From 158fe7596bad1684bbc9416140d99217bc29b734 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Tue, 9 Jul 2019 00:17:34 +0200
Subject: [PATCH] astvm eval of 'when'

---
 compiler/src/prog8/CompilerMain.kt   |  3 +-
 compiler/src/prog8/compiler/Main.kt  | 41 +++++++++++++++-------------
 compiler/src/prog8/vm/astvm/AstVm.kt | 17 ++++++++++++
 examples/test.p8                     |  2 +-
 4 files changed, 42 insertions(+), 21 deletions(-)

diff --git a/compiler/src/prog8/CompilerMain.kt b/compiler/src/prog8/CompilerMain.kt
index e5b272f8b..514be2d02 100644
--- a/compiler/src/prog8/CompilerMain.kt
+++ b/compiler/src/prog8/CompilerMain.kt
@@ -63,7 +63,8 @@ private fun compileMain(args: Array<String>) {
 
     val filepath = Paths.get(moduleFile).normalize()
 
-    val (programAst, programName) = compileProgram(filepath, optimize, optimizeInlining, writeVmCode, writeAssembly)
+    val (programAst, programName) = compileProgram(filepath, optimize, optimizeInlining,
+            !launchAstVm, writeVmCode, writeAssembly)
 
     if(launchAstVm) {
         println("\nLaunching AST-based vm...")
diff --git a/compiler/src/prog8/compiler/Main.kt b/compiler/src/prog8/compiler/Main.kt
index 193a537a6..2371dab64 100644
--- a/compiler/src/prog8/compiler/Main.kt
+++ b/compiler/src/prog8/compiler/Main.kt
@@ -24,7 +24,8 @@ import kotlin.system.measureTimeMillis
 
 fun compileProgram(filepath: Path,
                    optimize: Boolean, optimizeInlining: Boolean,
-                   writeVmCode: Boolean, writeAssembly: Boolean): Pair<Program, String?> {
+                   generateVmCode: Boolean, writeVmCode: Boolean,
+                   writeAssembly: Boolean): Pair<Program, String?> {
     lateinit var programAst: Program
     var programName: String? = null
 
@@ -89,26 +90,28 @@ fun compileProgram(filepath: Path,
             // printAst(programAst)
             // namespace.debugPrint()
 
-            // compile the syntax tree into stackvmProg form, and optimize that
-            val compiler = Compiler(programAst)
-            val intermediate = compiler.compile(compilerOptions)
-            if (optimize)
-                intermediate.optimize()
+            if(generateVmCode) {
+                // compile the syntax tree into stackvmProg form, and optimize that
+                val compiler = Compiler(programAst)
+                val intermediate = compiler.compile(compilerOptions)
+                if (optimize)
+                    intermediate.optimize()
 
-            if (writeVmCode) {
-                val stackVmFilename = intermediate.name + ".vm.txt"
-                val stackvmFile = PrintStream(File(stackVmFilename), "utf-8")
-                intermediate.writeCode(stackvmFile)
-                stackvmFile.close()
-                println("StackVM program code written to '$stackVmFilename'")
-            }
+                if (writeVmCode) {
+                    val stackVmFilename = intermediate.name + ".vm.txt"
+                    val stackvmFile = PrintStream(File(stackVmFilename), "utf-8")
+                    intermediate.writeCode(stackvmFile)
+                    stackvmFile.close()
+                    println("StackVM program code written to '$stackVmFilename'")
+                }
 
-            if (writeAssembly) {
-                val zeropage = C64Zeropage(compilerOptions)
-                intermediate.allocateZeropage(zeropage)
-                val assembly = AsmGen(compilerOptions, intermediate, programAst.heap, zeropage).compileToAssembly(optimize)
-                assembly.assemble(compilerOptions)
-                programName = assembly.name
+                if (writeAssembly) {
+                    val zeropage = C64Zeropage(compilerOptions)
+                    intermediate.allocateZeropage(zeropage)
+                    val assembly = AsmGen(compilerOptions, intermediate, programAst.heap, zeropage).compileToAssembly(optimize)
+                    assembly.assemble(compilerOptions)
+                    programName = assembly.name
+                }
             }
         }
         println("\nTotal compilation+assemble time: ${totalTime / 1000.0} sec.")
diff --git a/compiler/src/prog8/vm/astvm/AstVm.kt b/compiler/src/prog8/vm/astvm/AstVm.kt
index 872040741..ecc030dde 100644
--- a/compiler/src/prog8/vm/astvm/AstVm.kt
+++ b/compiler/src/prog8/vm/astvm/AstVm.kt
@@ -442,6 +442,23 @@ class AstVm(val program: Program) {
                     }
                 } while (!condition.asBoolean)
             }
+            is WhenStatement -> {
+                val condition=evaluate(stmt.condition, evalCtx)
+                for(choice in stmt.choices) {
+                    if(choice.value==null) {
+                        // the 'else' choice
+                        executeAnonymousScope(choice.statements)
+                        break
+                    } else {
+                        val value = choice.value.constValue(evalCtx.program) ?: throw VmExecutionException("can only use const values in when choices ${choice.position}")
+                        val rtval = RuntimeValue.from(value, evalCtx.program.heap)
+                        if(condition==rtval) {
+                            executeAnonymousScope(choice.statements)
+                            break
+                        }
+                    }
+                }
+            }
             else -> {
                 TODO("implement $stmt")
             }
diff --git a/examples/test.p8 b/examples/test.p8
index b6f51767f..8a2d6c09e 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -16,8 +16,8 @@
             4 -> {
                 Y=7
             }
-            5 -> Y=5
             else -> A=99
+            5 -> Y=5        ; @todo error; else already seen
         }
     }