Add dollar syntax for decimal operators, disallow identifiers ending in a dollar sign.

docs/lang/operators.md

@@ -41,6 +41,12 @@ Note that you cannot mix `+'` and `-'` with `+` and `-`.
 Certain operators (`/`, `%%`, `<<`, `>>`, `<<'`, `>>'`, `>>>>`, `:`, `!=`) cannot have more than 2 parameters,
 i.e. `x / y / z` will not compile.
 
+The decimal operators have two different forms:
+
+* apostrophe form (e.g. `+'`) – the original one, to be deprecated in the future, may be removed in Millfork 0.4
+
+* dollar form (e.g. `$+`) – available since Millfork 0.3.22
+
 ## Argument types
 
 In the descriptions below, arguments to the operators are explained as follows:
@@ -130,15 +136,18 @@ These operators work using the decimal arithmetic (packed BCD).
 On Ricoh-based targets (e.g. Famicom) they require the zeropage register to have size at least 4
 
 * `+'`, `-'`: decimal addition/subtraction  
+`$+`, `$-` (since Millfork 0.3.22)  
 `byte +' byte`  
 `constant word +' constant word`  
 `constant long +' constant long`  
 `word +' word` (zpreg)
 
 * `*'`: decimal multiplication  
+`$*` (since Millfork 0.3.22)  
 `constant *' constant`
 
 * `<<'`, `>>'`: decimal multiplication/division by power of two  
+`$<<`, `$>>` (since Millfork 0.3.22)  
 `byte <<' constant byte`
 
 ## Comparison operators
@@ -193,6 +202,7 @@ An expression of form `a[f()] += b` may call `f` an undefined number of times.
 `mutable long = long`
 
 * `+=`, `+'=`, `|=`, `^=`, `&=`: modification in place  
+`$+=` (since Millfork 0.3.22)   
 `mutable byte += byte`  
 `mutable word += word`  
 `mutable trivial long += long`
@@ -203,11 +213,13 @@ An expression of form `a[f()] += b` may call `f` an undefined number of times.
 `mutable trivial long <<= byte`
 
 * `<<'=`, `>>'=`: decimal shift in place  
+`$<<=`, `$>>=` (since Millfork 0.3.22)  
 `mutable byte <<'= constant byte`  
 `mutable word <<'= constant byte`  
 `mutable trivial long <<'= constant byte`
 
 * `-=`, `-'=`: subtraction in place  
+`$-=` (since Millfork 0.3.22)  
 `mutable byte -= byte`  
 `mutable word -= simple word`  
 `mutable trivial long -= simple long`
@@ -219,6 +231,7 @@ An expression of form `a[f()] += b` may call `f` an undefined number of times.
 `mutable word *= word` (zpreg)
 
 * `*'=`: decimal multiplication in place  
+`$*=` (since Millfork 0.3.22)  
 `mutable byte *'= constant byte`
 
 * `/=`, `%%=`: unsigned division and modulo in place  

docs/lang/syntax.md

@@ -13,6 +13,26 @@ Allowed line endings are U+000A, U+000D and U+000D/U+000A.
 Outside of text strings and comments, the only allowed characters are U+0009 and U+0020–U+007E
 (so-called printable ASCII).
 
+## Valid identifiers
+
+Identifiers are used for variable names, function names, array names, segment names.
+
+Identifiers have to start with a letter or an underscore, and they can contain letters, underscores, digits and dollar signs.
+
+An identifier cannot end with a dollar sign, nor can it contain two consecutive dollar signs. 
+
+Identifiers using dollar signs are reserved for internal use, do not use them without a good reason.
+
+There is no hard limit on the identifier length.
+
+    a     // valid
+    1a    // invalid
+    a1    // valid
+    _1    // valid
+    a$1   // valid, but discouraged
+    a$$a  // invalid
+    a$    // invalid
+
 ## Comments
 
 Comments start with `//` and last until the end of line.

src/main/scala/millfork/parser/MfParser.scala

@@ -435,7 +435,7 @@ abstract class MfParser[T](fileId: String, input: String, currentDirectory: Stri
       for {
         minus <- ("-".rep(min = 1).!.map(_.length().&(1).==(1)) ~/ HWS).?.map(_.getOrElse(false))
         head <- tightMfExpression(allowIntelHex, allowTopLevelIndexing) ~/ HWS
-        maybeOperator <- (StringIn(allowedOperators: _*).! ~ !CharIn(Seq('/', '=', '-', '+', ':', '>', '<', '\''))).?
+        maybeOperator <- (StringIn(allowedOperators: _*).! ~ !CharIn(Seq('/', '=', '-', '+', ':', '>', '<', '\''))).map(op => if (mfOperatorNormalizations.contains(op)) mfOperatorNormalizations(op) else op).?
         maybeTail <- maybeOperator.fold[P[Option[List[(String, (Boolean, Expression))]]]](Pass.map(_ => None))(o => (AWS ~/ inner ~/ HWS).map(x2 => Some((o -> x2.head) :: x2.tail)))
       } yield {
         maybeTail.fold[SeparatedList[(Boolean, Expression), String]](SeparatedList.of(minus -> head))(t => SeparatedList(minus -> head, t))
@@ -799,9 +799,12 @@ object MfParser {
 
   val letterOrDigit: P[Unit] = P(CharIn("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_.$1234567890"))
 
-  val lettersOrDigits: P[String] = P(CharsWhileIn("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_.$1234567890", min = 0).!)
+  val realLetterOrDigit: P[Unit] = P(CharIn("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_.1234567890"))
 
