refs #35 Buffer is not mutable, MutableBuffer added (to cache in serialized form)

docs/Buffer.md

@@ -1,7 +1,8 @@
 # Binary `Buffer`
 
 Buffers are effective unsigned byte arrays of fixed size. Buffers content is mutable,
-unlike its size. Buffers are comparable and implement [Array], thus [Collection] and [Iterable]. Buffer iterators return its contents as unsigned bytes converted to `Int`
+unlike its size. Buffers are comparable and implement [Array], thus [Collection] and [Iterable]. Buffer iterators return
+its contents as unsigned bytes converted to `Int`
 
 Buffers needs to be imported with `import lyng.buffer`:
 
@@ -10,6 +11,8 @@ Buffers needs to be imported with `import lyng.buffer`:
     assertEquals(5, Buffer("Hello").size)
     >>> void
 
+Buffer is _immutable_, there is a `MutableBuffer` with same interface but mutable.
+
 ## Constructing
 
 There are a lo of ways to construct a buffer:
@@ -36,15 +39,23 @@ There are a lo of ways to construct a buffer:
 
     >>> void
 
-## Accessing an modifying
+## Accessing and modifying
 
-Buffer implement [Array] and therefore can be accessed and modified with indexing:
+Buffer implement [Array] and therefore can be accessed, and `MutableBuffers` also modified:
 
     import lyng.buffer
     val b1 = Buffer( 1, 2, 3)
     assertEquals( 2, b1[1] )
-    b1[0] = 199
-    assertEquals(199, b1[0])
+
+    val b2 = b1.toMutable()
+    assertEquals( 2, b1[1] )
+    b2[1]++
+    b2[0] = 100
+    assertEquals( Buffer(100, 3, 3), b2)
+
+    // b2 is a mutable copy so b1 has not been changed:
+    assertEquals( Buffer(1, 2, 3), b1)
+
     >>> void
 
 Buffer provides concatenation with another Buffer:
@@ -58,12 +69,12 @@ Please note that indexed bytes are _readonly projection_, e.g. you can't modify
 
 ## Comparing
 
-Buffers are comparable with other buffers:
+Buffers are comparable with other buffers (and notice there are _mutable_ buffers, bu default buffers ar _immutable_):
 
     import lyng.buffer
     val b1 = Buffer(1, 2, 3)
     val b2 = Buffer(1, 2, 3)
-    val b3 = Buffer(b2)
+    val b3 = MutableBuffer(b2)
     
     b3[0] = 101
 
@@ -94,19 +105,17 @@ As with [List], it is possible to use ranges as indexes to slice a Buffer:
 ## Members
 
 | name          | meaning                            | type          |
-|---------------------|--------------------------------------|-------|
+|---------------|------------------------------------|---------------|
 | `size`        | size                               | Int           |
-| `+=`                | add one or more elements             | Any   |
-| `+`, `union`         | union sets                           | Any   |
-| `-`, `subtract`     | subtract sets                        | Any   |
-| `*`, `intersect`    | subtract sets                        | Any   |
-| `remove(items...)`  | remove one or more items             | Range |
-| `contains(element)` | check the element is in the list (1) |       |
+| `decodeUtf8`  | decodee to String using UTF8 rules | Any           |
+| `+`           | buffer concatenation               | Any           |
+| `toMutable()` | create a mutable copy              | MutableBuffer |
 
 (1)
 : optimized implementation that override `Iterable` one
 
-Also, it inherits methods from [Iterable].
+Also, it inherits methods from [Iterable] and [Array].
 
 
 [Range]: Range.md
+[Iterable]: Iterable.md

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Scope.kt

@@ -82,6 +82,11 @@ open class Scope(
         }
     }
 
+    fun requireNoArgs() {
+        if( args.list.isNotEmpty())
+            raiseError("This function does not accept any arguments")
+    }
+
     inline fun <reified T : Obj> thisAs(): T = (thisObj as? T)
         ?: raiseClassCastError("Cannot cast ${thisObj.objClass.className} to ${T::class.simpleName}")
 

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Script.kt

@@ -179,6 +179,7 @@ class Script(
             ImportManager(rootScope, SecurityManager.allowAll).apply {
                 addPackage("lyng.buffer") {
                     it.addConst("Buffer", ObjBuffer.type)
+                    it.addConst("MutableBuffer", ObjMutableBuffer.type)
                 }
                 addPackage("lyng.time") {
                     it.addConst("Instant", ObjInstant.type)

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjBuffer.kt

@@ -6,7 +6,7 @@ import net.sergeych.lyng.Scope
 import net.sergeych.lyng.statement
 import kotlin.math.min
 
-class ObjBuffer(val byteArray: UByteArray) : Obj() {
+open class ObjBuffer(val byteArray: UByteArray) : Obj() {
 
     override val objClass: ObjClass = type
 
@@ -30,16 +30,6 @@ class ObjBuffer(val byteArray: UByteArray) : Obj() {
         } else ObjInt(byteArray[checkIndex(scope, index)].toLong(), true)
     }
 
