echo java -cp "%cp%" -Dscala.usejavacp=true scala.tools.nsc.MainGenericRunner %args%

+java -cp "%cp%" -Dscala.usejavacp=true scala.tools.nsc.MainGenericRunner %args%

+endlocal&goto :eof

diff --git a/test/files/macros/macros_v0001.sh b/test/files/macros/macros_v0001.sh
new file mode 100644
index 0000000000..abe09836bb
--- /dev/null
+++ b/test/files/macros/macros_v0001.sh
@@ -0,0 +1,30 @@
+#!/bin/bash
+set -o errexit
+
+if [[ $(uname -s) == CYGWIN* ]]; then cpsep=";"; else cpsep=":"; fi
+scripthome="$(dirname "$0")"
+scalahome="$scripthome/../../.."
+scaladeps="$scalahome/lib/jline.jar;$scalahome/lib/fjbg.jar"
+scalalib="$scalahome/build/pack/lib/scala-library.jar"
+if [ ! -f "$scalalib" ]; then scalalib="$scalahome/build/locker/classes/library"; fi
+scalacomp="$scalahome/build/pack/lib/scala-compiler.jar"
+if [ ! -f "$scalacomp" ]; then scalacomp="$scalahome/build/locker/classes/compiler"; fi
+stdcp="$scaladeps$cpsep$scalalib$cpsep$scalacomp"
+function scalac { java -cp "$cp" -Dscala.usejavacp=true scala.tools.nsc.Main $*; }
+function scala { java -cp "$cp" -Dscala.usejavacp=true scala.tools.nsc.MainGenericRunner $*; }
+
+echo "Compiling macros..."
+cp="$stdcp"
+scalac -Xmacros "$scripthome/Printf.scala"
+
+echo "Compiling the program..."
+cp="$stdcp$cpsep$scripthome"
+scalac "$scripthome/Test.scala"
+
+echo ""
+echo "NOW LOOK"
+echo "==============================================="
+cp="$stdcp$cpsep$scripthome"
+scala Test
+echo ""
+echo "==============================================="
diff --git a/test/files/pos/macros.flags b/test/files/pos/macros.flags
index e1b37447c9..7fea2ff901 100644
--- a/test/files/pos/macros.flags
+++ b/test/files/pos/macros.flags
@@ -1 +1 @@
--Xexperimental
\ No newline at end of file
+-Xmacros
\ No newline at end of file
diff --git a/test/files/run/macro-range.check b/test/files/run/macro-range.check
new file mode 100644
index 0000000000..0719398930
--- /dev/null
+++ b/test/files/run/macro-range.check
@@ -0,0 +1,9 @@
+1
+2
+3
+4
+5
+6
+7
+8
+9
diff --git a/test/files/run/macro-range.flags b/test/files/run/macro-range.flags
new file mode 100644
index 0000000000..06a7b31f11
--- /dev/null
+++ b/test/files/run/macro-range.flags
@@ -0,0 +1 @@
+-Xmacros
diff --git a/test/files/run/macro-range/macro_range_1.scala b/test/files/run/macro-range/macro_range_1.scala
new file mode 100644
index 0000000000..15a018fcff
--- /dev/null
+++ b/test/files/run/macro-range/macro_range_1.scala
@@ -0,0 +1,94 @@
+import reflect.api.Modifier
+import reflect.macro.Context
+
+abstract class RangeDefault {
+  val from, to: Int
+  def foreach(f: Int => Unit) = {
+    var i = from
+    while (i < to) { f(i); i += 1 }
+  }
+}
+
+/** This class should go into reflect.macro once it is a bit more stable. */
+abstract class Utils {
+  val context: Context
+  import context._
+
+  class TreeSubstituter(from: List[Symbol], to: List[Tree]) extends Transformer {
+    override def transform(tree: Tree): Tree = tree match {
+      case Ident(_) =>
+        def subst(from: List[Symbol], to: List[Tree]): Tree =
+          if (from.isEmpty) tree
+          else if (tree.symbol == from.head) to.head.duplicate // TODO: does it ever make sense *not* to perform a shallowDuplicate on `to.head`?
+          else subst(from.tail, to.tail);
+        subst(from, to)
+      case _ =>
+        val tree1 = super.transform(tree)
+        if (tree1 ne tree) tree1.tpe = null
+        tree1
+    }
+  }
+  def makeApply(fn: Tree, args: List[Tree]): Tree = fn match {
+    case Function(vparams, body) => 
+      new TreeSubstituter(vparams map (_.symbol), args) transform body
+    case Block(stats, expr) =>
+      Block(stats, makeApply(expr, args))
+    case _ => 
+      println("no beta on "+fn+" "+fn.getClass)
+      Apply(fn, args)
+  }
+  def makeWhile(lname: TermName, cond: Tree, body: Tree): Tree = {
+    val continu = Apply(Ident(lname), Nil)
+    val rhs = If(cond, Block(List(body), continu), Literal(Constant()))
+    LabelDef(lname, Nil, rhs)
+  }
+  def makeBinop(left: Tree, op: String, right: Tree): Tree =
+    Apply(Select(left, newTermName(op)), List(right))
+}
+
+class Range(val from: Int, val to: Int) extends RangeDefault {
+  override def macro foreach(f: Int => Unit): Unit = {
+    println("macro-expand, _this = "+ _this) 
+    import _context._
+    object utils extends Utils {
+      val context: _context.type = _context
+    }
+    import utils._
+
+    val initName = newTermName("<init>")
+    // Either:
+    //   scala"{ var i = $low; val h = $hi; while (i < h) { $f(i); i = i + 1 } }
