parameter list as double linked list (work in progress)

2 files changed, 63 insertions, 29 deletions

diff --git a/ecomp-c/ec.c b/ecomp-c/ec.c
index 3c0d0f6..c32865a 100644
--- a/ecomp-c/ec.c
+++ b/ecomp-c/ec.c
@@ -866,7 +866,7 @@ typedef enum ExpressionNodeType {
 typedef struct ExpressionNode {
 	ExpressionNodeType type;
 	S_Symbol op;
-	struct ExpressionNode *left, *right, *next;
+	struct ExpressionNode *left, *right, *next, *prev;
 	int integer_value;
 	int boolean_value;
 	char character_value;
@@ -876,12 +876,18 @@ typedef struct ExpressionNode {
 	Symbol *actual_type;
 } ExpressionNode;
 
+typedef struct ExpressionNodeList {
+	ExpressionNode *head;
+	ExpressionNode *tail;
+} ExpressionNodeList;
+
 static ExpressionNode *create_expression_node( void )
 {
 	ExpressionNode *node = Allocate( sizeof( ExpressionNode ) );
 	node->left = NULL;
 	node->right = NULL;
 	node->next = NULL;
+	node->prev = NULL;
 	node->string_value = NULL;
 	node->intarr_value = NULL;
 	
@@ -899,6 +905,7 @@ static void free_expression_node( ExpressionNode *node )
 	if( node->next != NULL ) {
 		free_expression_node( node->next );
 	}
+	/* do not free node->prev! double linked list */
 	if( node->string_value != NULL ) {
 		free( node->string_value );
 	}
@@ -1582,29 +1589,54 @@ static void parseWhileStatement( Scope *scope )
 	free( jump_label1 );
 }
 
-static ExpressionNode *parseParameterList( Scope *scope )
+static void parseParameterList( Scope *scope, ExpressionNodeList *list )
 {
-	ExpressionNode *head, *tail, *node;
-	
+	ExpressionNode *node;
+/*
+ * function insertBefore(List list, Node node, Node newNode)
+    newNode.next  := node
+    if node.prev == null
+        newNode.prev  := null -- (not always necessary)
+        list.firstNode  := newNode
+    else
+        newNode.prev  := node.prev
+        node.prev.next  := newNode
+    node.prev  := newNode
+
+We also need a function to insert a node at the beginning of a possibly empty list:
+
+function insertBeginning(List list, Node newNode)
+    if list.firstNode == null
+        list.firstNode  := newNode
+        list.lastNode   := newNode
+        newNode.prev  := null
+        newNode.next  := null
+    else
+        insertBefore(list, list.firstNode, newNode)
+*/	
 	Expect( S_lparen );
-	head = NULL;
-	tail = NULL;
+	list->head = NULL;
+	list->tail = NULL;
 	do {
 		node = parseExpression( scope );
-		if( head == NULL && tail == NULL ) {
-			head = node;
-			tail = node;
+		if( list->head == NULL && list->tail == NULL ) {
+			list->head = node;
+			list->tail = node;
 		} else {
-			node->next = head;
-			head = node;
-		}
+			node->next = list->head;
+			if( list->head->prev == NULL ) {
+				list->head = node;
+			} else {
+				node->prev = list->head->prev;
+				list->head->prev->next = node;
+			}
+			list->head->prev = node;
+		}		
 		if( sym == S_comma ) {
 			sym = getSym( );
 		}
 	} while( sym != S_rparen );
 	Expect( S_rparen );
-	
-	return node;
 }
 
 static void parseProcedureCall( Scope *scope )
@@ -1612,7 +1644,8 @@ static void parseProcedureCall( Scope *scope )
 	Symbol *symbol, *param;
 	int nof_expected_params;
 	int nof_actual_params;
-	ExpressionNode *head, *node;
+	ExpressionNode *node;
+	ExpressionNodeList list;
 
 	symbol = get_symbol( scope, ident );
 	
@@ -1624,11 +1657,10 @@ static void parseProcedureCall( Scope *scope )
 	}
 
 	nof_actual_params = 0;
-	head = NULL;
 	if( sym == S_lparen ) {		
-		head = parseParameterList( scope );
+		parseParameterList( scope, &list );
 
-		node = head;
+		node = list.head;
 		while( node != NULL ) {
 			nof_actual_params++;
 			node = node->next;
@@ -1642,14 +1674,14 @@ static void parseProcedureCall( Scope *scope )
 	
 	/* check types */
 	if( nof_expected_params > 0 ) {
-		node = head;
+		node = list.tail;
 		param = symbol->param;
 		while( param != NULL ) {
 			if( !is_compatible_type( node->actual_type, param->type ) ) {
 				Abort( "Incompatible parameter type for parameter '%s' in procedure '%s', expecting type '%s', got '%s'",
 					param->name, symbol->name, param->type->name, node->actual_type->name );
 			}
-			node = node->next;
+			node = node->prev;
 			param = param->next;
 		}
 	}
@@ -1658,7 +1690,7 @@ static void parseProcedureCall( Scope *scope )
 	Emit( "; CALL %s", symbol->label );
 	if( nof_actual_params > 0 ) {
 		Emit( "( " );
-		node = head;
+		node = list.head;
 		while( node != NULL ) {
 			generate_expression_comment( node );
 			node = node->next;
@@ -1669,13 +1701,13 @@ static void parseProcedureCall( Scope *scope )
 
 	/* emit assembly to push parameters onto stack and call procedure */
 	if( nof_actual_params > 0 ) {
-		node = head;
+		node = list.head;
 		while( node != NULL ) {
 			emit_expression_code( node, scope );
 			node = node->next;
 		}	
 
-		free_expression_node( head );
+		free_expression_node( list.head );
 
 	}
 	Emit( "call %s\n", symbol->label );
diff --git a/ecomp-c/test1.e b/ecomp-c/test1.e
index 0dfad07..907e595 100644
--- a/ecomp-c/test1.e
+++ b/ecomp-c/test1.e
@@ -32,7 +32,7 @@ var
 	s2 : array 10 of character := "hello";
 	a1 : array 10 of integer;
 
-procedure B( n : integer, m : integer );
+procedure B( n : integer, m : integer, f : boolean );
 
 procedure A;
 const
@@ -44,16 +44,18 @@ var
 begin
 	a1[5] := 43;
 	s[0] := 'L';
-	B( a1[5], 7 );
+	B( a1[5], 7, true );
 end
 
-procedure B( n : integer, m : integer );
+procedure B( n : integer, m : integer, f : boolean );
 var
 	x : integer;
 	
 begin
-	x := n + m;
-	a1[4] := x;
+	if( f ) {
+		x := n + m;
+		a1[4] := x;
+	}
 end
 
 begin
@@ -98,5 +100,5 @@ begin
 	a1[3] := 42;
 	s2[a1[2]] := 'Z';
 	A;
-	B( 1, 2 );
+	B( 1, 2, false );
 end