fixed problem with var initialization with val

added support for by-value types and in-place assignment

library/src/commonMain/kotlin/net/sergeych/ling/Compiler.kt

@@ -389,7 +389,9 @@ class Compiler(
             Token.Type.INT, Token.Type.REAL, Token.Type.HEX -> {
                 cc.previous()
                 val n = parseNumber(true, cc)
-                Accessor{ n.asReadonly }
+                Accessor{
+                    n.asReadonly
+                }
             }
 
             Token.Type.STRING -> Accessor { ObjString(t.value).asReadonly }
@@ -494,6 +496,8 @@ class Compiler(
             var result: Obj = ObjVoid
             while (condition.execute(it).toBool()) {
                 try {
+                    // we don't need to create new context here: if body is a block,
+                    // parse block will do it, otherwise single statement doesn't need it:
                     result = body.execute(it)
                 } catch (lbe: LoopBreakContinueException) {
                     if (lbe.label == label || lbe.label == null) {
@@ -711,6 +715,7 @@ class Compiler(
         if (nameToken.type != Token.Type.ID)
             throw ScriptError(nameToken.pos, "Expected identifier after '$kind'")
         val name = nameToken.value
+
         val eqToken = tokens.next()
         var setNull = false
         if (eqToken.type != Token.Type.ASSIGN) {
@@ -721,12 +726,18 @@ class Compiler(
                 setNull = true
             }
         }
+
         val initialExpression = if (setNull) null else parseStatement(tokens)
             ?: throw ScriptError(eqToken.pos, "Expected initializer expression")
+
         return statement(nameToken.pos) { context ->
             if (context.containsLocal(name))
                 throw ScriptError(nameToken.pos, "Variable $name is already defined")
-            val initValue = initialExpression?.execute(context) ?: ObjNull
+
+            // init value could be a val; when we init by-value type var with it, we need to
+            // create a separate copy:
+            val initValue = initialExpression?.execute(context)?.byValueCopy() ?: ObjNull
+
             context.addItem(name, mutable, initValue)
             ObjVoid
         }
@@ -843,6 +854,12 @@ class Compiler(
             Operator.simple(Token.Type.PERCENT, lastPrty) { ctx, a, b -> a.mod(ctx, b) },
         )
 
+//        private val assigner = allOps.first { it.tokenType == Token.Type.ASSIGN }
+//
+//        fun performAssignment(context: Context, left: Accessor, right: Accessor) {
+//            assigner.generate(context.pos, left, right)
+//        }
+
         val lastLevel = lastPrty + 1
 
         val byLevel: List<Map<Token.Type, Operator>> = (0..<lastLevel).map { l ->

library/src/commonMain/kotlin/net/sergeych/ling/Context.kt

@@ -57,13 +57,8 @@ class Context(
         val newFn = object : Statement() {
             override val pos: Pos = Pos.builtIn
 
-            override suspend fun execute(context: Context): Obj {
-                return try {
-                    context.fn()
-                } catch (e: Exception) {
-                    raise(e.message ?: "unexpected error")
-                }
-            }
+            override suspend fun execute(context: Context): Obj = context.fn()
+
         }
         for (name in names) {
             addItem(

library/src/commonMain/kotlin/net/sergeych/ling/Obj.kt

@@ -31,6 +31,13 @@ sealed class Obj {
     //    private val memberMutex = Mutex()
     private val parentInstances = listOf<Obj>()
 
+    /**
+     * Some objects are by-value, historically [ObjInt] and [ObjReal] are usually treated as such.
+     * When initializing a var with it, by value objects must be copied. By-reference ones aren't.
+     *
+     * Almost all objects are by-reference.
+     */
+    open fun byValueCopy(): Obj = this
 
     /**
      * Get instance member traversing the hierarchy if needed. Its meaning is different for different objects.
@@ -273,6 +280,8 @@ data class ObjReal(val value: Double) : Obj(), Numeric {
     override val toObjInt: ObjInt by lazy { ObjInt(longValue) }
     override val toObjReal: ObjReal by lazy { ObjReal(value) }
 
+    override fun byValueCopy(): Obj = ObjReal(value)
+
     override suspend fun compareTo(context: Context, other: Obj): Int {
         if (other !is Numeric) context.raiseError("cannot compare $this with $other")
         return value.compareTo(other.doubleValue)
@@ -316,6 +325,8 @@ data class ObjInt(var value: Long) : Obj(), Numeric {
     override val toObjInt get() = this
     override val toObjReal = ObjReal(doubleValue)
 