-  val identifier: P[String] = P((letter ~ lettersOrDigits).map { case (a, b) => a + b }).opaque("<identifier>")
+  val identifierTail: P[String] =
+    CharsWhileIn("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_.1234567890", min = 1).rep(min = 1, sep = "$").!
+
+  val identifier: P[String] = (letter ~ ("$".? ~ identifierTail).?).!.opaque("<identifier>")
 
   val doubleQuotedString: P[String] = P("\"" ~/ CharsWhile(c => c != '\"' && c != '\n' && c != '\r').?.! ~ "\"")
 
@@ -895,13 +898,26 @@ object MfParser {
     }
 
   val mfOperators = List(
-    List("+=", "-=", "+'=", "-'=", "^=", "&=", "|=", "*=", "*'=", "<<=", ">>=", "<<'=", ">>'=", "/=", "%%=", "="),
+    List("+=", "-=", "+'=", "-'=", "^=", "&=", "|=", "*=", "*'=", "<<=", ">>=", "<<'=", ">>'=", "/=", "%%=", "=", "$*=", "$+=", "$-=", "$<<=", "$>>="),
     List("||", "^^"),
     List("&&"),
     List("==", "<=", ">=", "!=", "<", ">"),
     List(":"),
-    List("+'", "-'", "<<'", ">>'", ">>>>", "+", "-", "&", "|", "^", "<<", ">>"),
+    List("+'", "-'", "<<'", ">>'", ">>>>", "+", "-", "&", "|", "^", "<<", ">>", "$+", "$-", "$<<", "$>>"),
-    List("*'", "*", "/", "%%"))
+    List("*'", "$*", "*", "/", "%%"))
+
+  val mfOperatorNormalizations = Map(
+    "$+" -> "+'",
+    "$-" -> "-'",
+    "$+=" -> "+'=",
+    "$-=" -> "-'=",
+    "$<<" -> "<<'",
+    "$>>" -> ">>'",
+    "$<<=" -> "<<'=",
+    "$>>=" -> ">>'=",
+    "$*" -> "*'",
+    "$*=" -> "*'=",
+  )
 
   val mfOperatorsDropFlatten: IndexedSeq[List[String]] = mfOperators.indices.map(i => mfOperators.drop(i).flatten)
 

src/test/scala/millfork/test/ByteDecimalMathSuite.scala

@@ -16,7 +16,7 @@ class ByteDecimalMathSuite extends FunSuite with Matchers with AppendedClues {
         | byte a
         | void main () {
         |  a = $36
-        |  output = a +' a
+        |  output = a $+ a
         | }
       """.stripMargin)(_.readByte(0xc000) should equal(0x72))
   }
@@ -28,7 +28,7 @@ class ByteDecimalMathSuite extends FunSuite with Matchers with AppendedClues {
         | byte a
         | void main () {
         |  a = 1
-        |  output = a +' $69
+        |  output = a$+$69
         | }
       """.stripMargin)(_.readByte(0xc000) should equal(0x70))
   }

src/test/scala/millfork/test/ParserSuite.scala

@@ -1,7 +1,7 @@
 package millfork.test
 
 import millfork.Cpu
-import millfork.test.emu.{EmuUnoptimizedCrossPlatformRun, ShouldNotCompile, ShouldNotParse}
+import millfork.test.emu.{EmuUnoptimizedCrossPlatformRun, EmuUnoptimizedRun, ShouldNotCompile, ShouldNotParse}
 import org.scalatest.{FunSuite, Matchers}
 
 /**
@@ -60,4 +60,30 @@ class ParserSuite extends FunSuite with Matchers  {
         |const array a = ‟aa"
         |""".stripMargin)
   }
+
+  test("Various valid identifiers") {
+    // yes, this spews warnings.
+    // I'll deal with them later.
+    EmuUnoptimizedRun(
+      """
+        |byte a
+        |byte a$a
+        |byte a.$a
+        |byte a.a
+        |byte a.$a
+        |byte a$a$a
+        |byte a$.$a
+        |byte a...
+        |void main(){
+        |  a += 0
+        |  a$a += 0
+        |  a.$a += 0
+        |  a.a += 0
+        |  a.$a += 0
+        |  a$a$a += 0
+        |  a$.$a += 0
+        |  a... += 0
+        |}
+        |""".stripMargin)
+  }
 }

src/test/scala/millfork/test/emu/EmuI86Run.scala

@@ -162,7 +162,7 @@ class EmuI86Run(nodeOptimizations: List[NodeOptimization], assemblyOptimizations
         }
 
         (0x100 until 0x2000).takeWhile(memoryBank.occupied(_)).map(memoryBank.output).grouped(16).map(_.map(i => f"$i%02x").mkString(" ")).foreach(log.debug(_))
-        val resetN = source.contains("-'") && !options.flag(CompilationFlag.EmitExtended80Opcodes)
+        val resetN = (source.contains("-'") || source.contains("$-")) && !options.flag(CompilationFlag.EmitExtended80Opcodes)
         val resetNMethod = {
           val clazz = classOf[Z80Core]
           val method = clazz.getDeclaredMethod("resetN")

src/test/scala/millfork/test/emu/EmuRun.scala

@@ -214,7 +214,17 @@ class EmuRun(cpu: millfork.Cpu.Value, nodeOptimizations: List[NodeOptimization],
               }
             case _ =>
           }
-          if(!options.flag(CompilationFlag.DecimalMode) && (source.contains("+'") || source.contains("-'") || source.contains("<<'") || source.contains("*'")))
+          if(!options.flag(CompilationFlag.DecimalMode) && (
+            source.contains("+'") ||
+              source.contains("-'") ||
+              source.contains("<<'") ||
+              source.contains(">>'") ||
+              source.contains("*'") ||
+              source.contains("$+") ||
+              source.contains("$-") ||
+              source.contains("$<<") ||
+              source.contains("$>>") ||
+              source.contains("$*")))
             tmp += EmuRun.cachedBcd
           tmp
         }