-    override suspend fun putAt(scope: Scope, index: Obj, newValue: Obj) {
-        byteArray[checkIndex(scope, index.toObj())] = when (newValue) {
-            is ObjInt -> newValue.value.toUByte()
-            is ObjChar -> newValue.value.code.toUByte()
-            else -> scope.raiseIllegalArgument(
-                "invalid byte value for buffer at index ${index.inspect()}: ${newValue.inspect()}"
-            )
-        }
-    }
-
     val size by byteArray::size
 
     override fun hashCode(): Int {
@@ -144,18 +134,10 @@ class ObjBuffer(val byteArray: UByteArray) : Obj() {
                     thisAs<ObjBuffer>().byteArray.toByteArray().decodeToString()
                 )
             }
-//            )
-//            addFn("getAt") {
-//                requireExactCount(1)
-//                thisAs<ObjList>().getAt(this, requiredArg<Obj>(0))
-//            }
-//            addFn("putAt") {
-//                requireExactCount(2)
-//                val newValue = args[1]
-//                thisAs<ObjList>().putAt(this, requiredArg<ObjInt>(0).value.toInt(), newValue)
-//                newValue
-//            }
-
+            addFn("toMutable") {
+                requireNoArgs()
+                ObjMutableBuffer(thisAs<ObjBuffer>().byteArray.copyOf())
+            }
         }
     }
 }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjMutableBuffer.kt

@@ -0,0 +1,71 @@
+package net.sergeych.lyng.obj
+
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.toList
+import net.sergeych.lyng.Scope
+
+class ObjMutableBuffer(byteArray: UByteArray) : ObjBuffer(byteArray) {
+
+    override suspend fun putAt(scope: Scope, index: Obj, newValue: Obj) {
+        byteArray[checkIndex(scope, index.toObj())] = when (newValue) {
+            is ObjInt -> newValue.value.toUByte()
+            is ObjChar -> newValue.value.code.toUByte()
+            else -> scope.raiseIllegalArgument(
+                "invalid byte value for buffer at index ${index.inspect()}: ${newValue.inspect()}"
+            )
+        }
+    }
+
+    companion object {
+
+        private suspend fun createBufferFrom(scope: Scope, obj: Obj): ObjBuffer =
+            when (obj) {
+                is ObjBuffer -> ObjMutableBuffer(obj.byteArray.copyOf())
+                is ObjInt -> {
+                    if (obj.value < 0)
+                        scope.raiseIllegalArgument("buffer size must be positive")
+                    val data = UByteArray(obj.value.toInt())
+                    ObjMutableBuffer(data)
+                }
+
+                is ObjString -> ObjMutableBuffer(obj.value.encodeToByteArray().asUByteArray())
+                else -> {
+                    if (obj.isInstanceOf(ObjIterable)) {
+                        ObjMutableBuffer(
+                            obj.toFlow(scope).map { it.toLong().toUByte() }.toList().toTypedArray()
+                                .toUByteArray()
+                        )
+                    } else
+                        scope.raiseIllegalArgument(
+                            "can't construct buffer from ${obj.inspect()}"
+                        )
+                }
+            }
+
+        val type = object : ObjClass("MutableBuffer", ObjBuffer.type) {
+            override suspend fun callOn(scope: Scope): Obj {
+                val args = scope.args.list
+                return when (args.size) {
+                    // empty buffer
+                    0 -> ObjMutableBuffer(ubyteArrayOf())
+                    1 -> createBufferFrom(scope, args[0])
+                    else -> {
+                        // create buffer from array, each argument should be a byte then:
+                        val data = UByteArray(args.size)
+                        for ((i, b) in args.withIndex()) {
+                            val code = when (b) {
+                                is ObjChar -> b.value.code.toUByte()
+                                is ObjInt -> b.value.toUByte()
+                                else -> scope.raiseIllegalArgument(
+                                    "invalid byte value for buffer constructor at index $i: ${b.inspect()}"
+                                )
+                            }
+                            data[i] = code
+                        }
+                        ObjMutableBuffer(data)
+                    }
+                }
+            }
+        }
+    }
+}

lynglib/src/commonTest/kotlin/ScriptTest.kt

@@ -2477,12 +2477,14 @@ class ScriptTest {
             assertEquals( 3, Buffer(1, 2, 3).size )
             assertEquals( 5, Buffer("hello").size )
             
-            val buffer = Buffer("Hello")
+            var buffer = Buffer("Hello")
             assertEquals( 5, buffer.size)
             assertEquals('l'.code, buffer[2] )
             assertEquals('l'.code, buffer[3] )
             assertEquals("Hello", buffer.decodeUtf8())
             
+            buffer = buffer.toMutable()
+            
             buffer[2] = 101
             assertEquals(101, buffer[2])
             assertEquals("Heelo", buffer.decodeUtf8())
@@ -2503,6 +2505,12 @@ class ScriptTest {
             val b3 = b1 + Buffer("!")
             assertEquals( "Hello!", b3.decodeUtf8())
             assert( b3 > b1 )
+            assert( b1 !== b2)
+            
+            val map = Map( b1 => "foo")
+            assertEquals("foo",  map[b1])
+            assertEquals("foo",  map[b2])
+            assertEquals(null,  map[b3])
             
         """.trimIndent())
     }
@@ -2615,7 +2623,7 @@ class ScriptTest {
         
         import lyng.buffer
         
-        val b = Buffer(1,2,3)
+        val b = MutableBuffer(1,2,3)
         b[1]++
         assert( b == Buffer(1,3,3) )
         ++b[0]
@@ -2633,7 +2641,7 @@ class ScriptTest {
         
         import lyng.buffer
         
-        val b = Buffer(1,2,3)
+        val b = Buffer(1,2,3).toMutable()
         b[1]--
         assert( b == Buffer(1,1,3) )
         --b[0]