+    override fun byValueCopy(): Obj = ObjInt(value)
+
     override suspend fun getAndIncrement(context: Context): Obj {
         return ObjInt(value).also { value++ }
     }
@@ -368,6 +379,17 @@ data class ObjInt(var value: Long) : Obj(), Numeric {
             ObjInt(this.value % other.value)
         else ObjReal(this.value.toDouble() % other.toDouble())
 
+    /**
+     * We are by-value type ([byValueCopy] is implemented) so we can do in-place
+     * assignment
+     */
+    override suspend fun assign(context: Context, other: Obj): Obj? {
+        return if( other is ObjInt) {
+            value = other.value
+            this
+        } else null
+    }
+
     companion object {
         val type = ObjClass("Int")
     }

library/src/commonMain/kotlin/net/sergeych/ling/Pos.kt

@@ -2,7 +2,7 @@ package net.sergeych.ling
 
 data class Pos(val source: Source, val line: Int, val column: Int) {
     override fun toString(): String {
-        return "${source.fileName}:$line:$column"
+        return "${source.fileName}:${line+1}:${column}"
     }
 
     fun back(): Pos =

library/src/commonTest/kotlin/ScriptTest.kt

@@ -451,6 +451,62 @@ class ScriptTest {
         )
     }
 
+    @Test
+    fun testWhileBlockIsolation1() = runTest {
+        eval(
+            """
+                var x = 100
+                var cnt = 2
+                while( cnt-- > 0 ) {
+                    var x = cnt + 1
+                    assert(x == cnt + 1)
+                }
+                assert( x == 100 )
+                assert( cnt == -1 )
+            """.trimIndent()
+        )
+    }
+
+    @Test
+    fun testWhileBlockIsolation2() = runTest {
+        assertFails {
+            eval(
+                """
+                var cnt = 2
+                while( cnt-- > 0 ) {
+                    var inner = cnt + 1
+                    assert(inner == cnt + 1)
+                }
+                println("inner "+inner)
+            """.trimIndent()
+            )
+        }
+    }
+
+    @Test
+    fun testWhileBlockIsolation3() = runTest {
+            eval("""
+                var outer = 7
+                var sum = 0
+                var cnt1 = 0
+                val initialForCnt2 = 0
+                while( ++cnt1 < 3 ) {
+                    var cnt2 = initialForCnt2
+                 
+                    assert(cnt2 == 0)
+                    assert(outer == 7)
+                 
+                    while(++cnt2 < 5) {
+                        assert(initialForCnt2 == 0)
+                        var outer = 1
+                        sum = sum + outer
+                    }
+                }
+                println("sum "+sum)
+            """.trimIndent()
+            )
+    }
+
     @Test
     fun whileNonLocalBreakTest() = runTest {
         assertEquals(
@@ -459,14 +515,18 @@ class ScriptTest {
             var t1 = 10
             outer@ while( t1 > 0 ) {
                 var t2 = 10
+                println("starting t2 = " + t2)
                 while( t2 > 0 ) {
                     t2 = t2 - 1
                     println("t2 " + t2 + " t1 " + t1)
                     if( t2 == 3 && t1 == 7) {
+                        println("will break")
                         break@outer "ok2:"+t2+":"+t1
                     }
                 }
+                println("next t1")
                 t1 = t1 - 1
+                println("t1 now "+t1)
                 t1
             }
         """.trimIndent()
@@ -607,12 +667,15 @@ class ScriptTest {
     fun testAssign1() = runTest {
         assertEquals(10, eval("var x = 5; x=10; x").toInt())
         val ctx = Context()
-        ctx.eval("""
+        ctx.eval(
+            """
             var a = 1
-        """.trimIndent())
+            var b = 1
+        """.trimIndent()
+        )
         assertEquals(3, ctx.eval("a + a + 1").toInt())
-        assertEquals(12, ctx.eval("a + (a = 10) + 1").toInt())
-        assertEquals(10, ctx.eval("a").toInt())
+        assertEquals(12, ctx.eval("a + (b = 10) + 1").toInt())
+        assertEquals(10, ctx.eval("b").toInt())
     }
 
     @Test