+    // or:
+    //   scala"($_this: RangeDefault).foreach($f)"
+    _this match {
+      case Apply(Select(New(tpt), initName), List(lo, hi)) if tpt.symbol.fullName == "Range" =>
+        val iname = newTermName("$i")
+        val hname = newTermName("$h")
+        def iref = Ident(iname)
+        def href = Ident(hname)
+        val labelname = newTermName("$while")
+        val cond = makeBinop(iref, "$less", href)
+        val body = Block(
+            List(makeApply(f, List(iref))),
+            Assign(iref, makeBinop(iref, "$plus", Literal(Constant(1)))))
+        tools.nsc.util.trace("generated: ")(
+        Block(
+          List(
+            ValDef(Modifiers(Set(Modifier.mutable)), iname, TypeTree(), lo),
+            ValDef(Modifiers(), hname, TypeTree(), hi)),
+          makeWhile(labelname, cond, body)))
+      case _ =>
+        Apply(
+          Select(
+            Typed(_this, Ident(newTypeName("RangeDefault"))),
+            newTermName("foreach")),
+          List(f))
+    }
+  }
+}
+
+object Test extends App {
+
+  new Range(1, 10) foreach println
+
+}
diff --git a/test/files/run/macro-range/macro_range_2.scala b/test/files/run/macro-range/macro_range_2.scala
new file mode 100644
index 0000000000..15a018fcff
--- /dev/null
+++ b/test/files/run/macro-range/macro_range_2.scala
@@ -0,0 +1,94 @@
+import reflect.api.Modifier
+import reflect.macro.Context
+
+abstract class RangeDefault {
+  val from, to: Int
+  def foreach(f: Int => Unit) = {
+    var i = from
+    while (i < to) { f(i); i += 1 }
+  }
+}
+
+/** This class should go into reflect.macro once it is a bit more stable. */
+abstract class Utils {
+  val context: Context
+  import context._
+
+  class TreeSubstituter(from: List[Symbol], to: List[Tree]) extends Transformer {
+    override def transform(tree: Tree): Tree = tree match {
+      case Ident(_) =>
+        def subst(from: List[Symbol], to: List[Tree]): Tree =
+          if (from.isEmpty) tree
+          else if (tree.symbol == from.head) to.head.duplicate // TODO: does it ever make sense *not* to perform a shallowDuplicate on `to.head`?
+          else subst(from.tail, to.tail);
+        subst(from, to)
+      case _ =>
+        val tree1 = super.transform(tree)
+        if (tree1 ne tree) tree1.tpe = null
+        tree1
+    }
+  }
+  def makeApply(fn: Tree, args: List[Tree]): Tree = fn match {
+    case Function(vparams, body) => 
+      new TreeSubstituter(vparams map (_.symbol), args) transform body
+    case Block(stats, expr) =>
+      Block(stats, makeApply(expr, args))
+    case _ => 
+      println("no beta on "+fn+" "+fn.getClass)
+      Apply(fn, args)
+  }
+  def makeWhile(lname: TermName, cond: Tree, body: Tree): Tree = {
+    val continu = Apply(Ident(lname), Nil)
+    val rhs = If(cond, Block(List(body), continu), Literal(Constant()))
+    LabelDef(lname, Nil, rhs)
+  }
+  def makeBinop(left: Tree, op: String, right: Tree): Tree =
+    Apply(Select(left, newTermName(op)), List(right))
+}
+
+class Range(val from: Int, val to: Int) extends RangeDefault {
+  override def macro foreach(f: Int => Unit): Unit = {
+    println("macro-expand, _this = "+ _this) 
+    import _context._
+    object utils extends Utils {
+      val context: _context.type = _context
+    }
+    import utils._
+
+    val initName = newTermName("<init>")
+    // Either:
+    //   scala"{ var i = $low; val h = $hi; while (i < h) { $f(i); i = i + 1 } }
+    // or:
+    //   scala"($_this: RangeDefault).foreach($f)"
+    _this match {
+      case Apply(Select(New(tpt), initName), List(lo, hi)) if tpt.symbol.fullName == "Range" =>
+        val iname = newTermName("$i")
+        val hname = newTermName("$h")
+        def iref = Ident(iname)
+        def href = Ident(hname)
+        val labelname = newTermName("$while")
+        val cond = makeBinop(iref, "$less", href)
+        val body = Block(
+            List(makeApply(f, List(iref))),
+            Assign(iref, makeBinop(iref, "$plus", Literal(Constant(1)))))
+        tools.nsc.util.trace("generated: ")(
+        Block(
+          List(
+            ValDef(Modifiers(Set(Modifier.mutable)), iname, TypeTree(), lo),
+            ValDef(Modifiers(), hname, TypeTree(), hi)),
+          makeWhile(labelname, cond, body)))
+      case _ =>
+        Apply(
+          Select(
+            Typed(_this, Ident(newTypeName("RangeDefault"))),
+            newTermName("foreach")),
+          List(f))
+    }
+  }
+}
+
+object Test extends App {
+
+  new Range(1, 10) foreach println
+
+}