Refactor extend statement: remove unnecessary "as" keyword and push "this" variable context to the extend-statement scope

app/src/main/kotlin/io/smnp/callable/method/CustomMethod.kt

@@ -11,7 +11,7 @@ import io.smnp.type.matcher.Matcher
 import io.smnp.type.model.Value
 
 object CustomMethod {
-    fun create(type: Matcher, objectIdentifier: String, node: FunctionDefinitionNode): Method {
+    fun create(type: Matcher, node: FunctionDefinitionNode): Method {
         val identifier = (node.identifier as IdentifierNode).token.rawValue
 
         return object : Method(type, identifier) {
@@ -23,7 +23,7 @@ object CustomMethod {
                 new method signature body { env, obj, args ->
                     val boundArguments =
                         FunctionEnvironmentProvider.provideEnvironment(argumentsNode, args, env).toMutableMap()
-                    boundArguments[objectIdentifier] = obj
+                    boundArguments["this"] = obj
 
                     try {
                         env.pushScope(boundArguments)

app/src/main/kotlin/io/smnp/dsl/ast/model/node/ExtendNode.kt

@@ -2,23 +2,18 @@ package io.smnp.dsl.ast.model.node
 
 import io.smnp.dsl.token.model.entity.TokenPosition
 
-class ExtendNode(type: Node, identifier: Node, functions: Node, position: TokenPosition) : Node(3, position) {
+class ExtendNode(type: Node, functions: Node, position: TokenPosition) : Node(2, position) {
     operator fun component1(): Node = children[0]
     operator fun component2(): Node = children[1]
-    operator fun component3(): Node = children[2]
 
     val type: Node
     get() = children[0]
 
-    val identifier: Node
-    get() = children[1]
-
     val functions: Node
-    get() = children[2]
+    get() = children[1]
 
     init {
         children[0] = type
-        children[1] = identifier
-        children[2] = functions
+        children[1] = functions
     }
 }

app/src/main/kotlin/io/smnp/dsl/ast/parser/ExtendParser.kt

@@ -8,33 +8,38 @@ import io.smnp.dsl.token.model.entity.TokenList
 import io.smnp.dsl.token.model.enumeration.TokenType
 
 class ExtendParser : Parser() {
-    override fun tryToParse(input: TokenList): ParserOutput {
-        val simpleExtendParser = allOf(
-            terminal(TokenType.EXTEND),
-            assert(SingleTypeParser(), "type to be extended"),
-            assert(terminal(TokenType.AS), "'as' keyword with identifier"),
-            assert(SimpleIdentifierParser(), "identifier"),
-            terminal(TokenType.WITH),
-            assert(mapNode(FunctionDefinitionParser()) { BlockNode(Node.NONE, listOf(it), Node.NONE) }, "method definition")
-        ) { (extendToken, targetType, identifier, method) ->
-ExtendNode(targetType, identifier, method, extendToken.position)
-        }
+   override fun tryToParse(input: TokenList): ParserOutput {
+      val simpleExtendParser = allOf(
+         terminal(TokenType.EXTEND),
+         assert(SingleTypeParser(), "type to be extended"),
+         terminal(TokenType.WITH),
+         assert(
+            mapNode(FunctionDefinitionParser()) { BlockNode(Node.NONE, listOf(it), Node.NONE) },
+            "method definition"
+         )
+      ) { (extendToken, targetType, _, method) ->
+         ExtendNode(targetType, method, extendToken.position)
+      }
 
-        val complexExtendParser = allOf(
-            terminal(TokenType.EXTEND),
-            assert(SingleTypeParser(), "type to be extended"),
-            assert(terminal(TokenType.AS), "'as' keyword with identifier"),
-            assert(SimpleIdentifierParser(), "identifier"),
-            assert(loop(terminal(TokenType.OPEN_CURLY), assert(FunctionDefinitionParser(), "method definition or }"), terminal(TokenType.CLOSE_CURLY)) {
-                begin, methods, end -> BlockNode(begin, methods, end)
-            }, "block with methods' definitions or 'with' keyword with single method definition")
-        ) { (extendToken, targetType, _, identifier, methods) ->
-            ExtendNode(targetType, identifier, methods, extendToken.position)
-        }
+      val complexExtendParser = allOf(
+         terminal(TokenType.EXTEND),
+         assert(SingleTypeParser(), "type to be extended"),
+         assert(
+            loop(
+               terminal(TokenType.OPEN_CURLY),
+               assert(FunctionDefinitionParser(), "method definition or }"),
+               terminal(TokenType.CLOSE_CURLY)
+            ) { begin, methods, end ->
+               BlockNode(begin, methods, end)
+            }, "block with methods' definitions or 'with' keyword with single method definition"
+         )
+      ) { (extendToken, targetType, methods) ->
+         ExtendNode(targetType, methods, extendToken.position)
+      }
 
-        return oneOf(
-            simpleExtendParser,
-            complexExtendParser
-        ).parse(input)
-    }
+      return oneOf(
+         simpleExtendParser,
+         complexExtendParser
+      ).parse(input)
+   }
 }

app/src/main/kotlin/io/smnp/evaluation/evaluator/ExtendEvaluator.kt

@@ -2,7 +2,10 @@ package io.smnp.evaluation.evaluator
 
 import io.smnp.callable.method.CustomMethod
 import io.smnp.callable.util.FunctionSignatureParser
-import io.smnp.dsl.ast.model.node.*
+import io.smnp.dsl.ast.model.node.ExtendNode
+import io.smnp.dsl.ast.model.node.FunctionDefinitionNode
+import io.smnp.dsl.ast.model.node.Node
+import io.smnp.dsl.ast.model.node.SingleTypeNode
 import io.smnp.environment.Environment
 import io.smnp.error.EnvironmentException
 import io.smnp.error.PositionException
@@ -13,12 +16,11 @@ class ExtendEvaluator : Evaluator() {
    override fun supportedNodes() = listOf(ExtendNode::class)
 
    override fun tryToEvaluate(node: Node, environment: Environment): EvaluatorOutput {
-      val (typeNode, identifierNode, methodsNode) = node as ExtendNode
+      val (typeNode, methodsNode) = node as ExtendNode
       val type = FunctionSignatureParser.matcherForSingleTypeNode(typeNode as SingleTypeNode)
-      val identifier = (identifierNode as IdentifierNode).token.rawValue
 
       methodsNode.children
-         .map { it to CustomMethod.create(type, identifier, it as FunctionDefinitionNode) }
+         .map { it to CustomMethod.create(type, it as FunctionDefinitionNode) }
          .forEach {
             try {
                environment.defineMethod(it.second)

modules/collection/src/main/resources/list.mus

@@ -14,7 +14,7 @@ function _flatten(list: list, output: list) {
     return output;
 }
 
-extend list as this {
+extend list {
     function flatten() {
         return flatten(this);
     }

modules/collection/src/main/resources/map.mus

@@ -1,4 +1,4 @@
-extend map as this {
+extend map {
     function containsKey(key) {
         return this.keys.contains(key);
     }

modules/music/src/main/resources/main.mus

@@ -1,4 +1,4 @@
-extend note as this {
+extend note {
     function withOctave(octave: int) {
         return Note(this.pitch, octave, this.duration.get("numerator"), this.duration.get("denominator"));
     }

modules/text/src/main/resources/main.mus

@@ -1,4 +1,4 @@
-extend string as this {
+extend string {
     function find(char: string) {
         if(char.length > 1) {
             throw "Only single character can act as a pattern to be found";